More M42...

[Outcast (Carlton)]

Okay, sorry if I'm boring anyone with repeated pictures of M42 but, I'm trying to resolve some issues, namely related to FOV.

I haven't taken quite as much care with rendering this one mainly because I am trying to trouble shoot the FOV issue.. the colour issues I think might be related to the camera settings I used.. I'll pay some more attention to that next time I shoot....

Anyways, these are taken with the ZWO ASI224MC using f3.3 focal reducer which is attached directly to the back of the 8" SCT, then I use my 1.25" Visual back then the camera with a 1.25" nosepiece.

My DSLR will not come to focus with this reducer but, the ZWO does.

Images have all been converted to lowres JPEG to enable posting here, images in the following order:
1. Single frame data capture (FITS format 8bit)
2. DSS stacked image (48 frames, no darks or anything)
3. Final render from Startools

Comments on FOV or anything else are most welcome...

Cheers

Carlton

[Karlzburg (Karl)]

You can try through the day at something a good distance away, I've got a hill over 2 km away that I can check focus as well as fov when I have my reducer on or off. You might not be able to travel far enough in with the dslr, trial and error. There will be a difference from the sensor on between both of your cameras, you have to a count for that.
I can tell in pic 3 you put a lot of sharpening into it, I've done that to a couple of pics lol

[The_bluester (Paul)]

It looks like the focus is not right, and with the way the stars are flaring, have you checked the collimation with the camera attached? I had to tweak mine and before I did that it had the same affect of stars blown out to one side, the collimation tweak to fix it was minor.


Assuming you can do a live view, you can check the collimation on a defocussed star the same way you do it visually. Centre it in the frame and defocus until you can clearly see the shadow of the secondary and adjust as required to bring the shadow into the centre of the star image (When the star is centered on the chip)


Given the comparatively small sensor on the 224 compared to my ASI294 that FOV is probably about it. I am not familiar with ASICAP so I cant comment on that settings wise, I am using APT to run the mount and control the camera as well with just the basic camera drivers behind it.

[Outcast (Carlton)]

I don't know that I did that much sharpening, I didn't pay a great deal of attention to the processing to be honest.. more an exercise in FOV differences with the two focal reducers I have so, I pretty much put that one through all the auto settings...

Still trying to get my head around what all the different sliders do in Startools.. sometimes it does stuff I really don't like...

Love the program, just a steep learning curve as with anything new...

Originally Posted by Karlzburg

You can try through the day at something a good distance away, I've got a hill over 2 km away that I can check focus as well as fov when I have my reducer on or off. You might not be able to travel far enough in with the dslr, trial and error. There will be a difference from the sensor on between both of your cameras, you have to a count for that.
I can tell in pic 3 you put a lot of sharpening into it, I've done that to a couple of pics lol

[Outcast (Carlton)]

Yeah Paul, you are probably right about focus...

My collimation is a touch out, I know that from some star testing I did about a month ago.. I haven't touched it yet as I need to clean the inside of my corrector plate (mould is a problem here in FNQ & I think I might just be getting some very small blooms.

Once I get a drop in relative humidity (below 60% which does happen even in the wet season) I will get it all cleaned, give my mirrors a quick inspect & blow off any dust then get it out & collimate on the basis that it's gonna need it anyways..

In terms of focus, I was getting tired by the time I took these & it was really just a test of FOV changes on the 1/3" sensor with both an f6.3 & f3.3 reducer; I think I put the bhatinov mask on but, I don't think I was that anal about the focus though..

Cheers

Originally Posted by The_bluester

It looks like the focus is not right, and with the way the stars are flaring, have you checked the collimation with the camera attached? I had to tweak mine and before I did that it had the same affect of stars blown out to one side, the collimation tweak to fix it was minor.


Assuming you can do a live view, you can check the collimation on a defocussed star the same way you do it visually. Centre it in the frame and defocus until you can clearly see the shadow of the secondary and adjust as required to bring the shadow into the centre of the star image (When the star is centered on the chip)


Given the comparatively small sensor on the 224 compared to my ASI294 that FOV is probably about it. I am not familiar with ASICAP so I cant comment on that settings wise, I am using APT to run the mount and control the camera as well with just the basic camera drivers behind it.