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Image scale question for a 16” meade

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#1 Bouldermatt

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Posted 18 September 2020 - 10:10 PM

I’m liking to evolve my 16” meade lx200gps from visual to Astrophotography. Thinking of image scale and was wondering if any one has advice on cameras. I currently use the ASI2600mc pro on my refractor. If I used it with the 16” I’d be below 0.3 even with a focal reducer. I know the magic number for image scale is 1.0. So what’s the best approach here?

#2 RogeZ

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Posted 18 September 2020 - 10:43 PM

Matt:

Most modern cameras have small pixels. I think the common approach is to bin and up the scale. You can always image at 1x1 first and then at 2x2 and see if there is any gain in resolution. Tracking will need to very good to sustain that focal length.

#3 Bouldermatt

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Posted 19 September 2020 - 10:18 AM

That makes a lot of sense with binning. With that being said it seems like going with a mono camera instead of OSC is the way to go if binning is part of the work flow?

#4 Coconuts

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Posted 19 September 2020 - 10:29 AM

https://www.cloudyni...lor/?p=10516264

 

All the best,

 

Kevin



#5 Bouldermatt

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Posted 19 September 2020 - 11:22 AM

Great link and discussion. Thank you. If you’re binning 2x2 or 3x3, having a large full frame like to ASI6200mm should leave you plenty of resolution on the back end.

#6 sdbodin

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Posted 19 September 2020 - 03:16 PM

Since I use a Meade 16 LX200, I'll explain my setup for imaging. I use a Starizona reducer/corrector for about 2500mm efl at f6.2. Coupled to an Atik 460ex mono CCD that I bin 2x2 yielding 9 microns/ pixel for 0.74"/pixel which is just about right for my average 2" seeing. Binning a CCD results in very low noise and very efficient gathering of photons. There are plenty of forum threads about binning a Cmos camera and that it results in no gain. I do have an ASI1600MC-cool that I use on my 80 APO, but test on the 16 have shown me that the Atik is far faster and less noisy. Of course, there are other things to do to the scope like replacing the standard Meade back plate for a 2 inch size and getting a micro-focuser or custom adapter to fit the bigger plate and moving to a Bortel 2-3 site to take advantage of the scope.

 

My standard imaging run is 9/5 minutes of luminosity and 2/5 minutes of RGB, a very short amount of time for many, but suits me fine. Average magnitude reached is 21. Field of view is small, about 17 by 14 minutes, so this rig is a galaxy getter, which is my passion. Just an example of that FOV and exposure time attached at 60% full size:

 

n3718_16f6small.jpg

 

 

 


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#7 Bouldermatt

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Posted 22 September 2020 - 12:36 AM

Thank you. This is really helpful. Another question I have is about the load capacity of the scope mounted on a wedge? I want to make sure I don’t overload it.

#8 sdbodin

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Posted 22 September 2020 - 08:52 AM

In my case, wedge, pier, bolted to one ton of concrete, I have not found a load limit yet. Scope usually has an 80 APO mounted on rails above the OTA and either another 80 or my Meade 4in sct mounted below. Then a camera, reducer, OAG, filter wheel combination out the back. The 80s have cameras too. Probably 30 additional pounds of gear. 

 

Bigdog_in_home4.jpg

 

Biggest problem for me has been cable management, just too lazy to sort it out, I guess.



#9 555aaa

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Posted 22 September 2020 - 08:56 AM

Look for a used SBIG STL1100 camera. It has big pixels and is full frame. I use one on my Meade 16 SCT. I don't use a reducer. You can see images on my astrobin page as user brucev.


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