Fo_Cuss

Big Update - Lots to talk about... With Crimbo fast approaching, and my son back for the hols ... a field trip was planned. There was no chance of completing the big upgrade ... and anyway, I was (and am) still in learning mode. Consequently, the objective was to continue upgrading the starter scope, and learn what needed to be learn't. Flocking - Black 3.0 It doesn't provide the required light absorption. I'm so pleased that I didn't buy the flocking material. If I had, I would have never tested Black 3.0 It's not that Black 3.0 is bad ... it's an extremely matt black paint. The problem is that, in a tube, the photons hit like Barnes Wallace's bouncing bomb. ... they skim the surface, rather than being absorbed; and the tube lights up and dazzles. Having said that ... I watched a video of someone flocking their scope, using a torch to see how the flocking was laying. All the fibre tips lit up like a Christmas tree. The big lesson was : Use baffles. In this way, the photons might bounce, but most of them will collide directly with a black wall (and be absorbed). Flocking will be used, but in conjunction with baffles, that follow the cone of light (like multiple field stops). Prior to the field trip, I fitted two baffles. One masking the focus tube assembly; the other being placed 90 mm up the scope, towards the objective lens. At 25 mm diameter, it was smaller than the focus tube internal diameter. It made a big reduction to the reflected light. Tripod ... was completely re-engineered. Each element was drilled, and computer screws (for add in PCI cards) were used to form new threads. They are ideal ... not self tappers, not machine screws ... between the two. With care, and lubrication; in a 2.5mm hole, they will roll a female thread ... which is very strong, allowing decent torque to be applied. The central tray, that doubles as the rigid coss member (though it was nowhere near rigid). ... was made rigid, with two screws and repair washers for each arm. The original top leg clamps were rubbish ... being slotted, it was impossible to clamp the tripod rigid. Tube spacers were cut, and placed between each slot. The wing nuts were replaced by large repair washers and nylon lock nuts. (Note the O ring - to be referenced below) The tripod is now as rigid as any tripod. Azimuth Mount This was stripped for re-re-engineering 😎 This time I created a stand-alone bearing assembly, to join the mount to the tripod. The central shaft from the mount is a hollow cylinder, enabling the creation of an internal bearing surface, using an O ring as the central bearing element. The face indicated by my nail, bears on the O ring (image in tripod section). The threaded rod pulls the azimuth mount face, down onto the tripod face, and pulls up the bearing assembly onto the O ring, whilst inserting the central O ring into the azimuth mount hollow spindle ... the threaded rod being adjusted so that it binds into the blind threaded hole in the azimuth mount. Phew! If that sounds complicated ... it was. ... but it was well worth the effort, to gain a perfect 'pan' mechanism for the scope ✌️ The outside of the shaft was shimmed using a wafer thin Herring can 'pull lid'. The lower internal end of the shaft bears on a second O ring The top face of the tripod, and lower face of the mount, were lapped together using grinding paste. Ideally a shim is required ... I used a circlip as a temporary shim. The mount can now be clamped up tight, whilst it can be turned without any judder, and it stays where you leave it. Focus Tube Assembly Without any PTFE sheet, I turned once again, to electrical tape, to shim-bush the focus tube. It is now effectively, an interference fit ... there is no play between the focus tube, and the focus tube housing. The rack teeth were cleaned up. The assembly was then given the computer screw treatment, when fitting into the scope tube, whilst simultaneousy laser collimating. ... gaining excellent tracking throughout the focus range. 4mm Omni Plossl Rebuild ... didn't happen. The UV bond arrived ... how did I get through life without it? Amazing stuff. It can be applied in the most difficult areas (even using an artists paint brush) and then set, by using the supplied torch. ... the whole package for around €7 No time though, to do the doublet rebuild. The Original 60mm Objective Doublet ... was cleaned up, as were the eyepieces. Whilst cleaning the 60mm ... when breathing on the lens, I noticed that it's surface was made up of concentric bands. I reckon that this is not great. Having said that; on the... Field Trip ... Terrestrial viewing wasn't too shabby. We could identify a balcony rail at 11Km - perhaps 50mm in diameter. Celestial viewing was problematic, as we were drenched in dew, and all the stars were made up of concentric rings. Polaris ... DK UMa Perhaps this is due to the 60mm lens construction, or perhaps the dew. If anyone has any ideas...? The azimuth mount, tripod, and focus tube, performed excellently. The scope could be easily panned, tilted, and nudged ... keeping the moon in the FOV was not at all difficult. It was very low in the sky at around 22deg. The focussing was dramatically improved ... very little wobble during focussing. However, it is still not perfectly stable. Examination, before ordering more bits... There are a few things that I want to do ... like fitting a degree plate, and a scope 'guide arm/handle' ... but mainly, I want to get rid of the last bit of vibration, when focussing the scope. What concerns me is that a small amount of wobble on the 60/f700 scope, will be a substantial wobble on the 90/f1000. Some time has been spent on a gas mount (off a washing machine). I've eliminated lateral movement, but it is now very stiff ... and the geometry doesn't help. It might be hard to get it moving. Anyway, it has been put aside, until the 90/f1000 has been assembled. I'm going to drill and tap, three 8mm holes around the azimuth mount, and fit 'shaped shoes' to perfectly clamp the mount. Other than that, I will substantially increase the contact area at the pivot point, and ensure that each face is flat and square. This will entail fitting stainless steel plates, either side of the felt damping. More on that, as it happens .... 🌝

