Adding Filter Factors- B&W

[timbo10ca]

I've read on a number of occasions that additional exposure should be added on top of a filter factor, originally suggested by Gordon Hutchings- 1 extra stop for an orange #16 and 2 extra stops for a red #25. I've never done this when shooting 35mm, spot metering TTL and filter, and have had no obvious problems. I have also not applied additional exposure when using infrared film (HIE, EIR or SFX).

Since moving to LF I haven't added filters to the equation until recently. When I did however, I found that when I metered as usual (through the red filter) and did not apply additional exposure, the neg was quite dark. I'm thinking I should have added that extra 2 stops of exposure.

Do many people apply that extra exposure? To all formats, or just LF? Why would I notice an effect in LF and not in 35 mm?

Thanks,
Tim

[Scott Kathe]

I usually shoot the yellow I have at +1 stop, my orange at +2 and my red at +3. But there are different yellows, oranges and reds as far as the amount of color, ie a light yellow may only require +1 while a dark yellow would require more. I have no idea why you didn't observe this with 35mm.

Scott

[timbo10ca]

I usually shoot the yellow I have at +1 stop, my orange at +2 and my red at +3. But there are different yellows, oranges and reds as far as the amount of color, ie a light yellow may only require +1 while a dark yellow would require more. I have no idea why you didn't observe this with 35mm.

Scott

Are you refering to their filter factors, or what you give in addition to the FF's, according to Hutching's reccomendation?

[thetooth]

I usually shoot the yellow I have at +1 stop, my orange at +2 and my red at +3. But there are different yellows, oranges and reds as far as the amount of color, ie a light yellow may only require +1 while a dark yellow would require more. I have no idea why you didn't observe this with 35mm.

Scott

with the 35mm you are metering through the lens and the filter , so there is no factor the meter has already compensated for the filter . with large format most use a hand held meter and the filter factor would come into effect .

that's the way i understood it . i have never factored when using 35mm i just trust the meter .

[timbo10ca]

with the 35mm you are metering through the lens and the filter , so there is no factor the meter has already compensated for the filter . with large format most use a hand held meter and the filter factor would come into effect .

that's the way i understood it . i have never factored when using 35mm i just trust the meter .

I meter through the filter when using my handheld meter for LF, so essentially the same effect as when I do 35mm.

[thetooth]

I meter through the filter when using my handheld meter for LF, so essentially the same effect as when I do 35mm.

yes . but what type of meter . if you screw the filter directly on to the spot meter that may work . but if you are just holding it in front of the incandescent or reflected meter that's probably no good . i imagine you would get a lot of stray light in the reading , then i would factor .

it also depends on how you meter . i find the point in the scene that i want 18% grey and base my exposure off of that . at that point i would factor in filters depending on the scene .

thanks

tim

[timbo10ca]

yes . but what type of meter . if you screw the filter directly on to the spot meter that may work . but if you are just holding it in front of the incandescent or reflected meter that's probably no good . i imagine you would get a lot of stray light in the reading , then i would factor .

it also depends on how you meter . i find the point in the scene that i want 18% grey and base my exposure off of that . at that point i would factor in filters depending on the scene .

thanks

tim

Yes, I see what you mean... I'm using a Soligor spot meter and holding a square filter in front of it. I thought I was doing it with good contact....
Thanks.

[Scott Kathe]

To do this the correct way you need to do a film speed test with no filter and then another speed test with the filter on the lens and use the meter with no filter in front of it. That will give you the correct filter factor for each of your filters. I've never bothered with that. You can take a meter reading through your filter but depending on your subject it may be off. I had a yellow filter on my Nikon FM2n with a 50mm lens last year and was taking pictures of plants on the dunes by the ocean and everything came out way overexposed.

Scott

[GaryT]

Have you added in a bellows factor?

FWIW, you are correct in thinking that if you meter through the filter you've already included the filter factor...all things being equal. Reflected reading from a gray card?

