Hi Moose, Ken, Chuck and all,
From: Ken Norton <ken@xxxxxxxxxxx>
>At issue is that you cannot automate the process in many situations. The
>imager/film converted the lavender or purple flower to blue. But there are
>other blue objects in the same photograph. When you do a color match to
>correct for the flowers, the other objects will also shift. This forces us
>into masking.
Yes, I expected that.
>Astronomy photographers are well aware of the
>cut wavelengths for nearly every camera and film out there.
Certainly. The 'Hydrogen-alpha' wavelength (656 nm) is very important in
Astrophotography because it the colour of most emission nebulae -- but most
B/W films are almost totally blind to it :-( Notable exceptions are the
defunct Kodak Technical Pan and the Rollei SuperPan 200.
In colour, Ektachrome films seem much more sensitive to it than Fuji
films... and many astronomers today get their DSLRs modified, with the IR
film removed.
>And that's really what I'm suggesting is that we test our cameras to know
>what are the limits.
Amen to that. I'm doing some tests on our classic Zuikos... just stay tuned!
>Without testing I wouldn't know that Fujichrome Velvia 100 resolves more
>than the Nikon D2X and E-3. but both cameras give sharper images.
Resolution and sharpness are quite different concepts.
From: Chuck Norcutt <chucknorcutt@xxxxxxxxxxxxxxxx>
>I was a bit surprised to discover on my first use of my Alien Bees with
>ebay radio triggers that the max sync speed with my 5D was 1/160 rather
>than 1/200.
I can understand that. The transmitted signal must be decoded by the
receiver before it can trigger the flash -- certainly fast but not
instantaneous. It takes just 1.25 ms to go down from 1/200 to 1/160.
Cheers,
--
Carlos J. Santisteban Salinas
IES Turaniana (Roquetas de Mar, Almeria)
<http://cjss.sytes.net/>
--
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