Gimp Version (does a better job IMHO) Below are : Original Image .... PixInsight Modded Image Gimp Modded Image (exact details) .... Gimp Colour Enhanced Image Note The PixInsight stars are not the same colour as the original (and colours are washed out). The 1st Gimped image has extracted the exact colour details from the original image. The 2nd Gimped image lifts the original colours (as an option if wished) Do appreciate that I figured this method by myself ... I'm sure it can be improved. The most important element, is that Gimp enables accurate extraction of the detail, with the option of colour enhancement ... and it doesn't cost a penny. However, it is thanks to Rikyuu's original work, that guided me to this method 👍 I suggest that I write up the method as a separate tutorial. Whether it should be stuck is up to the admins ... but as the original LE software is no longer available, and Gimp will be free and with us forever.... 🌝

Ha! This is one of those 'can't do without' bits of knowledge. I note from later comments that the software is no longer available. However, my guess is that this operation can be completed in Gimp. ... the only problem is figuring it out However, your examples provide good clues. I'll download the original image and the subtraction image, and figure it out from there There's always Gimp Forum

Here is the moon at around 22 deg ... the gimped version & the original: I am not an expert with Gimp. The objective was to remove the central haze. The moon was masked using paths, to create an inverted selection, enabling the background to be removed. The hard edge was then healed. At least it gives us something from our field trip. I must now learn how to stack the images. But I was wondering about the star images. They show what we saw. Can anybody inform me as to why we see concentric rings? Is it down to the objective lens, and the banding that I saw when cleaning the lens? Or maybe it's the dew? The lens is going to be changed, but I'd appreciate some feedback on this. Oh and does anyone understand how read the dew information on forecasts, because it really killed off the night viewing?

Yes, I do need an onsite map. I was thinking that a laptop will be useful, with a sky map application. But I also need to fit an angle disc to the central axis, and one to the horizontal axis. In fact I need lots of things....

Overall; a highly successful mini expedition; though it was always going to be successful, regardless of results, as it was all about learning and gaining experience. Kit The kit for one day, is pretty much the same as the kit for a week, except less food. That caught me out, because normally, food planning is fairly detailed. In this case, I had simply written food... This resulted in our central heating 'microwaved jacket potatoes' remaining on their plinth, for later viewing on our return The moral being ... make your list detailed (the Devil is in the detail). Thankfully, a belt & braces approach meant that there were no problems, and there was only a breeze (northerly), so adequate clothing and double socks, meant that we were not at all cold. Journey Followed the signs (stupidly, because we are in France), meaning that we lost 45 minutes down increasingly difficult tracks. ... consequently arriving at the site at 15:30hr. However, we got a break, as ... The site was perfect A hard standing for both the car and setup together - no carting gear around. Due to brain fade, and arriving late; annoyingly we didn't get an image of the site and setup. Neither did we measure scope elevation; though it's flat, so a guesstimate is 1.4m above sea level. There was a scrub hedge behind us to the South, but this didn't obstruct (what I believe to be) Venus @ 19 deg. Therefore, we can say that this elevation offered unobstructed views, with... The scope set to 1m ... as we were using the prism (which isn't a prism). The prism seemed to give no problems, so we left it in and avoided procedural changes. The mount, with it's new bearing design, was utterly perfect ... the difference between happiness and continual frustration. So too, the newly bushed focus tube. These two elements, combined with the re-engineered tripod, meant that panning was simply 'a pleasure', and focussing was almost straightforward in respect to vibration (though there is still room for improvement). The 'tilt & lock' requires further work. However, for the most part, it functioned well - the moon filling the FOV could be easily tracked, though there were the odd occasions when the friction failed, and reacquisition was required. All these issues will be solved, during the major upgrade that will follow. Focussing With the vibrations minimised, there remained the issue of difficulty in finding 'absolute focus'. There seems to be an arc of movement, where little happens, unless focussing on stars. Perhaps this is down to 'contrast' and more work being required on flocking and baffles. Also, a larger diameter rotary focus knob may help ... it is on the upgrade list. Overall, I believe the limitation lies with the objective doublet lens. When cleaning it, I discovered that its surface is produced from concentric bands, that are only visible when breathing on the lens. Of course, this is being anyway replaced. Terrestrial Viewing We had used the scope 'as is' for the first time, back in early November. This doesn't count as a field trip, as we knew nothing about scopes, and it was simply a fun day out. However, we had witnessed a very strange phenomenon, where distant objects were mirrorred, presumably by a differing thermal layer. As much as anything, it was this that kickstarted 'the telescope project'. Would we see the same phenomenon again? No ... not this time. The atmospheric conditions were obviously different. We could see everything ... even just making out balcony rails at 11km !!! (what will it be like with a 90/f1000 setup?) However, we did accidently stumble upon a refraction proof ... discovered when examining the images. This was really exciting, when it dawned on me, what I was seeing. Remember the simple experiment of 3 horizontal lines drawn on a card, and placed behind a body of water? The middle line stays at the same height. The top line is higher. The bottom line is lower. This means that everything above the viewing line of sight is stretched up ... and everything below, is stretched down. We were always told that an aquarium amount of water would mimick a large volume of air. Hahaha ... the terrestrial viewing experiment proved it, with the aid of google street views. A wall painting of a tree was stretched, and on further investigation, I found the houses behind it were stretched ... and clearly, everything was stretched, regardless of the image position through the lens. What a fantastic excuse for a school science field trip 😁 Celestial Viewing Flushed with success, and a tuned finder scope, we entered the twilight zone. The moon was clearly viewable, and we gained some good images (for the scope spec). To the right and down, was a very bright object (I presume to be venus). However, the image was dissapointing. I think that it must be a failure on my part, to adjust the ISO setting ... a lesson learned (or to be learned) Venus (perhaps) Polaris Ha! I said that I would get Polaris Capella (perhaps) This was the first object to become visible in the East... DK UMa I am fairly confident with this ID... Kite Cluster My son assures me that the main cluster looked like a kite. It was to the right and up from DK UMa. We couldn't capture the full cluster with the 12mm Omni Plossl... By this time (around 19:00hr)... The 2nd battery was failing, and everything was completely wet through with dew. It was as if we had been in a downpour. On top of that, we could see that every image was of concentric circles. We hadn't achieved our objectives, but that was always on the cards. For ourselves, the trip was a huge success, as we had experienced the difficulties. This will enable us to be much better prepared for the next time. ... which hopefully will not see a repeat of the incredible condensation drenching that we, and all our kit, recieved. 🌝

