dan_adi

After a long long time, my imaging setup is complete, and now I have my first subs :). Took about 4 years to get here but last night I was really excited. I chose randomly M110. The image was taken with a CFF 8 inch triplet, f 6.5, 1300 mm FL. The mount is a Mesu 200 MK1. The camera is a Moravian G3 16200, at a pixel scale of 0.93 arcsec/pixel. For offaxis guiding I used a Lodestar X2 with a OptecSaggita OAG The control/capture/guiding was all done in Prism v.10. The autoguiding RMS varied between 0.3 and 0.5 arc sec. I think the Mesu 200 will handle the scope well. I was most interested to see if I got the distance from flatner to sensor ok. Stars seem round to the edge, at least to my eyes. It is just a single sub with some stretching. All I need now is clear nights and time to learn PI

Hello, I was thinking about the larger ones.

Hi guys, do any of you have a Fornax mount? How do they perform? Haven't any luck finding some reviews out there.... usually not a good sign, but I am curious

Hi guys, this is a small tutorial about modeling I did some time ago, maybe some will find it useful. I hope the link to the pdf still works. The testing was done with a 12 inch SCT, not ideal, but it was very educational for me. Since then I got an 8 inch APO that rides on the Mesu 200 . This week I'm receiving the last adapter for the imaging train, and I am back in business. I went the refractor way, because the SCT was not what I had hoped for, imaging wise, but thats another story. I am really excited to see how the refractor-Mesu pair will perform. The only thing I don't like about the Mesu is the lack of options for absolute encoders ... (a friction drive mount with absolute encoders will give 10 micron a run for its money 😀)other than that, it has a learning curve as everything else. Be patient, learn the Sitech software and everything should work ok

Well, put that Celestron on a real astroimaging test ;), the moon is way too easy and doesn't require much. Let's not fool our selfs, with regard to amateur astroimaging of DSOs the refractors will outperform many reflectors. They are well designed, well build, and a lot and I mean a lot more easy to work with. I tried for 2 years to work with a 12 inch SCT on a Mesu mount and the SCT ended up sitting in a corner collecting dust., no matter how much I tried to "optimize it". Try modeling a mount with a Celestron or Meade? forget about it, they simply are not built well enough. For lucky imaging of moon and planets, sure a Celestron or Meade will do because you don't need guiding or mount models or any kind of precision. If you want a good reflector that won't give you much trouble you still have to pay the big bucks .... see those 12-17 CDKs from Planewave (they are not cheap).. and even so they still need collimation from time to time, "thermal management" and all the management a reflector demands. Using a refractor demands almost 0 effort.. you have to focus before imaging and that's it. They cost much? Well that depends on the budget, but just for the "hassle factor" involved with imaging, I will gladly choose a refractor any day, even with their small aperture, keeping in mind that for long exposures the resolution will be limited by the seeing

CFF 8" f6.5

If you are referring to planetary imaging, where seeing is not a problem because of ultra fast exposures yes, otherwise no.

It depends. The "aperture rules" rule is not always true. The resolution of the scope will be limited by seeing. There is no point building a 10 meter scope in a back yard, cause it will perform no better that a 10 inch scope. Sure the image will be brighter but in terms of resolution ... I guess a more important factor is the quality of the optics and mechanics. A small scope with high quality will go head to head with bigger, less quality scopes. I used only a few designs, 10 inch newt, 12 inch SCT, 4 inch doublet frac and lately 8 inch Apo triplet. It might seem strange but the 8 inch frac performs better that the other scopes on DSOs. Is it the quality? Is it the design? I don't know, but all the other scopes were donated to friends. The major downside is cost, but for me the views and general versatility of the refractor justified the purchase. Bottom line I think quality is more important than aperture

I have a small obsy ontop of my house. I had no issues with heat. The big advantage is 360 degrees clear view.

Very impressive refractor! How are the views? I received my 8 inch frac a few weeks ago, but in my area winters are mostly cloudy, and I can't test it :(, the suspense is killing me :)) hope spring comes early

CCD photometry could be a solid reason for the SCT. Did you find mirror shift/flop to be an issue in photometry? I'm guessing with shorter exposures the impact will not be important? I have to say, the SCT drove me in the hands of a big refractor, and I might become a refractor man for life, if only the clouds will go away

For a while in college I had an 10 inch DOB. That scope impressed me almost every night. Glad to see others had similar experiences!

