Infrared on slow shutter speeds with "homemade filters"?

[carina]

Last year I spent some time reading the posts here and elsewhere on

the use of infrared film. I benefited from this quite a bit. My

question now is, for the people who made b&w filters from aerial

stuff and via other 2-nd-hand outfits, how did you keep this "stuff"

from just making slower shutter speed vibrations even worse? In

other words, if you made an adaptor or pracket, how did you keep it

from being less reliable than the camera without this accessorized

equipment? I would think that using outer thread adaptors and

filters would just make possible vibration and shake worse. If you

had some insight into this I would like to hear about it. I have,

now, many military surplus filters, but the custome-mount they seem

to need seems a serious drawback. Any help appreciated...

[carina]

I should say that the question above is not my entire question: I have come into ex-U.S.-military infrared and deep reed filters in the last few months. These filters are huge, and quite thick. My main question is that, since I now have the Pentax 45mm and 75mm lenses, which share a large 82mm filter, can I adapt this nice, new clean class to my Pentax system without having to create some new incredible tripod system? Since these aerial units are larger than thr 82mm I really need, I was unsured how to affix them in a truly useful way.

[miles stoddard]

Carina,

If you have mounted glass, then you probably want to try adapting the old aerial ring to the 82mm size; if you have unmounted glass, you have more flexibility. If it is unmounted, then the first option is to have it "ground" to size, so it fits in an 82mm ring (if you have one or both of the new zooms, you would of course want to use that size). Ideally, get it thin enough in diameter and thickness to fit a ring you already own. If the ring cannot be fit into a current 82mm filter ring, then you need make it into a standard ring of sorts. If you can get the "homemade" filter to fit either an exterior ring or infrared ring, then you have made the accesory highly useful. There is nothing that says you cannot hold the filter in front of the lens, as you take the photo (film doesnt know the difference)!

[miles stoddard]

Per my previous answer: If you are concerned with vibration and a different tripod and the weight of the surplus filters -when placed on the end of your lenses- what you might be looking at on these filters is more than the filter and ring, for instance, the entire mount assembly. If these are B&L filters in brass holders, you don't need the square, metal assembly part, and it and the backing plate can be removed with a spanner wrench or two screwdrivers from the backside. Loosing this could cut the weight by more 50-75%. This drops weight, but doesn't get it on your camera.

 

My previous comment on having it ground to size was unclear. This is a feasable option if the filter thickness is not too deep (some of these aerial ones are 1-2 cm thick!). If it is extremely thick, it wont fit any ring you could swap out, and having it done would be far more time-consuming and expensive.

 

Most adaptations I have seen were for the original 55mm P6x7 lens, which used huge hard-to-find filters; in the case of that lens it was far more cost-effective to play around with this stuff. If you filters are thick and over 150mm in diameter, it is probably not worth the effort, though if one is truly an infrared filter, it probably is.

 

If they are reasonably close to 82mm, and you don't forsee using them on a lens with a larger diameter, you could either: (a) Use an industrial adhesive and mount an 82mm filter ring with glass removed, right to the glass (ugly, but will work), or (b) Simply "make" a Cokin-like adaptor, and affix an old 82mm sky to the backside. This latter option, like the comment on holding the filter (as long as it is in the mount with that flange still on it), will work in most daylight situations with the B&W stuff or traditional B&W film. If you intend to be shooting infrared, you could not use this second setup; you would have to have some thing light-tight.

 

Most aerial filters are yellow, not red, and very few are truly infrared; if you have infrared filters they are probably some other kind of military surplus other than aerial (and most surplus infrared are rather small, closer to 37-48mm). Unless they are labeled in some way, you will have to experiment to find the NM rating of it/them.

 

If I can find a picture of the aerial-adaptor I have seen made for the original 55mm lens, I will send it to you; it can hold up to two filters, and it mounts to the outside rim of the filter-thread area, not the inner filter rings. I believe it was designed for B&L 5" filters.

[cjtower]

Such a project may or may not be worth it to you (my guess is not). I have made several "holders" over the years. In most cases, it is someone with the original 55mm wide which used the big 100mm filter who goes this extra mile and adapts stuff. Since you don't have this lens, you might consider selling the glass to someone who has this lens, or one of the new zooms (though people with the new zooms can probably aford the step rings/filters?); this is not a pathetic attempt to buy your surplus lenses, only a free adice comment that since you need 82mm filters, you might consider selling the filters and putting the money towards factory 82's which or course pose no problem nor hassle. The adaptors I have made and seen are basically hinged rings with a lock-down tensioner which clamps around the outside of the big 55mm Pentax len - something easier to do on this lens due to physical shape, than on a 45 or 75mm lens. If your tripod can hold your camera steady, it can hold your camera steady with an adaptor like this installed - even if there are two filters in the adaptor. As noted above, it the setup you have is VERY heavy, much of the weight is probably tied up in the brass hardware which is unnecessary to the setup you want. If you have the 5" filters and the 82mm thread lenses, and are not using the infrared filter and just doing traditional B&W, as odd as it sounds there are big rubber plumbing step-up which are a perfect fot on the lip of the 82mm-filter lenses, and the 5" filters when removed from their rings and holders are a tight yet perfect fit inside. I have seen people shoot aerials with such a device. The tension form the giant rubber "hood" also holds the focus to infinity. Not pretty, but it works. A lot would depend on just what filters you have. If you sell the filters, you should probably sell the infrared seperately. Quality NM glass holds a certain value even if not in a ring (try buying something from Corning or someone; you wouldn't believe the price they quote you!).