It's all madness. The workshop is a mess. The scope final assembly was this morning ... but it collimated perfectly, and the focus tube is now effectively an interference fit. Only got two extra baffles in last night - cleaning the lenses took forever. Anyway, everything is piled up outside, awaiting my son. I've cleaned up a 20mm Kellner for spotting, and the finder scope can be tuned at 10km during daylight. It's not how I wanted it to be. Realistically, it's a trial run. Looking forward to getting there ... some calm at last. Hahaha ... it's a beautiful day 🌝

Inbetween preparing (what should have been prepared yesterday, if I'd had time) ... I've expanded and modded the target acquisition list. The moon is now on the list, as I've read that it can be seen, though through atmospheric haze. M33 is below M31, and has been added as an alt. IC405 is purported to be visible, so it too is on the list. I've saved the sky maps and gimped them to B&W to save ink. Of course, having never done this before, there is a high possibility of 'failure to find anything specific'. I'm banking on M81, as it is below Polaris. Surely I can find Polaris 🌝

Just found this page : http://www.jb.man.ac.uk/astronomy/nightsky/ Ian Morison suggests Uranus and M31/3 and he provides instructions on finding them (which is great)! He makes no mention of Neptune, so perhaps it is not easy to view. http://www.darkskytelescopehire.co.uk/viewing-m81-and-m82-galaxies-in-a-telescope/ ... suggests that M81/2 can be found and viewed - they also provide instructions. Therefore, I think that these will be the target objects 👍 Interestingly, both sources mention the use of binoculars, so I put those on my expedition list. I'm thinking that it might be useful to discover what the brightest object will be in the sky ... the first object that will become visible as we enter the twilight zone 🌝

1st Field Trip - What to target 29th Dec 2019 42.83 2.95 - Twilight to Darkness ... It's all going to be last minute.com. Er... Just accidently posted, before writing the post ... give me 15 minutes to complete ...................... Development Phase 1 will be completed The Tripod is done ... totally re-engineered. I have to 'bush' the focus tube tonight. Tomorrow, I need to add photon baffles ... it has one; I'm going to add another four (Black 3.0 cannot deliver to scope requirements ... will post the details). I also must black the objective lens doublet (how did that get left till the death ?) ... oh; and clean the 4mm Omni Plossl, because I have Pixies living with me. I do believe 'that is it' for phase 1 IE. An upgraded 60/f700 refractor scope, with Omni Plossls 4, 12, 2x Barlow Setup My guess is that the main tent will be down, and we will just have a beach windbreaker in action. Hopefully not needed, as the forecast is for 20 kph gusts, averaging at 8 kph. We will have chairs, and a table, and we should be calm, having arrived early. The concept is to gain a broad range of terrestrial observations, during the afternoon. ... meaning that we should be comfortable with the setup. As the light begins to go, the camp will be dismantled, leaving us pret for the sky observations. (Warm clothing and lots of food, is prepped.) State of Mind and Body My guess is that we will be back-endish; and consequently in need of 'getting on it'. If we can successfully latch on to an objective, then we will get our second wind (and progress). If we struggle ... the sea air, cold, and previous festivities will take their toll. Prior Research None at all until tonights look at in-the-sky.org All the terrestrial stuff has been researched, because it doesn't move. This date wasn't known until now - I guess it's normal, cos it all depends on viewing conditions, and festivities. Anyway ... 29th looks very good. So, what do you think re targets? I've noted Uranus and Neptune ... and M81/2 seems isolated on the map (but may be wayyyyy beyond first viewing capabilities). Maybe first lift the spirits with a planet, and have a crack at a distant object (accepting an honorable failure) 🌝

Images from the modded Omni Plossl The clamp nut ring turned out to be the field stop. Removing it, would increase the FOV, but the increased area would be degraded. So, that was a job saved Lens glue is UV bond. It melts in acetone. UV bond has been ordered. The lens edges were blacked ... as was the EP body, and clamp nut. The adapter tube threads were flocked using card. A hybrid black was created using acrylic primer, cement pigment, and Black 3.0 ... this improves the Black 3.0 durability. With the lens realignment for later, the eyepiece was reassembled. The camera adapter was firmed up with a reinforcing band ... it's perfect now (well, almost) ... it was blacked with a permanent marker - not great, but fine enough for the mo. ... the camera ring was also blacked. I was good to go Weather was bad, so couldn't get a benchmark image ... instead resorting to 'opening the windows'. The opportunities are limited to a treetop at maybe 1km. Difficult to image, with the wind. Post processing was simple 'levels', to correct the overexposure. (I look forward to trying 'stacking') Seedballs without stalks Taken with the unmodded 12mm Omni Plossl; what is interesting is that the seedballs are suspended freely in mid air. Perhaps their colour did not get focussed ... or the breeze caused them to disappear into the background. I'm pleased with the image though; particularly at this early stage, on the old objective lens, and an unflocked scope. Artistically, I love it. It would make a great dinner place mat Seedballs without Stalks - at 1km - 12mm Omni Plossl Seedballs with Stalks Taken with the modded 4mm Omni Plossl; we get to see the stalks in some detail. The black perimeter band appears large due to the levels lifting it. However, it is much smaller than previously ... due to the chamfer mod to the EP aperture. (The chamfer will be increased, when the lens realignment is executed) Also, the white banding has gone ... presumably as a result of blacking the eyepiece. I like this image also ... I can't help thinking of a fruit bowl ... There is a large nest behind the seedballs ... and trapped falling leaves Seedballs with Stalks - at 1km - 4mm Omni Plossl 🌝

