View Full Version : Behind the Lens Diffusion - any experience here?

5-Jun-2008, 19:51
Hi. With the going price of professional LF portrait lenses, I was thinking of putting a diffusion screen or plate in behind the lens on my B&J 5x7.

Yeah, I know, go do it and report back, but wanted to know if anyone here does that on a regular basis?

I was thinking of some really fine black netting on a frame or a optical flat with tiny flecks of black paint in a "vignetting oval" fashion.

Kind of a poor man's Harrison black dot filter...

6-Jun-2008, 01:29
there was a post here in Feb when Mark Woods stated that he did this sometimes. Maybe he could give some details on technique if he is looking in, or you could contact him.

7-Jun-2008, 08:40
black netting works.. So does hairspray (or vaseline) on a cheap UV filter. You could breath on your lens right before taking the shot. You could buy an actual diffusion filter (cokin or similar). You could even crumple up an acetate sleeve and cut a hole in the center.

For black netting, go to a craft store and get one of those round wooden hoops that they use for embroidery. These are available in many sizes so you can find one that fits pretty well over the outside of the lens. You can double or triple the material if you want more diffusion/vignette. You can also use colored netting if you want some sort of color shift...

Like this: http://www.createforless.com/Wood+Embroidery+Hoop+3/pid546.aspx?SI=856e65dd-2fb1-44fd-a441-6b9ced4709e5

Also, as homemade material like this differ greatly in density, just take an incident meter reading with your diffusion material covering the dome of the meter, compare that to the reading without the diffusion material and you'll know how much to compensate for that specific material.

7-Jun-2008, 13:38

Thank you! All wonderful suggestions!


7-Jun-2008, 21:40
You're welcome.. Just a few of the stupid tricks you learn in photo school! :)

8-Jun-2008, 04:16
Tzabcan got it right. Just remember to stick to the same f stop for all your shots.
Things change as you stop down. If your lens is small enough for a Hasselblad filter, the old lenticular diffuser is more consistent than a black stocking or breath. If you can double expose, diffuse a keylight shot and shoot normal for the fill.
In the end, you've got rid of microcontrast but you've got haloes round the hightlights.
You may get shot down for that. See the pictorial photography post.