Re: [APML] Poor Blue in 400F?

[Wei-Hao Wang <astrophoto@gmail.com>]

Hi everyone,

I think Alen's case is very rare.  I would expect to see A LOT on a
30min/F5.6 shot on M45 with Provia 400F.  

Look at my picture:
http://www.ifa.hawaii.edu/~wang/gallery/picutres/m45-2003.htm
This is a 85min/F9.4 shot.  Without reciprocity failure, this one is 
accuratly equivalent to 30min/F5.6.  With reciprocity failure at work, 
30min/F5.6 should capture even more than 85min/F9.4.  Of course, 
I push it two stops.  But it's hard to believe that pushing has such 
dramatic effect.  It shouldn't have.

As Jim pointed out, sky condition may be the reason.  In addition,
reciprocity failure might be another factor.  If the shot was taken
in a humid and warm environment, reciprocity failure may be
stronger than usual.  

Just my $0.02

Cheers,
Wei-Hao


-- 
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Wei-Hao Wang  :)

Institute for Astronomy at University of Hawaii

Address:                       
2680 Woodlawn Drive         Personal Website:
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