Adding a filter ring to the CV 15mm LTM

[squirrel$$$bandit]

I've been wanting to do this ever since I saw this article (scroll down) on the LHSA site a few weeks ago, so last week I ordered a crap 39mm UV filter from eBay for the purpose of ripping it apart. It came today. The project took about an hour.

Basically, as Benson Schuman explains in that LHSA piece, you remove the glass, grind off the male side of the filter, epoxy it into the CV15, and Bob's yer uncle. I managed it with a dremel and some sandpaper--several blisters later, I got it into shape. The filter was some off-brand and was much thicker than the B&W I would be screwing into it, so I had to grind down the ouside of the ring as well. When I finally got it to fit, my plan was to hold it in place with some tape, shoot a few test frames on film to make sure that it didn't vignette with no filter screwed in, then adjust to suit. But in the end, the adapter snapped in and I can't get it out! (I'm sure I could by screwing a little stack of 39mm filters into it and pulling on that, but whatever.) It is quite solid right now without any epoxy.

I was also shocked to see how much shallower my adapter is than Schuman's...so if his doesn't vignette on film, mine certainly won't. Here's his:

And here are some shots of mine:

One thing I kind of prefer about my version is that I have shaved off the flange on the base of the adapter, so you can still read the vanity ring on the lens. Anyway, I should be in pretty good shape, but I'll report back if the adapter does indeed vignette on film. Of course, any actual filter on there will vignette on film, but not on the M8.

 

[squirrel$$$bandit]

If you leave the male side on, I'm pretty sure it will vignette with the UV/IR attached, and certainly it will on film. You could give it a try, just by screwing two 39mm filters together and slipping them in there...

 

[squirrel$$$bandit]

I was going to try a bit of silicon adhesive--the clear, rubbery stuff--but it turned out I didn't need any.

 

[Ben Z]

That was my article. The reason I used a B+W was because it's made from brass (Heliopans are too). Aluminum filters, as some others are, sometimes tend to seize, especially to another aluminum filter--as the Leica UV/IR's happen to be. Also the reason I didn't remove the base flange was to provide more surface area for the epoxy. However I really like the way yours integrates nicely without obscuring the writing on the lens, and I would imagine the area between the adapter and the "petals" would provide more than enough glueing area. I wish I'd thought of it.

Ben

 

[baycrest]

Thats a great looking piece of workmanship. It lets you change the ir cut off and put a plain UV for your film camera.

For myself, I took the easy way out, slapped a dab of silicone on the lens and placed the B&W ir cut filter in.

 

[squirrel$$$bandit]

That was my article. The reason I used a B+W was because it's made from brass (Heliopans are too). Aluminum filters, as some others are, sometimes tend to seize, especially to another aluminum filter--as the Leica UV/IR's happen to be. Also the reason I didn't remove the base flange was to provide more surface area for the epoxy. However I really like the way yours integrates nicely without obscuring the writing on the lens, and I would imagine the area between the adapter and the "petals" would provide more than enough glueing area. I wish I'd thought of it.

Ben

Thanks for posting your piece on this! It was very informative. I considered finding a cheap 39mm B&W, but in the end I decided to go with something I knew would be easy to grind down, and which, if I messed up, wouldn't represent much of a loss. So far it's plenty smooth, but you're right, i've had trouble with aluminum filters at times, too.