On 15 Nov 2003, at 17:35, Bob Marchant wrote:
Thanks for the reply Bob. This is what I thought you meant. You're referring to a possible two stop "move" which of course I can achieve in RAW conversion for my D100 but I'm starting with a chip that has a high sensitivity to start with and it still applies that even with all the available latitude best practice is a correct exposure to begin with. If the backs that you mentioned in your original reply have a nominal ISO of 50-100 there is no way you could move the curve enough to equate to 1250 ISO or worse so I still feel my original comment was correct that a MF back couldn't achieve what a D100 or similar could using it for ridiculously low light performing arts photography. This is without going into all the other areas of operational ease etcetera, which is why I don't use my RB system in theatres in the dark! I wish I could get MF quality during photocalls. As it is the D100 slaughters 35mm film and actually does a good impression of the tonal graduation you get with MF that you don't get with 35mm. As an aside I saw a shot on a 1DS taken at ISO 800 which is out of it's best range I think and the visible noise was worse than my D100 would have been. At low ISOs its better quality for sure.
On 15 Nov 2003, at 12:31, Patrick Baldwin wrote:
You said that 1250 was a misnomer and was really just messing with curves. I know what curves is/do but can you clarify. Sorry to be so longwinded.
On the Sinar we seemingly have the choice of 25 , 50 or 100 'ASA '....... except that we don't really. The CCD chip has one sensitivity , and records accordingly. All that we do when we 'change ASA ' is move the film curve up and down the histogram of recorded information. So if all the info falls into the bottom third of the histogram , I can set my white point at the first point at which information registers , reset the mid tone and black point , and thus increase my apparent ASA. On the Sinar software , I can achieve the same effect by hitting command B and step up the exposure by third stop increments , but once again , I'm only shifting the curve.
Best wishes. Patrick.
http://www.patrickbaldwin.com
020 8891 2516
07802 408 638
A member of The Association of Photographers
=============================================================== GO TO http://www.prodig.org for ~ GUIDELINES ~ un/SUBSCRIBING ~ ITEMS for SALE
