starwatcher_ch
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Interesting discussion here! Thanks! A while ago I've asked myself what happens, if during collimation the primary is pushed inside when using extensively all 3 collimation screws. Thanks for the answer 🙂
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Yesterday I took M 57 test shots again (12 exposures, each 60sec, no flats, no darks). With the camera rotated by 90°. This time it doesn't seem to suffer from reflections... but only at first glance. There is also a faint reflection in the lower left area. When I check the field of view in Stellarium, the reason for these reflections has to be bright stars outside of the field of view on the oppisite side... Sulfat on my first M 57 and Sheliak on yesterdays image. They are the brightest stars in the outer filed of view at around Mag. 3.5. After the M57 test shots I switched to NGC 6946 Fireworks Galaxy. There is also a very very faint reflection in the stacked image that must be caused by HIP 102011. So far I've no other explanation...
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Looks great! Well done.
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It's exactly this one: https://www.teleskop-express.de/shop/product_info.php/language/en/info/p8075 I've only used it once so far... so the only thing I can say about it: its stiff enough to attach the Bahtinov mask to it for focusing. My hope was the dew shield will eliminate reflections I'm struggling with, especially on M57 Ring Nebula wide field. But also with the dew shield there are reflections...
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I'll check if there are any scratches later. But I think if there would be a scratch, there would be reflections on every target...
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Thanks. Had the same idea. This is my plan for next CS 🙂 At least I know now that the dew shield makes no difference.
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I don't think so. Yesterday I did some M13 abd M57 exposures in a row, with the dew shield in place. Also I use a "swimming hat" for the primary mirror area to block stray light. This was my initial "problem" image: Yesterday I had the same reflection on M57 again... exactly the same position like before. But not on M13. It seems to be related to the selected field of view and most probably the CC. Each image is a stack of 12 sub exposures, no flats, no darks.
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My focuser tube is protruding into the OTA around 16mm (measured from the black outer tube) while MPCC/DSLR is in focus position. Maybe with a TSGPU it would be much better, since I read it extends the focus point about 10mm... I don't know... Maybe someone here with a 130PDS/DSLR/TSGPU combo still in its original condition (tube not shortened)? What this combo looks like would be very interesting...
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Wonderful Heart Nebula! Great processing!
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The only reason I don't own the TSGPU already is because of it's price. It's more expensive than the 130PDS scope itself 😉 It feels somehow "unnatural" to spend more money on a cc than on a telescope... the 130PDS/MPCC combination seems perfect in this regard. But I'd rather buy the TSGPU than cut the focus tube 😉 I'm still trying to figure out the optimal MPCC-DSLR sensor distance. But if I am not satisfied after trying all possible distances with 2 sets of spacers (2 x 0.3mm, 2 x 0.5mm and 2 x 1mm) and the reflections occur constantly, I'll order the TSGPU. I'm a little surprised to hear that. Thank you for your frank words! Yes, we live and learn... But no problem at all, you could buy a new 130PDS... it's sooo inexpensive! 😉 (I'm joking!)
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Thank You, Pierre!!! Much more than yours! Unfortunately I can not check it at home because I'm on a business trip until tomorrow... but I'll measure it once I'm back home! Do you use a TSGPU cc (Update: I just saw that you use a SW Aplanatic cc)? I read that it extends the focus around 10mm. I guess if I would use the TSGPU it would look like on your images... Honestly I want to avoid shortening the tube as much as possible since it's irreversible. Only if nothing else will help... BTW: Thanks for the video link! Will give it a try next session 🙂
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You're right! Actually there are a lot more lines which I didn't notice... thanks! I use the Baader MPCC, I don't know if it comes from it... the three previous images taken with the 130PDS didn't have these lines. A few sessions ago, my 70D almost slipped out of the focuser, so I've been tightening the compression ring quite a bit since then... maybe to strong? Would that produce such an effect? I really had fun with the 400mm Canon, but now with the 130PDS at 650mm I feel like a kid in a toy store again 😉 Focusing with 10:1 speed is a dream compared to a photo lens... and finally GoTo on the GEM28... it make things easier 😎 I have a dew shield but have never used it. Maybe I'll give it a try next session. Bahtinov mask and flat fields are the reasons I never used it. But maybe removing the dew shield for focusing and flats isn't as problematic as I think... Clear skies 🔭
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@Pitch Black Skies The past 3 days were intense 😉 But I read the whole thread! I see everybody struggles with more or less the same issues, but about one thing I didn't find enough information... On my M13 and M57 images there are some reflections: faint on M13 (top mid right - vertical direction) but bright on M57 (bottom right - horizontal direction). What causes these reflections? Are they caused by bright stars outside of the FOV? I double checked the field of view in Stellarium and for M57 it's obviously caused by the star Sulafat. But is it possible that the 3 faint stars (almost in a row) outside of the FOV are responsible for the faint reflections (top mid right) in my image? What would help to prevent such reflections? Flocking the scope/spider?
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Hi This is a lovely thread about the 130PDS! I own the 130PDS since 6 weeks and luckily the weather managed that I have been able to use it 6 times since then 🙂 I started with AP 7 years ago with the Star Adventurer and Canon lenses up to 400mm. Since refractor prices are rising and rising I decided to upgrade my setup with the small Newton, even if I don't really like diffraction spikes. But so far the spikes don't bother me... until I'll shoot the Pleiades 😉 Setup: Sky-Watcher Explorer 130PDS iOptron GEM28 Lacerta MGEN II guider / 50mm guide scope Canon EOS 70D (modified) Baader MPCC Mark III Upgrades: Primary mirror ring 2" adapter with compression ring "swimming hat" Still searching for the optimal distance sensor-mpcc... but all-in-all I really felt in love with this little scope! CS Karol (The images are captured from my balcony in Derendingen, Switzerland, Bortle 5)
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I'm on page 32 out of 153... so not as bad as 7000 😉 I still have one question unanswered... I'm curious if I can find the answer on the remaining 121 pages... 🤯 If not, I'll come back 🤓
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