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Equipment Discussions >> Mounts

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gdd
Pooh-Bah


Reged: 11/23/05

Loc: N Seattle suburb, WA
Re: Sky View Pro RA tracking error new [Re: Falcon-]
      #4386496 - 02/14/11 06:26 PM

Hi Matthew,

You can get a G11, or maybe even a MACH1GTO for no more cost than your camera and lens. Or maybe that is your camera OR your lens!

Gale


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dale c
member
*****

Reged: 03/30/09

Loc: Sedro-Woolley, Wa.
Re: Sky View Pro RA tracking error new [Re: mfarrell]
      #4386520 - 02/14/11 06:38 PM

Matthew, if you don't mind push to you might consider a used or even a new Losmandy G11. I have used the GM8 with good results but the G11 is better. Presently using a 10 year old MI-250 for photography and the GM 8 for visual. Both mounts will last longer than I have left....

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gdd
Pooh-Bah


Reged: 11/23/05

Loc: N Seattle suburb, WA
Re: Sky View Pro RA tracking error new [Re: dale c]
      #4386559 - 02/14/11 07:03 PM

Hi Matthew,

I'm getting a G11 with the OPW upgrade for better unguided tracking. Will add autoguiding as I get to longer FL.

Gale


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mfarrell
member
*****

Reged: 06/14/07

Loc: Northern California
Re: Sky View Pro RA tracking error new [Re: Falcon-]
      #4387196 - 02/15/11 01:09 AM

Quote:

Too bad about not having the dual axis drive... If that 300 f/2.8 is as good or better then the 300L f/4 I have been able to use I would indeed recommend you keep using it, including after you get an Atlas or CGEM! There are quite a few objects much to large to fit in the FOV of the AT6RC so it is very good to have a "wide field astrograph refractor" like that 300mm lens




Oh yes, the 300/2.8 is a gem with amazing resolution and pinpoint stars all the way to the edge...I definitely want to keep using it, especially once I can get exposures over 60s...

Quote:

That being said though I can think of a way to use the AT6IN on your existing mount - try some planetary photography! There is some software called EOS_movrec that will record the live-view video output of DIGIC III and 4 cameras, you can use that to capture some short video of the Saturn or Jupiter or the Moon and stack the results with RegiStax. Since video is going to be on the order of 1/15th of a second or faster exposures the tracking error will not be a problem at all.

I should note that I have not seen anyone use eos_movrec with a 1D MK III yet, but it is DIGIC III based so I would *think* it should work.




oooh, that's a good idea! I didn't know that was possible to pull video from the older cameras but I should give it a try. I've gotten some decent single shot images of the moon, but I haven't even tried getting the planets.


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mfarrell
member
*****

Reged: 06/14/07

Loc: Northern California
Re: Sky View Pro RA tracking error new [Re: gdd]
      #4387201 - 02/15/11 01:12 AM

Quote:

You can get a G11, or maybe even a MACH1GTO for no more cost than your camera and lens. Or maybe that is your camera OR your lens!




Haha, that may be true, but a new mount isn't going to help pay the bills, unfortunately. I have the Canon gear for the freelance sports photography I do, but it takes nice astro photos too!


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Falcon-
Post Laureate
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Reged: 09/11/09

Loc: Gambier Island, BC, Canada
Re: Sky View Pro RA tracking error new [Re: mfarrell]
      #4387226 - 02/15/11 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.

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gdd
Pooh-Bah


Reged: 11/23/05

Loc: N Seattle suburb, WA
Re: Sky View Pro RA tracking error new [Re: Falcon-]
      #4387521 - 02/15/11 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.

Gale


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Falcon-
Post Laureate
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Reged: 09/11/09

Loc: Gambier Island, BC, Canada
Re: Sky View Pro RA tracking error new [Re: gdd]
      #4388184 - 02/15/11 02:08 PM

Quote:

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.


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gdd
Pooh-Bah


Reged: 11/23/05

Loc: N Seattle suburb, WA
Re: Sky View Pro RA tracking error new [Re: Falcon-]
      #4388375 - 02/15/11 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?

Gale


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Falcon-
Post Laureate
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Reged: 09/11/09

Loc: Gambier Island, BC, Canada
Re: Sky View Pro RA tracking error new [Re: gdd]
      #4388449 - 02/15/11 04:08 PM

Quote:

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


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mfarrell
member
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Reged: 06/14/07

Loc: Northern California
Re: Sky View Pro RA tracking error new [Re: mfarrell]
      #4400221 - 02/20/11 08:09 PM Attachment (24 downloads)

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!

Unfortunately, it's been nothing but clouds and rain here for the last week, so first light is yet to come. 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.

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.

Can you tell I want it to be clear?


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Falcon-
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Reged: 09/11/09

Loc: Gambier Island, BC, Canada
Re: Sky View Pro RA tracking error new [Re: mfarrell]
      #4400378 - 02/20/11 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!


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dale c
member
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Reged: 03/30/09

Loc: Sedro-Woolley, Wa.
Re: Sky View Pro RA tracking error new [Re: mfarrell]
      #4400548 - 02/20/11 10:45 PM

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


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mfarrell
member
*****

Reged: 06/14/07

Loc: Northern California
Re: Sky View Pro RA tracking error new [Re: Falcon-]
      #4400837 - 02/21/11 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?

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Falcon-
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Reged: 09/11/09

Loc: Gambier Island, BC, Canada
Re: Sky View Pro RA tracking error new [Re: mfarrell]
      #4400844 - 02/21/11 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.


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mfarrell
member
*****

Reged: 06/14/07

Loc: Northern California
Re: Sky View Pro RA tracking error new [Re: dale c]
      #4400849 - 02/21/11 02:44 AM Attachment (20 downloads)

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! 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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mfarrell
member
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Reged: 06/14/07

Loc: Northern California
Re: Sky View Pro RA tracking error new [Re: mfarrell]
      #4400855 - 02/21/11 02:54 AM Attachment (24 downloads)

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.


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