pipnina

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...

I'm going to email him I think, but I wanted to try and get some more info first. I just spun the camera around to see if it's on the front end or back end of the scope. Here's the two files, when I look at matching stars in each corner, I see much the same error. So it seems to me that the corrector is probably fine. Either the scope's optics are just not all that, or Mr Reid's work has been undone in transit perhaps? Maybe there is an issue in my camera train causing this, though I'd know not what. In have noticed the focuser barrel seems to wobble a tad, Not sure if that could cause all this or not... LUM 180 degrees.fits LUM NO ROTATION.fits These being the stars I paid most attention to: one image with the camera unrotated, other with the camera and corrector turned 180 degrees. Star shapes look the same to me, near enough. But in a full image the shape changes in each corner, with the corner opposite these stars being much tidier.

Unfortunately all is not well. Some issues remain with the scope, maybe it has even worsened as there is now a notable amount of colour at the corners! I got the chance to give it a test last night. Of course having not had the opportunity to til now, I sent her to look at M42! Aside from my constant amazement whenever I image this target at how little exposure is necessary for a clean image (in this case, 6 minutes!), I am rather disappointed to learn that this endeavour of sending the scope off for service has largely been in vain. I wouldn't say useless as I need to investigate further, and Mr Reid did affix my focuser which I did not attach properly the first time, as well as clean some "mist" from the fluor element. But coma is still present, and maybe pinching (looking at Hatsya, that halo's points seem a bit odd, I don't notice it anywhere else and to be honest, that effect doesn't bother me much). And worst of all chromatic aberration at the corners! I am not sure if this could mean the lenses are misfigured, or if I now have an issue where the corrector at the other end is just not up to task. I have always meant to replace it with a higher quality one but maybe this is the time? I don't know. But if we assume Mr Reid's work stayed in place in transit, the problem must lie elsewhere! Keen to hear anyone's thoughts on this 😬

Why stop there? https://www.astrosysteme.com/en-us/products/az2500-f6-f2/ Anyone got 7 million euros to spare?

The retail pages say it is threaded for 2" filters, which use M48 thread. You can see the thread on the camera side is smaller than the barrel on the focuser side, so the camera side thread is almost certainly M42x0.75mm (T2) You can see in this thread a version with M48 connection on the camera side, and see how much bigger the thread on the camera side looks compared to the same 2" focuser barrel. Hope this helps

I think lasers can't collimate cassegrain telescopes fully, as your beam goes from focuser to secondary, then when the secondary is properly collimated the beam comes back to your laser source. I.e. you get no reflection onto the primary. I think there are multi-beam tools that let you collimate cassegrain telescopes with a focuser-mounted tool, like this one: https://www.teleskop-express.de/shop/product_info.php/info/p11188_TS-Optics-2--LED-Collimator-for-RC-Telescopes-and-all-other-Types-of-Telescopes.html But like you I have little experience collimating a cassegrain scope, so I can only offer up the little knowledge I have... This might be some help, even though a CC and an RC are a bit different:

Looks good! Did you use the Astronomik UV-L3 cut trick with your FMA180 or are you shooting it "full spectrum"? Trying to work out if this little thing is going to satisfy me or if I will want to save up for something like the ACL200 or Borg 55FL

For my 571, the hot pixels are there but get removed by the default settings in pixinsight. I do dither though on every 3rd sub. I also found that for my much noisier Nikon D3200 which had super bright hot pixels, that the hot pixels would overpower the signal even when dithering and the hot pixels would trail all over my images. However the ultimate savior for me was the Sigma-clipping stacking method. It does a phenominal job of removing hot pixels if you dither your subs. Here is the rejection map for a 1.5 hour stack of 17 second exposures taken on my google Pixel6 on the main camera, when using sigma clipping in pixinsight. My goodness! And the final stack, once I finished processing... Those hot pixels are gone! Ok, the image isn't exactly "clean", but we are dealing with a very tiny and poor quality sensor, plus optics that have a very complicated distortion and abberation pattern which makes it impossible to work with in a desirable way for astro. But if sigma clipping can make a phone produce an image this good and remove all that gunk from it, it should work just as beautifully on a much higher quality astrocam!

The colour in those stars is gorgeous!

I agree it looks like the IR light on the phone reflecting off of the eyepiece. Like Elp says you can probably stick something over the IR bulb (use online diagrams to find it, it's quite well hidden from the eye on my phone). I'd say you should experiment with your current gear and consider upgrading only when you feel confident that it's the right next step, after you've tried things like stacking phone videos on planets etc. Good luck!

The telescope has made it home! Es said he cleaned the lenses, identified the middle element as a "fluor crown" and said it had a slight mistiness to it, but he has attempted to clean it up. He also epoxied the focuser to the tube so it should now be nice and rigidly attached, unlike when i sent it to him. Sadly the weather tonight is poor and the forecast doesn't show much hope either, but I hope to test it soon! I actually thought he was underselling himself a bit when he gave me the bill, but as long as he's happily compensated and i haven't broken my bank all is well I suppose. Fingers crossed!