Test procedure for even development?

Jeff Bannow · Aug 2, 2012

I would like to run a test of my 4x5 sheet film development process, specifically looking for evenness from agitation. Here's my plan:

1. Find an evenly lit wall in the sunshine and meter for middle gray. Take a picture.
2. Develop.
3. Examine and look for any anomalies on the light table.

This seems so simple, that I must be missing something. Anyone have a preferred method?

Overkill-F2 · Aug 2, 2012

Are you tray developing your 4x5's?
I might expose three sheets, zone 3, 5 and 7, contact print, then examine them.
...Terry

Jeff Bannow · Aug 2, 2012

This will be inversion processing.

wildbill · Aug 2, 2012

Jobo, expert drum.

albada · Aug 2, 2012

Jeff Bannow said:
I would like to run a test of my 4x5 sheet film development process, specifically looking for evenness from agitation. Here's my plan:
1. Find an evenly lit wall in the sunshine and meter for middle gray. Take a picture.
2. Develop.
3. Examine and look for any anomalies on the light table.
This seems so simple, that I must be missing something. Anyone have a preferred method?

Illumination of lenses tend to fall off near the edges and corners. Perhaps expose the film using the enlarger at f/16 instead? Or put the film on the counter and blink a light in the darkroom?
Also, the human visual system has a hard time seeing gradual changes in luminance. I suggest using a densitomer, or placing a light meter in various places on the film to measure densities.

Mark Overton

Jeff Bannow · Aug 2, 2012

wildbill said:
Jobo, expert drum.

Sold my Jobo, Vinny.

Jeff Bannow · Aug 2, 2012

Michael R 1974 said:
The best way to do it is use your enlarger - assuming it illuminates evenly. You raise the head way up and stop down so there's no falloff. Expose a sheet of film to some mid-tone density. Process it. And then contact print it.

Interesting - I've never exposed film via my enlarger before actually.

So:

Turn off safelight.
Get the enlarger head to a point with even illumination and stop down lens.
Use incident meter to make exposure in the multiple second range.

I assume I could just do all of this in a normal double-darkslide 4x5 holder.

Jeff Bannow · Aug 2, 2012

Michael R 1974 said:
What kind of tank/system for inversion?

Mod54 in a Patterson tank.

Lee L · Aug 2, 2012

You might find that exposure from a sufficiently distant, possibly diffuse light source will give a more even exposure on the original neg.

Also contact print the neg under even light on grade 5 paper or with grade 5-6 VC filter to make uneven development more apparent.

Lee

ic-racer · Aug 2, 2012

Lee L said:
You might find that exposure from a sufficiently distant, possibly diffuse light source will give a more even exposure on the original neg.

Also contact print the neg under even light on grade 5 paper or with grade 5-6 VC filter to make uneven development more apparent.

Lee

Yes, I'd expose and print like Lee suggests. To quantify evenness you can check the center and 4 corners with your densitometer (or send it to one of us).

Jeff Bannow · Aug 2, 2012

Thanks guys. Any suggestions on a light source?

And I assume I set my light meter to f1?

ic-racer · Aug 2, 2012

I'd expose the film in a film holder with a light from across the room.

Bill Burk · Aug 2, 2012

Haaa, Let's see... I just went through this...

TMY-2, set enlarger so incident meter reads EV0 with the "flat" dome (at ISO 100)

Expose for 5 seconds...

That gives me the same amount of "light" as my sensitometer.

Now you want something middle gray I suppose, a density around say 0.60 sound good?

That graphs under Stouffer scale step 14 which is 1.98 density.

So if you expose film that much less than the full 5 seconds at EV0, you will possibly get 0.60 density when developed.

1.98 divided by 0.3 is 6.6 stops...

So somewhere about an 1/8 or 1/15 second should do the trick...

Mark Fisher · Aug 2, 2012

Is there any light fall off in your enlarger....I'd check that with a light meter before using that method. I know that I get a little fall off with my D2 in 4x5. If you do it in-camera, I'd still check the corners just to see how much light variation there might be.......also, you might defocus heavily just to remove any texture

dpurdy · Aug 3, 2012

I would suggest using a zone 7 density rather than zone 5 because in my experience uneveness problems will show up more.
Back in my days of shooting products on a blank light grey it was a real headache getting it even.
Also because it is useful to have your zone 7 processing time down.

If using your enlarger make sure it is way out of focus from the light source.

