Red Filter Question

[Avotius]

Ok, I have to be really stupid or something because I could never figure this out.

When I shoot either film or digital with a red filter for that punchy black and white, I never get punchy black and whites. No dark skies, no bright skin tones, no heavy contrast. All I get is a lowish contrast image and thats about it.

Can anyone help or point me somewhere that has extensive information about using filters?

 

[Jocko]

Hallo Avotius!

I use red filters a great deal and encountered similar problems. This is particularly the case with commercially produced prints, which aim for mediocrity. The simple answer is to print on hard paper or adjust contrast on scans for a similar effect. You will also possibly have to use some selective printing or it's digital counterpart.

The thing about filters is that they alter the whole picture, thus a red filter will produce a dramatic sky but also darken vegetation (unless using certain films). In this case the final print is either a compromise, full of muddy mid-tones and unlikely to satisfy anyone, sacrifices all to a particular effect or will need some work to balance the parts. It is also desirable that the scene portrayed is innately contrasty.

In regard to the sky it is also important to remember that the direction of the sun is very significant. A shot into the sun or an adjacent part of the sky will be less dramatic than a shot in the opposite direction. But my basic advice would be "print hard" and so avoid mid-tones which undercut dramatic contrast.

All the best, Ian

 

[back alley]

are you accounting for the change in exposure required when using the filter?

 

[captainslack]

Look at your negs. Do they have the same muddy look that your prints do?

 

[vladhed]

Ok, I have to be really stupid or something because I could never figure this out.

When I shoot either film or digital with a red filter for that punchy black and white, I never get punchy black and whites. No dark skies, no bright skin tones, no heavy contrast. All I get is a lowish contrast image and thats about it.

Can anyone help or point me somewhere that has extensive information about using filters?

side question: is there any point to shooting digital with a colour filter? That is, is shooting through a filter any different than applying the same filter when post-processing the RGB image to B/W using the colour mixer?.

 

[Avotius]

are you accounting for the change in exposure required when using the filter?

I was under the impression that using TTL metering that you didnt have to change the exposure.

 

[NL2377]

I had this problem with shooting digital... are you shooting with an external meter, or TTL?

If you're shooting with an external meter, you're going to have to compensate for the light loss, otherwise you wil get exactly what you're describing.

With digital, even with TTL, I will usually over expose by a stop or two...

Film with an external meter, I over expose by two or 3 stops... that's what I've found the best for compensation.

 

[NL2377]

I was under the impression that using TTL metering that you didnt have to change the exposure.

as one of the above posts stated, the idea behind the meter is to adjust for medium grey, so essentially, you are compressing the majority of the image color range when using certain filters... therefore a TTL meter will still assume medium grey and shoot for that, rather then the contrasty punch that you are looking for. so over compensate a little bit, and you'll see more dramatic results

 

[NL2377]

side question: is there any point to shooting digital with a colour filter? That is, is shooting through a filter any different than applying the same filter when post-processing the RGB image to B/W using the colour mixer?.

using a color mixer is not the same as using a filter... If you use specific filter effects, (red, green, yellow, etc...) then your results will be similar, but just using the color mixer/channel mixer itself will not. Take for example, a red filter... It allows the red colors to come in more readily than yellow or blue, so not only will your reds be relatively overexposed compared to a normal image, but anything that has blue or yellow in it will be relatively underexposed. it would be kind of like this (though Im sure the numbers would be different for exposure values):

.................................R......B......Y
Standard exposure:.....0......0......0
Red Filter applied:......+1.....-1....-1

 

[OldNick]

I've been told that film and meters respond to light differently, hence TTL metering will give a "rough" compensation for the presence of the filter, but it will not be optimum. My approach is to use an external meter as I would do without the filter, then apply the proper filter factor to the exposure. For a deep red filter, this would probably be a Filter Factor of 8, or about a three-stop correction. Another approach would be to divide the film speed by the filter factor, and set the result into the meter as the "effective" film speed.

Jim N.

 

[robin a]

Good thread,learning alot.I once took some shots of our orange and white training jets in B&W with a orange filter.The sky looked great,the planes bleached out.Learning ............Robin

 

[fgb2]

Both different meters (whether TTL or handheld) and different B+W films can have different degrees of sensitivity to different light wavelengths, the extreme film example being the old ortho films that were red-insensitive and could be handled under a red safelight. The red filter most often needs an additional compensation even for TTL meters, maybe because so much of the visible spectrum is excluded.

Many instruction books for cameras with TTL meters state that exposure should be adjusted when a red filter is used. For example, the Nikon FM3A instructions state to overexpose by one stop with a red filter, the FA manual says +1 stop but only in tungsten light, and the M6 manual says +1 for orange and +2 stops for a red filter (and blames it on the film).

 

[iml]

When I use an orange filter I always overexpose by one stop, it generally seems to work out OK.

Ian

 

[photophorous]

I was under the impression that using TTL metering that you didnt have to change the exposure.

This is true, except when the filter significantly shifts the overall tone of the shot. IOW, if you take a shot of a blue sky, using a red filter and TTL metering, you'd expect an almost black sky, but your meter is trying to make it middle grey, thus over exposing. As photogs, we typically tweek the exposure that our meters suggest based on the fact that the meter is going for middle grey and not all scenes average out that cleanly. It's the same with a filter and TTL metering, except that it's not always as obvious how it looks to the meter and how we should compensate.

Oh yea, I just wanted to add that this may be less of a problem with yellow or orange, because it is less likely to have that much of an effect on the tones in the shot. The more dramatic the change, the more you need to consider compensation.

Hope this helps.

Paul

 

[Mike Richards]

side question: is there any point to shooting digital with a colour filter? That is, is shooting through a filter any different than applying the same filter when post-processing the RGB image to B/W using the colour mixer?.

Dominic,

This probably applies only to extreme cases, but check out the images I posted on the "Filters for High-Altitude" thread. If you use a filter on the lens, it's sometimes possible to "cut through" the colors you don't want (e.g. haze), and get an image of what was behind them. Admittedly, I posted an infrared example, but the idea holds. Once you take an unfilterd photo, you don't get any information on what was behind the unwanted colors. All you can do with digital processing is darken them, usually muddying up the image.