Shooting Daylight Balanced Color Film Under Tungsten Lighting With a Correction Filter

[_T_]

I'm contemplating purchasing an 80A light balancing filter to use when shooting daylight balanced film under tungsten lighting, but I'm a little unsure that it will provide the utility that I need.

I have been shooting Portra 400 under tungsten lights and the spec sheet states that under 3200K lighting I should use an 80A filter and an ISO of 100, but I'm not exactly sure what to make of that statement.

When I have shot Portra 400 under tungsten without the filter I have set my ISO to 100 to account for the diminished sensitivity of the film and the photos came out properly exposed but very warm, though it was possible to correct the scans of my negatives in photoshop.

Does that mean that if I use the 80A filter I will lose an additional 2 stops of light to the filter factor and have to meter at ISO 25? Or does the color balancing effect of the filter mean that I can rate the film at 400 and account for the 2 stops of filter factor allowing me to meter at ISO 100 but with the color corrected in camera?

Sorry if my question is worded in a confusing way. It's because I am confused.

 

[pentaxuser]

If you check on the number of stops that an 80A needs and that is 2 then I'd assume that the statement you mention indicates that EI 100 accounts for the two stops. So this part of your quote is correct " Or does the color balancing effect of the filter mean that I can rate the film at 400 and account for the 2 stops of filter factor allowing me to meter at ISO 100 but with the color corrected in camera?"

So if your camera's meter corrects accurately for the 80A and you can easily check this by looking at the meter before and after attaching the 80A then do nothing more

If it increases the exposure by less than 2 stops you might want to adjust your ISO dial slightly

That's my assumption anyway but others will reply as well so wait and see what a few people say

pentaxuser

 

[BrianShaw]

The spec sheet can be believed.

 

[MattKing]

The spec sheet can be believed.

Brian is correct.
But note the "Do not change" wording.

Historically, these sorts of approaches were used a lot with cameras that did not offer through the lens metering.

 

[_T_]

I think I understand now that I am correct in assuming that the statement on the spec sheet accounts for the filter factor and that I don’t have to meter at ISO 25.

Just so I’m clear: I’m talking about metering with a handheld meter, not through the filter but rather accounting for the filter factor in my calculations based on the reflective readings. So by setting my meter to the spec sheet suggested ISO of 100 with the 80A filter fixed to the camera lens, but not my meter, that should take care of all.

 

[MattKing]

Just so I’m clear: I’m talking about metering with a handheld meter, not through the filter but rather accounting for the filter factor in my calculations based on the reflective readings. So by setting my meter to the spec sheet suggested ISO of 100 with the 80A filter fixed to the camera lens, but not my meter, that should take care of all.

Correct!

 

[Nicholas Lindan]

I've always found that prints from photos taken with tungsten room lighting returned good prints. Yes, a bit warn, but I don't know that I would want a daylight rendition of interior scenes.

 

[BrianShaw]

Color balance is more important I some people, as well as being more important with some subjects and some film. Warm is often okay with color neg film.

 

[_T_]

Thanks to all for the help. You’ve cleared up everything for me.

I don’t mind shooting the scenes under tungsten with no filter and cooling them down in software but I find that it can lead to some rather extreme adjustments to the blue channel due to its limited tonal range when scanned and inverted and I’m interested in maximizing the quality of the color information in my scans, if only intellectually. Just hoping that something like a $30 piece of plastic can help me refine my process. And now I’m certain that there’s no downside in terms of exposure so I’m excited to try.

 

[BrianShaw]

You probably won’t regret using the filtration.

 

[btaylor]

I think it’s always better to get it right “in camera” than trying to fix it in post whether digital or film. It saves time and frustration.

 

[Sirius Glass]

The spec sheet can be believed.

Correct. Follow the spec sheet. I have been doing that for over 60 years including for color balance.

 

[foc]

I think it’s always better to get it right “in camera” than trying to fix it in post whether digital or film. It saves time and frustration.

+1

 

[DREW WILEY]

There is always a risk metering through a filter, since their own spectral sensitivities are not necessarily all the same. It's better to simply apply the recommended filter factor (2 stops in the case of an 80A with 3200 K lighting).

Trying to post-correct things can be risky. Color conversion filters are cheap enough.

Of course, if you are trying to do this in a critical manner, you should have a color temp meter on hand, and a set of light balancing filters as well, not just an 80A conversion filter. Fortunately, today's chrome as well as color neg films are much more batch to batch consistent than, say, 40 years ago. But light sources often aren't spot on, Kelvin-wise.

Hopefully you have in mind an actual tungsten photoflood lamp specifically made for photography, and not any CFL or LED alleged substitute. Here in the US, traditional tungsten residential light bulbs are rapidly being phased out everywhere.