Am I Over Agitating?

gone · Feb 24, 2015

I haven't developed much film lately, and there's a problem now. The top corners of outside shots of skies are darkened. At first I thought it was my hood vignetting, but it has happened on two different cameras. If it were the hood, wouldn't the bottom be darkened in the corners too? The two photos below are from two different cameras, and both were developed in different developers. I'm wondering if I'm being too vigorous when I do my inversions. Or something. The strange thing is that it's not happening on every frame w/ skies, just on some.

Pioneer · Feb 24, 2015

I am not sure how you over agitate to get vignetting? And I do see darkening in all 4 corners of your 1st photo so that could still be the hood.

I use continuous agitation quite a bit and don't see that result. I have also used vigorous and gentle intermittent agitation with nothing of that sort.

I think a more complete definition of your process may be needed before a cause can be identified.

removedacct1 · Feb 24, 2015

I see vignetting in all four corners of your images. Over-agitation does not result in corner vignetting - oversized/inappropriate lens hoods do. You may want to check your lens shade sizes. Its nothing to do with your film processing.

Paul Howell · Feb 24, 2015

What enlarger, what lens, looks like 6X6 do have the right condenser set, and is the enlarger bulb at the height for your enlarger?

ParkerSmithPhoto · Feb 24, 2015

momus said:
I haven't developed much film lately, and there's a problem now. The top corners of outside shots of skies are darkened. At first I thought it was my hood vignetting, but it has happened on two different cameras. If it were the hood, wouldn't the bottom be darkened in the corners too? The two photos below are from two different cameras, and both were developed in different developers. I'm wondering if I'm being too vigorous when I do my inversions.

When I agitate, I turn the tank completely upside down and then back up again, while giving it a slight rotation. That's one cycle per second and I do five cycles per minute. That and the empty space in the SS tank give the film a big old healthy agitation, and I've never seen anything like that. Also done continuos agitation with a motor base and plastic tanks with no problem.

pentaxuser · Feb 24, 2015

Take two identical shots; one with the hood and one without then examine the two negs. That seem a sure test for the hood.

As the others have said I have never seen vignetting caused by over agitation - why would the developer be able to confine itself to the corners rather than simply increasing contrast all over the neg?

pentaxuser

Sirius Glass · Feb 24, 2015

It could be the 1/cos4(angle off center axis) loss in the corner of the lens. Is is a wide angle lens?

gone · Feb 24, 2015

The bottom photo only has dark corners in the top, and the top photo has much more vignette at the top compared to the bottom. Seems to me that if it was the hood, wouldn't it be equally dark in the bottom corners too? I'm just guessing on the agitation thing, as I can't figure out how else the hood would only do the top corners. I use a swirley motion on agitation. It could be uneven development? I'd better run a roll in a camera that I know never vignettes and see what happens. Weird.

Photo Engineer · Feb 24, 2015

Over agitation does not cause the appearance of vignetting. Since it is an abundance of developer it causes overall density and contrast increases depending on developer and film. Your problem is not over agitation.

PE

RobC · Feb 25, 2015

Its your lens, camera or enalrger I don't know which.

A very simple thing for you to do is take your image in photoshop or similar and increase the contrast greatly. You will see the vignetting in the corners, both bottom and top very easily and also see the curved inner shape leaving a circular central area which would never be caused by agitation in all four corners like that.

Xmas · Feb 25, 2015

It is very useful to do two things.

Look at the negatives - like on a light box.

If the negatives show the effect. Remove back of camera and look through the camera. Otherwise you have an enlarger or scanner problem.

Filter too deep, hood too deep, five will get your four horses...

Noel

SLVR · Feb 26, 2015

May I ask what camera you used to shoot these with?

Judging by the scratches, square format, and vignetting the first image looks like it may be from a holga or toy camera. If thats the case, vignetting is fine.

Also what is your agitation scheme? What developers did you use? What films did you use?

I don't think that you are agitating too vigorously as I don't see any surge marks but the frequency may be too much.

Bob Carnie · Feb 26, 2015

Exactly how I do it... I make sure constant for first 15 seconds

QUOTE=ParkerSmithPhoto;1953710757]When I agitate, I turn the tank completely upside down and then back up again, while giving it a slight rotation. That's one cycle per second and I do five cycles per minute. That and the empty space in the SS tank give the film a big old healthy agitation, and I've never seen anything like that. Also done continuos agitation with a motor base and plastic tanks with no problem.[/QUOTE]

MattKing · Feb 26, 2015

Bob Carnie said:
Exactly how I do it... I make sure constant for first 15 seconds

QUOTE=ParkerSmithPhoto;1953710757]When I agitate, I turn the tank completely upside down and then back up again, while giving it a slight rotation. That's one cycle per second and I do five cycles per minute. That and the empty space in the SS tank give the film a big old healthy agitation, and I've never seen anything like that. Also done continuos agitation with a motor base and plastic tanks with no problem.

[/QUOTE]

Just to add variety, I use the same technique, but my "cycles" are both slower, and more frequent.

Two inversion cycles in 5 seconds, repeated every 30 seconds.

The solutions need to cascade through the film and reel, not surge through the film and reel.

Am I Over Agitating?

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