ASI462MC as a mono Near IR camera

banjo1000

I purchased the ASI462MC as a Near IR camera, but I have been thwarted because the SDK that developers like Torsten (FireCapture) use read out the ASI462MC as a color camera. This affects how 2x2 binning in the camera work. In a mono camera, 4 contiguous pixels are summed. In a color camera the 4 R from RGGB super pixels are summed, likewise for G1, G2, and B if I am not mistaken. It would be useful to have the mono-style 2x2 binning. An application would be imaging Jupiter and Saturn with a CH4 filter.

Even without 2x2 binning, it would still be useful to have access to the "mono" data, but the RGB pixels have slightly different responses to NIR light. To use the camera unbinned, but still at its full resolution, the relative response of the R/G/B pixels needs to be calibrated for the particular filter choice and target. NIR runs usually require a dark subtraction. I am suggesting that after a dark calibration, one puts the camera on source and integrates over the entire region of interest to determine the global relative gain of the dark-subtracted RGB pixels, so that the different sensitivity correction can be calibrated away during readout. Are dark subtractions being handled in the SDK or by application developers, and could this global spectral sensitivity calibration be done in the SDK? Why would I want the full resolution for NIR use? Neptune and Uranus!

Of course, what I really want is an ASI462MM camera, but that doesn't exist yet. Any word on whether Sony will developing a mono version of there 462 sensor?

Thanks,
Joe

Tech@ZWO

What you are asking looks advanced which takes efforts to implement this, Why not try ASI290MM instead？

a.cidadao

@tech@zwo#47391 Hi! Just to tell you that I clearly and completely subscribe Banjo request.

QE along the spectrum is one of the aspects we take into consideration when choosing a camera, and in this respect the 290 is completely different from the 462. Methane-band or IR >1000nm imaging are paradigms of such situation. I have both 290MM and 462MC, so this statement reflects real data.

Sometimes one has to compromise, and thus, in my scope dedicated to both lunar and planetary imaging, I have a 183MMPro, because large fov, high pixel density, and cooling (since methane-band filters often require long integrations), have priority.

For H-alpha full disk imaging, to skip more expensive cameras, I chose the 178MM due to its "enough" fov with a focus reducer and high pixel density to match my Daystar spatial resolution.

So..., I have various ASI cameras that were chosen for specific and different contexts. They are all distinct, they are all excellent, and some of them have issues similar to that Banjo mentioned. Specifically:
178MM
642MC
183MM Pro

The latter exhibits different flat-field behaviour along the spectrum, namely in the IR, which is perfectly normal but requires careful flat correction.

The two former cameras, one color the other monochrome, exhibit patent 2x2pixel patterns when images have to be heavily sharpened (e.g. moon, sun, planets).

This pattern can be eliminated with home-made "low tech" processing approaches that provide sub-optimum camera performance. It works, I and other have been doing that.

What Banjo asked for is a way that observers that know which camera is the best for them, are allowed to get the best of their best hardware. It is also a way for all users profit from a turn-key solution that immediately allows them to reveal the excellent hardware they have.

I understand ASI priorities, so far they have been providing great products and results. But sometimes an automatic solution for optimization can became a natural priority, only noticed a posteriori...

Thanks and keep producing great solutions

António

banjo1000

I appreciate the validation of my feature request from a.cidadao. I appreciate that changes to an SDK are non-trivial, but it would seem to be a generally useful feature to allow users to choose whether a color camera can be read out as if it is mono. For a camera which is justifiably promoted for its extended NIR sensitivity, it is a realistic expectation to have this feature. To the extent that competitors like QHY do not offer this feature, it would give ASI products a distinct advantage.

Has ZWO given any further consideration to this request.

One notes that Jupiter and Saturn are approaching opposition, and users who image the pair in the CH4 band would benefit from this feature.

Tech@ZWO

banjo1000 To the extent that competitors like QHY do not offer this feature, it would give ASI products a distinct advantage.

Thank you for your support! But we have own priorities, if more users are responsive to this feature, we may consider it.

doliometer

The current (June 2022) Ekos driver can record in 16 bit raw mode.

I also bought the camera for NIR phography. I have not completed testing but it looks as if the Bayer filters are not so equally transparent to wavelengths longer than 850 nm as one might surmise from the QE graph. Blue is significantly more transparent than red and even more so than green. Sony has a monochrome IMX462 sensor. I hope that ZWO develops an ASI462MM. But can understand if ZWO projects too little demand.