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tgtaylor
22-May-2011, 11:51
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
22-May-2011, 13:07
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
22-May-2011, 15:02
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
23-May-2011, 10:55
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:

http://farm3.static.flickr.com/2172/5751266647_f133d524b0.jpg

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
23-May-2011, 12:46
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
23-May-2011, 13:02
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
23-May-2011, 13:45
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
23-May-2011, 14:17
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
23-May-2011, 14:22
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
23-May-2011, 14:26
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.

Daniel Stone
23-May-2011, 14:31
why not just stick a 2-3 stop nd gel above the diffusion sheet/plate in the enlarger? This would cut down light transmission a bit, and this could all be a moot point ;)

and gels aren't all that expensive, about $5-8 at the local big photo stores that cater to pro's

-Dan

Leigh
23-May-2011, 14:58
But you can increase the M and the Y filtration without increasing the C filtration to get the same results.
If you'll look back through this thread you'll see that the test prints posted by the OP are in COLOR, not B&W.


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.
Serious misunderstanding of basic photographic materials.

Variable-contrast B&W paper has two emulsions, one sensitive to blue, one sensitive to green.

There is no "filter" incorporated in the paper by any possible definition of that term.

And BTW, cyan is minus red, not minus orange.


- Leigh

Leigh
23-May-2011, 15:00
why not just stick a 2-3 stop nd gel above the diffusion sheet/plate in the enlarger? ...and gels aren't all that expensive,
Changing the dial settings is free and requires no trip to the store.

- Leigh

Vaughn
23-May-2011, 15:07
Leigh, please review Post #7 -- especially the quoted text. We were talking about B&W paper. Sorry for the mis-understanding.

Also, I was just trying to explain it a different way -- hence the quotation marks. And actually VC paper only has one emulsion -- or if you prefer, two emulsions that are mixed together and laid down as one emulsion.

Leigh
23-May-2011, 15:20
Leigh, please review Post #7 -- especially the quoted text. We were talking about B&W paper.
Yes, the thread veered off from the OP's original discussion of color printing to the effect of the adjustment on VC B&W.

My comment at the end of post #7 was intended to bring it back on-topic.

Admittedly changing the cyan channel will not affect VC B&W, since cyan passes both green and blue light unattenuated.


And actually VC paper only has one emulsion -- or if you prefer, two emulsions that are mixed together and laid down as one emulsion.
You can make VC paper from two emulsion components, and I expect that's how it was originally invented.

Ilford chooses to use three, as described in their "Contrast Control for Ilford Multigrade Variable Contrast Papers" document, thus:

"MULTIGRADE papers are coated with an emulsion which is a mixture of three separate emulsions. Each emulsion is a basic blue sensitive emulsion to which is added different amounts of green sensitising dye."

- Leigh

Vaughn
23-May-2011, 15:30
...
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

Ahhh. I see where my misunderstanding is...I thought you meant that one had to add the cyan filtration in order to work as a neutral density filter for B&W. Instead of what you meant -- that one can add it, but it does not make any difference if one does or not.

Good! I see we are on the same page now! Vaughn

Leigh
23-May-2011, 15:33
Good! I see we are on the same page now! Vaughn
Yep. It's good when the left coast is in sync with the right coast (I think :p ).

- Leigh

tgtaylor
23-May-2011, 16:35
Are you guys saying that it will or won't work with B&W VC paper?

The setting to achieve a grade 2 print on Ilford MGIV RC paper with my color head is 0C, 41Y, 32M. If I add 45cc of Cyan into the pack while also increasing the Y and M settings by 45cc respectivly (i.e., 45C, 86Y, 77M) would I be introducing a neutral density filter into the mix which would only increase the paper exposure time but otherwise produce a print equivalent to that I would have obtained without adding 45cc to each of the filters?

Thimas

Leigh
23-May-2011, 16:38
Are you guys saying that it will or won't work with B&W VC paper?
Yes, it will work with VC B&W.

The point of the earlier discussion is that you do not need to change the cyan setting for B&W printing, just add the appropriate settings to the yellow and magenta channels.

However, if you want to use this technique with color printing, you DO need to change all three channels by the same amount.

Therefore, it's probably reasonable to change all three regardless of the type of printing just so you become accustomed to the routine.

- Leigh

Vaughn
23-May-2011, 17:33
...The setting to achieve a grade 2 print on Ilford MGIV RC paper with my color head is 0C, 41Y, 32M. If I add 45cc of Cyan into the pack while also increasing the Y and M settings by 45cc respectivly (i.e., 45C, 86Y, 77M) would I be introducing a neutral density filter into the mix which would only increase the paper exposure time but otherwise produce a print equivalent to that I would have obtained without adding 45cc to each of the filters?

Thimas

As Leigh suggests, one does not have to add the cyan filtration for B&W VC paper. You may need to fine tune the filtration a little to get the exact contrast. Just adding 45 units of each (going from 41Y, 32M to 86Y, 77M) may not get you exactly at the same contrast level...but probably close enough to make it easy to fine-tune. The reason for this is that the M filter does seem to have a higher "filter factor" -- proportionally, it seems to reduce the over-all exposure more than the yellow.

Adding 45 units of Magenta might raise the contrast more than 45 units of Yellow reduces it. Thus it may not be a totally neutral situation. If one looks at the charts for colorhead filtration equivilents for VC filters, one notices that the amounts of M or Y filtration one adds to change one grade is different for the Y and M filters.

An example: For a Omega D5500 color enlarger, using only a single filter:

The equiveilent of a VC filter #2 is 0 filtration. Up the contrast to the same as a #4 filter, one adds 95M. But to change from a #2 VC filter to the same as a #0 filter, one adds 110 units of Yellow filtration.

tgtaylor
23-May-2011, 17:44
Ahhh - I got it! Thanks guys.

I glad now that I typed in that hypothesis about B&W printing. Now I know why!

Thimnas

tgtaylor
26-May-2011, 10:26
Last night I reprinted the image in post #4 above eliminating the tree branch at the far left top, toned down the blue in the sky to a more pleasing blue, and softened the pink color in the stone to the point where it was just visible with a color correction of a mere 2.5cc. I made 2 11x14's and with the remaining chemistry decided to make a 16x20. Unfortunately the 16x20 turned out too weak as I adjusted the lens to f16.25 and it should have been f16.5. I should have placed an 8x10 sheet in the easel to check the exposure as I did when making the 11x14's.

Anyway, I am very impressed with Kodak Porta 160NC film and hope that the new Porta 160 is the same.

Thomas