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Found 48 results

  1. Hi, Folks I am only a few weeks into astronomy and started off with a Celestron 9.25" Evo on the standard AZ mount. I guess with hindsight this wasn't the best place to start and also with hindsight I would have done better to have bought a GEM mount. Anyway, lesson learned and at 71 years old I have to speed up the learning process compared to younger enthusiasts I have 2 issues. 1/ Its a pain dragging the scope out into the garden and setting it up every time I think the fickled weather might be obliging. 2/ I now know that the mount I have is useless for long exposures and a wedge is fiddly to get polar aligned. My question is, though I gather wedges are a PITA to setup etc is if I was to build or buy a pier for the backyard and use my existing mount + a wedge is this a reasonable way to go? Though it's fiddly to set the thing up once set I could leave the mount, wedge, etc covered up and would just need to drop the OTA on when I wanted to use it. Is this reasonable or am I missing something fundamental down near the bottom end of my learning curve Any advice much appreciated and don't feel you have to spare my feelings
  2. lets imagine I wasn't to see a nice DSO about 15' size and I think it should look good nicely framed with a 1 deg field of view in the EP.. Which would give the better (or higher probability of seeing anything at all ) view from a semi urban light polluted home site (e.g Bortle 6)? a) an 100mm f/6 refractor (fl 600mm) and a 10mm EP (60 deg afov, gain 60x = fov pf 1 deg) (and exit pupil of 100mm / 60 = 1.6mm) or b) a 200mm SCT with focal reducer to give f/6 (fl 1200mm) and a 20mm EP (60 deg afov, gain 60x = fov of 1 deg) (and exit pupil of 200 / 60 = 3.3mm) My gut feeling is that the SCT should give a better view just based upon its 2xaperture - but Im not sure I understand fully the maths why. Is the larger exit pupil going to result in a better / brighter / more successful view? Or will the view be 'roughly' the same ? Or have I got it all wrong..... Thanks.
  3. Wife says to get rid of something before I can buy a new toy! C6 is in perfect condition. I am located in North Georgia and would rather not ship. Scope sells for $800 but will let her go for $500 !
  4. I recently acquired a used CPC800 SCT. I thought a 'First Light' report might be of interest. First impressions: the tripod is a heavy duty affair with thick legs, a folding lower spreader and a big cast alloy eyepiece tray/steady. The OTA/fork assembly (not separable) is very heavy (21Kg/44lbs) but has a couple of grab handles. You need to be fit to handle this. ? (I was seriously tempted not to go ahead with the purchase after trying the weight.) With the legs retracted it is just possible to pass the tripod through a standard doorway, but it is just as easy to pull up the lower spreader and carry it folded. It is much heavier than a C8SE tripod but more comparable with a EQ5 tripod in weight. Once in position, I checked the level with the handy built-in bubble level and left it. I forgot to screw up the eyepiece tray/upper spreader but I don't think this made any difference. Scope stored on a table with faceplate down and rear handle uppermost. Took the weight with my left arm, elbow fully bent, forearm vertical. Got it on the tripod which took the weight till I got the base to drop over the centre pin, spun it till something clicked into place and then did up the three thumbscrews. I would not try this with an equatorial wedge unless I had a helper. Celestron also sell a CPC 9.25 and CPC1100 - if I had one of those I'd need a sheerlegs or a brawny assistant.? Fitted the visual back (same as C8 SE), prism diagonal (same as C8 SE), straight-thru 50mm finder, handset (Nexstar+) and handset bracket which holds it facing rearwards (a handy feature not implemented on the C8 SE). Fitted a 25mm X-Cel LX that came as an extra. Connected my new lithium powertank and its DC cable, and powered up. It comes ready (CPC Ready) very quickly. Selected 2-star auto align - it whizzed past a time display showing the time ahead of my watch by 1 hour - more on this later. Aimed at Arcturus and afjusted the finder aim. Selected Capella - it nearly got there and then blackout! The cable had snagged and pulled on the plug. I ran the cable through the side handle on the fork and tried again. (It appears that the CPC's supplied cable has a locking ring and the other end has a cigarette lighter style plug.) Capella ... Arcturus .. aligned. Told it to find Mizar (named star menu). It did. Also found M48, the Ghost of Jupiter planetary, Gamma Leo (split ), 54 leo, 88 Leo, 90Leo. The scope appears to be collimated and resolution OK. GoTo is just accurate enough to drop doubles into the bottom of 9mm X-Cel Lx field. Even at 200x and a gusty night the view is rock steady. A pier mount could hardly be stiffer than this! And no obvious backlash in use (unlike C8 SE). Fiddled with the menu, found the GPS is obviously working, and the time set for daylight saving. Corrected it to standard time. GoTo still works. Teardown: tube horizontal, power off, tube cap on, diagonal off, handset and bracket off, left visual back on and capped it, loosened clutch to point tube straight down. Got OTA/fork assembly off and back indoors on table, twirled it into position. Folded up tripod and carried it indoors. I would not try carrying the tripod and scope together. Verdict: Very solid mount should be good for planetary imaging. Some nice features not on C8 SE, otherwise same optical performance. Alarming weight.
