Protect lens/filter holder for long exposure

[Audii-Dudii]

hi Audii, thanks for the useful information. As far as digital goes, I have great experience with long exposure.

I've done a lot of research on film (and I've been using 35mm and 6x6 for a year now, mostly street photography) and I think I'm ready for 4x5.
But I did notice, for example, that the lever for cocking the shutter might be a potential source of light leak, and generally speaking lenses are not made for long exposure.

There could also be light leaks coming from the lens board and who knows what else could be an issue. I'm just trying to make sure I won't fail miserably.

My point was that depending on the specific camera / lens / etc. combo you end up buying -- especially because you appear to be looking to buy used equipment -- there are an almost endless number of potential ways that your camera setup can leak light.

The only way you'll know which ones are problematic for you is to test your camera and see what results you get. Then, if you can't figure out why light is leaking in a certain way or from some area, you can post here with some specifics and receive some informed, knowledgeable assistance.

Good on you for thinking ahead, though, and good luck with your adventure!

[rpagliari]

You should find a screw in ND filter instead of a filter holder, as some LF lenses are critical that the filter is perfectly aligned in front, because if tilted just a little bit, they can set up severe internal reflections with some types of lenses...

Lenses with a flat element inside seem to double highlights or blob flare under certain conditions when heavy filters are out of alignment...

Steve K

Could you possibly elaborate on this? For example what do you mean by perfectly aligned?

I can't see the problem unless the filter holder is damaged mechanically.

I believe the flare is mostly due to light leaks, at least in my experience, which is why I use a hood for the filter and wrap a scarf around it.

[Bob Salomon]

Could you possibly elaborate on this? For example what do you mean by perfectly aligned?

I can't see the problem unless the filter holder is damaged mechanically.

I believe the flare is mostly due to light leaks, at least in my experience, which is why I use a hood for the filter and wrap a scarf around it.

A filter is actually also a lens but one of extremely long focal length that would be measured in meters. The best filters are extremely flat so they won’t effect resolution. It is imperative for a filter to be parallel to the lens. That is why holders are not the best choice. Screw in or bayonet or magnetic mounts are far better.

[6x6TLL]

Tangential to this, in regards to protecting the lens, is a UV/skylight filter recommended? Years and years ago when first learning photography, I was taught to always have one mounted, to protect the front element from damage, and that a good filter would not affect sharpness, contrast or resolution.

Is there any reason that wouldn't also be the case for LF today?

[Dan Fromm]

Could you possibly elaborate on this? For example what do you mean by perfectly aligned?

I can't see the problem unless the filter holder is damaged mechanically.

I believe the flare is mostly due to light leaks, at least in my experience, which is why I use a hood for the filter and wrap a scarf around it.

You are mistaken. Flare is due to internal reflections between elements in the lens. LF photographers don't use zoom lenses at all, let alone high ratio zooms so we rarely see any bright flare spots that are reflections of the diaphragm, let alone the long strings of such spots that some zooms produce when the sun is in the frame or near its edge. The typical LF lens doesn't have that many elements, and this helps cut down on veiling flare even with uncoated lenses.

Lens hoods reduce flare by eliminating non-image forming light. Many LF photographers use compendium hoods, bellows whose rear surrounds the lens (with huge gaps, the bellows are square, the lens is round) and extend a variable distance in front of the lens. We set the compendium's length so that it just doesn't cause mechanical vignetting.

LF cameras by and large don't suffer light leaks. When they do, the usual sources are pinholes in the bellows and failure to seat the film holder in the back. Less common causes are failure of the front standard's light trap, failure to cover the hole for a shutter anti-rotation pin in the front standard.

You've been asking about center filters for w/a lenses. These all screw in. Filters, such as the NDs you're going to need, that attach to them also screw in. When the filters are screwed properly in place -- not cross-threaded -- light leaks through the threads are not a problem. And if the filters are well made and haven't been horribly abused, screwing them in guarantees that their surfaces will be perpendicular to the lens' axis. Ain't no gaps or wiggle room.

Y'know, we were all born naked and ignorant. We've had to learn a lot, including to wear clothes most of the time. OP, you really should buy a book on LF photography and read it, you'll learn more that way than from a string of questions and short answers, not all very good. The list mentions a couple or three good ones and suggest where to buy them. Do yourself a favor, ...

