Using The Cyan Filter to Increase Printing Time

[tgtaylor]

Enlarging lens are at their sharpest when stopped-down about 2 or 3 stops from their maximum aperture. On my 150mm f5.6 El Nikkor that translates to a printing aperture of f11 or f16 and I have found that the latter and f22 aperture provides reasonable printing time for B&W (12 to 20 or so second range) but not for color negatives. Case in point: Last night I was printing from a perfectly exposed and developed Kodak Porta 160NC negative that required that the above enlarging lens be stopped all the way down to f45 to achieve a printing time of 13 seconds!

Having read Bruce Barnbaum's take on stopping down when printing:

"Don't worry about any supposed lack of sharpness as you stop down, because you'll never see the difference. It may be visible on a super-enlarged optical bench, but it isn't visible to the naked eye at any enlargement that you (or I) will ever make." The Art of Photography, Page 10-6 - 10.7.

But when shooting 4x5 and 8x10 I routinely try to limit my aperture LF lens to around f22 and to f11 and f16 on MF. In fact, I recall Pentax stating that it was not necessary to stop their 67 lens' down to achieve sharpness and advised not to. If you strive to keep the exposure in the sweet spot as I do when taking the photo, why not continue this in the darkroom when printing? As noted above, this is easy to do when printing B&W but with color it's necessary to stop way down to achieve anywhere near a reasonable printing time.

In an earlier thread in this category about a week ago a poster requested help in printing C-41. In that thread he stated that his filter pack was 44C,62Y and some similar setting for M which gave him a 52 second printing time. However his image never appeared which was the reason for the post. That got me to thinking about using the Cyan filter as a neutral density filter in conjunction with the yellow and magenta filters. How would that work? Specifically:

1. If my current filter pack is say 0C, 45Y, 45M, then would 10C, 55Y, 55M be equivalent?

2. How much time would each 10cc of cyan add to the total printing time?

3. Would using the cyan filter to increase printing time and thereby decreasing the aperture to the lens sweet spot be desirable. In other words would it result in a "better" print?

Thomas

[ic-racer]

15cc is one half a stop (like 0.15 log d) but this is not an ISO/ANSI standard that I know of.

F22 with a 150 is about 7mm which should be fine.

Many color enlargers have some form of non-diffracting aperture or disk with holes in it above the negative to control the light output also.

[Leigh]

In theory what you want to do will work.

However, dyes change as they age, particularly when subjected to high heat.

So your resulting pack may not be exactly right, and may require tweaking.

- Leigh

[tgtaylor]

Well it works!

I set the cyan at 45cc and added that to the starting Y and M filters and the result was a 9.7 second printing time at f22. Since no dodging or burning was needed I didn't go further than adding 45cc of cyan to the pack. I found the image to be sharper at f22 than when printed at f45.

Here's a fairly decent scan of the test image - comments and critiques are solicted as this is a work in progress:



Adding equal amounts of cyan to the filters is a great way to increase exposure time and will come in handy not only when printing color but for those B&W images that require complex dodging and burning.

Thomas

[ic-racer]

Adding equal amounts of cyan to the filters is a great way to increase exposure time and will come in handy not only when printing color but for those B&W images that require complex dodging and burning.

Thomas

The cyan has no effect on B&W paper. Remember, cyan is 'anti-RED' and the paper is not responsive to red. The paper does not care about the cyan filter, it just makes it dimmer for your eyes!

[Vaughn]

Instead of "no effect" I would say little effect, as the cyan filter will block a small portion of cyan...perhaps up to 10% or so based on some transmission curves of various filters I just looked at.

[Leigh]

The cyan has no effect on B&W paper. Remember, cyan is 'anti-RED' and the paper is not responsive to red. The paper does not care about the cyan filter, it just makes it dimmer for your eyes!

You're missing the point due to poor wording on the part of the OP.

The idea was to "add cyan", which was initially at zero, and ALSO add equal amounts to the yellow and magenta dials.

Adding the same amount of filtration to all three channels is the same as adding a neutral density filter. It works with both B&W and color.

- Leigh

[Vaughn]

Leigh, I have been working this in my head and I don't believe it is as straight forward as you suggest. Photo paper is not sensitive to orange light (comb of magenta and yellow). So filtering out orange light via a blue (actually cyan, I suppose) filter will make very little difference to the over-all exposure. The effect will be limited to the small percentage of blue light that does not get pass the blue filter (as it is not 100% efficient in transmitting blue light).

I suppose a neutral density filter which blocks out all colors equally might be a better choice since I would assume that it would work without changing contrast on VC papers. The other way would be to use both Magenta and Yellow at the same time to increase exposure times, yet get the contrast you want,

[Leigh]

Leigh, I have been working this in my head and I don't believe it is as straight forward as you suggest. Photo paper is not sensitive to orange light (comb of magenta and yellow). So filtering out orange light via a blue (actually cyan, I suppose) filter will make very little difference to the over-all exposure.

You're still missing the point.

It's unfortunate that the OP chose to mention cyan rather than all three controls. This is causing terrible confusion.

The idea is that you reduce all three channels by the same amount, thus reducing the red, green and blue components equally.
This is the same as using a neutral density filter.

- Leigh

[Vaughn]

But you can increase the M and the Y filtration without increasing the C filtration to get the same results.

Looked at in a different way, B&W paper has a "built-in" filter that already "blocks out" all the orange light already (ie it is not sensitive to it), so no matter how much orange light you filter out with a blue(cyan) filter, the results are the same.