[thetooth]

To do this the correct way you need to do a film speed test with no filter and then another speed test with the filter on the lens and use the meter with no filter in front of it. That will give you the correct filter factor for each of your filters. I've never bothered with that. You can take a meter reading through your filter but depending on your subject it may be off. I had a yellow filter on my Nikon FM2n with a 50mm lens last year and was taking pictures of plants on the dunes by the ocean and everything came out way overexposed.

Scott

but did you factor for the sand ? which would throw off the meter by a stop or 2 ( reflected light )

[thetooth]

Have you added in a bellows factor?

FWIW, you are correct in thinking that if you meter through the filter you've already included the filter factor...all things being equal. Reflected reading from a gray card?

just curious what is FWIW ? and no i don't use a grey card i just try and image what part of the scene i want to fall in that space ( 18% grey space )

[GaryT]

just curious what is FWIW ? and no i don't use a grey card i just try and image what part of the scene i want to fall in that space ( 18% grey space )

"For what it's worth"...in other words, I was just agreeing with your assumption that using your meter through a filter would effectively incorporate the filter factor...but wanted to make clear the it was only my opinion and was worth very little!

You've stumped me as to the problem. i would think that by metering through the filter in an area that you want to render at 18% should yeild a negative that would print that way, provided that it's developed properly.

[Scott Kathe]

but did you factor for the sand ? which would throw off the meter by a stop or 2 ( reflected light )

Good point.

Scott

[Peter K]

There are two main characteristics of a film: the exposure index and the color sensitivity. So the filter factor depends strongly on the color sensitivity of a certain film.

The sensitivity of a photometric cell used in an exposure meter differs from that of a film. Normaly this is adjusted with buildt-in filters in the exposure meter to simulate the color sensitivity of an average panchromatic film. So than the color sensitivity differs from this, the filter factor differs also.

But this has nothing to do with the film size. With the same kind of emulsion the filter factor is the same with 35mm- and LF-cameras.

[thetooth]

"For what it's worth"...in other words, I was just agreeing with your assumption that using your meter through a filter would effectively incorporate the filter factor...but wanted to make clear the it was only my opinion and was worth very little!

You've stumped me as to the problem. i would think that by metering through the filter in an area that you want to render at 18% should yeild a negative that would print that way, provided that it's developed properly.

no problem i just couldn't figure out the FWIW . still learning .

take care

tim

[steve simmons]

The other 'factor' no one has mentioned is the reflective value and color of the subject and that of the filter,i.e. that a subject reflecting red light will get more light through a red filter than a subject reflecting blue light. This is why Hutchings recommends metering through the filter and not just applying an arbitrary factor.

Just do it the way Hutchings recommends, he has done all of the studying and testing for you already. View Camera magazine and Using the View Camera have covered this topic extensively, I am surprised there are still questions.


IMHO (In my humble opinion) you should not simply meter for the supposed middle value. This does not tell you about the contrast range of the scene. You could easil;y not have enough density in your zone 3 to get good detail and texture and/or blow out your high values. Or, if the scene is low in contrast, get a very flat negative. I always meter the low value I want on zone 3 and that gives me my exposure, and then the high value where I still want some hint of detail and texture, for me this is zone 8, and this determines my development time.
steve simmons

[gregstidham]

When I purchase a new filter, I use my spot meter and compare a reading with the filter and without to determine the filter factor of the filter. I then mark the factor on the filter case. When working in the the field, I simply apply the filter factor of the filter without regard for the format I am shooting or the type of film (color or BW). I've never had any problems.

[timbo10ca]

The other 'factor' no one has mentioned is the reflective value and color of the subject and that of the filter,i.e. that a subject reflecting red light will get more light through a red filter than a subject reflecting blue light. This is why Hutchings recommends metering through the filter and not just applying an arbitrary factor.

Just do it the way Hutchings recommends, he has done all of the studying and testing for you already. View Camera magazine and Using the View Camera have covered this topic extensively, I am surprised there are still questions.