[Bob Salomon]

Tangential to this, in regards to protecting the lens, is a UV/skylight filter recommended? Years and years ago when first learning photography, I was taught to always have one mounted, to protect the front element from damage, and that a good filter would not affect sharpness, contrast or resolution.

Is there any reason that wouldn't also be the case for LF today?

Yes, if you use low end stuff.

[rdeloe]

I do a lot of long exposure with a digital camera and will start soon with LF (4x5).
Also, do I need to worry about protecting the back (I usually do between 4 to 8 minute exposure)?

If everything is in order you shouldn't have to worry about light leaks from pinholes in the bellows, leaks through the back, etc. However, if your gear is old and heavily used you should probably check. My current camera had a new bellows put on it, and they used a clear glue which let some light in where the bellows glued to the metal frame; that was one source of light. More light came in via leaks around the light seals between the bellows frame and the camera; the original seals were compressed due to age and the bellows frame was a bit bent.

These are fixable problems, but you need to find them. My technique is pretty simple. Do you have a spare lens board, ideally Copal 0? Or a lens in a Copal 0 board that you can temporarily dismount from the board? You need to replace the lens with a light source. I had an old clamp lamp for incandescent bulbs. Incandescent bulbs are too hot so I used a nice cool LED "bulb". Mount the lamp in the board, put the camera on your tripod, mount the board in the camera (making sure to tape around the socket so there are no light leaks), insert a film holder, pull your bellows out to max extension, and park yourself and your camera in a totally dark room. Wait 15 minutes if you can so your eyes adapt, and then turn on the light. Crawl around your camera looking at it from as many angles and directions as you can. If you see any light, note where it's coming from so you can do repairs (a whole other subject).

When they're shooting, some people seem to like covering the whole camera with their dark cloth for extra protection. That's not my practice but everyone has their preferred approach.

[Doremus Scudder]

hi Audii, thanks for the useful information. As far as digital goes, I have great experience with long exposure.

I've done a lot of research on film (and I've been using 35mm and 6x6 for a year now, mostly street photography) and I think I'm ready for 4x5.
But I did notice, for example, that the lever for cocking the shutter might be a potential source of light leak, and generally speaking lenses are not made for long exposure.

There could also be light leaks coming from the lens board and who knows what else could be an issue. I'm just trying to make sure I won't fail miserably.

It's a good point about the camera that might make a difference. I just ordered a 4x5 viewfinder camera by Stenopeika.

No, no and no.

Lenses and shutters are light tight. LF lenses are fine with long exposures, and, unless your equipment is defective, your lensboard won't leak light either.

The biggest problem you will likely have in that regard is stray light getting in behind the filters in your holder and reflecting around. That's why Dan and others here recommended screw-in filters (no way for stray light to get in). Lee makes a nice hood... maybe that will solve your problem.

Really, I see no insurmountable problem using the Lee system as long as you realize that you'll have to protect the filters from stray light somehow if that looks like it might be a problem. Use a hood, wrap your scarf around it, whatever; it's not rocket science.

Do read up on reciprocity failure and get yourself the charts for the films you intend to use. With many films, a two-minute exposure on the meter needs to be lengthened to 20 minutes or more. An eight minute exposure on the meter might need an hour or more.

FWIW, I've done this a lot, i.e., shot 20-120 minute (and longer) exposures with black-and-white film and a view camera. No light leaks, even though I usually don't use a lens hood (I do use screw-in filters). And, no problems with exposure once I tested my reciprocity failure and made my own tables. Once exposures get into the minutes with film, it's really hard to overexpose, since doubling the time plus more reciprocity correction (which may result in tripling or quadrupling the time) only adds an extra stop exposure. Err on the side of too long to start with.

Best,

Doremus

[Dan Fromm]

Doremus, the OP has, in other threads, stated that he needs to use a center filter on a wide angle lens with an ND filter to allow very long exposures. I'm not sure that the Lee system is compatible with a center filter. Do you know? Me, I never touch the stuff..

[6x6TLL]

Yes, if you use low end stuff.

Yes it would be a problem, or yes it's recommended to use a UV filter?

I'm using a Rodenstock APO Sironar-S 210mm f/5.6.