April 9 (just) 2017: Just about my best Jupiter with C8 and ASI224MC

[michael.h.f.wilkinson]

I had to ditch a load of SER files due to bad seeing, but shortly after midnight I hit a patch of decent seeing. The result is probably the best so far. One important change compared to earlier shots is the use of the 2.5x PowerMate, rather than the 2x Meade TeleXtender. In theory, the latter should provide enough image scale, but my impression is that he PowerMate gives better results.

 

Baby Red can be seen on the western limb. Very pleased with this result from the humble C8.

 

 

[faulksy]

that is brilliant. damian peach eat your heart out

[Kokatha man]

Nice one Michael..!

[CATLUC]

Hello Michael

Your image has more potential but your collimation needs to be improved.

I allowed myself to reprocess it.

Clear skies.

Luc

 

.

[Chris]

Well done Michael, really good rendition.

[PeterCPC]

Very nice image Michael.

Peter

[chiltonstar]

Very nice Michael! It was a good night wasn't it!

Chris

[Tommohawk]

Lovely image - nice job! Useful for me to see the image scale "in the flesh" as I'm thinking about an ASI224 with a PMx2.5

[michael.h.f.wilkinson]

2 hours ago, CATLUC said:

Hello Michael

Your image has more potential but your collimation needs to be improved.

I allowed myself to reprocess it.

Clear skies.

Luc

 

.

Hi Luc,

Your rendition does show a tad more detail, but also a bit more noise (inevitable trade-off). What exactly leads you to conclude collimation is off? My impression is that my main issue in terms of imperfect PSF stems from an internal reflection (I have clearly seen that in an earlier shot in one of the moons). I checked collimation before and it seemed correct, and as SCTs are highly sensitive to any collimation error, I would not think you could get this kind of image with a poorly collimated SCT.

Cheers,

Michael

[Gina]

Amazing image, one of the best I've seen from an amateur setup

[knobby]

Top stuff ! , it was lovely out last night, well captured and processed.

[michael.h.f.wilkinson]

1 hour ago, Tommohawk said:

Lovely image - nice job! Useful for me to see the image scale "in the flesh" as I'm thinking about an ASI224 with a PMx2.5

Note that this is a crop from the full sensor size, but I didn't scale the image 

[Tommohawk]

2 hours ago, michael.h.f.wilkinson said:

Note that this is a crop from the full sensor size, but I didn't scale the image 

Doh! Sorry, bit dim of me forgetting that processing routinely crops the image!

[bob-c]

very nice image.

                         bob

[chiltonstar]

Nice image Michael - the 8" SCT is certainly a good scope for planetary imaging!

I was imaging the same scene t about the same time (180 Mak, barlowed to f30) although the seeing was no better than goodish here (4/5), so the result is not as sharp as yours, and my processing skills are C minus! For comparison....

Chris

 

[Pete Presland]

A fine image. I guess its a personal choice thing how far you push the data, but the first looks about right to my eyes as well.

As for the collimation, I would also be interested in what gives this impression. I would think the seeing conditions could also be the culprit. 

[CATLUC]

10 hours ago, michael.h.f.wilkinson said:

Your rendition does show a tad more detail, but also a bit more noise (inevitable trade-off). What exactly leads you to conclude collimation is off? My impression is that my main issue in terms of imperfect PSF stems from an internal reflection (I have clearly seen that in an earlier shot in one of the moons). I checked collimation before and it seemed correct, and as SCTs are highly sensitive to any collimation error, I would not think you could get this kind of image with a poorly collimated SCT.

Hello Michael

Yes the image is noisy it is a little normal starting from a jpg.

For the collimation ideal is to do it with all the acquisition chain, so make it through the computer screen.

How I know your collimation is not perfect : looking at your image and increasing the gamma if the planet was in the center of the collimation

during capture we should not have this style of bow. This will be just a little flexion.

Clear skies.

Luc

 

 

[knobby]

1 hour ago, CATLUC said:

Hello Michael

Yes the image is noisy it is a little normal starting from a jpg.

For the collimation ideal is to do it with all the acquisition chain, so make it through the computer screen.

How I know your collimation is not perfect : looking at your image and increasing the gamma if the planet was in the center of the collimation

during capture we should not have this style of bow. This will be just a little flexion.

Clear skies.

Luc

 

 

Surely that's just a result of slightly off stacking ...

[michael.h.f.wilkinson]

1 hour ago, CATLUC said:

Hello Michael

Yes the image is noisy it is a little normal starting from a jpg.

For the collimation ideal is to do it with all the acquisition chain, so make it through the computer screen.

How I know your collimation is not perfect : looking at your image and increasing the gamma if the planet was in the center of the collimation

during capture we should not have this style of bow. This will be just a little flexion.

Clear skies.

Luc

 

 

Thanks for the feedback, Luc. I think that the effect you see could easily be an artefact of stacking and wavelet processing or (more likely) of the internal reflection I mentioned. I think I might do a blind deconvolution (using the MatLab image processing toolkit) on the raw data to see if that can recover the PSF from the data. That should show if there is a collimation issue or that there is an internal reflection, as I suspect. Flexion is highly unlikely in the short, stiff SCT set-up of the Celestron C8. In Newtonians (like my old 6"F/8) it is much more likely. If collimation is only slightly of in an SCT, image quality degrades very rapidly. I have seen this in the astonomy institute's 10" SCT giving FAR worse images on Saturn a few years back than my C8, purely due to bad collimation.

[U Cyg]

Nice image!

Angie