adox/efke 50 + red filter = no good :(

[timeUnit]

Most of you probably know this already, but I didn't... I just shot a couple of frames in the snow with efke 50 and a red filter. I compensated "correctly", but the shots were underexposed by about 1,5 stops. Until I checked the spectral sensitivity on the film I just couldn't explain why the negs were so thin, I thought it might be reciprocity failure as the shots were 4 sec. Reciprocity probably added to disaster, but the red sensitivity must have been the culprit.

Live and learn...

*h

 

[avandesande]

why not put how you calulated your exposure here? did you add 1-2 stops for shooting in the snow?
Most people would say that with the 25 speed film the filter factor will be higher than normal for a red filter. Sounds like you need to add a stop or two.

 

[Aggie]

For snow use a polarizing filter

 

[timeUnit]

Ok, this is what I did for exposure:

Pull out my DigiSix to check incident light. Battery dead. No spare.

Plan B: Use the meter in the Mamiya 7. So I choose f16 for a decent DOF and aim the camera at the snow and around the motif. The meter shows 1/8 sec. To compensate for the bright snow I choose 1/2 sec, i.e. two stops up. Later I decide that I'll make it 1 sec, because I'd rather have a little overexposure than under, and I have not tested this film's true speed in my process.

Most shots on the roll taken at 1 sec look OK. Could be a little denser I think (longer development needed to compensate for flat light).

I took the last three shots with a red filter on. Filter factor is 5x, that means 2 1/3 stop. So I open up to f11,5 (approx, the M7 doesn't have half stops...) and 4 sec. The shots are quite underexposed. I could save one in a scan, but wouldn't print it. The shadows look really bad.

Afterwards I realised I was shooting in the reciprocity failure area of the film and should add another 1/3 stop or so.

Here's a scan: Dead Link Removed

Lesson learned: a red filter on Adox/efke 50 needs a lot more compensation than 5x because the red sensitivity on the film is very low.

Cheerio,
*h

 

[Soeren]

..

 

[noseoil]

You might try a yellow filter next time. A red filter with Efke 25 and 50 would not be my first choice in any situation. The yellow should help break up the snow enough to add contrast in the areas with small shadows. Aggie's suggestion is good as well, but it will cost you about 2 stops of exposure. tim

 

[Flotsam]

Just to toss in a bit of related info, Adox/Efke 50 has comparatively, very good reciprocity characteristics.

 

[Donald Miller]

Ok, this is what I did for exposure:

Pull out my DigiSix to check incident light. Battery dead. No spare.

Plan B: Use the meter in the Mamiya 7. So I choose f16 for a decent DOF and aim the camera at the snow and around the motif. The meter shows 1/8 sec. To compensate for the bright snow I choose 1/2 sec, i.e. two stops up. Later I decide that I'll make it 1 sec, because I'd rather have a little overexposure than under, and I have not tested this film's true speed in my process.

Most shots on the roll taken at 1 sec look OK. Could be a little denser I think (longer development needed to compensate for flat light).

I took the last three shots with a red filter on. Filter factor is 5x, that means 2 1/3 stop. So I open up to f11,5 (approx, the M7 doesn't have half stops...) and 4 sec. The shots are quite underexposed. I could save one in a scan, but wouldn't print it. The shadows look really bad.

Afterwards I realised I was shooting in the reciprocity failure area of the film and should add another 1/3 stop or so.

Here's a scan: Dead Link Removed

Lesson learned: a red filter on Adox/efke 50 needs a lot more compensation than 5x because the red sensitivity on the film is very low.

Cheerio,
*h

I don't know which red filter you were using but a red 25 requires three stops and a red 29 requires 4 1/3 stop adjustment. Thus your correct exposure would have been 10.5 seconds with a #25 filter (including 1/3 stop reciprocity) and 35 seconds with a #29 filter (including 2/3 stop reciprocity). All times are at F16.

I don't alter the aperture of the lens for filter factor and reciprocity since you indicated that you wanted F16 for depth of field.

As others have said, with this film I would not use a red filter. Considering the orthochromatic characteristics, I would opt for an yellow 15 or an orange if I wanted to hold texture in the snow in open sunlight. This would have gained as much as 2 to 3 stops additional speed over your red filter. However, considering your description of flat light, I don't know that I would have used any filter.

 

[fago]

Efke 25

Efke is ortocromatics film for red filter

 

[wildbill]

I don't know which red filter you were using but a red 25 requires three stops and a red 29 requires 4 1/3 stop adjustment. Thus your correct exposure would have been 10.5 seconds with a #25 filter (including 1/3 stop reciprocity) and 35 seconds with a #29 filter (including 2/3 stop reciprocity). All times are at F16.

I only red filter i own is the b+w 091 or #29 which recommends 3stops of compensation. I've never tried more than 3 stops for this filter. Even though it was recommended not to be used with efke 25, i had to try it anyway or i wouldn't know for sure. Yep. Not a good idea.
In flat light i think you'd be better off rating it at 100 and giving n+1 development. Or go with efke 25 and rate at 50 with n+1 like i did for some stuff in my personal gallery. Try it before you give up.