A quick bit of good news... The mods to the 4mm Omni plossl appear to have worked 😀 The added chamfer to the EP aperture, has reduced the perimeter shadow ring. It's a proof of concept. When the lens is dismantled, to realign the doublet, I will reduce the chamfer angle to make it flatter. The mid-way banding appears to have gone. I put this down to the blacking of the EP body and clamp nut. For good measure, I also flocked the adapter tube internal threads. There now remains the general lack of contrast; which should be cured by flocking the scope. I didn't get a benchmark image for the mods (it's rainy), which is a shame. ... but from what I've seen, the EP is definitely better, so the 12mm will undergo the same treatment 👍

Yes. My intention is to use a hybrid mix - Black 3.0 and consumer matt black - to gain durability (as used for the EP face and interior). The Field Stop = 4.5 mm D The cylinder beneath the FS = 5 mm D ... providing 0.25 mm potential coverage depth I will not be ladling it on, and it will be baked, so it should be fine 🌝

Thanks everyone for the explanation Just by knowing the correct terminology for this baffle, has allowed me to carry out some additional research. That research threw up a cloudynights thread, where an equation was presented by Starman1 : For my scope therefore... In current spec TFOV = (4.5/700) * 57.296 = 0.368° In 90/f1000 TFOV = (4.5/1000) * 57.296 = 0.258° There was some discussion concerning the FS removal ... some did, others didn't. As suggested here; I'll leave it in place. My objective is to tidy up the image, not increase the TFOV. ... though I will first flock this component, as it is the most shiny anodising that I have ever seen. That massive mirror-like chamfer that terminates at the Field Stop, must surely be bouncing light down through the FS aperture. That (surely) cannot be beneficial. Or can it ? 🌝

What is the purpose of the 'aperture reduction baffle', on the lens clamp nut? The clamp nut has a central 5 mm diameter cylinder. However, at the top of the cylinder (scope-side), there is an intruding lip of 4.5mm diameter. I see no reason for this lip, other than to cast a shadow onto the 5 mm diameter cylinder. (for all I know, it could even be a repurposed component that comes with the lip) Does anyone know of any other reason, for the existence of this lip? If my suspicions are well founded, this lip can be removed, and the cylinder flocked with Black 3.0 In doing so, this would increase the amount of focussed light entering the eyepiece, by over 10%. For an eyepiece that is already suffering from lack of light .... 10% increase, would be a significant improvement. The thing is ... the chamfer brilliance will already be defeating the 'shadow creating' lip (if that is what it is). My guess is that it is this combination that is causing the banding aberration on the image. To be honest, if I had a 5.2mm drill, or a 5.3mm broach, I'd expand the cylinder slightly, to make way for the Black 3.0. ... then matt the chamfer surface, to complete the clamp nut upgrade. However, this lip may serve some purpose that I am not aware of. Does anyone have any knowledge that might inform the next step that I might take ? 🌝

Thanks John; you were correct ... and the link is definitely worth bookmarking. This is an excellent thought; and to be honest ... I had not considered this outcome. My best estimate is that it doesn't apply to this eyepiece. From a manufacturing perspective, 'laser axial alignment' is possible. However, it would be vastly more expensive than simple physical alignment. The high end optics probably get that treatment, and perhaps even 'tolerance blueprinting' of components. More likely, this error was noticed (at least by the operator or QC). Note how it is not edge blacked ! This doublet lens was sticking out like a sore thumb Depending upon failure rates, it could be either recylced, placed in the B channel, or passed. (I'm not stating that there IS a B channel) Yes. But without a lab setup, and a standardised 4mm Omni Plossl, I can't know the comparative image error. There were a number of issues noted, though in a test environment that was not ideal. ... yet enough to cause me to examine the eyepiece, and look for solutions. I can understand the concept of 'binning it'. However, this is a project, rather than a 'purchase and go'. Consequently, the issue does fit the bill ... though it is bloody annoying, at this moment in time. Of course; afterwards it will be great. Brownie points cascading down in my direction, and the chance to round off a video with : "... a tricky job, but you can do it. That's how you do it..." Hahaha! Regardless though; I see the real benefit of building a scope, being that it creates a constant learning stream, that would otherwise be missed. UV bonding and de-bonding being just one of many lessons learned. ... not in abstract, but true learning. The other issue, relates to the fundamental fact, that mass produced kit often has a much greater potential than is realised by the production process. A touch here and there, can very often produce a far superior end product. There are risks ... but in a worst case scenario, the cost element is very low (and usually the risk pays off). ... and I have one such risk identified. I think that another thread is in order 🌝

Good information to know :) This particular lens is new, so I'm taking a punt that it is the UV type glue. Anyway, I have the acetone, and have just ordered : https://www.ebay.co.uk/itm/New-5-Second-UV-Light-Fix-Liquid-Plastic-Welding-Compound-Glue-Repair-Pen-Tool/264447738745?hash=item3d92504379 We'll see when it comes 🌝

