M42 in HDR at 1800mm now with large image

avandonk · #1 06-01-2008, 12:01 PM

This needs more data to minimise the noise.
Details
TAL200k 1800mm f/9, Canon 5DH, no filter. All at 1000ISO.

(8, 15, 30 ) sec, (1, 2, 4, 8) min. Converted from RAW to TIFF and corrected for flats with images plus. Aligned with Registar and generated an LDR from this data with EasyHDR.

E and F are visible as little bumps? I will try to get more data weather permitting.

Bert

tornado33 · #2 06-01-2008, 02:04 PM

Gee I love the inner detail there.
Scott

avandonk · #3 07-01-2008, 02:35 PM

I collected more 8min data. So now a total of 10x8min at an ISO of 1000.

Large image 1.5MB

http://members.optusnet.com.au/~trlee8/m42f.jpg

This high res stuff is hard work I think widefields are a bit easier. Gradients are not as big problem at high res compared to wide field.

Bert

Ingo · #4 07-01-2008, 03:44 PM

You need more dark frames for noise reduction! These are very very noisy!

Nonetheless, great, smooth, HDR images.

avandonk · #5 07-01-2008, 04:59 PM

If you think about it carefully Ingo, HDR will show from the noise to the strongest signal in the one 8bit image! If it is done correctly! Which this JPG is. The tiff is much better at showing the noise.

The noise you see is the inherent thermal noise of the sensor. I will in the future cool the whole camera with a Peltier fridge on this optic. I do not take dark frames as they are a waste of time. I get far better results with the in camera noise reduction (ICNR).

It would be far easier to hide the noise by applying curves or brightness and contrast till it is minimised. But then you lose subtle detail or as it is really known, dynamic range.

Bert