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Old 13-10-2020, 05:29 PM
evltoy (Wayne)
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Help me choose a ZWO Camera for my C8

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
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Old 13-10-2020, 05:57 PM
Hemi
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Hi Wayne...Welcome

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

Cheers

Hemi
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  #3  
Old 13-10-2020, 06:16 PM
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multiweb (Marc)
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Got a 462MC. It's very sensitive. Lot of potential.
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Old 13-10-2020, 06:20 PM
astro744
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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/astr...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.
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Old 13-10-2020, 06:53 PM
evltoy (Wayne)
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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 ��
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Old 14-10-2020, 01:36 PM
Ittaku (Con)
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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.
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Old 14-10-2020, 01:48 PM
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Tulloch (Andrew)
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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/Sieber...s-barlows.html

Andrew
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Old 14-10-2020, 01:54 PM
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Quote:
Originally Posted by Tulloch View Post
The 462MC is the pick of the bunch for planetary - don't forget to get an IR-CUT filter with it.
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?
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Old 14-10-2020, 03:27 PM
Ittaku (Con)
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Quote:
Originally Posted by Tulloch View Post
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/Sieber...s-barlows.html
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?
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Old 14-10-2020, 03:37 PM
evltoy (Wayne)
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Quote:
Originally Posted by Ittaku View Post
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.
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.
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Old 14-10-2020, 03:39 PM
Ittaku (Con)
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Quote:
Originally Posted by evltoy View Post
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.
I'd say in its current form it is nigh on useless to be quite honest.
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Old 14-10-2020, 03:39 PM
evltoy (Wayne)
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Quote:
Originally Posted by Ittaku View Post
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?
IR imaging??? not that I'm aware off.... at least for now
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Old 14-10-2020, 03:41 PM
evltoy (Wayne)
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Originally Posted by Ittaku View Post
I'd say in its current form it is nigh on useless to be quite honest.
So the consensus is to go with a 462MC
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Old 14-10-2020, 03:43 PM
Ittaku (Con)
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Quote:
Originally Posted by evltoy View Post
IR imaging??? not that I'm aware off.... at least for now
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...2-QE-curve.png
224:
http://astronomy-imaging-camera.com/.../QE-ASI224.jpg
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Old 14-10-2020, 04:06 PM
evltoy (Wayne)
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Hmmm. If I require to put an IR filter on the list, so be it.
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Old 14-10-2020, 04:15 PM
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Quote:
Originally Posted by evltoy View Post
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.
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.
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Old 14-10-2020, 04:27 PM
Ittaku (Con)
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Quote:
Originally Posted by multiweb View Post
The calculator is suited for deepsky imaging where your typical seeing sits at ~2".
That makes more sense, thanks.
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Old 14-10-2020, 10:30 PM
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Quote:
Originally Posted by multiweb View Post
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?
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-...lter-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
Attached Thumbnails
Click for full-size image (Focal ratio 5x pixel size proof.jpg)
157.1 KB11 views
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Old 15-10-2020, 09:18 AM
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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.
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Old 15-10-2020, 07:54 PM
echocae (Brian)
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Read this article in the link below... its interesting and help u decide

https://agenaastro.com/articles/guid...ers-guide.html
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