Not too expensive : https://www.ebay.co.uk/itm/10ML-CRYSTAL-REPAIR-UV-RESIN-GLUE-FOR-GLASS-METAL-FURNITURE-9-LED-UV-TORCH-/251849837936? Or there is a pen type for £5.50 with a UV lamp in the pen. Here is what Permabond have to say about de-bonding : UV Cure Adhesives: Extra care needs to be taken as substrates are typically glass and cannot be peeled, whacked or levered of course! The heating method of adhesive de-bonding could be a problem if the substrate materials are glass to metal as differential thermal expansion and contraction could cause glass cracking. However, glass to glass you could heat to the point the adhesive degrades permanently (>200°C). Glass to metal can be soaked in solvent as per other adhesive types. Plastics which have been bonded with UV adhesive such as polycarbonate or acrylic will be attacked by solvent. Even if you manage to get the components apart, removing cured adhesive will be a problem. Check the water absorption rates with the manufacturer; some products will absorb water. Boiling the parts in water may allow the adhesive to absorb enough water to soften it. Complete the removal while the adhesive is still wet as upon drying the strength will return. So it's messy. Cooking will do it, but the glue is permanently destroyed, and would then need removing. Acetone would presumably work, but the disolved glue would go everywhere ... though ultimately would entirely dissolve, allowing a fresh acetone rinse. Boiling water would work, but that would leave a mess of soft glue that will reharden. Out of the three options, it looks like acetone will be the best route. Thanks again Ruud for that mission critical information 🌝

Thanks Ruud. That is the sort of insight that I'm looking for. I guess that I need to tap that into a search box :)

Has anyone unglued and reglued an eyepiece doublet? In order to solve some problems that I was having, with a Celestron 4mm Omni Plossl, the eyepiece was dismantled. The scope-side doublet was found to have been misaligned during assembly : I'm guessing that the lenses are superglued together. The method that I'm considering, would be to place the lens, flat(ish) side down, on wood, in a pre-cut delve, probably adding panel pinning for stability ... and place in the oven. Over-cook the lenses, in order that they stay above the bond temperature... Using plastic pincers, and a piece of card ... clamp to wood, and apply the micrometer anvils (or vice versa - probably less risky). Then leave it ... hoping that the bond remakes. I'd be loath to apply liquid superglue, because it is likely to wick through the gap. I need 'gel superglue', to reinforce what I would hope would be auto rebonded lenses. It sounds simple enough, but it's a task that can easily go wrong, and end up with superglue being smeared across the lens faces. This is why I'm thinking that panel pins would be a good idea. Another Risk might be glue vapour. Over-cook yes ... but not enough to vaporise the glue. Anyway, that's one current planning option. Perhaps another method would be to melt the glue in boiling water (if it will melt), and then clean off the lenses with acetone. ... before cold gluing. The other option is to leave the task for the moment, and re-benchmark the eyepiece after completing the various required mods. ... but, it's out, it needs doing, and after a few practice runs, the actual task might be done in under 30 seconds. Either way, the task needs reviewing. If anyone has any prior experience in this area ... I'm all ears 🌝