IMHO (In my humble opinion) you should not simply meter for the supposed middle value. This does not tell you about the contrast range of the scene. You could easil;y not have enough density in your zone 3 to get good detail and texture and/or blow out your high values. Or, if the scene is low in contrast, get a very flat negative. I always meter the low value I want on zone 3 and that gives me my exposure, and then the high value where I still want some hint of detail and texture, for me this is zone 8, and this determines my development time.
steve simmons

This is exactly what I do- I have found in the past that the same filter can have a different ff, depending on the light and subject. What stumps me is that I've tested my LF system the same way I tested my 35mm system. I've never applied the "Hutching's Factor" before, because I never knew about it. I read your book and thought "Hmmmm- I've never had to do this before and I've been O.K."..... so I didn't when I tried it with LF. I discovered I should have applied the extra exposure. I'm stumped on the discrepency. If it ain't broke with 35mm, why fix it. If it is broke with LF, I'll fix it, but that doesn't make me any less confused in my situation.

Tim

[john borrelli]

Just wondering ...are you comparing the results to two different meters, that could make a difference. For example, if you are comparing a 35mm camera's meter to a separate spot meter perhaps there is a difference there. Maybe the 35mm meter was slightly overexposing. Also, when metering with the 35, the 35 took into consideration the lenses focal length which might provide a different meter reading as well. Another possibility might be due to using different film types or different processing. I have used the technique that Steve Simmons describes above and it has worked for me.

[steve simmons]

OK, time for a true confession. I did not do what I suggest in a recent 7x17 shot, I just taped the #12 filter inside the camera on the lens, cut the film speed in half and shot. The results, not very good, are in the March issue. The neg was underexposed and the results are flat and kinda mucky. No amount of work in the darkroom or PS could save me.

I'll follow my own suggestion next time.

steve simmons

[Daniel_Buck]

If I'm using a filter, I shoot my spot meter through the filter.

[Jorge Gasteazoro]

The best way to determine filter factors is to actually photograph a gray card or even better a color chart like the Jobo with the filter. Different films have different spectral responses and if you have a film you use constantly this is the best way to determine the filter factor.

[steve simmons]

this

The best way to determine filter factors is to actually photograph a gray card or even better a color chart like the Jobo with the filter. Different films have different spectral responses and if you have a film you use constantly this is the best way to determine the filter factor.

won't do this

The other 'factor' no one has mentioned is the reflective value and color of the subject and that of the filter,i.e. that a subject reflecting red light will get more light through a red filter than a subject reflecting blue light. This is why Hutchings recommends metering through the filter and not just applying an arbitrary factor.


Meter through the filter each time (this will take into account the color of the light - mid-day blue or early/late warmer light) and follow Hutchings' instructions. It is so simple and so accurate.

steve simmons

[blevblev]

I agree that it could be the difference between the hand held and TLR meters. I'd try pointing them both at an 18% grey card and see what you get. The 35 mm is also probably an averaging meter, so it will work for average scenes. On the other hand if you aren't assesing what zone to place your spot meter readings on, that would put it off as well. Another variable is the shutter in the LF lens compared to the shutter in the 35 mm.

How about using just the spot meter, and exposing both the LF and 35mm by it's readings, and then comparing?

You probably should do Zone I ISO / EI tests with the LF setup anyway.

[Jorge Gasteazoro]

this

The best way to determine filter factors is to actually photograph a gray card or even better a color chart like the Jobo with the filter. Different films have different spectral responses and if you have a film you use constantly this is the best way to determine the filter factor.

won't do this

The other 'factor' no one has mentioned is the reflective value and color of the subject and that of the filter,i.e. that a subject reflecting red light will get more light through a red filter than a subject reflecting blue light. This is why Hutchings recommends metering through the filter and not just applying an arbitrary factor.


Meter through the filter each time (this will take into account the color of the light - mid-day blue or early/late warmer light) and follow Hutchings' instructions. It is so simple and so accurate.

steve simmons

Steve, Steve.... You are wrong, the purpose of using a gray card is to see how much light the filter absorbs WITHOUT the interference of color, that is the purpose of filter factors. It is really not important to know how much more light of the same color the filter lets through.

In fact, if you meter through a red filter on a red subject you will get a gross under exposure using your method. The important thing is to see how your FILM reacts to the filter, NOT your meter... :rolleyes: