CMOS camera advice

[astro mick]

Hi Guys.

I recently purchased the ZWO ASI 1600MM Pro,but i have found the microlensing and bad halos a big problem especially with Narrowband Filters.  I,m thinking about switching back to a ccd.Just before i do that i wonder if anyone knows of a ZWO cmos mono that does.nt suffer with this problem.Similar price range.

Cheers.

Mick.

 

[vlaiv]

Have you tried altering the distance between filters and sensor?

As far as I know - latest ASI294MM does not have issues with micro lensing - but I might be wrong on that one.

[astro mick]

13 minutes ago, vlaiv said:

Have you tried altering the distance between filters and sensor?

As far as I know - latest ASI294MM does not have issues with micro lensing - but I might be wrong on that one.

Hi Vlaiv no i have,nt but i only have 1.25 Filters,and even being very close to the sensor i get vignetting in all four corners,am struggling to flat them out as well.Further away i would imaging it would be worse.

I have recently read that this camera is prone to this issue.Funnily enough it only shows itself with Narroeband Filters.

Mick.

[jetstream]

On 26/01/2021 at 17:04, vlaiv said:

micro lensing -

Vlaiv what is this and how does it manifest?

[vlaiv]

Micro lens are optical additions to pixels that increase their efficiency. It is piece of glass that acts almost like regular lens and is built on top of pixel photo site to increase effective photon gathering surface.

It appears that shape and type of glass used with Panasonic sensor in ASI1600 creates interference type reflections with other optical elements in imaging train under certain conditions. Most of the time people get this with narrowband filters.

Usually appears on very bright stars and looks something like this:

I once saw it with my camera and OIII filter - although much smaller in magnitude:

Sometimes people have it, sometimes not. I think it depends on other reflective elements in optical train like filters / reducers - whatever can create interference by reflecting light - and in particular spacing of these elements.

It is for example interesting that people having it in narrowband images - don't have it in luminance although nothing else in optical train is changed. I would think that if it was some sort of interference on particular wavelength - it would be there with luminance as well as it contains all wavelengths - but it is more likely that it happens with particular filters and filter properties rather than in general.