R2 red filter compensation question

[bobomoon]

Bit of a b&w filter newbie here. I shot a roll of apx400 @320 with a red filter but I didn't compensate for the filter. Does this mean I was shooting closer to 800asa?

 

[laptoprob]

You mean a 3200 ISO film? Then a 800 ISO film would be three stops slower.
That is what I use to compensate for a red filer. But what exposures did you use for the film? On what camera? Automatic Exposure? That defines how to proceed. If on AE set on 3200 you effectively have 800 'left'.

 

[Doug]

Bobo, it all depends on whether your camera meters through the taking lens... If so, then the meter "sees" the filter and automatically compensates. Othewise, you got an underexposure by 2 or 3 stops depending on what red filter you're using. A light red 090 (Wratten 25) has a 2-stop factor while the dark red 091 (Wratten 29) has a 3-stop factor. The factor actually varies a bit according to the color of the light (less factor in reddish light), and the color sensitivity of the film (some films have less sensitivity to red light than others)

So if you had your separate meter set to 320 for APX400, and you were using a #25 red filter but didn't set a compensation for the filter, you were effectively shooting at EI 1280 (2 stops under). If your meter is TTL, then all is cool and there shouldn't be any underexposure. Make sense? 🙂

 

[laptoprob]

If you start out with a 320 film and use a 2-stop red filter you end up effectively with 80 ISO for exposure (4x longer exposure). Red filter stops light therefore you need more of it on the film.
Metering without filter at 320 gives you an exposure with filter like EI 1280: effectively a 4x shorter exposure time.
Like DOug said: AE sould tackle this. The CLE manual suggests an extra half stop overexposure on top of AE for the use of red filter. That is why I usually take 3 stops extra for a medium red filter, when working in manual mode.

 

[ClaremontPhoto]

Tell the lab that you 'pushed' the film two stops, or three stops, whichever, and they will process it accordingly.

If you do it yourself you'll need to Google around for push processing + your film + your developer and find a suggested new time for developing.

 

[jonasv]

Sorry but most of the advice in this thread is wrong. The R2 meters TTL so no compensation needs to be done.

 

[ClaremontPhoto]

Sorry but most of the advice in this thread is wrong. The R2 meters TTL so no compensation needs to be done.

Thank you for that.

I just checked and found that my R3A is TTL too. Good thing I never use the meter (or filters)!

 

[laptoprob]

It all depends what camera was used and how. R2 can also be the red-filter type...

 

[former member]

Well, given that this is in the Voigtlander Bessa Forum, I hope the "R2" was the cameras model number. Then the TTL will have corrected it. That works unless you have Infrared film.

I know "Y2" filters are common, nor sure how "r2"'s are.

 

[laptoprob]

OK, OK, Bessa Forum... I will hide in a corner 'til this blows over... :bang:

AFAIK Y2 is yellow and R2 is red.
The CLE does suggest extra overexposure for a red filter though... And it is better!

 

[former member]

I'm used to the Nikon filters, color followed by a number. The number is the wavelength.

Y44 and Y48 is same as a Y and Y2.

An R60 is a "R" red, and I think R72 is the same as an R2 deep red filter.

R60 cuts off everything below 6000 Angtroms.

 

[bobomoon]

Sorry about the confusion. I should have been more clear the it was a Bessa R2 with the dark red filter (didn't know that R2 could be an abreviation for the red filter!). Like I said I'm a b&w filter newb 😀.

But just to confirm: with the Bessa R2's ttl meter I should develop at the rated speed of 320. I might develop a tad longer just in case.

Once again, thanks for the help!

Young-Ki