Ilford SFX and the Contax meter

[gaius1]

I have observed that my Contax 645 meter "sees" a 2-stop difference in

a scene with a B+W 029 filter mounted in bright sunlight, a filter

that theoretically has a factor of 4. This ought to mean that I can

simply dial the magazine to 50 with SFX 200 loaded and shoot merrily

away, right?

 

Just for comparison's sake, the spot meter in a Nikon F6 sees 7 stops

difference, same filter (a 72mm).

[gaius1]

When I say a factor of 4 I mean 4 stops - the *factor* in that case is of course 16 :-)

[lee hamiel]

Might want to calibrate the in camera meter(s) with that much of a shift & then compensate accordingly.

 

With the F6 how were you metering? matrix/center/spot?

[joseph_e._forks]

The problem here is that your meter is reading ambient light even through the filter but the film is recording near infrared light.

 

For example, when exposing Konica 750IR through a Hoya R72 on an RZ67 I set the ISO to 100 even though the base is ISO 32 or something and the filter factor would suggest lowering the ISO - it's backwards!

 

The solution is to take a test roll and calibrate your setup. Take notes on each exposure and examine your negs. When properly exposed your negs will look great, even 1/3 stop over and your highlights will go and the negs will be difficult or impossible to print.

 

Even after you establish a good base you should bracket your shots because it's difficult to judge just how much IR or near IR light is being reflected.

 

That's my experience anyway, how do your negs look?

 

Forky

[gaius1]

Lee, with both cameras I was in spot metering mode, aiming at some green foliage.

 

Joseph, I have shot a bit of SFX in 135, but I am still waiting for a shipment of 120. My dealer bought the last 400 rolls of the stuff from Ilford, I ordered 3 10-packs, he says he has 4 left! The Contax writes exposure data onto the film edge, so I should be able to burn a roll to test quite easily.

 

Thanks :-)