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joelshort

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About joelshort

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    Nebula

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    http://www.buckeyestargazer.net

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  • Location
    Indiana, USA
  1. Tomato, one thing to also consider is what are your skies like? Will you benefit from larger aperture or are you limited by sky glow? If you have some amount of light pollution I'm not sure that going with a big scope will be as beneficial as from a dark sky. Without any doubt at all, were I making the choice again I would go with the much more robust CFF over a GSO. And that's saying something because I am incredibly cheap. Normally I look for the least expensive thing to get the job done. In this case, the best optics in the world won't work unless they can be carefully tuned mechanically and maintain that careful alignment. This is the difference. The GSO mirrors are fine by all accounts, bu the CFF scope is just so tight and smooth and will keep things in alignment. Once I got the replacement mirrors it literally took me 15min to collimate the scope under the stars. What would you like to see? Equal LUM data from both scopes?
  2. For this image the CFF/16200 was 0.61 arcs/px and the SV80ST/QHY163 was 1.62 arcs/px. Once I get the system all tuned up I plan to use the CFF at f/6, which will give me an image scale of 0.81"/px.
  3. I am extremely pleased to report that a plan I put in place 1 year ago, to have a dual scope/camera imaging rig, has finally come together and I am very, very pleased with the initial results. It all began last November as I was looking for a longer focal length scope in order to image more galaxies and smaller objects, and given my sky conditions and mount capacity I felt that a 10" RC was best suited for my needs. I settled on a CFF250RC, which I finally received several weeks ago. Shortly after ordering the CFF last December I began to see the benefits of CMOS cameras that thrive on many short exposures, specifically as it relates to dual scope imaging. Dual scope imaging carries with it several inherent problems, one of the largest being differential flexure between the scopes. This is particularly true when using two of the exact same scopes that both need to be pointed at exactly the same position in the sky. This leads to another large problem with dual scopes, needing to align those two scopes precisely. So I began to think about a dual scope/camera rig that does not use the same scopes. Long story short, I paired my SV80ST with a QHY163M and the CFF with a 16200 camera. Since the SV80ST/QHY163M has about twice the FOV and image scale, I don't have to worry too much about exactly aligning the scopes to the same position in the sky. I just clamped the SV80ST on top of the CFF and hoped alignment was good enough. I did need to shim one scope ring to move the focuser end of the SV80ST up a little, and I also needed to shift the dovetail plate slightly laterally in one direction, but the star alignment between the scopes is "good enough" and I didn't have to bother with some kind of X/Y positioning plate. Also, since the QHY163M is taking short exposures it avoids differential flexure or polar misalignment problems that would lead to star rotation etc that would happen with longer exposures. So while the CFF/16200 is taking 10min LUM subs, the SV80ST/QHY163 is taking 3min RGB subs. So on average I get an RGB image for every LUM image. I really don't have the knowledge to professionally plan all this out. In fact, a few people kindly advised me to reconsider, or at least warned me about what I was in for. grin.gif But really, with the CMOS camera it was easy. I just bolted everything together and hoped for the best, and I'm pretty pleased with things so far. As a first test, I had the CFF scope at f/8 (in normal practice I will probably keep it at f/6). I chose NGC891. When I began this I wasn't really expecting an image to come out of it as I was just testing things out, but the tests went well so I kept getting data. The really cool thing....I got most of the 17.5hrs of data in ONE NIGHT. Getting 10hrs of LUM data really helps smooth things out and I didn't do ANY noise reduction on the LUM data. The RGB was of course more noisy and I was somewhat aggressive with noise reduction in the RGB, but that's the beauty of LRGB imaging. Below is a pic of my imaging rig. And here is NGC891 [URL=http://buckeyestargazer.net/Pages/Galaxies/NGC891.php][/URL]
  4. Hello all, I'm new to this forum and thought I'd introduce myself with an image I recently took, a 2 panel mosaic of vdB 7, 8 and 9. I took this image at my first star party back in September. [URL=http://www.buckeyestargazer.net/Pages/Nebulae/vdB7-9.php][/URL]
  5. Very nice! I really like the new ArcsinStretch too. It works really well on RGB data.
  6. I'm taking a slightly different track with a dual imaging setup. I am pairing a CFF 250 RC (working at f/6) with a Stellarvue SV80ST f/6. The plan is to capture LUM data with the CFF and lower resolution RGB with the 80mm. The image scale of the CFF is 0.82" and the image scale of the 80mm will be 1.61". Since the effective FOV of the 80mm scope is about 1/3 to 1/2 larger than the CFF, I'm not worried about the scopes being super accurately aligned. My imaging cameras are a Moravian G3-16200M and QHY163M. What makes this possible is the advent of CMOS camras that allow for (and some would say need) shorter exposures, which will avoid many of the issues involving flexure between the scopes. And in one 10min LUM image with the RC I can get 1 each of RGB at 3min each. I'm getting this set up soon and hopefully in another month I'll have an image to show for it!
  7. I have a QHY163M and use it with 1.25" Astrodon filters. This was mentioned, but I think it needs to be stressed that focal length can be a big factor. At f/6 I do not see ANY mechanical vignetting, and that is with the camera at the standard 18mm backfocus, and the clear aperture of Astrodon filters is actually a bit less than other manufacturers. I use an Atik EFW2 and it has the ability to precisely center the filters. You can adjust the filer position slightly in either direction.
  8. Thanks for posting the link! I just received a new CFF 250 RC and of course it came with a test report...now I know how to read it. And it looks good!
  9. I'm looking for a QHY OAG-M. If you have one to sell let me know your price.
  10. I have some interest in finding a small Riccardi reducer, the M3 version, for testing purposes on a project I'm working on. If you have one to sell let me know your price.
  11. Thanks for the reply, Olly. I currently have a QHY8 camera, which has a larger chip than the 383L+, and have used my 80mm apo many times with it. I also have a field flattener (not reducer) and even with the flattener I do get a bit of vignetting with the APO and QHY8, but nothing that flats can't take care of. I suspect with the smaller chip of the 383L+, even using 1.25" filters will not produce more vignetting than I am currently getting with the QHY8. However, if I use a combination REDUCER/flattener, that will take the f ratio of the APO down to f/4.7, will the flattener part of that offset the lower f ratio, in terms of how much vignetting I get? As you can tell, I'm really just trying to bide my time until the new camera arrives in a few weeks (hopefully), at which time I can actually test everything out. joel
  12. I am anticipating getting an Atik 383L+ mono camera in the next few weeks, and I was hoping some of you Europeans who have this camera could give me a bit of advice (I'm in the USA). 1. I will be using an 80mm APO (f/6.25) and 200mm Astro-Tech RC (f/8), along with 1.25 inch (31mm) filters. Atik says 31mm filters are OK down to about f/5, but will I experience vignetting with my setup? 2. Is a focal reducer and/or flattener necessary with this camera? Thanks in advance for any advice. joel
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