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Old 23-01-2018, 10:22 AM
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John K
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New mono camera considerations for a 9.5" f/7 instrument

Hi everyone,

I guess this is another one of these "which camera" threads, so hopefully those that have been there and done that can assist further.

Looking for some recommendations to be used with a 9.5" f/7 ODK scope which will have a 50mm imaging circle and be used with 1.25" LRGB and narrowband filters.

Narrowband will be done from severely light polluted skies using 4.5nm filters and LRGB from dark skies - set up will be portable but potentially left in the same location for several nights.

I do not intend to upgrade my filters and will not change from 1.25".

At a focal length of 1700mm, I don't need a full frame sensor (which the 50mm imaging circle won't handle anyhow) and 3/4 full frame is a nice compromise for Galaxies and Nebula's in my mind at this focal length.

Have played around extensively with all the CCD calculators, and some of the cameras I am currently considering:

* ZWO ASI 1600MM

Pros:
- Can take 1.25" filters
- High QE numbers
- Price

Negs:
- Small sensor
- Small pixels

Strategy: Bin 2 x2 and on excellent nights not Bin

Question: How does the 1600mm perform when binning 2x2 on a 9.5" f/7 system overall and for narrowband?

* KAF 8300 BASED CAMERA

Pros:
- Price
- Medium Sensor
- Larger pixels

Negs:
- Lower QE
- Old Technology
- Will get some vignetting?

Again planning on using a binning strategy as required


* KAI-4022 CCD based camera

Pros:
- Price
- Medium Sensor
- Larger pixels
- Can use 1.25" filters

Negs:
- Lower QE
- Very old CCD Technology

Look forward to recommendations from everyone.

Clear skies.

John K.
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Old 23-01-2018, 12:10 PM
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Andy01 (Andy)
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Hi John,

Whilst I am very happy with the build quality and performance of my QSI 683wsg8, if I were shopping now I'd take a good looooong look at those ZWO cameras.

Several people here on IIS are producing outstanding images with them, and the exposure times are are considerably less than those required by the KAF8300 chip.

At first I thought they were rubbish, but a few years on they now seem to be delivering excellent results, and good bang for the buck too!

My 2c worth...
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Old 23-01-2018, 12:24 PM
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Atmos (Colin)
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The ASI1600 has near enough to the same sensor size as a KAF8300. They’re both a micro 4/3rd sized sensor (smaller than APS-C). You also cannot use a sensor larger than either of these with 1.25” filters.

As for the imaging circle size, a full frame sensor (36x24mm) needs an imaging circle of 43mm so it would fit nicely within it.

Binning with the ASI1600 is not worth it on camera, it does a software bin natively so it doesn’t matter when you bin (at capture or during processing). The KAF8300 kinda bins but it isn’t a true bin, it is worth while doing it in camera if needed.
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Old 24-01-2018, 06:21 AM
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ZeroID (Brent)
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As a beginner in the mono imaging arena I can't really comment on other technologies but I have to say my foray into the black art with the 1600mm-c has been outstanding. A steep learning curve for myself but the camera and filter set have behaved perfectly and produced the results I had been hoping for.
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Old 29-01-2018, 10:36 AM
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Image scale will be your big problem here John.

If you use the KAF8300 with that scope it will be around 0.66" per pixel. That is about as low as you are really wanting to go at 1x1. The KAF8300 is an aging tech but it still delivers.

The use of 1x1 on the 1600 sensor is most likely not going to be possible as you will be around 0.46" per pixel. That is nearly unworkable in traditional guiding. You would need to bit quite a lot of the time in my opinion.

The sweet spot I think is around 0.76-0.95, so maybe look for sensors that will give you that sort of scale.
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Old 29-01-2018, 12:52 PM
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Also, the KAF8300 has a horizontal bloom issue when binning 2x2. I've never found 2x2 binning with my KAF8300 to be useful.

Peter
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Old 29-01-2018, 01:17 PM
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Amaranthus (Barry)
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Software 2x2 binning on the ASI1600 is excellent, and will give you 0.92 arcsec/px, with dimensions of 2328 x 1760 superpixels (4 MP) and a FOV of 36 x 27 arcmin with little to no vignetting. Looks like a match made in heaven for galaxies and planetary nebs
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