Modding the 4mm Omni Plossl - Part 2 - The Components Lens Adapter Tube Nicely machined, with a continuous internal thread, through the length of the adapter. The threads are black anodised. This anodising can come off, due to screw friction, though the glare would be hidden by the lens body. The problem would be when filters are screwed in and out, leaving bare aluminium when filters are not being used. Otherwise, the taper of the thread causes the light to bounce back into the scope. When viewed from the other side, there is only a small percentage of reflected light entering the lens. Sorry about the quality of the images. I moved from 'stills' to 'video', in order to capture the project. Of course, one then forgets to take stills. Here's an image showing the light bouncing back towards the light source (out of focus - damn!) ... and another image, viewed from the other side. Do we want ANY light bouncing around? Probably not; and then there is the knowledge that ultimately there will be anodising wear. My solution to this, will be to make up a removable flocking tube. Problem solved Lens Disassembly There are two glued pairs of lenses, separated by a matt anodised steel spacer ring. These are clamped into the body, by a bright (why ???) anodised aluminium slotted nut. The required screwdriver head, is the largest cheese-head 'bit' that is included with the typical impact driver set (shown further below). It fits perfectly, requiring a firm twist to break the friction, before it screws out smoothly. Both lens pairs appear to be the same in design ... (if someone knows different, please say) To remember the lens orientation ... think of the scene in the film Stalin Is Dead, where the guys 'belly bump' each other If you've not seen the film, then seek it out, because it is hilarious. Anyway, you will now never forget the Omni Plossl lens orientation, because the fat bellies face each other 😁 Lens Examination The eye-side lens appeared to be fine, with sufficient edge blacking. The scope-side lens was found to be less than ideal. ... being misaligned during assembly, and lacking edge blacking. Error It hard measures to 0.06 mm (with cockle), and can be physically lifted at 0.07 mm. My estimate is that the shift is 0.075 mm. Not ideal. ... and it's such a small lens, that is known to be pushing the limits. What to do ? Leave it, for a later job ? Or stick it in the oven, melt the bond, and realign the lenses correctly ? Bloody hell; I've got so much to do ... I just didn't need this Has anybody succesfully completed an ungluing and regluing of a lens pair ? I'm guessing that the lenses are superglued together. The question is ... will the bond re-make on cooling? The method that I'm considering, would be to place the lens, flat(ish) side down, on wood. Over-cook the lenses, in order that they stay above the bond temperature... Using plastic pincers, and a piece of card ... clamp to wood, and apply the micrometer anvils (or vice versa - probably less risky). Then leave it ... hoping that the bond remakes. I'd be loath to apply liquid superglue, because it is likely to wick through the gap. I need 'gel superglue'. Hahaha ... I might have some; only that if I find it, I'd probably be tempted to execute the repair. It's not that it can't be done. It's the risk of knocking the lenses, and smearing the faces with melted superglue. ... and it's a two man job, yet it is such a tiny work area ... and the temperature will be rapidly falling, as soon as the anvils make contact. However, it IS doable, and should be well within my capabilities ... only that it must be done correctly at the first attempt, if a whole range of complcations are to be avoided. Lens spacer ring This component appears to be well made. The production team did an excellent job with the matt anodising. Here it is, under lights : Clamp Nut Why on earth didn't Celestron get the same team to make the clamp nut? ... because it is the most brilliant shiny black anodising, that I have ever seen This image doesn't do justice to how shiny this component is.... Note how the chamfer will bounce light directly onto the mirror surface of the the nut cylinder face. ... and there's more... The clamp nut has a central 5 mm diameter cylinder. However, at the top of the cylinder (scope-side), there is an intruding lip of 4.5mm diameter. I see no reason for this lip, other than to cast a shadow onto the 5 mm diameter cylinder. Does anyone know of any other reason, for the existence of this lip? If my suspicions are well founded, this lip can be removed, and the cylinder flocked with Black 3.0 In doing so, this would increase the amount of focussed light entering the eyepiece, by over 10%. For an eyepiece that is already suffering from lack of light .... 10% increase, would be a significant improvement. The thing is ... the chamfer brilliance will already be defeating the shadow creating lip (if that is what it is). My guess is that it is this combination that is causing the banding aberration on the image. To be honest, if I had a 5.2mm drill, or a 5.3mm broach, I'd expand the cylinder slightly, to make way for the Black 3.0. ... then matt the chamfer surface, to complete the clamp nut upgrade. Eye-side lens shoulder - chamfer creation (eyepiece body) This shoulder (that the lens is clamped to) projects around 1 mm from the lens surface. It is this that is causing the shadow to the camera lens. It had a minuscule chamfer - principally to remove the sharp edge. The chamfer needs to be much deeper. to allow free passage of light from the eyepiece lens to the camera. While. this area of the image may not be the best ... the objective is to eliminate the dark shading at the edge. The shiny aluminium chamfer will then require blacking ... at the same time the eyepiece face can be matt blacked, as it is a highly reflective anodised surface. I've already cut a chamfer, and carried out a large amount of experimental work with paints, primers, pigments, and two part epoxy. I'll leave that for the next post, but here is an image of the chamfer, after it has been roughed with a diamond file. In the meantime I'll leave you with an image of the kit that I used. Oh ... and if anyone has any experience with the lens glue situation, and the strange baffle on the lens clamp nut; I'd be interested to hear from you 🌝

Modding the 4mm Omni Plossl - Part 1 - Introduction It exhibited problems. Perhaps much is due to the scope requiring flocking ... but even still... If we examine the image - the eyepiece aperture is ringed ... An external glare is clearly visible; and so too an internal band, that starts black, but then changes to white(ish). The External glare can be highlighted in Gimp : So too the internal issues : Ha! It shows that the camera lens was not quite aligned to the eyepiece; though that is nothing compared to the bizarre banding problems. Yes ... the whole image contrast would (will) benefit from flocking, but the primary issues relate to the lens, the camera lens, and the bouncing light and shadows. From the images, there was no escaping the fact that there were issues relating to the aperture edge, and the light bouncing between the camera lens, and the eyepiece face... That's not mentioning the progressive banding, that could be coming from internal issues within the eyepiece. Identifying the areas for improvement The first issue was that the camera lens FOV was greater than the eyepiece aperture, and this was creating a shadow. Also, the light was bouncing off the camera lens ring, and the eyepiece face. Within the eyepiece, the locknut was finished in mirror black anodising, with a major chamfer that would bounce light incorrectly into the lens. What else would be discovered, depended upon dismantling the eyepiece. ... something that had to be done, if the shadowing was to be removed, by executing a chamfer to the eyepiece body aperture. Opportunities Dismantling would enable further investigation of internal reflection, lens edge blacking, and lens construction. ... and so, the adventure began.... 🌝

