pipnina

I also only have a Pixel 6 (the middle tier one that doesn't have a telephoto lens) and I did try the AP mode by itself, once using the RAW + AP mode built into the phone, plus stacking some of those together with PixInsight. Another I made with DeepSkyCamera app and pix stacking. Here are my results: Sadly I found the camera to be severely lacking, mostly in the optical department but the sensor was a bit hit-and-miss too. The two big things optically are distortion (it seems to ripple in waves from the center, no distortion and sharp image gives way to STRONG coma, a few times), and very intense vignetting. I was unfortunately unable to use flats to get rid of it and so had to rely on teasing the background extraction tools in Pix. The big thing sensor wise is dark current. The sensor was more hot pixel than not, requiring dithering. But as you can see from the images above (Cassiopeia image was dithered, Cygnus was not) dithering does make the distortion much more pronounced in the final image. I think the way forward with the P6 is to take raw images using the 4 minute AP mode and stack them, as the P6 will automatically remove hot pixels with its own stacking process. Taping an ice pack to the screen side of the phone and controlling it remotely with developer controls might help too haha. Would I buy this phone for the AP capacity? I don't think so. But if I were considering it regardless, I think its capabilities are surprising! Not least that it picked up the hydrogen in cygnus from NAN to SADR. The eagle-eyed may even spot the veil nebula and the heart & soul neb. This is what PixInsight rejected from the Cassiopeia pic during stacking (stretched):

With such a massive range of flatteners about, it's hard to say which ones, or at which price ranges, are any good. I certainly found that the TS Photoline 0.79 I used with my APO was not very good (chroma, undercorrection etc). Not knowing how much I might need to spend, I decided to go for a "cheaper" option on FLO first: The Starfield comes in at only £220 which is quite low-end for big-scope flatteners (WO sell one at £700+, the small Riccardi sets you back nearly £500). But it also comes with the benefit of a big set of lenses and rare feature of adjuatable backspacing! I got my old kit off the back of my scope, assembled the focuser with the new corrector, and a WO rotator I picked up to allow me to continue adjusting the camera rotation. Immediately I found that this corrector moves the focal plane a lot more than the Photoline. So much so that even though the corrector sits in a similar place to the Photoline, my focuser ran out of travel! I had to remove the rotator to give me enough slack, and I only have a few mm left either way. Impressions once I got my focuser re-straightened for the new kit were quite good. Stars seem quite tight around the field, with a small bit of coma right at the corner of my APS-C frame, however this may be related to backspacing which also needs some discussion. I started off with it at 0 on the adjustable scale. I noticed it might be a little short so I moved it, in two goes, about 5mm further out. Surprisingly this had little affect on the image! My Photoline flattener was so intolerant of backspacing error that missing 5mm of backspacing produced a warp-speed effect! This one almost doesn't seem to care, but I will need some more testing to be sure. As for a more "final result" here's a stack and a single-frame (3-sub R-G-B) colour image of the results: I think the biggest issues with the corner stars here come from the optics of my OTA and not the corrector, I think my focuser is still slightly mis-aligned or maybe my front cell now isn't 100% tilted properly because the focuser has moved. Either way I think this is a big improvement over the photoline in various ways (less vignetting and nowhere near as much chroma spread at the corners for one, better tolerance for poorly set backspace for another. And the price is quite reasonable. This is on an APS-C sensor. Photo taken with the Photoline for comparison:

Signed! I was very disappointed a few months ago, when the fire station on the street below me finished its renovations. While the building is far better for the fire service and looks nicer as well: The builders have installed the outdoor lights neigh on pointing upwards! There's one floodlight that is so bright and poorly angled, that I (50 meters away at least) could use its light to read by in my kitchen when it's on. Ludicrous! It literally lights up the side of the house, not nice...

I thought I was having it bad with no imaging from dec to february! You've gone very deep in the limited time you had at least!

I think finally this is coming to a close! This last month has had horrid weather and clearoutside has shown me nothing but red, unltil an island of green appeared at 00:00 last night! I had to run outside and set up so I could make use of it! My setup routine by this point is well rehearsed so aside from me forgetting to polar align (again) I got everything set up and quickly saw that Mr Reid's work had survived the postage this time! I feel a great sense of relief that all my work (now about 6 months worth) with this scope has begun to pay off... All I think needs to be resolved now is a probable flattener upgrade, as the one I got from the previous owner seems better suited to smaller sensors (maybe 4/3 size) I've looked at the riccardi m63 0.75x and the explore scientific 3" 0.7x and both seem promising but finding real world examples of their quality is hard! The market for third-party flatterers seems to have little middle ground between super-cheap and super-expensive. Most seem to be tailored for a specific scope. Thank you all who have offered kind words and advice in this time!

That's fair. I just know that when belts are assessed on printers it seems to show tighter is better, reduces vibration and ghosting etc. There isn't a huge load there either really, but if high tension proves important it might be a relatively easy fix. Vlaiv already has a long slot for the motor to be moved around so in theory hand tightening could be done easily enough. Like you say it took me a few goes to get the rowan mod right but I managed it by hand... I dunno

Perhaps the 3d printed belt tensioner for 3d printers could be adapted a bit to fit the motor, allowing people to just twist a little thumb screw and tension/relax the belt? Or at least, the principle of it anyway. https://www.thingiverse.com/thing:4718212

Re: Belt drive If you used a reduction from motor shaft to an intermediary shaft with one belt, then put the smaller size pulley on the intermediary shaft above the larger pulley, you can then have a second thicker belt attach between that small pulley and a very large pulley for the RA axis shaft. I found pretty cheap pulleys that are very thick (2cm thick 45cm length). Thicker pulleys means less stretch effect as well, and if tensioned properly, no appreciable backlash. For a "poor man's EQ5", maybe doubling up the pulleys would be necessary to reach the 10KG imaging limit without stretching... Printed pulleys probably would let us get a bigger reduction than the pulleys I've seen available commercially too. For a larger mount especially however... A clutch or brake needs to be considered. Worm mounts naturally cannot move without the motor driving them as the worm gear can drive a gear but cannot be driven by it. This protects our equipment from the consequences of poor balancing and random power or software failures! For the small tracker belts could still work though, maybe easier as the free-fall problem isn't as much of a concern for small 1-3kg payloads.

I think one thing to consider is that barn door trackers are very limited and, imo, not very good and actually kind of bad value. If this star tracker was even twice as expensive at 100 euros or so, chances are its performance would outstrip the typical barn door by so much, it would still be a worthwhile price. Especially as the cheapest manufactured tracker otherwise costs €300+. My gen1 star adventurer makes a little clock ticking noise, the stepper in there is probably only using a resolution of something like 2 steps per arcsecond or so, this project is targeting about 4 ticks/second as a homebrew project! Your eccentric gear looks very promising to me, I think it could be optimised by getting the number of teeth in the inside gear to be as close to the outside gear without locking them together, then making the eccentric movement roughly the same as one tooth pitch. If this is right it becomes a bit like a cheaty strain wave gear in my mind?

Ah yes, assembly would be a bit tricky. The only way I can think of to make that buildable is to split a herringbone gear into two halves, then using a bolt going top-down to secure them. This way each half of the gear can be twisted into place I think... Regardless as you say, a bit too complicated. As for single-helix gears, I think they should still work fine as any axial force is going to be very small compared to the rotational forces we desire. Consider that the HEQ5 only produces a torque of around 2.4 newton meters at the driven end... I can far exceed that with a torque screwdriver and my wrist, and this is a big mount for up to 10kg payloads + counterweight and ideally operating at arcsecond accuracy or better. As for the vertical sweeping motion, maybe i am missing something but I think actually the gear does not shift vertically during a gear mesh, the horizontal plane doesn't move and it just creates a barber shop pole illusion. The layer lines should be safe I think. For the freecad screenshots, I think you are in perspective view, if you switch it to orthographic I think it will be easier to see the tolerance between gears!

The only thing I can think of immediately that could stop the cement grinder noise is switching to helical gears. These are good because they have multiple teeth engaged at once and "ease" into each mesh, unlike straight cut gears like used here and in the SW EQ mounts. I believe the main disadvantage of helical gears comes from efficiency and limitations on maximum torque, but in most applications (car gearboxes for example) the benefits in terms of noise and smoothness outweigh the negatives. Other factors certainly at play here but this gearbox makes very little noise for example with the helical shape Might be worth an experiment with two gears side-by-side instead of redesigning the whole planetary gearbox at first.

A lot of camera lenses are distortion-free already thankfully. If anyone wanting to try this already has a DSLR and an 18-55mm kit lens, it is likely to be pretty distortion free wih no post processing. Can't say the same for the typical 55-200 kit lens option however. (as I understand, most of these kit lenses are basically rebrands even if they have Nikon or Canon stickers on them)

This indeed. My stock Ender3 printer makes an awful racket. Sounds like some sort of robot orchestra when it's printing. My boyfriend bought a second hand Ender3, with some mods including the mobo replaced with the Ender3 S1, which has upgraded stepper controllers. It. Is. Silent. No noise besides that of things sliding over eachother and the fans. As for the noise the gears make at higher RPM, this could be tolerance or backlash as gears should in theory sound relatively smooth when applying continuous force in one direction. But when switching direction even metal machined gears sound cataclysmic (unmodded skywatcher EQ mounts with the brass motor-to-worm train sounds like someone tried to put a car into reverse while going 70 down the motorway, as many of us have first-hand experience...) Also Vlaiv, I'm very keen to see how you test the smoothness with a laser, I have envisioned using an optical mouse sensor myself as they can detect exceptionally small movements as well.

Sometimes I struggle to get my head around this. My best guestimate is that as stars are pinpoint, we capture 4x of their light with a 2x as big mirror, but because they also shrink with mirror size they appear brighter? I.e. if we had a 1 meter scope and viewed way above the seeing limit, we'd reach the end of returns for brighter stars as the smudge gets larger with magnification? I think this can also mean imagers see fewer stars with a 50mm frac than a 130mm? I have seen some photos that show really tight narrowband images where the stars almost seem to have disappeared but they still seem quite strong in NB in my 130mm frac and in my 200mm newt

I sometimes run outside to swear at my equipment mid-session (things like the mount bugging out and needing the old off/on treatment, or me forgetting to plug something in etc) totally fear-free. Other times my mind is trying to tell me I'll need to fight for my life at any moment. I have jumped a fair few times, once when I heard walking, only for it to be a hedgehog! Another time when I heard a soft but loud snap and THUD. That turned out to be the apples falling from the tree haha.

If a mirror-based scope, the only service you can really get is a re-coating, where you send the mirrors away and they remove the old coating and apply a new one to the glass. Mirror alignment is easily handled at home, and would be lost in transport between you and anyone who could do it for you anyway. For a refractor, the most common need for a tune-up is fungus or re-coatings. Fungus often grows between lenses that get water between them. Happens a LOT in normal photography. Sometimes it can be cleaned off, sometimes it's a bit too stubborn. Refractors can sometimes need adjustment of the lenses, if they are de-centered. This is a bit specialist, especially when you get to triplets. But for the most part refractors stay the line if well built so unless dropped should be fine in that regard.

Struggling to find the 400 iso version, but 100 is available https://analoguewonderland.co.uk/products/kodak-ektachrome-film-35mm-colour-iso-100

I wonder how many of the types of film mentioned in this book are still in production! Many that went off the market have come back due to film getting a resurgence in recent years, but some (Fujifilm Across 100 for example) came back with a slightly different recipe. By my understanding, few films available today are suitable for astro, as they either suffer from insensitivity to Ha or they have intense reciprocity failure (6 minute sub on rollei infrared 400 got me 4/5ths of nothing haha) I am trying illford 3200 now, and might try the fujifilm across 100 II next, but my poor star adventurer isn't guided so I am a bit worried I'll be getting star trails if I go much longer on exposure. Unless I find a way to put it on my HEQ5, but then I'd rather image with my main scope on a given clear night if possible! I hope the book proves a good read!

That definitely busts the myth I heard then! Maybe the myth applies when these scopes are used with the 0.67x reducer/flattener... This thread is making me want one of these now ha.

One factor to consider is that (as I understand) all of the affordable 6" and 8" RC scopes are rebrands of the GSO RC line. This means they all have a small flaw in the primary baffle (you can print or buy a print to pop over the baffle tube to fix it, but unless you do, flat calibration isn't as good.) Another is cost. At the end of the day you're pitting these scopes against others in their price range. The only type of scope I can think of that is cost competitive with the 6 & 8 inch RCs is a newtonian. But as you say despite being cheaper for more aperture, they are heavier and take up more storage space! Other compact options like those from celestron could work but do cost a lot more. Then there's the collimation, which seemingly can be quite complicated on an RC as the focuser needs to point at the center of the secondary, but the secondary then needs to be tilted to bounce the laser back to the source in the focuser. This can apparently create a little dance that can take some doing. I forget the final step for getting the primary lined up but I recall it being easier than getting the secondary and focuser to behave! Another factor is that RC scopes get better with size, their illumination and corrected diamater get larger with a bigger primary, and they can even go down to f6 above a certain size instead of the common f8 or even f9 for small ones. I think (?) the RC6 struggles to provide a well illuminated and corrected view for APS-C Sadly I don't have direct experience, but as I understand this is some of the more prudent info when considering one.

I had something similar happen when I switched from a newt to a refractor. The GPU coma corrector and the flattener both have the same 55mm backfocus, so I figured I could just take one corrector off, new one on! Job done, time to image. I had astigmatism lines off axis on my images that looked like they stretched for lightyears! After a few weeks of imaging without the corrector, not sure WHAT was going on, I realised... The GPU has an m48 thread, the new corrector has an m42... So the 6.5mm of length in my m48->m42 adapter was no longer present! 5 quid on ebay later for an m42 extension tube, all is well haha.

To be totally clear: You have a dew shield of some sort extending from the scope? I could see light from the moon, street lamps, house windows or even far off-axis stars/planets refracting or scattering on the front corrector plate if it's not shielded. Other than that, I don't know what to suggest as I've no experience with this scope, but I wish you a quick resolution!

I should imagine it depends a lot on the method used to manufacture. One would expect a lathe to produce very good, concentric and round parts. But if it's cutting too fast, too much pressure on the part, and the part is not supported at both ends, you may end up with the part being produced with an undesirable shape. I think gears are also not easy to dimensionally inspect. Mind I don't have any experience with that aspect of machining myself... In theory, a larger gear being driven by the worm would be less affected by backlash between the gear and worm, as 1mm of movement at 200mm diameter is half that of 1mm of movement at 100mm diameter driven gear. Could be that, given less-than-perfect materials, the real solution is to make the whole thing bigger? Alas brass is rather expensive, but other materials must be suitable too, like hardened mild steel, if properly lubricated and protected... I keep thinking about if some way might exist to re-circularise the worm, some kind of lapping process perhaps? Lapping paste instead of lubricant on the worm and driven gear, get the backlash just shy of binding and take her for a whole shaft rotation or two. Then adjust again. Maybe after a few goes around it will be much closer to a snug fit? I might not be brave enough to try it on my own kit, mind you haha.

I got the pegasus power box advance, It's been great at keeping my kit going. My only wish was that it'd have more USB ports instead of the 4 wide 12V sockets. One more USB would let me plug the mount into it, meaning only one cable going from laptop to telescope. I didn't get to test if it powered my HEQ5 properly as I abandoned last night's session. But given as when the accessories are all powered up, dew heaters at 90% each, main cam using TEC cooling to 0c, and mount on standby only used about 1.5A of the 3A my power supply could provide... I think it would have worked? Maybe slewing would send it over the edge though...