Dennis

Bob Carnie · Aug 3, 2012

Jeff we would do a basic copy shot of a large greycard.. make sure that the original is evenly lit.
process as normal and read the film on a densitometer.
If all is well each film that is in different positions of the rack , or each film within the run if Jobo should read identical.
If not your process is off.. I suspect this has to do with the nitrogen burst thread and it is a really good idea to do this, test to check for even development
If you do not have a densitometer on hand someone in your area could read the film and sharpie the numbers.
We measured 9 spots on each film to see how even the run is.

Jeff Bannow said:
I would like to run a test of my 4x5 sheet film development process, specifically looking for evenness from agitation. Here's my plan:

1. Find an evenly lit wall in the sunshine and meter for middle gray. Take a picture.
2. Develop.
3. Examine and look for any anomalies on the light table.

This seems so simple, that I must be missing something. Anyone have a preferred method?

ic-racer · Aug 3, 2012

All enlargers with lenses have light falloff, unless you have a density filter/diffuser made especially for a particular magnification ratio and lens and aperture.
Exposing a film under the enlarger is a different test. That is a test of enlarger light evenness.
Graph shows composite results from 135 and 150mm Schneider Componon-S. The picture is a piece of film exposed under an enlarger and processed to a high gamma to accentuate unevenness.

Bill Burk · Aug 3, 2012

I was going to say that is awful - makes using an enlarger for sensitometer look like a bad idea.

Until I realized. I keep the enlarger locked at the height to make an 11x14 print from 4x5 neg. So I am only using the sweet spot near the middle.

I placed the film squarely under the lens, but positioned the test strip on the left-hand side - so maybe I fortunately avoided the hot-spot at dead center.

And I am using a grid light source, not condenser.

What is your light source (does the lens really have a hot spot in the middle or do condensers play into it)?

Bob Carnie · Aug 3, 2012

Michael is right, he is not using the edges. I have used enlargers for this test as well as lighting on a copy board.
I prefer the copy board method as I am tethered and can read the numbers for eveness.

Michael R 1974 said:
Any light source is subject to falloff off-axis.

I raise the enlarger head (diffusion) way up for a giant print size. The little 4x5 negative is in the middle of a comparatively huge imge circle and within that 4x5 area I don't have variations of even 1/10 stop. That's good enough for me. But if someone prefers to use a softbox 30 feet from film taped to a wall that's probably good too.

Anyhow best of luck to OP. I would be curious to hear about your results with the Mod54.

Jeff Bannow · Aug 3, 2012

Thanks everyone for the advice.

Bill Burk · Aug 3, 2012

dpurdy said:
I would suggest using a zone 7 density rather than zone 5 because in my experience uneveness problems will show up more.
Back in my days of shooting products on a blank light grey it was a real headache getting it even.
Also because it is useful to have your zone 7 processing time down.

If using your enlarger make sure it is way out of focus from the light source.

Dennis

That graphs under Stouffer scale step 11 which is 1.56 density.

So if you expose film that much less than the full 5 seconds at EV0, you will possibly get 1.0 density when developed.

1.56 divided by 0.3 is 5.2 stops...

So somewhere about a 1/4 or 1/8 second should do the trick...

DREW WILEY · Aug 3, 2012

Glad to see that others have pointed out the potential errors in using an enlarger if you don't select
the even part of the field. If you don't have a good transmission densitometer, then contact print
onto a hard grade paper to exaggerate any issues with the film itself. Try to expose the film somewhere around an even middle gray or gray card value. There are any number of ways to dev
film very evenly - tray, drum, brush dev, nitrogen burst, whatever - the most important thing is practice, consistency, then learning the finer points of each technique.

Jeff Bannow · Aug 3, 2012

Bill Burk said:
That graphs under Stouffer scale step 11 which is 1.56 density.

So if you expose film that much less than the full 5 seconds at EV0, you will possibly get 1.0 density when developed.

1.56 divided by 0.3 is 5.2 stops...

So somewhere about a 1/4 or 1/8 second should do the trick...

How could I get that short of an exposure under the enlarger though? I don't think my timer is that accurate.

Bill Burk · Aug 3, 2012

Jeff Bannow said:
How could I get that short of an exposure under the enlarger though? I don't think my timer is that accurate.

I'd put a camera body under the lens with the back removed.

Or, once you find EV0 close down the aperture on the enlarging lens as far as you can, and then cut the time to one or two seconds, for this test - close is good enough.

Bob Carnie · Aug 4, 2012

ND filters will help

Jeff Bannow said:
How could I get that short of an exposure under the enlarger though? I don't think my timer is that accurate.

Test procedure for even development?

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