Decisions?

[TheThing]

I currently have a ZWO ASI462MC camera but have been offered an Altair Astro 224c usb 3 for a bargain price.  

I know that the 224 has 3.75um compared to the ZWOs 2.9um which, if I'm not mistaken, makes it slightly more sensitive but the ZWO has a slightly larger sensor.  Other than that they seem pretty even.

Just wonders if anyone had any thoughts?

Edited December 1, 2022 by TheThing

[newbie alert]

Larger sensors don't make it anymore sensitive, just captures a bigger surface area

The 224 is a cracking sensor but the 462 has newer technology, sensitive especially in the IR and methane band compared to the 224... I'd look at the QE curves and see what suits you in what you're shooting, IE broadband or beyond the visible light 

[Elp]

I'd stick with the 462, it's newer too but it depends what scope you're using it with.

[TheThing]

Mainly with my 127mm mak for planetary but also, possibly, with an 8" newt and/or a 80mm frac.

[ollypenrice]

Pixel size determines resolution of detail (assuming you are not over sampled), chip size determines field of view and quantum efficiency (mainly) determines sensitivity.

A good rule of thumb regarding decisions is not to make any. Buy everything.

lly

[Elp]

1 minute ago, ollypenrice said:

Buy everything.

I think it's an undiagnosed endemic within this field.

[TheThing]

4 minutes ago, ollypenrice said:

 

A good rule of thumb regarding decisions is not to make any. Buy everything.

 

Sound advice! N+1 and all that.

[vlaiv]

Think of replacing one sensor with another?

I'd say - don't bother. Specs are so very close and ASI462 will have advantage in some areas that you might like

- pixel size is not important for planetary - you will dial in optimum F/ratio with barlow in both cases

- peak QE is comparable (no solid data on that to be 100% certain, but going by common numbers, I say 224 has very small edge there, but again, no data), but 462 is much much better at IR photography - if you fancy that sort of thing, like methane band or just simply IR pass filters (>825nm)

- comparable read noise, both have around 0.5e

- slightly larger sensor is advantageous when doing lunar (or solar) - for full disk images - less panels per mosaic

[Elp]

You are likely to get slightly more detail with the 224 paired with the mak for planetary but very subjective difference, to be honest I have the 224 as well as other cameras of different pixel sizes, QEs, sensor sizes and very rarely have seen much of a difference quality wise between any of them other than the quantum efficiency producing better range of colours on certain cameras. The 224 is mainly used as a secondary guide cam for me now.

Edited December 1, 2022 by Elp

[vlaiv]

Just now, Elp said:

You are likely to get slightly more detail with the 224 paired with the mak for planetary

How come?

1 minute ago, Elp said:

the quantum efficiency producing better range of colours on certain cameras

What do you mean by better range of colors?

[Elp]

I would have thought the smaller pixels paired with the higher resolution offered by the aperture can resolve slightly more detail, but I could be wrong. I found very little difference imaging Jupiter with my Z61 and my C6 with the 224. Seeing on planetary will have more of an impact.

Some cameras I've used capture much more muted colours which can also be related to the bit depth. This is evident in the star fields whereby there's little difference between yellow and blue stars depending on what I'm imaging. My 294mc and 183mm (mono is a different kettle of fish I know) produce much more range of colour compared to my 485mc for example. My post processing remains the same between them.

I just try with what I have available, each camera has their own strengths and weaknesses.

 

[vlaiv]

8 minutes ago, Elp said:

I would have thought the smaller pixels paired with the higher resolution offered by the aperture can resolve slightly more detail, but I could be wrong. I found very little difference imaging Jupiter with my Z61 and my C6 with the 224. Seeing on planetary will have more of an impact.

In planetary imaging we match effective pixel size (compared to our target) to what the aperture can resolve - by using barlow lens and opting for certain F/ratio (or focal length).

It does not matter whether you have 2.9um or 3.75um pixel size if you end up with same "/px (or sampling rate) for each that is dependent on aperture size.

In either case, provided you are correctly sampled - you will capture all there is to be captured.

10 minutes ago, Elp said:

Some cameras I've used capture much more muted colours which can also be related to the bit depth. This is evident in the star fields whereby there's little difference between yellow and blue stars depending on what I'm imaging. My 294mc and 183mm (mono is a different kettle of fish I know) produce much more range of colour compared to my 485mc for example. My post processing remains the same between them.

Yes, that is the "problem" with some cameras - but it's really not the problem with cameras, but the way we treat our data.

Each camera has different QE in different parts of spectrum - but none "is correct".

We take raw data from the camera - and we just assign it to R, G and B of our working color space - without really doing anything to properly adjust it / transform it.

When we do that - we simply get wrong color. From every sensor (none is "better" with regard to this). Only difference is that one produces colors - that "we think are more correct" - or perhaps "that are more pleasing to our eye".

With additional step of color calibration - they would all produce correct color information and they would all produce the same image (ish - there would still be some small differences - but barely noticeable to human eye, if at all - every measuring device has measurement precision, and within that precision should produce correct results).