Using Oversized Filters

**Two23** · 27-May-2011, 23:44

I have an interesting potential problem I was hoping to get some info on. I bought a TH Anthony RR lens with wheel stops, c.1895. It's a tiny lens with barrel about 35mm outside diameter. No shutter. I have a set of 62mm ND filters and shoot Efke 25. Here's what I'm wondering. With my Petzval lens, I shoot in the daytime by simply placing enough ND filter over the front of the lens to give me a 1s exposure. I wear a black glove and simply press my hand tightly over the filters (which are taped to the lens barrel to hold them in place.) The 62mm filters fit tightly against the ~62mm diameter of the barrel. I intend to do this with my new TH Anthony lens too. I am worried that since I can't tape the 62mm filter(s) tightly to the lens barrel and instead must press them tightly, that I might be getting a light leak? Can light travel through the portion of the filter that is hanging out around the diameter of the lens barrel and then travel in to my negative? Is my solution to either buy smaller filters to fit tightly, cut out some kind of black ring with center cut-out for the 62mm filters, or do I really have nothing to worry about here? I don't have time to experiment as I want to do some important shooting this weekend and negs take a week to get back to me.

Kent iN SD

**John Schneider** · 28-May-2011, 00:53

I've always wondered about this. I think you only have to worry about back light coming in and reflecting off the second (front) filter surface and back into the lens. A black cloth or schrunchie (sp?) around the lens OD and placed against the back of the filter should eliminate any potential problems.

**Robert A. Zeichner** · 28-May-2011, 03:31

Another way to solve this is with a push-on series filter adapter and a step down ring. To do this you need to first know the actual outer diameter of the lens barrel. You say the Petzval is ~62mm. What is it exactly? Do you have a caliper to measure it? The other lens is a different outer diameter. What is that dimension? I have a collection of push on series 8 (67mm) filter adapters to which a screw-in step down ring (67-62mm) could be attached and would then accept your 62mm filters. No tape, no black gloves, no light leaks.

**Jim Jones** · 28-May-2011, 05:22

I sometimes hang larger filters on small lenses, or hold the filter just in front of the lens without touching it for longer exposures. Little unfiltered light should enter the lens.

**ic-racer** · 28-May-2011, 05:33

Rear mount the filter.

**Brian Ellis** · 28-May-2011, 07:02

I don't use any filter holders of any kind any more. I just hold the filter up against the lens with my hand. Works fine, no need to tape or use a holder or do anything else as long as the filter is big enough that your hand doesn't get in the way of the photograph.

**Two23** · 28-May-2011, 10:40

Outside diameter of E&TH Anthony lens is 34.8mm. Outside diameter of Derogy hood is 60mm. When I turn a 62mm filter around backwards, the hood fits in fairly well along the side. Most of my filters are multicoated. Since these lenses don't have a shutter, it's awkward to hold on to the filter and remove/replace the darkslide, and keep the filter in place with the other hand while taking exposure.

Kent in SD