My latest image

LT_5

Hi,

The night on March 3rd was clear but transparency really very poor. The polaris was just barely seen with my aged eyes.

So as to see how my modded 350D would perform with a 6" F5 Newtonian, I decided to go out to have a try though the sky was not so promising.

This shot is a result of 11x60s, manually guided. Stacking in DSS and post-processing in PS. No flat field applied. That is my best effort on doing it. It should still have some improvement required but I have been happy with it.

Any comments?

Clear skies,

LT

P.S. The 2nd one is the original stacked image. Would you like to have a try on processing it?

LT_5

Forgot to mention. This image was taken at the carpark of Tai Mo Shan Visitor Center.

LT

ericng

Good try LT and the detail of outer part of the M42 is very well shown~~

2 suggestions for you:

- You ca captured another 10 sets of 10 sec exposures so that you can maintain the details of central core by using layer mask with unsharp masking.

- Do the flat field so that the dark corner can be further improved.

Cheers,

Eric

universe24

If the file in raw, then is possible to maintain the central core detail without take another set of exposure. Considered the optics is only f/5.

universe24

I try to process it and end up like below.....

Think because the file I try is compressed too much, many thing cannot adjust out.

CHYeung

原帖由 universe24 於 2008-3-11 14:06 發表
If the file in raw, then is possible to maintain the central core detail without take another set of exposure. Considered the optics is only f/5.

The core is overexposed in this case and no detail can be extracted.  Even if the file is raw (12 or 14 bits), it do not have the dynamic range to record the much much brighter core and the outer dim details at the same time.  The only way is to expose the core with shorter exposure to make sure that it is not saturated and then combine the short exposure (for core detail) and long exposure (for outer region) shoots.

LT_5

Thanks Eric for your opinion.

I don't mind the core is overexposed when processing the faint details out. For me, I would regard that is natural for the distribution of brightness across the object. The bright part should be bright in the final image. I don't want to change its original distribution of brightness because I took wide field and deep sky photos not for scientific purpose. That is only my personal preference, and you may not agree with my philosophy.

Actually I was trying flat calibration these days but  coming out with much noise issue after the processing. Some of my resultants had been posted in another forum to seek for solution and help.

If you have seen them, could you suggest any possible solution?

After experimenting the flat calibration a few times more, I will post here for discussion.

Clear skies,

LT

LT_5

Hi Universe 24,

Thanks for your trial.

For the core, it has been overexposed. No detail can be retrieved no matter it is in any file format I think.

LT