Help me choose a ZWO Camera for my C8

[evltoy]

Hey All,

I gather I'm not the only newbie asking this question. I'm in need of some advice as I'm starting to look at camera's to suit my needs and to match my evolution8.

My requirements are;
- Primarily I want to use this camera for Planetary images
- Have the ability to dip my toes into DSO for the interim on the AZ mount
- Have the capacity to be a guide camera in a DSO setup
- My budget only allows for $500-$550 just on camera
- Would prefer to stick with ZWO as its widely used in the community
- Colour or Mono is not an issue. I will be going mono with a DSO camera in future

Down the track the camera will be used as a guide camera after getting a more suited DSO camera and a EQ mount.

Searching around my options looked to be:
ASI120MC-S
ASI224MC
ASI290MC
ASI290MM
ASI462CM
ASI385MC

Please let me know if I have missed something to think about.

Cheers
Wayne

[Hemi]

Hi Wayne...Welcome

I think the 462 would currently tick of those requirements and suit your current scope.

Cheers

Hemi

[multiweb]

Got a 462MC. It's very sensitive. Lot of potential.

[astro744]

Have a look at Bintel’s astronomy calculator or better still give them a call. According to their astronomy tool this camera/telescope combination produces significant oversampling at f10 which only gets worse with Barlow’s.

Now I must say I am not an imager but have been looking at various camera/telescope combinations should I ever want to try some imaging.

See https://www.bintel.com.au/tools/astronomy-calculator/?focallength=2032&fratio=10&pixelsize=2.9&xpixels=1936&ypixels=1096&eyepiecemm=&eyepiecefov=&binning=1&multiplier=1&target=moon&p1=&p2=&p3=&telescope=&camera=&eyepiece=&v=322b26af01d5

If I change the focal length to say 540mm, f5.4 then this camera is a good choice.

Note instead of picking the telescope and camera from the list just enter the parameters manually. You can get the camera pixel size and number of pixels from their web site offering the cameras. This is because not all the cameras and telescopes are listed in the drop down.

I’m not really sure how much of an issue oversampling is especially significant oversampling. Imagers can perhaps answer that one.

[evltoy]

Thank you to all so far for giving me some advice, I must admit the 462 was not on my radar which is quite interesting. I’ll have to look more into that one. In regards to camera and telescope combination I did go on the Bintel website to have a look and the oversampling is minor on all of these cameras. It does gets better if I use a .63x. reducer for beginners DSO. With a Barlow I don’t think I would go down the path of using one with these cameras on the c8.

Keep it coming guys ��

[Ittaku]

That Bintel calculator seems to grossly overestimate the ideal resolution. Oversampling is an issue only when you have more than 5x the pixel size in F stops. They're using 2x in their calculations.

[Tulloch]

The 462MC is the pick of the bunch for planetary - don't forget to get an IR-CUT filter with it. Optimal focal ratio with the camera is around f/15, so look into a barlow to achieve this. Siebert Optics in the USA make good 1.5x barlows.
https://www.siebertoptics.com/SiebertOptics-barlows.html

Andrew

[multiweb]

Hi Andrew, just noticed this post. Does the camera optical window already acts as an IR cut? Never checked. It's also very sensitive in IR. Why would you want to cut that out? Avoid bloating?

[Ittaku]

Size of pixels aside since they can be worked around with different barlows, is there really an advantage to the 462 over the 224 if you're not going to be doing IR imaging?

[evltoy]

Very interesting as I went through all the cameras I listed and the only ones that came up to be ok (Slight Oversampling) was the 120MC/MM, 224MC and ASI385MC.

Both the 290MC and 462MC (same specs as 290) gave me Significant Oversampling which was conflicting to what every here was recommending.

Looks like the Bintel Calculator needs to be taken with a grain of salt. The question is.... how much salt as I dismissed the 462MC based on the results they provided.

[Ittaku]

I'd say in its current form it is nigh on useless to be quite honest.

[evltoy]

IR imaging??? not that I'm aware off.... at least for now:shrug:

[evltoy]

So the consensus is to go with a 462MC

[Ittaku]

For visual imaging, you would always use an IR filter with these cameras, and the 462 has a lot of extra near-infrared sensitivity which you'd just be blocking out.



462:
https://astronomy-imaging-camera.com/wp-content/uploads/ASI462-QE-curve.png
224:
http://astronomy-imaging-camera.com/wp-content/uploads/QE-ASI224.jpg

[evltoy]

Hmmm. If I require to put an IR filter on the list, so be it.

[multiweb]

The calculator is suited for deepsky imaging where your typical seeing seats at ~2". With planetary regardless of your camera pixel size you're after much smaller details and you're using very long FLs. So you want a camera that is sensitive enough to give you a high frame rate and good SNR in low light. You want to capture the maximum number of frames within a set time period. That's the name of the game.

[Ittaku]

That makes more sense, thanks.

[Tulloch]

If you don't use an IR cut filter, then the RGB channels will be swamped with IR and the planet's colours will be incorrect. Here is some more information on that (written for the ASI224MC, but also applicable for the 462 as the IR sensitivity is even higher). The 462 has an IR transparent window, so you need to get an IR cut filter for colour imaging (I just bought the ZWO IR cut filter when I bought the camera).
https://www.planetary-astronomy-and-imaging.com/en/ir-cut-filter-asi224mc/

The 462 sensor is more sensitive than the next best sensor (the 224MC which I have), it has a lower noise level (0.5e vs 0.8e) and the smaller pixels mean that its best focal ratio is f/15 rather than f/20.

The maths which shows how the focal ratio = 5x the pixel size of the camera is determined is attached. Don't worry about the Bintel sampling tool, as mentioned above it's designed for DSOs not planetary.

Andrew

[Camelopardalis]

Also bear in mind that different wavelengths of light come to a focus at different positions, so what might be in focus for visual (where green dominates), won't be the same as in the Infra-Red.

You can see this if you use any kind of colour filter with a camera...the focus shifts accordingly.

[echocae]

Read this article in the link below... its interesting and help u decide

https://agenaastro.com/articles/guides/cameras/zwo-astronomy-cameras-buyers-guide.html

[multiweb]

Cool. :thumbsup: Some more reading to do. I have various IR cut filters. Will fit one in the light path next session. You've mentioned the ideal focal ratio before. Will check that out too. To date I have gone as long as the optics and mount allow me which is ~8m @ 200mm aperture.

[evltoy]

this is all very good information & more then what I was anticipating.

I think I'll go with the 462. With the IR cut filter, I only need this if I'm planning to just view the object on my screen, but for recording I would remove the IR filter?

Cheers
Wayne

[Ittaku]

You have to use the IR filter for capturing.

[evltoy]

Hey all
I ended up getting the 462mc. Weather has been crap so I haven’t had a chance to test/play with.

In regards to an IR cut filter, I have a Baader Neodymium (Moon & Skyglow)-Filter which is an IR cut. Should this filter be ok or will the colour shift be to great to give me incorrect colours?

[Tulloch]

While the M&SG filter will remove the IR, it will also cut out a fair bit of the visible spectrum in the yellow region which is probably not ideal. I bought a ZWO IR cut filter from Bintel when I bought my ASI224MC, they are not that expensive...

[evltoy]

Thanks Andrew. I was looking at the zwo UV/IR cut filter... it is the cheapest brand name going around, but not in stock :(

Another brand I was looking at is the Astronomik IR-Block Filter... what is everyone's thoughts on this?