After 2 or maybe 3 years with an 12 inch Meade SCT I started to wonder what I was thinking Most certainly it was aperture fever, but I did not find the scope to excel at anything. Visually the views are average, DSO imaging is a pain with mirror shift, focusing by moving the mirror..etc. The only thing we use SCTs are planetary imaging? Why did you guys get an SCT? And what are you using it for? Are you happy with it?

Don't mind me asking but why buy such a big SCT? In my case (with the 12 inch SCT) it was aperture fever, and lack of knowledge, and lack of experience .. :)) . I am at the point when the only thing I would use it for is planetary imaging. Perhaps I am just curious why we buy SCTs..?! On topic. I didn't need to clean my corrector plate, but the youtube videos are very informative. You should give it a try

Have you considered CFF refractors? Top quality, same as TEC or APM-LZOS. Their 140 mm APO is around 6000 EUR, close to your budget. They make their own field correctors (flatteners), and even adaptors for your camera. I received my 8 inch last week from them, but its been cloudy and rainy ever since so I can't test it, but from exterior inspection everything is perfect. https://cfftelescopes.eu/product/refractor-140-mm Or if you want a triplet with some fluorite in it check https://www.astro-theke.de/astro-optik-manufaktur/produkte/, Their 135 mm is around 7000 eur if I recall. (I don't know if fluorite makes a big difference in imaging vs FPL53, we should ask some experts) If I were you I would wait a little bit longer, and get a high quality refractor for imaging. You can't go wrong with a frac. I'm not saying the Esprit is bad or anything, but why not gather a little more cash and get the best one you can. Also, a high quality frac will keep its value over the years, so you can resale with little loss. PS: Did the same mistake as you... have an 12 inch SCT and trying to dso image with it.... total frustration, never got it to work well so I ordered a refractor

I totally forgot to check if the focuser has a rotation feature :)) This is what happens when I m to tired, the neurons stop firing properly :))

Thank you for the detailed response. The manual rotator is not really a big necessity anyways, and I didn't think I can just put the rotator in front of the flattner if I really want to use it . The scope is f 6.5 at 1280 FL, so with the above calculation, the optimal distance prism to guide-sensor would be 52 mm. And I assume the same distance applies to prism - main imaging sensor.

Well I have 90 mm at disposal between the flattner/corrector and the ccd sensor. I was looking into Optecs motorized Sagitta OAG but it eats up 31.7 mm. The G3 with filter wheel eats up additional 47 ish mm and I have a manual rotator with about 30 mm... So I am over the limit with Optecs Sagitta. Would it be a bad ideea to place the OAG before the flattner?

Hello, What do you consider is best for a refractor with a FL of 1280 mm, guidescope or OAG?

Thanks, in the near future I am hoping to get some Chroma filters too.

Hey, where did you order the filters from? Directly from Chroma's website?

Vlaiv gave an exceptional answer. I did try to image with a 12 inch SCT and a Mesu mount. I found it very frustrating, not because of the mount, but because of the scope. The 2500 focal length was too much, minor but evident mirror shift after a merdian flip, minor but evident shift if you focus by moving the mirror. I am going the refractor route myself. If you want a mirror scope, that's just fine, but pick one with a stable mirror like an RC or a CDK.

This is the topic with mesu modeling

Hey, a mesu 200 user here. The mount is a great value for the price. The sitech 2 controller has a learning curve, but on the sitech groups you will find help fast. Also mr. Mesu himself answer any email as soon as posible. The sitech software incorporates mount modeling. With modeling you get better pointing accuracy and tracking. I did try different models just to learn the software, and the best rms value I got was 17 arcseconds (that is very good for a mount with no absolute encoders). Mount modeling is best done with a rigid imaging gear aka a refractor on the mount. When I tried modeling with my sct I did not get consitent results because of mirror shift/flop. I did write a small tutorial about modeling a mesu on this forum (search mesu mount model). Absolute encoders are nice to have, but not a necesity, more like a luxury. Even with absolute encoders, if you have a long focal length scope you may need to guide! Just remember if you choose a Mesu, read the manuals and take your time with it. Sometimes I got frustrated with the sitech software because I did not have pacience to learn the software. Some users said it was build by an engineer for an engineer , but the mount delivers the goods! I hope I gave you some advice. I highly recommend the mesu.

Thanks for the additional info. There are few reviews of big apos out there. Every bit of information is useful when trying to make a decision! I only found one bad ‘bad’ review for CFF, and 0 bad reviews for the APM LZOS 175