View Full Version : Is it my meter technique or the lab?

Scott Kathe
5-Oct-2007, 13:53
All my Velvia 100 and Provia 100F 4x5 sheets have been at least one stop to dark. Exposure times are typically 5-30 seconds due to low light and a polarizer (I add two stops for the polarizer). My primary meter is a Gossen LunaPro SBC and I use reflective if I can't get into the shot and incident if I'm in the same light. I have checked the LunaPro SBC against a little Sekonic L208 twinmate and the meter in my Nikon D40, everything set at 200 since that is the lowest I can go with the D40. They all agree with each other which is great. This morning I shot off a roll of Provia 100F 120 in my little Minolta Autocord TLR at N-1, N-1/2, N, N+1/2 and N+1 according to my LunaPro SBC. I did two compositions this way and kept the shutter speed at 1 sec (pretty reproducible and accurate) and varied the f-stop. The last two shots I did at N and N+1. In every case the N+1 was the best, I maybe should have gone to N+1 1/3. There is no problem with 135 slides from this lab but they are down to 1 E6 run MWF when it used to be two runs every day just a couple of years ago. I did Velvia 100 4x5s in June that came out fine.

For what it's worth I did a film speed test with FP4+ 4x5 sheets and this meter earlier this year and I rate it at 64 but I think a lot of people rate it near there.

So, is it something I'm doing or should I talk to the lab?


Rick Moore
5-Oct-2007, 16:01
Did you compensate for reciprocity failure?

Greg Lockrey
5-Oct-2007, 16:20
Reciprocity failure for 5 seconds indicated is calculated to be 20 seconds of exposure with developing at -10% and 20 seconds indicated exposure is calculated to be about 3 minutes of exposure with about -20% less development. This particular chart that I am referencing I made about 25 years ago for Plus-X film developed in HC-110 and it may be different for your color slide film. But I recall that it worked for Ektachrome 160 at the time.

Greg Lockrey
5-Oct-2007, 16:43
Here is the chart that I use for reciprocity and a sample photo to illustrate. If I recall the actual exposure time was about 10 minutes but was indicated to be 60 seconds. The development time was reduced about -25%. The furnace was shot with available light only, some skylight through very dirty windows and a 1000 watt sodium fixture overhead.

Scott Kathe
5-Oct-2007, 18:13
1/4000 to 128 sec doesn't require any reciprocity correction with Provia 100F and Velvia is good out to a minute (hard to believe). I have a chart for FP4+ in the case with my meter for reciprocity correction with that film. Thanks for the ideas.


Deane Johnson
5-Oct-2007, 18:15
Do you know that your shutter speeds are accurate? Is two stops the right amount for your polarizer?

Rick Moore
5-Oct-2007, 18:21
Well, I stand corrected. I just checked FujiFilm's web site for the data sheets. Velvia 100 (RVP 100) needs no exposure or color compensation for exposures up to 60 seconds. Provia 100F (RDP II) needs no exposure or color compensation for exposures up to 128 seconds.

So it looks like reciprocity failure is probably not the cause of Scott's problem.

Scott Kathe
5-Oct-2007, 19:24
The shutter speeds on the TLR are pretty good but when I was using the 4x5 they were from 5 to 30 seconds depending on the condition and I used a watch to make sure the times were accurate. I may have been off by a fraction of a second for an exposure of 5- 30 seconds that is nothing.


9-Oct-2007, 10:31
I had a lab running "hot" on me once. Maybe a bit over a half stop. They soon were out of the E6 business. I'm guessing they had just not enough work to stay consistent.