  5. Hello I bought my first telescope last year (Celestron Nextar Evo 8), I've used it several times already and never had any problem with moving it/putting it together. Last night I was out doing some photography with my scope and at one point my glove came in contact with the corrector plate. I noticed a small smudge when I came back in. As it's my first scope I've tried to be very careful and got a little scared that it would affect the performance of it. Looking for a professional opinion on this. Does this need to be cleaned? Will it make a difference in my photography/visual? Added two pictures. Regards Brant
  6. bit more from a frosty last night c gem pier in obsy sct 9.25 hd 720* logitech some colds hands and i did some other stuff will sort later but for now enjoy these close ups sit at least 3 feet away from yor monitor please to get the full beauty of the moon pat
  7. After a great hour viewing i stuck the dmk 21 mono into the 9.25 sct and put the IR pass 742nm filter and did a few barlow shots then just some random rilles ect enjoy i did avaerage 1200 frames 900 stacked
  8. Hi all gazers, i am having second thoughts about getting a crayford for my C9.25 (non HD) and that is because of the 0.63 Reducer / Flattener that i am imaging with. As camera i use the Nikon D7100. According to my calculations, and what i have read on internet, the optimal distance between the reducer and the chip is 105mm, the only focuser that allows for this distance (107-ish mm) is the feathertouch with the "shorty" sct-adapter witch is 56mm, my nikon T2-flange to the chip is 50mm. The Steeltrack and moonlite is far to long (93 and 91mm) But, according to some people, i can put my FR after the focuser with good performance, but how would that effect the reducing, and flattening? are there any out there who use crayfords and reducers on their SCT's with DSLR's? If nothing seems to work, i am getting the feathertouch microtouch replacement for the stock SCT-focuser. // Daniel
  9. My lovely 8" LX200 Classic has been de-mounted from my observatory pier and I'm selling a load of accessories that used to be used with it. 8" Bahtinov Mask - SOLD Astrozap 8" dew shield - SOLD Pair of 5" Asymetric mounting rings - £22 Astroengineering 3D counterbalance system with 2kg counterweight - £45 Baader SCT Crayford Focuser - SOLD All prices include postage to UK mainland Both remaining items for £62 posted
  10. Having an EVO 9.25 I am thinking of one classic upgrade path, a 2" diagonal, which would also help to share eyepieces with the planned buy of a big dob. I have read plenty of existing discussions, but am still lacking enough information on the right one to choose. In particular, the missing point is about clearance and combinations: I have read a short diagonal that fits directly in the SCT thread (like WO) should allow for clearance (pushing up the OTA), therefore allowing the scope to work at its full potential. My doubts are: 1) does getting rid of the visual back cause big problems? I have read it makes hard to block the diagonal at the right position, and that it can make the diagonal dangerously swivel 2) if there are indeed problems, and keeping a visual back (like 2" Baader's click-lock, for instance) is better, wouldn't this prevent clearance? 3) I am tempted by the 2" baader click-lock dieletric for its no screws capablity: is there a combination that allows clearance for this diagonal? Anybody help please? Thanks! Ab
  11. Hi - Was wondering if anyone could help me? I've recieved a second hand Orange C8 but it has a rotating secondary. It just spins around in the corrector plate with about .5 mm wiggle room. To make things worse I think the previous owner has attempted to remove the corrector at some stage so I'm not sure what to do. I know I have to align all 3 optical elements but not the foggest where to start. The corrector appears to have two lines etched on the edge at right angles. Say 12 and 3 O'clock - but dont know if this is 11 or 2 O'clock or what ever configuration. I can not discern an corresponding marks on the tube body or down at bottom on the mirror. Ant
  12. Hi, I've come into possession of a Vixen Flip Mirror (Link) however it looks like I need an adaptor of some sort to attach to the back of my telescope, a Celestron Evolution 8 SCT. Can someone point me in the right direction please which one I need. Also, I have a T-ring so presume I just screw this to the other end of the flip mirror once in the mirror and then add canon camera to the t-ring or is there a better way? Many thanks in advance. Incidentallly, I'm compiling a ton of these newbie type questions for a planned FAQ blog of my own one day!
  13. Found an old (apparently USA model) celestron C8 SCT a while back, its a bit hit n miss with collimation and the optics - (some very strange star test shapes :P) but when it works it works well Here is a couple images from a couple months back. Thanks for looking. This particular night seeing was reasonably good, and collimation wasn't too bad either. Celestron C8 / ASI120MC / 2X barlow - captured in sharpcap2, stacked in autostakkert!2, wavelets in registax6
  14. Morning all, Been a bit slow sharing this cos I keep trying to reprocess to get a better result - this one is from 90s captures in each channel, de-rotated the AVIs in Winjupos, but I've just aligned the final RGB images in Photoshop. I'm having real trouble with the RGB image de-rotation process in Winjupos; it seems to add loads of noise that's not there in the source images...? Anyone else seen this? Anyway, this one is still somewhat noisy but I'm fairly satisfied considering I haven't done much with this equipment for a while! I got several other captures that night so am considering doing a little animation just for giggles. Haven't tried that before. Cheers folks Jim Celestron 9.25" SCT, DMK21 w/ ICX618 cip, Astronomik LRGB filters, EQ6 SE London murky smoggy 'orrible skies
  15. Read much on Celestron but not so much on Meade these days. How do the big 2 compare and with other SCT makes?
  16. I just finished a transport box for my Edge 8" and AVX mount. I'd built a similar setup for the C6 I have, I wanted something I could use to store the telescope and mount in that would protect it, plus have something to make it easier to transport when going afield for viewing or AP. This is made from 1/2" birch veneer plywood, it's nothing really fancy, just butt joints, glue and brass screws . I wanted it to remain more utilitarian than "furniture", but dressed it up a little with brass hardware and a nice stain and polyurethane finish. It's in two pieces to make it easier to lift and pack into a vehicle; one box for the OTA, the other for the mount and accessories. These two boxes clamp together and fit on a small hand truck that can be used vertically or horizontally. The tripod I plan to get a bag for, and will strap it to the outside somehow, and all my EP and diagonals are in a separate case. The only other thing I'll have to hand carry is my dew shield. The OTA box is padded with foam rubber cut to fit and covered in a heavy upholstery fabric, the mount uses the large closed-cell cutout that it came shipped in, I dimensioned the box so it would slide in or out, so I can still use the cutout if I ever have to ship the mount for repairs, etc (hope not). Both the OTA and mount have retaining straps with quick-release buckles. Alongside the mount are compartments for gear; I have the counterweights, dew heater, controller and power cord for the mount, the finder scope for the OTA, a couple of field books and my notebook and manuals, and an accessory weight for the OTA. There's still room for other stuff, and I suppose it won't take me long to fill it up. The last picture shows both carriers. The one for the C6 will also carry the tripod.
  17. Okay folks, so, for a variety of reasons, including but not least an appalling sequence of poor weather since my last post on this particular topic, I have been unable to obtain an accurate measurement of the focal length off my 8” EdgeHD incorporating Baader SteelTrack Focuser and Click-lock Diagonal. I managed to remedy this situation over the weekend just past. Initial measurements based on adding the optical path of each of the components together, had the complete resulting optical path at about 2400mm, however this was not bourne out in practice. Using my 22mm T4 Nagler, at 2400mm focal length this should have given approx 45’ TFOV. Using M81 and M82 as a yardstick (approximate separation 36’), they should easily have been visible in the same field of view, however they were not. Extrapolating back from these values seems to be indicating a focal length somewhere between 3000 and 3225, which makes the revised speed of the system a whopping F15 to F16. This must be having a significant detrimental impact on the sub-aperture correction inherent in the Edge HD design, so I’m thinking of removing the Steeltrack from the system and replacing with a FeatherTouch or equivalent. This measurement is actually consistent with a drift measurement I made last year, (instructions courtesy of Don Pensack), but discarded due to it being so far removed from the expected result nearer 2400mm. But the proof as they say is in the pudding. So for those considering adding a Crayford to their EdgeHD, based on this experience I would say don’t. From feedback on this topic in CN, it is very possible that it is something to do with either the slightly faster primary/secondary combination in th EdgeHD and/or the sub-aperture correction in the baffle tube, possibly resulting in significant vignetting. (Thanks to Don Pensack and Edggie from CN, for their input). If you are interested in reading the CN thread discussing this you can find it here: https://www.cloudynights.com/topic/574002-calculating-effective-focal-length-of-an-edgehd/ Kind Regards Paul.
  18. Does anyone know what the strange diffraction spikes are in this image? I know the star Alnitak is pretty bright but wasn't expecting this. I've never seen this happen before. Is it an SCT thing, or a MY SCT thing? I've seen straight diffraction spikes, but never curved. Is there anything I can do to stop this? Could it be a collimation issue? I did check before I started imaging, but thought everything looked ok. My scope is a Celestron C9.25 XLT, and I'm using a f/6.3 corrector/reducer with modded Canon EOS 600D. Thanks in advance
  19. I recently posted about my first successful collimation experience (an SCT). I'm sure we all have our stories, of those moments when we perceived optical clarity. Come on everyone tell us of those collimation 'eureka' moments and your experience of your first observing session immediately following. Paul.
  20. Hey everyone, I have yet another query.... So, attached are 2 pics I snapped with my phone last night. The first was taken through a zoom ep at about 12mm. The second was through a 25mm plossl. I see a noticeable color difference, so my question is which one is true? or better yet, which eyepiece yields the truest color? I have also seen it mentioned that sct's take away some contrast, but do ep's also have an effect on this?
  21. Hi there, could someone please provide depth and thread pitch for the front cell screws on an 8" Edge HD, as in the empty socket portrayed in the attached photo:8" Edge HD, as in the empty socket portrayed in the attached pho Kind Regards Paul J.
  22. Just took a look at the inside of my SCT and there appears to be a lot of dust and what appears to be manufacturing debris on the inside. Its a Celestron C800 CPC and I've no experience on internal cleaning. I don't think I want to chance it either. Does anyone know of a commercial cleaning service?
  23. Chris’s Backyard Astronomy. January 2017. A view beyond Earth’s lifetime Happy New Year to everyone. This month I am going to concentrate upon one topic only; something that came to my attention at New Year. The item in question is described as a QUASAR and makes a year in my life appear extremely insignificant. Eyewitness report: “Almost Older Than Time. Would we be able to see it? On Monday the 2nd of January we gathered in Chris's back garden observatory to spot a tiny pinprick of light that had been travelling 8 billion years, yes that's right 8 BILLION YEARS to reach us! Chris had done his homework, mapped out its position and identified a few pointer stars to help us in our search. The bright moon and lovely Venus stayed handily behind the house so a reasonably dark, clear sky helped us in our search. Our luck was in, the pointer stars in the shape of a triangle were in the (telescope) field of view and using averted vision I spotted our faint target, impossible to grasp the enormous distance through space and time the photons from this QUASAR had travelled. Once spotted it was easier to see it again as we all took turns to look at this black hole in action; a successful night, thanks Chris.” Susan Feist Quasi Stellar Radio Sources (QUASAR) The name was adopted originally because such objects were first observed by ‘seeing’ their radio waves and so they were assumed to be stars. Remember, telescopes are not just available to see things with your own eyes but some are capable of detecting lots of other forms of energy. The Jodrell Bank telescope near Manchester for example was once the greatest radio telescopes in the world. Jodrell Bank Radio Telescope: Image credit mattbuck Up until the 1960s a multitude of radio wave sources out in the sky were listed and catalogued. Critical to identifying these objects were to accurately log their precise position and then try and get identification too with a powerful visual telescope. This proved possible in some cases and as a bonus it was possible to catch the light and determine the spectrum of the object (see my previous column). Once you have the spectrum you can find out a lot of important information. However, visual recognition and thus scientific interpretation of some of these QUASARs eluded astronomers. 3C 48 I quote a lot of numbers and acronyms but really it’s not that complicated. QUASAR 3C 48 was the 48th entry in the 3rd Cambridge catalogue of radio sources. In 1960, using a huge 200 inch telescope, astronomers Sandage, Matthews and Bolton finally pinned this particular radio source to a 16th Magnitude star. Mount Palomar 200-inch telescope. Image credit: Coneslayer at English Wikipedia A refresher on magnitude Remember, the magnitude scale works counter-intuitively in reverse. Each step is a change of about 2.5 times in brightness. For example, to us the full Moon looks about 60,000 times brighter than the bright star Vega. On the other extreme QUASAR 3C 48 is about 10,000 times DIMMER than the dimmest star we can see with the naked eye! Object Magnitude Brightness we see on Earth The Sun - 26 Midday Sun Full Moon - 12 Moonlit sky Venus (now) - 4 Bright evening ‘star’ (now) Jupiter - 2 Yellowish star like Vega (bright star) 0 5th brightest star in the sky Yildun + 4.5 Star just visible with your eye Neptune + 8 Farthest planet appearing reasonably bright in a 10 inch ‘scope 3C 48 QUASAR + 16 At the limit of a very large amateur ‘scope Capturing the light from the QUASAR to enable a spectrum to be examined was some feat in those days but they did so. Sandage though was quoted describing the spectrum as “exceedingly weird”. What followed was a 3-year period of doubt and false reasoning because the spectrum just could not be interpreted within the range of known objects. In 1963 two other scientists, Schmidt and Greenstein, re-examined the spectrum of 3C 48 from 1960. Schmidt had previously examined a spectrum of a similar object (3C 273) and was thus experienced in these matters. What he immediately concluded was not weird but that object 3C 48 showed a “redshift of 0.37”. So, now we need a recap on redshift. Hearing an ambulance Recall the last time you stood by as the ambulance sped towards you and then away from you. We are all familiar with characteristic change in pitch of the siren. As it approaches you the pitch gets higher then as it leaves you the pitch gets lower. The lowering of the pitch as the sound source moves away from us is due to a ‘stretching’ of the wavelength caused by the speed of the ambulance relative to us. This is the Doppler effect and applies to all types of radiation including light. Normal spectrum above and red-shifted spectrum below. The tell tale absorption lines are moved to the right. Credit: Georg Wiora (Dr. Schorsch) via Wikimedia Commons So Schmidt was saying that the spectrum of QUASAR 3C 48 told us that it was (and still is) moving away at truly phenomenal speed! As we have discussed before, the painstaking work of Edwin Hubble in the 1920s enabled a connection to be made between the speed that an object is receding and its distance. On doing the maths 3C 48 was located at 4 BILLION LIGHT YEARS distant. Ancient photons hit Bishop Monkton This dramatic distance estimation created disbelief in the astronomical community. Knowing how bright the object looks to us (Magnitude +16) and also knowing its distance, enables us to quite easily determine its true brightness close up and thus its power. The calculation for most QUASARs shows they have the luminosity of 10 Trillion (10,000,000,000,000) Suns, easily one of the most energetic objects in the Universe! As you may imagine this stimulated a decade long argument as to whether the observations were true or were these QUASARS just objects in our own galaxy that demonstrated weird physics? In more recent times, advancements in technology have enabled astronomers to study ‘normal’ galaxies in the region of these QUASARS and confirm that indeed they are very distant objects. On the 2nd January 2017 a group of villagers and friends congregated in my humble shed known as the Observatory and eventually, one by one caught a glimpse of light that has taken 8 BILLION years to get here. I stumbled across a reference to QUASAR 4C 11.69 also known as CTA 102. It is in the constellation of Pegasus looking west from the village at the moment. The old 9 inch SCT telescope used to spot the QUASAR This particular QUASAR was originally falsely classed as a magnitude +17 variable star. Variable stars are quite common but are usually quite regular in their variability. Not this one! Recently its magnitude has changed from +17 to nearly +11, which is an increase in brightness of 250 times. Think about this for a moment. This is an object that is TWICE the age of the Earth, more than half the age of the entire Universe as we know it and visible in my 9 inch telescope. Surely this is the most powerful and most distant visible object any of us will witness. Its brightness currently varies quite substantially on a daily basis so what is it? CTA 102 was discovered in the early 1960s from its varying radio source but was laughingly thought to be signals from an extra terrestrial intelligence and American folk rock band The Byrds wrote a song about it in 1967 called ‘Younger Than Yesterday’. It is in fact a giant black hole at the centre of a distant elliptical galaxy and its brightness is determined by what it is currently consuming. So the recent huge increase in brightness is a burp of cosmic proportions quite possibly as it gulps in stars or even other galaxies. I write this in the present tense but it is highly likely this object ‘died’ eons ago and no longer exists. A QUASAR; a disk of stellar material feeding a huge black hole and artist’s depiction of data via NASA’s Spitzer and Chandra telescopes. Credit: Nasa JPL The village group found it a challenge to observe but with careful attention to excluding all other light sources and using averted vision I believe all present witnessed the 8 BILLION year old photons. Retiring to the kitchen to consume a well earned cuppa, some of us had another peek about an hour later and it had significantly increased in brightness in that time so obviously it had done similar to us. What next? A few days later, from the observatory I captured a star field image to show the QUASAR CTA 102 here in the centre of frame against known reference stars. This is a stack of 20 x 30 second exposures. QUASAR CTA 102 approximately Magnitude 12. 8th January 2017; Chris Higgins CTA 102 is now going out of reach. If it is still belching at the same rate in the Autumn we should check back then to see if it has satisfied its hunger. Feel free to join me. Follow my Twitter feed for regular updates on this and new topics from the backyard observatory. Twitter: @owmuchonomy Astrophotos: https://www.flickr.com/photos/blue5hift/sets
