Edge Effects?

[John_4185]

Kevin B's post regarding slow rotation w/JOBO brought this to mind again.

I would be dearly interested in seeing edge effects. If I have ever seen an edge effect, then perhaps I am not recognizing them. Any examples to show the effect would be greatly appreciated.

[Michael Veit]

I think Sandy King posted some extreme crops that clearly showed them quite a while ago. Maybe he could re-post.

As for myself, I've tried all different kinds of film/developer combinations with stand and semi-stand development and have never been able to achieve them. I was of the opinion they were a myth until I saw King's examples.

[sanking]

I can not locate the sample files I posted to show edge effects but if memory serves they were posted on photo.net about two years ago. A search of the site might find them.

The comment about slow rotation with JOBO brought something to mind that may be worth pursuing. There are several causes of edge effects but one of them is that the film is allowed to rest. Most people do this with stand development, using moderately dilute solutions. I believe it might also be possible to also get very good edge effects with extremely dilute developers used with very slow rotation, the idea being that the developer will exhaust locally when parts of the film are out of the solution, which is at least half of the time.

BTW, when edge effects are so pronounced as in the image files I posted on photo.net they obviously detract from the pictorial qualities of the image, so what you want is just enough to increase apparent sharpness but not so much that the image looks artificial. This is somewhat analagous to the use of the Unsharp mask in Photoshop. A little is good but too much ruins the image.

[Bruce Watson]

If you have access to a local university's library, you might find copies of the Henry and Haist books somewhere in the stacks. One or both have discussions about and illustrations of edge effects. If you just want to see examples of edge effects, that's where I'd start.

[Scott Davis]

I have some images I posted that show good edge effects, at least in the real print. I can't remember the image file titles, or I'd post the link now. When I get home, I'll find the file names and post a link.

[John_4185]

If you have access to a local university's library,

oooooh, that's going to leave a mark.

My office is in a university library. I'm fifty steps from the photography stacks. Only book is Haist's the Monobath Manual.

[Craig Wactor]

here is the link to Sandy's post

[Andrew O'Neill]

"so what you want is just enough to increase apparent sharpness but not so much that the image looks artificial. This is somewhat analagous to the use of the Unsharp mask in Photoshop. A little is good but too much ruins the image."

Sandy is absolutely correct here. I've found a rest period of two minutes after 5 sec agitations in pyrocat-HD sufficient (in a tray). You also minimize the risk of uneven development, mottling, etc.

[paulr]

how much is enough vs. how much is too much will depend on the amount of enlargement, among other things. edge effects that work beautifully and subliminally in a contact print may look coarse and nasty in a 4X enlargement.

this is one nice thing about unsharp masking ... you can choose the radius to match your intended print size. you can also restrict it to edges (so it doesn't increase grain and nooise in areas of smooth tone) and restrict it to midtones, where it does the most good and the least harm.

my hat would go off to anyone who's found this degree of control through development.

[sanking]

Paulr: "my hat would go off to anyone who's found this degree of control through development."

Yes, my hat is also off that person. Obtaining this degree of control in development is not a simple matter. But it can be done.

Ultimately it boils down to nothing more and nothing less than how much control of his/her process a person wants to maintain. Some people are perfectly happy to just make a "picture." Others want more.