Thank you Happy-Kat and Cornelius Varley for providing the mission critical terminology: Knowing the terminology enables easy research 👍 Yes, my use scenario is 'afocal imaging'. ... a method that seems to be mainly based upon trial and error (from the documents that I read). The fundamentals appear to be lost in the chaotic mix of variables. It certainly doesn't help either, when information is contradictory. ... I thought that I had the explanation, when I saw these diagrams: They both show parallel light being emitted from the eyepiece. I thought that this might explain the infinity/closeup camera focus question (if I thought long enough on the subject). However, I was then researching eye relief, as this was repeatedly mentioned as a factor. This produced this diagram: Clearly, the light is shown to converge on the eye pupil. I'm wondering ... perhaps the triple lines are indicating the RGB split. Perhaps there is some relationship with the white banding on the turbine pillar. Text ... was not easy to decipher. Most docs stated to set the camera to infinity. One doc stated both ... set to infinity, but idealy set to macro! Use an eyepiece with long eye relief. Couple the end of the camera lens as close as possible to the eye lens of the telescope eyepiece. Set the digital camera at macro mode rather than infinity. Use digital camera at full optical zoom. If possible, use a camera lens with a focal length longer than the eyepiece focal length. I don't understand why long eye relief is required, if the camera lens is close against the eyepiece lens. Does anybody have any thoughts on that? The other complicating factor, is that none of the docs discussed smart phone cameras. They all discussed DSLR's which have a large CCD sensor. My Setup The Omni Plossl eye relief is stated as: 4mm = 6mm ER 12mm = 8mm ER I don't think that this is classed as long, but they are what I have. My camera lens is close up to the eyepiece lens. Closeup focus does appear to be better than infinity (more tests required). The full optical zoom ... does he mean digital zoom, or optical zoom? ... why mention 'digital', in this statement? Either way, the digital zoom (all that I have) is definitely useful for focussing purposes. Also, some degree of digital zooming may help. ... I believe that it crops the sensor pixels, before running the image through processing software. Conclusion Hahaha ... Forget the fundamentals, and test various setups Further Thoughts Tube Connector For testing, I need to firm up the 'camera to eyepiece' tube connector. I will probably also add an additional support, to enable the phone to be held upside down, hanging above the eyepiece. This will enable erect images to be recorded. lock image to camera position Open Camera provides a 'lock image to camera position' setting. Without it, the camera can be inverted, but the image isn't. This latter point highlights the fact that the camera can rotate or not rotate the image. Theoretically therefore, there must be potential to display an upside down image, as a vertical image. I have a feeling that this potential has not been exploited ... probably because it is only relevant to telescope imaging. Hmmm! I'll have a check; and if not, I'll contact the Open Camera developer, and suggest that this would be a highly useful mod. ... particularly if the image could be flipped horizontally. Then, there would be no need for a prism. The image could be recorded as is, and displayed as is. Macro or wide-angle camera lens attachment These are magnetic lenses, that are larger than the camera lens in the phone. The phone lens aperture = 7mm Macro = 9mm Wide = 13mm 4mm EP = 5mm 12mm EP = 11mm The macro lens works at very closeup, producing a sharp centre surrounded by blur. The wide seems to allow closer focussing, without gaining the detail of the macro, though it eliminates the blur. I have them, so I will try them 🌝

Imaging fundamentals required I'm upgrading a scope; and prior to making irreversable moves, the scope was benchmarked a few days ago. Done, using an LG4 smart phone, and 'Open Camera' software. A tube fixed to the phone skin, that corresponds to the eyepiece outside diameter, was used to mount the phone/camera. ... the viewing end of the eyepiece is inserted into the tube, and the camera/eyepiece assembly is inserted into the focus tube. The images captured were, what I consider to be, fine enough for a first attempt. ... mistakes were made, and anyway, the scope engineering is not yet to the required standard. It was as much a learning exercise as a benchmarking exercise. ... only that, a couple of lessons were not fully comprehended. Consequently, I'm here, wondering if someone has crossed these bridges, who might be prepared to share their knowledge I thought that we might examine the first problem, as any answer might inform other questions Understanding the camera Open Camera appears to use contrast focus, as it focusses while the lazer emittor is covered. It was not clear, when taking the images, which was the correct camera focus setting, between infinity, and closeup. ... until viewing the images on a monitor. As can be seen ... at the infinity setting, the image more or less remans in focus, only that a broad white band accompanies the wind turbine pillar. Okay ... so I have learned to set focus to close up, though......? The stated minimum focus is 100mm ... nowhere near how close the camera lens is to the eyepiece lens. With this in mind, at my desk, I have just checked distance to focus, with 'macro' selected. It can then focus to 70mm (it auto fucusses, as if on auto focus). I'm not sure how it is doing this. It may be that 100mm is an arbritary choice, that suits all phone cameras. Setting to 'auto' the camera will reliably focus to 70mm (the same as macro). This, therefore seems to indicate that the actual reliable focus distance is in the region of 70mm Note: Interestingly, one can get slightly closer ... the camera still focusses, only the centre of the image is soft, while the exterior is in focus. Other than that; let's say that the camera will attempt to focus, based upon best contrast, to 50mm. At 45mm, multiple taps on the screen might result in a best attempt, but often it just fails. It is a blur. It probably can't get enough information to set the focus to the very limit Objective lens, to eyepiece, to camera lens, to sensor From the images taken, we have established that the image remains in focus, whether the focus is at infinity or close up. It is this that forms one of my struggles. Normally, if I manually change the focus ... anything other than the correct focus will result in a blur. ... but not with the image from the eyepiece. There is obviously a good reason for this, but for the moment, let's call this 'strange'. That strange behaviour, calls into question the camera focus system. If the image remains in focus, when the focus distance is at the opposite of the ideal ... can the auto focus even begin to function? If not, then I can forget auto & macro, and simply set the camera to a fixed focus of 100mm. ... a shame, because true focus can go down to 70mm at least. Of course, the camera lens is almost touching the eyepiece (just millimeters away). So, where is the image, vis a vis ideal camera focus distance? Yes, yes, yes ... I get the bit about objects further away producing 'closer to parallel light'. But the eyepiece lens changes that. (Ha! You've maybe guessed that the next question relates to focus without an eyepiece) Does an ideal camera focus distance exist? Does that change for each eyepiece, or perhaps object distance ... or both? These multiple questions lead me to believe that I need to understand the fundamentals. Can anyone explain them ? 🌝

