30Dor and a bit of the LMC in HDR with 100ED

[avandonk]

Details
Canon 5DH. 100ED with AP FR/FF f/6.7, Hutech LPR filter.
All at 1000 ISO 5x( 30s, 1m, 2m, 4m, 8m) with fridge at 1C. Converted from RAW to TIFF and corrected for flats with images plus. Aligned with Registar and generated an LDR from this data with EasyHDR.

Large image 2.3MB

http://members.optusnet.com.au/~fmlee/lmchdr100ed.jpg

Thats not noise in the background. They are stars.

I have also uploaded a better version and note the lack of stars in the dark nebulae..

Bert

[Peter Ward]

Bert,

This is a good wide field image! Colours correct, dead nuts on guiding, the optics are very tidy indeed, no obvious coma at the edges.

As for the noise...nah...sorry..not all stars. Another hour or so of data and it will take it up several notches.

Peter

[avandonk]

The first image is the jpg out of the camera of an eight minute exposure at an ISO of 1000 with the dust cover on the 100ED. The camera was in a Peltier fridge at 4 degrees C. Exif data is intact.

The second is a 100% crop from the center of the same image in max quality jpg from a tiff digitally developed with ImagesPlus with the following parameters

ImagesPlus Color Project v1.0
Final Image Saved As : I:\2008-01-15\DARKFRAME8m1000iso\CVT_IMG_0236_ d1.tif
User Comment :
Date: 1/16/2008 2:15
Operation : Read
Apply to: Red Green Blue
Operation : Digital Development
Background : 0
Background Weight : 1.01
Break-Point : 100
Sharpening Filter :None
Red Emphasis : r
Green Emphasis : g
Blue Emphasis : b

The third image is a crop of a jpg of the exact same area with the dust cover off same conditions as above ie eight minutes at an ISO of 1000. I always use ICNR which if anything tends to leave small dark 'holes' which disappear with median stacking if images have a slight drift. These holes are almost non existent if the camera is cooled to -12C.



Bert

[theodog (Jeff)]

Great image Bert, I could find nothing wrong with it except a little vignetting, and geez I had to look hard to see that.
Well captured, processed and presented.

Originally Posted by Peter Ward

As for the noise...nah...sorry..not all stars.
Peter

Ahh.. Perfection, a little like virginity. Few have either -none have both.

Your right again Peter, if you look really, really hard there are some defects.

[tornado33]

Very impressive. Some green oxygen emission is also seen in the centre of 30 doradus. Looks like the fridge works well, thats a very dark dark frame for 8 minutes.
Scott

[avandonk]

Thanks Jeff and Scott and Peter. Jeff the vignetting is caused by the 2 inch nose piece (48mm ID) going into the Astro Physics 2.7 inch focuser. I am getting an adapter made which will get me at least 55mm clear aperture to the 52mm filters close to the camera. In order to get the correct (0.75) focal reduction with the AP FR/FF I use Borg bits between the camera and the AP focuser. The bottle neck is the 2" nose piece.

Virginity and perfection I will leave to others to pursue. I just do the best I can with what I have got.

Scott that is a dark frame with the ICNR set to ON. See how well ICNR works.

Peter the distance between the camera and the AP FR/FF was varied to get the flattest distortion free field with the 100ED. Guess what, it was best at a focal reduction of 0.744.

Bert