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Sky View Pro RA tracking error

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#26 Falcon-

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Posted 15 February 2011 - 01:39 AM

I should note that Jupiter and Saturn will still be quite small in the resulting image, to REALLY get them big you need something like a C14 with a barlow at 8000mm focal length (and amazingly good seeing) rather then a AT6RC at 1370mm focal length. Still though, I think it is a fun project. I have been wanting to try it since I got my own AT6RC but have not had clear weather alas. Last year I did get this shot of jupiter using an old webcam and a 912mm focal length scope. I would expect the AT6RC and your 1D MKIII in zoomed-liveview mode to get as good or better.

#27 gdd

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Posted 15 February 2011 - 08:24 AM

Falcon took some great shots with at 912mm with is CG-5 unguided. His copy must have very low PE. I believe the CG-5 can be guided.

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#28 Falcon-

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Posted 15 February 2011 - 02:08 PM

Falcon took some great shots with at 912mm with is CG-5 unguided. His copy must have very low PE. I believe the CG-5 can be guided.


Gale: Thanks for the compliment, however nearly every shot you see on my site is guided. In fact this M13 image is the only unguided image from the 912mm focal length scope, and that was with only 30 second exposures. I did though take quite a few shots at 300mm, 50mm, and 28mm unguided.

#29 gdd

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Posted 15 February 2011 - 03:29 PM

Hi Falcon,

Are you going to try any long exposures on your Celestron CG-5 ASGT with your AT6RC when the weather clears?

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#30 Falcon-

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Posted 15 February 2011 - 04:08 PM

Are you going to try any long exposures on your Celestron CG-5 ASGT with your AT6RC when the weather clears?


Yes I certainly will! I did in fact already give it a first try but my temporary guide-scope mount solution induced far to much flexure and I was not able to properly get the longer exposures I was looking for, also seeing was not very good at that time. I have a couple of threads with the results here (flame nebula, 300s exposures), here (Double Cluster, 60s exposures), and here (NGC891, 600s exposures).

While the 60s shots look fine you can see in the 300s and 600s shots evidence of the flexure and bad seeing conditions so I would not consider those a really good test of either the CG-5 or the AT6RC. Hopefully next month I might get the chance to give it a test in better conditions and with a better guide scope mount solution

#31 mfarrell

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Posted 20 February 2011 - 08:09 PM

Well, I bit the bullet and bought an Orion Atlas/EQ-6. I have to say that most pictures don't really do it justice...it's quite impressive in the flesh. Makes the old SVP look like an EQ-1! :lol:

Unfortunately, it's been nothing but clouds and rain here for the last week, so first light is yet to come. :cloudy: I have been very good and resisted the temptation to rip it open and start tweaking...at least until I have a chance to get an idea of it's performance out of the box. :jump:

Here's a shot of it with the new AT6RC and my 300/2.8 lens. I figure once I get settled in, I'll use my el-cheapo 4" F/6 achromat as a guidescope next to whatever I'm using for imaging. :woohoo:

Can you tell I want it to be clear? :grin:

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#32 Falcon-

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Posted 20 February 2011 - 09:19 PM

Nice setup!

Wow... that 300 f/2.8 is a BEAST of a lens! Somewhat interesting to see an f/9 and f/2.8 system set up side by side that way!

If you ever get the chance/if you have a second camera handy you should image with both at once. I do that quite often and find it interesting to get Wide and Narrow shots of the same target at the same time. Of course then you need to figure out how to mount the guide scope *and* those two! :)

#33 dale c

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Posted 20 February 2011 - 10:45 PM

Matthew, That's a good looking mount and from what I have heard it will probably serve you well...
Dale

#34 mfarrell

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Posted 21 February 2011 - 02:32 AM

Thanks Falcon. Yeah, the 300/2.8 is big, although the oversized lens hood makes it look even bigger...both in length and diameter. I haven't made up my mind yet, but I'm considering whether I'd be better off getting an autoguider rig next or a modded DSLR. I think it would be interesting to use both sets of optics at the same time. Maybe I could modify my 50mm finder to be a guidescope? :question:

#35 Falcon-

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Posted 21 February 2011 - 02:39 AM

I would get a Guide setup before modification - especially with so many targets being Galaxies in the next short while and considering your AT6RC.

The 50mm finder-guider has worked well for me so far. :)

#36 mfarrell

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Posted 21 February 2011 - 02:44 AM

Somehow...miraculously, the clouds parted around sunset and I was able to get some time outside with the new mount! I tested the polar scope earlier during the day and found it to be well centered. Since I bought the Atlas mainly for tracking and not for the GoTo, I just did a quick 2-star alignment. It was pretty easy, except I quickly realized that I will have to brush up on all my Arabic star names! :lol: I only did 4 or 5 goto's, and they were all within the edges of my camera frame, so I'd say within 0.5 deg or so. Not bad considering I sloppily did a 2 star align.

And now for the important stuff: tracking and PE! In summary, I am very pleased. 60s unguided on M42 was no problem (a couple of throw-outs but nothing like the old SVP). 90s on M81/82 gave me 80-90% keepers (although in my rush to test the mount I didn't collimate the scope and didn't focus very critically either). I have a lot of data to sort through, but for now, this is a redo 100% crop of the core of M42 that I posted early in the thread. This is a 60s exposure vs 30s previously, but everything else is the same (different mounts of course!).

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#37 mfarrell

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Posted 21 February 2011 - 02:54 AM

And here is an intentional drift test to reveal the PE. The image is a 20min exposure at 50% crop like before, this time I rotated the images so that they appear "level". I think I did the analysis correctly (same as last time) but I will have to double check myself. In any case, it is a huge improvement and I think it is pretty good out-of-the-box performance! From what I've read on the forums, 11-12 arc sec PE is pretty good for an Atlas.

Thanks to all for the good advice and comments. I think I have a good setup that will serve me well and keep me content for at least a little while. :grin:

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