[APML] rosette nebula and E200 vs Centuria 800

[Wei-Hao Wang <wang@IfA.Hawaii.Edu>]

Hi,

Just finished another image from last month:
   http://www.ifa.hawaii.edu/~wang/gallery/picutres/rosette-2004.htm
You can see a zoom-in by moving the mouse over.  I didn't do any
vignetting correction.  Similar to the IC2177 picture, I did
lot of smoothing on the Centuria 800 shot because of its grains.
This demaged the resolution.  I may take a few more Centuria 800
shots next winter to average out the grains without spatial smoothing.

Using the E200 and Centuria 800 shots, I made a mouse-over image
for comparing these two films.  They are here:
   http://www.ifa.hawaii.edu/~wang/misc/E200vsC800.htm
The Centuria 800 shot is a single one-hour shot.  The E200 shot
is an exposure time-weighted mean of 4 shots (60min, 30minX2, 21min).
I only match the contrast and color of the images.  No smothing or
sharpening were applied.

This is not a fair comparison since the exposure times are different 
for the films.  However, I think I can still make a few conclusions:

1. E200 has much finer grains and higher resolution.  Nebula on 
   Centuria 800 is very noisy and grainy.  Not surprising at all.  
   
2. Although grain sizes are very different, E200 and Centuria 800 
   produce similar stellar sizes on the faintest stars.
   
3. Althogh very grainy and low resolution, Centuria 800 produces    
   very sharp stellar images and nebula details.  (Yes, sharpness
   and resolution are two different concepts.  A sharp image doesn't
   necessarily have higher resolution.)
   
4. There are extended halos around stars on E200.  This is very similar
   to E100S and is likely due to light scattering inside the film.  
   These halos are very annoying.  They make stars look very fat when
   the image is strongly enhanced.  Centuria 400 and 800 don't have
   this problem.
   
Hope this helps the people who want to try Centuria 400 and 800.

Cheers,
Wei-Hao

______________________________________________________________________
Wei-Hao Wang  :)

Institute for Astronomy at University of Hawaii

Address:                       Phone: 808-956-9867                  
2680 Woodlawn Drive            Personal Website:
Honolulu, HI 96822             http://www.ifa.hawaii.edu/~wang
______________________________________________________________________



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