Metering again: Polarisers

[Rodchenko]

Thanks to all for contributing to the previous threads on metering. That's been very helpful in refining my technique.

But I'm moving into using slide film, and have a couple of questions.

Firstly, it used to be advised by old hands to adjust exposure by a third of a stop under to increase saturation. Is this still the case, is it an old wives' tale, or has it been accommodated in the speed rating of modern emulsion?

Secondly, I am well used to allowing a stop for the orange filter I often use with black and white, but how much should I allow for if I'm using a polariser? I'm guessing one stop, but I'd welcome advice.

 

[Chriscrawfordphoto]

THe filter should have come with an instruction sheet with the filter factor. If you are using your camera's built in meter, it'll automatically adjust for the filter (if its a TTL meter). Note that SLRs that use beamsplitter mirrors to direct light to a TTL meter cell give inaccurate readings through normal polarizers. For those, you need a Circular Polarizer.

 

[tsiklonaut]

Depends on polariser - but usually they're fit pretty straight into 1,5-2 stops range. Multi coated high-quality ones can be around 1 f-stop.

 

[thegman]

Thanks to all for contributing to the previous threads on metering. That's been very helpful in refining my technique.

But I'm moving into using slide film, and have a couple of questions.

Firstly, it used to be advised by old hands to adjust exposure by a third of a stop under to increase saturation. Is this still the case, is it an old wives' tale, or has it been accommodated in the speed rating of modern emulsion?

Secondly, I am well used to allowing a stop for the orange filter I often use with black and white, but how much should I allow for if I'm using a polariser? I'm guessing one stop, but I'd welcome advice.

I tend to shoot slide film at box speed, and be fairly precise with my metering. On the occasions where I have under exposed it, I'd say saturation was increased. So I'd say if you want to go for a saturated look, you could try a little underexposure.

 

[summar]

Under-exposing by 1/3 stop works well for a saturated look, but in my experience only in bright light. In dull overcast I shoot at box speed. Just my preference.

 

[Robert Lai]

Don't bother underexposing. Most modern films are saturated enough. The relatively neutral films such as Fuji Astia have been killed. All you do get with underexposure are dense shadows that won't scan well.

 

[Rodchenko]

TTL meters? What fiendish magic is this? 😀

Actually, the meter on my SLR should cope, as should the Trip and ECRs, but most of my cameras need some sort of manual intervention. I hadn't considered the instructions, tbh, which should have been an obvious thought, but I tend to get equipment second hand, so that might not be possible.

 

[Ronald M]

If your camera changes exposure when pola is rotated, then peg the exposure on the least exposure it reads, then rotate for effect.

This also works for linear polas on cameras where they say they can not be used.

 

[charjohncarter]

So with Kodachrome 25 if you HAD (then) a metered camera you would set it at 32. If you are using a polarizing filter I find a varying light change with TTL. So I drop the ISO on P filters 1.5-1.67 stops therefore 25 would become 8-10, but if you add speed then use a hand held meter; I would be using 12 ISO.

Sounds hard and it is: unless you use a hand meter. These are with maximum P effect.

All considered with your parameters cut the ISO in half and possibly a half plus 1/3. That should confuse you.

 

[Rodchenko]

Yup. It did confuse me. 😀

But it does make sense.

ftr, I tend to use a Weston Master IV, and have an Invercone.