reciprocity failuregreenspun.com : LUSENET : Large format photography : One Thread
recently i have been taking closed up with velvia.low light plus bellow factor,i frequently encountered exposure time 1 to 20 sec. all the literature i have don't really tell how to correct this for color film.my questions are: 1.Does the film speed decrease in the same manner as B&W film?So at least I can get correct exposure. 2.To which direction does the color shift? 3.What do yo do? Thanks
-- tao wu (firstname.lastname@example.org), March 21, 2000
Fuji publishes the Fujifilm Data Guide, which lists reciprocity and color shift characteristics for their films. Their U.S. technical hotline number is (800) 788-3854. My copy says that Velvia requires a 5 magenta filter and + 1/3 stop for exposures longer than 4 seconds and a 10M +2/3 stop for 16 seconds. Longer than that is not recommended. Note that other films, like Provia, have better characteristics for long exposures.
-- Steve Singleton (email@example.com), March 21, 2000.
Remember that the published Fuji reciprocity values include the use of the cc filters... if you do not use the filters, subtract out the filter factor from the exposure time....
-- Bill Glickman (firstname.lastname@example.org), March 21, 2000.
I recall seeing a table published in View Camera several years ago. The author found that 2/3 stop extra exposure worked well for times out to 2 minutes. I've used 2/3 to 1 stop from 16 sec out to one minute and have been happy with the results. I don't use the correction filters.
You could run a few tests with this information as a starting point and decide what you like.
By the way, I've found that Kodak's E100SW or E100VS are good alternatives when I'm not looking for blurred features due to the long exposure. I've used both with no exposure compensation for times exceeding 1 minute.
Best wishes, Bruce
-- Bruce M. Herman (email@example.com), March 22, 2000.
Steve Simmons published a table of recip values in View Camera Techniques that I have used with good success. I've never used a cc filter but that doesnt mean I shouldnt have. Certainly with shorter exposures it is less critical I dont know if these take filters into account or not, but here's an abbreviated list of exposure times and the corrected times for Velvia:
I can dig out longer times if anyone needs them.
-- Wayne (firstname.lastname@example.org), March 22, 2000.
Dont rule out tungsten films for long exposures. Kodak EPY is made for exposures from 1 sec. to 100 sec. with no corrections. You will of course have to filter, unless you can use tungsten light sources. I use both Kodak EPY and Fuji RTP often, and both are wonderful films. EPY has a fairly neutral color balance, and RTP is a bit more saturated.
-- Ron Shaw (email@example.com), March 23, 2000.
I just ran into this myself and found that I did not enjoy the cold feeling I got when I used the long exposure times with velvia. Adding a magneta filter seemed to add too much pink to the white spectral highlights. So I tried using warming filters instead. What a difference. So now when I am working on table top with color film photographing under lights I still use Velvia, (my favorite color transparency) I use either a number 2 or number 3 warming filter. It gives the nice feel to my images without being an in your face shouter. Oh I also rate the film at 32 instead of 50.
-- jacque staskon (firstname.lastname@example.org), March 24, 2000.
There is a thread in the Q&A of Photo.net if you haven't seen it yet covering this topic. "Velvia color shifts" Tom Johnson shoots alot of Velvia; I'd go by what his response was since he shoots 4x5.
-- wayne Crider (email@example.com), March 24, 2000.
Thank you guys.They are very helpful. Tao
-- tao wu (firstname.lastname@example.org), March 27, 2000.