alacant

Hi Best to avoid laser collimators. One time job: centre the secondary using a Cheshire eyepiece. One with cross hairs makes life easier. It's then just a case of a quick tweak of the primary now and the. Have a look here. HTH

It's far more than a smooth tube;) It works fine. You just need to fit new M4 screws. Maybe a lathe rather? Cheers

I used Siril for calibration and stacking. This is a 10 minute thrash in st.

https://www.teleskop-express.de/shop/product_info.php/language/en/info/p6706_TS-Optics-NEWTON-Coma-Corrector-1-0x-GPU-Superflat---4-element---2--connection.html

Yes, everything. Apart from the clamp. In the end though, we got a GPU. Which just works. Boring eh? Good luck anyway; it's what ap is all about!

Yeah, the undercut on the Baader is a pain. Use a thin 2" parfocalising ring so that the compression ring misses the lip of the undercut. Or remove it altogether and have the screws bear directly on the cc. HTH.

Hi The op is -wisely- using the m48 connection. So he needs around 58mm, not 55mm. I copied Baader's diagram, here.

Hi The Baader cc needs 58mm backfocus. Stick a 3mm m48 spacer -or a low profile 2" filter ring without the glass- between the OAG and the cc and you should get you as close to coma free as you're gonna get over aps-c. Cheers and HTH.

Yeah, thanks. I'm gonna have to rethink this. Maybe mosaics with a reflector is the way to go... Anyway, not given up yet. I'll try with a uv-ir tonight. I seem to remember that that gave some improvement to an 80ed I once suffered! Cheers

Hi Thanks, no filters though. In the end, I just cheated!

I think you're spot on, and yeah, I'd forgotten about st's fringe killer. One more go with st and I think I'm nearly there. Also reminder to self not to process in a sunlit room. This is where it stands:

Hi and thanks for your reply. Do you have an example with bright stars? it would really help us decide. 128mm is the working distance from the ff to the camera chip for fl 420mm. I suppose it could be the ff or maybe just the bright stars. I tried a different field with fewer bright stars and it came out better. Maybe need to adjust the processing. lightly does it perhaps. Cheers and clear skies

Ah, ok. It's: Guide tab -> options Using EKOS you also have the option of multistar guiding which will help with your star shapes and sizes. I see PHD2 have multistar at the 'coming soon' stage too. If you can get your hands on one of the newer eos cameras, especially the ones with the 18mp sensor, so much the better. HTH

Hi The 450d is noisy so best to lose the dark frames, dither between each exposure, use IS0 400 and stack using a clipping algorithm. HTH

Hi everyone Could anyone tell me if this is what we can expect? It seems rather shot-quiqly-with-an-old-achro style. Unfortunately I can't find anything with which to comapre. Maybe just my processing but i would have thought even a cheap doublet would produce less blue than this. Please tell me I'm mistaken! Must say, I like the FOV it gives. SW 72ed with ff tsflat2 at 128mm. TIA and clear skies

+1. With no information, all we can do is guess. If you post -links to- example light, flat, bias and dark frames, or whatever you used, and an explanation of how you produced each, we'd be able to nail it. Cheers

Hi I'm in agreement with @almcl and @tomato Walking noise is easy to prevent by adding a dither to your sequence in between each frame. Calibrate your light frames with bias and flat but don't use dark frames, the latter will introduce more noise. Finally, stack using a clipping algorithm Siril does an excellent job of all stacking work and is 100% free. HTH

Hi everyone Visitors due with their shiny new 72ed had the flight cancelled at the last moment. Unfortunate. I was curious to see if there had been any improvement in sw refractors since my experience with an 80ed. Not as much of that nice dark nebula as the 72, but... The lack of moon as you carry out the telescope gives a false sense of optimism. Within an hour you could read a book by moonlight. Anyway, enough excuses. This is with the Bresser nt150s and EKOS' very solid multistar guide and PPEC. Alas, seem to be back without blue stars, despite Siril's photometric database:( Thanks for looking and please share your images of the same. eos700d @ ISO800

Hi If you wish to keep your current telescope and fit in the whole galaxy in one go in a ccd, then you're going to need something like this. I don't to think your telescope will cover that size camera though. You could do a mosaic instead however, with either of your choices. HTH

Hi At €35, maybe worth a go, if only to satisfy curiosity. A good 135 which I can recommend from hands-on is the Asahi Takumar 135. It doesn't cost that much more. There are f2.5 and f3.5 versions, although I believe the former to have fallen into the 'investment' category, with silly prices to match:( HTH

Hi Pre process the frames from each telescope using flat and bias master frames taken using each camera. Place both series of pre processed frames into the same folder. In Siril, the use the 'convert' tab, to take care of the renaming Register all the pre-processed frames. Stack the now registered frames with your favourite algorithm. HTH

I think the main requirement for dither to be effective is to move the camera in a random direction by a random amount BETWEEN frames, not constantly during them and drift or no drift, not always along the same axis. Cheers and clear skies.

Hi Unfortunately the moon is going to interfere for faint stuff like the veil. @bruno's suggestion of a cluster instead looks a better bet.

Hi So you could focus with whatever method you used before, but not with APT? Deneb is in frame and close to focus? Not sure...

Hi. Well done for getting 5 minute frames under those conditions. Are you sure they were reasonable well exposed? I think the weak link isn't that you're using a dslr, but rather the noisy sensor of the dslr you're using. The 450 is showing its age these days. If you can get one of the more recent models with the18mp sensor, you'd notice a big improvement. No exposure details, so I'm guessing that you used ISO 400, dithered between frames and stacked with a clipping algorithm without dark frames. If you didn't, there maybe something you could try. It may also help to go easier on the processing, stop before the noise gets out of hand? But hey, it's working great:) Cheers and HTH