ASI 1600mm Pro versus ASI 2600mc

[The_bluester (Paul)]

Within reason I don't see the glows as hugely problematic.

I did some ten minute subs with my ASI294 at one point and even a couple of 20 minute ones and the glow could still be calibrated out. So long as they do not become so pronounced that actual data is lost to saturated pixels in the areas where there are glows I don't see a great issue, the raw subs might look ugly but if it calibrates out to nothing then what issue unless you are trying to look at things live?

[gregbradley]

Good point Paul.

The calibrated darks I saw still leave residual photon noise in the area though. That may not show up in the final image though, it probably doesn't. But its not something you want as its another point of possible failure in processing.

Greg.

[Camelopardalis (Dunk)]

I have an ASI183MM (uncooled) and find the amp glow to be quite manageable, so long as I used darks from comparable ambient temperature (of course).

It just looks horrendous if you create a master dark and then apply an STF on it in PixInsight

The thermal noise on the 183 is very low. It might be nice to upgrade to the cooled version for summer, and for ease of darks libraries, but not a worthy upgrade for me with the current exchange rate

It's not a big sensor, about the same size as a 694 IIRC. Kind of a sweet spot for most scopes, if one considers the spot diagrams

[gregbradley]

Thanks Dunk.

Yes that size sensor works well in many medium to short focal length scopes.

Good to hear the amp glow is manageable, I was sure it must be as I have seen many superb images on Astrobin from a few imagers using them.

The 695 sensor was very good but I found the 19,000 electron well depth to often be inadequate.

Worst case here is to use 2x2 binning as with 20mp there are plenty to bin an still have good resolution.

Greg.

[Camelopardalis (Dunk)]

There are certainly pros and cons.

There's no escaping the smaller pixels and shallower well depth of the 183, and the read noise is about 30-40% higher at "optimal" gain levels when compared to the 1600, but the lower thermal noise balances it out. I find exposures (on the same scope) are about 2x longer with the 183 than the 1600. The 1600 has the larger FOV of course, at the potential risk of resolution under the right conditions at shorter focal lengths.

As a bit of an extreme example, I've been doing some lunar imaging with the 183 this past week and it's proven itself to be very adept at it, with practically no noise in the shadows while not overblowing the highlights.

[gregbradley]

Twice the exposure compared to the ASI1600? Is that because you are undersampled - ie. less than 1 arc/pixel? What about 2x2 binning does that help?

Greg.

[Camelopardalis (Dunk)]

Most likely undersampled with the 1600 at ~1.4”/px and 0.98”/px with the 183 on my Esprit 100, the latter especially dependent on the conditions.

I don’t typically bin. I want all the resolution I can get.

[gregbradley]

Right.

Greg.