Benchmark Testing - The Results What is a Benchmark? This is a record of a current setup, prior to implementing modifications ... in order to be able to gauge the degree of improvement, or lack of improvement. Consequently, it is an education aide, as one can precisely reference what hes been done well, and not so well. Similarly, it is used for material and component comparison. Why not just see if the new kit is better? For simple comparisons, this is possible - I got a new pencil, and this one doesn't break all the time! But in complex scenarios; sense and feeling is often based on how you got out of bed that morning 😀 Also, if a large sum of money has been spent on new kit, you may tend to believe that it's better, when it may be no different 😉 Can results be valid in a complex atmosphere? Validity of results is always open to question, outside of controlled laboratory testing. The best that can be done, is to take a record of atmospheric, and sunlight conditions. There may also be a questionmark over the improving skills of the tester, between benchmark tests ... Er ... That applies to me, because I have very little prior experience with telescopes and telescope imaging. Consequently; a set of benchmark results can masquerade as precision data, when it is no such thing. This caution certainly applies to the benchmark results below - the difficulty in focussing, wind, and camera settings However, these factors are referenced. ... and from this, we can view the results as being a benchmark for a starter scope. IE. This is what you might expect, with a 60/f700 with these lenses. When all that has been learned is input into the next version 90/f1000 ... we will see the improvement. Hence, in this context, the results below are valid. Tests Wind turbines at 10Km Through the 90° prism Through the focus tube Through the focus tube and Barlow 2x All the images were taken at JPG 90% 145 images were taken in total Note: Having analysed the images, I discovered that the camera should be set to close-up, not infinity. The difference is in, more or less, ghosting. Annoyingly, other than the first images, the setting used is not known. (the opening images are presented to show the difference) Note: The Kellner lenses are starter eyepieces (came with the scope) The Omni Plossl range were in fully marked up Celestron packaging. The 6.3 Plossl (marked as Celestron) was gifted in a white box. (I say this because the 6.3 results appear to be sub-par) Results Format For each test completed, the best image was chosen. The post processing was limited to : Rotate where necessary Crop to 946 x 946 Crop and RESIZE up to 946 x 946 where necessay to compare specific object image reproduction ... relates to comparing high magification or camera zoomed images (big to start with), to what a low magnification image provides when zoomed in Gimp (interesting) Processed images were saved at JPG 100% Weather for the test period : RESULTS - By Prism Prism_20_Kellner_Infinity . . . . . . Prism_20_Kellner_CloseUp Infinity and closeUp refers to the camera focus setting. Actual scope focus probably changed between each shot. Prism_12.5_Kellner_CUT . . . . . . Prism_9_Kellner_CUT Prism_4_Kellner_CUT . . . . . . Prism_6.3_Plossl_CUT Prism_12_OmniPlossl_CUT_RESIZE . . . . . . Prism_12_OmniPlossl_CUT Prism_12_OmniPlossl_CAMZoom_CUT . . . . . . Prism_4_OmniPlossl_CUT CAMZoom was a different image, hence a resized cut of the first image was produced ... to indicate whether camera zoom should be used (or at least the difference) Just to be clear: The top two images are exactly the same. RESULTS - By Focus Tube (direct) Direct_12.5_Kellner_CUT . . . . . . Direct_12_OmniPlossl_CUT Direct_4_OmniPlossl_CUT_RESIZE . . . . . . Direct_4_OmniPlossl_CUT Direct_4_OmniPlossl_CAM_ZOOM_CUT . . . . . . Direct_12_OmniPlossl_CUT_RESIZE These somehow bypassed the rotation phase ... and yes ... the top two images are the same! The 12 RESIZE is from Direct_12_OmniPlossl_CUT (above) - would you believe it Direct_6.3_Plossl_CAM_ZOOM_CUT . . . . . . Direct_4_Kellner_CUT For Direct 6.3 Plossl only a camera zoomed shot was worth posting ... the Direct 4 Kellner compares quite well. RESULTS - By Focus Tube & Barlow Barlow_12_OmniPlossl_CAM_ZOOM_CUT (6mm) . . . . . . Barlow_4_OmniPlossl_CUT (2mm) Barlow_6.3_Plossl_CUT (3.15mm) For the Barlow 4 (2mm) - walk 3 paces from the screen, and look (the image is there). Conclusions At this stage, with this first benchmark set of results ... due to all the reasons stated in the preamble, we can only judge the results, and not the kit. Was the 6.3 Plossl doing a 'Hulkenburg' ... basically good, but didn't pull off a good shot? I have my doubts. It seemed to perform worse than the starter Kellner 4 (which I thought shone, considering its lowly status). We can place our bets on eyepiece performance in the upgraded scope. However, having contacted BET Free Six Five ... there is no money to be earned on the 4mm & 12mm Omni Plossl's ... both of which put in a very good performance (regardless of the crappy choice of camera focus). Interestingly, there is a good gamble on the Barlow. It showed a hint of promise, when mated to the 12 Omni Prossl. The thing is; it was last out, the wind was up, the light was starting to go. It might be worth a fiver on it ... or am I just being hopeful, after burning so much wax? Genuinely ... I don't know ... and that's exciting. Will it, or won't it come good, in the 90/f1000 hyper scope ? 😎 The Winning Image Ha! This is the strange thing about pictorial elegance. The brain just likes a good photo, even if it might not have the best data ... zoom in, and you could have a good argument. But there's no doubt that the Direct_12_OmniPlossl_CUT appears to have that confident 'look at me' stance ... and eye's are drawn to it. The Omni Plossl 4 has a lot to say about this, but is wisely keeping its powder dry for the next showing 😉 So let's leave the 60/f700 Benchmark Tests, with the 'Direct_12_OmniPlossl_CUT' on display : Wind Turbines at 10Km (Celestron Omni Plossl 12mm - Direct through the scope) 🌝