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Redcat 91 with small pixel camera vs LZOS 115/805 with IMX533

Equipment Refractors CMOS
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Brian avatar
Brian avatar
Hello, I am currently using a 115/805 LZOS refractor with an IMX533 color camera.
The LZOS is unfortunately quite heavy, and on top of that, you have to deal with things like backfocus. Recently, I got a Redcat 91, which I use with an IMX571 mono camera.
The telescope is nice and lightweight, and you don’t have to worry about backfocus or similar adjustments. Since I use the LZOS on my AM5, I also need a sturdy tripod.
Currently, I’m using a Berlebach Planet.
For the Redcat, however, a ZWO carbon tripod would suffice. I’ve been playing around a bit on astronomy.tools, and I noticed that when using the Redcat 91 with an IMX585 or IMX183 sensor,the field of view and resolution per pixel are very similar to the LZOS with the IMX533.

     Red = LZOS with IMX533
    Green = Redcat 91 with IMX585
    Blue = Redcat 91 with IMX183

With the LZOS and IMX533, I get 0.96" per pixel, and with the Redcat and IMX585, it’s 1.33".
With the Redcat and IMX183, it’s 1.1" per pixel. Now I’m considering getting a mono IMX585 or IMX183 and using it with my Redcat.
This would allow me to switch to a lightweight tripod.
I could then use the LZOS instead of my 80mm APO for visual observation. Am I correct in thinking that the results would be similar, or are there significant disadvantages to using the Redcat with one of these cameras? The LZOS is a fantastic telescope, but if I can avoid it, I’d prefer not to lug it around and instead go for a nice, lightweight setup.

I ask
 Best regards,
Brian
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Jonathan avatar
Jonathan avatar
or are there significant disadvantages to using the Redcat with one of these cameras?

The "disadvantage" of these cameras is that they are pretty small sensors, so you're not taking advantage of the full capability of the telescope, though arguably even an APS-C isn't taking full advantage of it either. 
I would also avoid the 183 now that there is better sensor tech available. No amp glow, bigger full well capacity, etc.
Brian avatar
Brian avatar
Jonathan:
The "disadvantage" of these cameras is that they are pretty small sensors, so you're not taking advantage of the full capability of the telescope, though arguably even an APS-C isn't taking full advantage of it either. 
I would also avoid the 183 now that there is better sensor tech available. No amp glow, bigger full well capacity, etc.

 Thank you for your reply.I know that the small sensors don't fully utilize the image circle of the 91mm Redcat.
But that's not my focus here. I'm looking for an alternative to the LZOS + IMX533 setup.
The field of view would work for me with both the IMX585 and the IMX183 on the Redcat.
The resolution per pixel is quite similar, aside from minor (?) differences.The question is whether I would face any significant disadvantages using a smaller sensor on the Redcat compared to the IMX533 + LZOS setup:
Of course, the LZOS has a slightly larger aperture, but what about other factors?
Would I face any drawbacks?I'm also unsure about the IMX183.
However, the pixels are nice small, and the field of view is slightly larger then the IMX585.
The low full well capacity doesn’t seem too problematic—you’d just use shorter exposures—and amp glow should be manageable with dark frames, right?
Tony Gondola avatar
Tony Gondola avatar
The 585 is my main camera and it's working really well. I think you'll find that the non-square frame shape and smaller FOV will inspire you to create interesting compositions that can make the same old objects seem new. Not having amp glow is certainly a plus. In fact, the 585 is so clean you can do without dark frames in most cases.
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