  24. Okay, the setup: I stayed out all night last night, set up the Edge 8 just before dark and viewed for a couple of hours before the Moon could come over the trees and fully wash out my sky, which was absolutely cloudless, with the best seeing since......probably last Spring. Unfortunately, the Full Moon rose about 8pm, so it wasn't a dark sky. I just looked at thing toward the north and west as much as possible. I took a break about 10pm, went in to get a cup of coffee, and Blade Runner-Director's Cut was just starting, so I had to get my sci-fi fix for the day. Went back out about 1:30am, the Moon was high by then and you could easily read a book by the light. Undeterred, I restarted my scope (AVX, used "last alignment" and it was dead-on). I was limiting myself to stars, looked at a bunch of doubles, and then I thought....clusters. M13 being rather far removed from where the Moon was, I skewed over to it and, expectedly, saw a dim blob, which would have been much better in a dark sky. So, I wondered if taking a picture would work. I had a 13mm Ultima Duo eyepiece in, it's threaded for a T-ring, so I attached my D3400, set it to bulb and ISO 6400, and commenced shooting some EPP, starting at 10 seconds and working up to 30 seconds at 5 second intervals. I had to shoot quite a few, checking focus and adjusting as I went, but finally got something you could identify. I looked at M42 for quite a while, managed to split Rigel, looked for a while at Alnitak. I considered looking for "attack ships burning off the shoulder of Orion" (movie quote from replicant Roy Batty). I saved my eyes for the last, looked at the Moon, unfiltered, then broke everything down and went inside about 4:30 am. Nothing fabulous, but for a bright night and early AP effort, I'm happy with the outcome. This is a single-exposure at 27.5 seconds, ISO 6400.
  25. Hi very new to guiding and using an OAG on my CPC9.25 SCT and need some help. A few weeks back I managed to capture 10min subs of IC434 without any real issue. I had my CPC9.25 mounted on a wedge, did an EQ North Align, then Polar Align > Align Mount routine. I slewed to a target and set about getting both my guide camera, Lodestar X2 & my DSLR both into focus on my attached Celestron 93648 OAG. My setup as follows: SCT > OAG > DSLR via Baader 2958550 Protective T-Ring The complete OAG thickness calculated from the manual is 66.8mm, comprising (SCT Adapter 25.3mm, OAG Body 29mm & Male M42 Camera Adapter 12.5mm) I can't seem to find info on optical thickness of the Baader T-Ring but can only assume that when attached to my DSLR, gives the norm 55mm to sensor. If this is the case then I am already at 121.8mm. To get focus in the guide cam I had to add a 1.25" nose piece extension and the original end of the guide cam is just visible above the top of the guide cam holder. Now skip forward to last night, I thought I'd try getting wider FOV images of the same target, no problem or so I thought, I have a Celestron f6.3 94175 reducer, I'll just install that directly onto the back of my SCT and attach everything else exactly as above, behind it. Well, getting my DSLR into focus was no big issue, just had to turn the focus knob a bit, the usual when using the FR but my issue was with my guide cam, the stars were huge doughnuts. Through a process of elimination I figured that I had to move the guide cam in nearer to the prism, so I had to remove the nose piece extension and push the camera all the way in to the holder as well as winding the OAG guide cam focuser all the way down. Doing this I managed to get sharper results from the guide cam but these stars were no longer round, they were very oblique circles, pointed at the narrow ends. After lots more fiddling and swearing I came to the conclusion that I could not solve this issue on site so gave up and removed the reducer. Later on I realised that it may be that I needed to adjust the position of the prism i.e. slide it in more to the light beam. As it happens I did not have a suitable allen key with me to try this. My question/s is/are: am I correct in thinking that I was possibly picking up stars right on the edge of the FR in the guide cam, the edge where all the aberration is? just wondering why it was necessary that I had to reduce the distance to light source of the guide cam but the DSLR distance was fine staying put & only needed refocusing? Thanks in advance
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