Filters and apertures

[seany65]

Can I ask about using filters for mono as, I suppose you could call it, 'extra apertures'? What I mean is, if my meter tells me to use 1/30th and f22 and my camera has a fixed speed of 1/30th, could I set my smallest aperture to f16 and hold a yellow filter in place to give the effect of the aperture now being f22?

I think I could also use the same yellow filter to increase the exposure time to 1/30th if my meter tells me to use 1/60th at f8, f11 or f16, the only 3 apertures it's got. Am I correct?

Any help would be much appreciated.

 

[Jake Mongey]

you need to vary it depending on the filter factor for example my yellow filter needs 1.3 stop compensation so I would need to open up my aperture less than a stop. meanwhile my orange filter has +1 stop meaning i open up the aperture a full stop

 

[dmr]

A filter will reduce the exposure but it will not increase the depth of field that you would expect from going to a smaller aperture. It will also change the color response, like an orange or yellow filter will make blues darker.

 

[seany65]

Thanks for the replies.

@Jake. I've been thinking about that already. I have got a yellow-green filter but it needs 1 1/3 stops extra so I was thinking of using a yellow for +1 stop 'darker' ie. to 'convert' f16 to f22 and a green for +2 stops 'darker' to 'convert' f16 to f32, and to allow slowing the shutter down to 1/30th if 1/60th or 1/125th are given by the light meter.

@dmr. I've been thinking about that too. I don't think I'll bother with an orange filter as that'll just darken any greens too much. I'd not considered whether using a filter would affect the depth of field. But of course you're right. Well, I suppose the idea is a bit 'heath robinson' so we can't have everything.

 

[Steve M.]

Don't worry about 1/3 stops, just use 1 stop gradients w/ B&W film. You'll be fine. I never cared for orange filters although some people like them. After shooting a few test rolls w/ different filters I finally settled on a yellow and a red one. Sorta the classic B&W combo. It was interesting seeing how people's complexions looked quite different w/ those filters. Most of my shots were w/ the yellow filter, but I was very partial to the red one as well, especially for skies and clouds.

 

[ferider]

Don't worry about 1/3 stops, just use 1 stop gradients w/ B&W film. You'll be fine. I never cared for orange filters although some people like them. After shooting a few test rolls w/ different filters I finally settled on a yellow and a red one. Sorta the classic B&W combo. It was interesting seeing how people's complexions looked quite different w/ those filters. Most of my shots were w/ the yellow filter, but I was very partial to the red one as well, especially for skies and clouds.

Me too.

For the OP, there are also ND filters that you can buy to reduce exposure by anything from 1 to 10 stops (depending on the filter).

 

[Godfrey]

Yes, you can use filters that way ... I can and do when I have a camera with limited shutter speeds and f/stops. Just be sure to test so that you know for sure how many stops of light you're consuming with the filters.

BW color filters do change the grayscale balances. My standard setup for years was a deep orange (about 2.5 stops) and a deep green (about 3.5 stops). The orange lightens skin tones on light-complexion people quite a lot and pushes down green tones quite a lot. The green does almost the inverse.

To get a feel for what BW filters do across the whole spectrum, it's useful to shoot a few photos of an Xrite Color Checker and compare the tonal values from filter to filter, and in different lighting.

G