High Dynamic Range Image with Photomatix

[avandonk]

Photomatix is a program for mapping intensity data from a series of vastly differing exposures to an image of far lower dynamic range to give a representation of the original intensity information.
Previous thread here. Thanks to 74tuc.
http://www.iceinspace.com.au/forum/showthread.php?t=17582

Details. Canon 5DH, Canon 300mm F2.8L, Hutech LPR filter.
Exposure details 30, 60, 120, 240, 480, 960 seconds, at an ISO of 200.

Large image here 2.2MB
http://members.optusnet.com.au/~avandonk2/CAR_HDI01.jpg

I am sure I could do better as it is early days yet. I did not correct for flats or use any other program apart from PhotoShop to adjust levels and GradientXterminator, to sort of fix up lack of flat correction.

If one took a series of these exposure sets each time slightly moving the mount a better signal to noise would result. I had to adjust the mount polar alignment until it was perfect so alignment of the different time exposures was not a problem for Photomatix.

The most interesting thing is all the stars are much smaller as they are not 'overexposed'. The star colours are also 'preserved' for the same reason.

This won't take the place of more traditional programs but would be a good adjunct as for example you could average two images, one produced with ImagesPlus say and Photomatix. Or any other mix.

Bert

[h0ughy]

wow - and I mean wow. can you explain exactly what you did Bert to get the image. I understand the exposure differences, but its the other HDR process

[rogerg]

Interesting... something I've often considered in photoshop but haven't know the correct blending methods to do it in a practical way. Good that there is instead a program which will do it for us. Very interesting indeed.

Nice shot too, although a little saturated for my tastes.

Roger.

[janoskiss]

That is great Bert. I often wondered why DSO images covering a wide dynamic range are never processed to show the full range to the eye w/o clipping high or low brightness areas, eg, intensity -> log intensity.

[avandonk]

hOughy just download it and play with it with terrestial images.

Steve my 5DH has 12 bit A to D converter. So for image aquisition we have a dynamic range of 12 bits. The human eye can see a huge dynamic range from dim star light to full Sun.
Astro images have the same problem they can only be recorded faithfully at 12 or 16 bits yet we have a much greater range in the objects we wish to image, pick a number!
All this program does is map the very wide dynamic range into a far thinner dynamic range. The JPG image is only 8 bit!

One further thing this image shows how good the Canon 300mm F2.8L is, as not all stars are bloated due to overexposure.

Bert

[Gama]

Berts right, the lens is very important in producing tak sharp pin point stars, and faint nebulosity that would normally be lost in lower quality lens's.
But be prepared to sell a kidney for one. Unless one comes really cheap..