Re: Close up of M81 without CCDT67

Dale Ghent

How good would 2.5um pixels look on a 2.5m focal length at 0.21"/pixel? Pretty good provided you have the extra time that will be required to expose the target and if "normal" seeing for you is also in the realm of "pretty good." You'll certainly have the roundest stars on the block, assuming your mount and other mechanics are also up to the task.

Oversampling isn't inherently bad if you're blessed with time and stability. Most people in that situation would start at 2x2 binning, maybe 3x3... at which point you must ask yourself if you're really using the right tool for the job because you would be paying for a lot of sensor real estate that is being used just to make up for the time and conditions.

On Feb 14, 2020, at 3:14 PM, Robert Chozick via Groups.Io <> wrote:

Thanks Roland. My last dark sky outing was my first use of this scope and camera. I am really confused on the whole image scale question. I bought this camera because it has the largest pixels of any of the CMOS cameras. The image scale is .6 with this camera and 1600mm. My scale is about 1.8 with my FSQ 106 - 530mm. If the recommended guidance of a scale of 1-2 for image scale is used the 1600mm should be too small an image scale. Most CMOS cameras have only 2.5-3.5 micron pixels vs 4.63 on my ASI294. Is oversampling bad? The .6 scale in my image sure looks ok. What about .4 or .3? I intentionally did not get larger than a 1600mm focal length because of this issue (and yes, guiding issues are not as bad vs 2000 and over). Everyone asks why I got an 8 RC instead of a 10 or 12 inch RC. The above reason is why. Each new CMOS camera that comes out still has really small pixels. How good would 2.5 micron pixels look on a 2500 mm scope?


On Feb 14, 2020, at 1:18 PM, uncarollo2 via Groups.Io <> wrote:

That's really nice. Sharp and great color.

A question: do you think that 1600mm is a sweet spot for all kinds of deep sky imaging, especially for high resolution work? Especially since the newer Cmos cameras have such small pixels and would be able to take advantage of a high resolution optic for small faint galaxies.


-----Original Message-----
From: Robert Chozick via Groups.Io <>
To: main <>
Sent: Fri, Feb 14, 2020 12:06 am
Subject: [ap-gto] Close up of M81 without CCDT67

I got another shot of M 81 on the same trip as the M81-82 image, this time at f/8 1620mm.

Robert Chozick

Robert Chozick

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