40 Rokkor Lens & filter threads

[WestMichigan]

Advertisement (gone after registration)

Hi,

I have a 40mm Rokkor f2 (2nd version) and I have a puzzling problem. The lens' filter size is 40.5mm and my B&W UV filter threads on perfectly. My vented lens hood from Heavystar also threads on perfectly. My problem is that the B&W UV/IR Filter I recently acquired doesn't thread on correctly. Yet, the lens hood threads on the front of the uv/ir filter perfectly.

 

Can anyone enlighten me?

 

My suspicion is my new uv/ir has the filter pitch used on 40mm Summicron lenses, but then why would my other 40.5 accessories thread on the front of the filter correctly?

 

Thanks in Advance

 

Richard in Michigan

[Advertisement]

The Leica Q3 is available for pre-order at B&H Photo Video and Adorama

[naturephoto1]

Hi,

I have a 40mm Rokkor f2 (2nd version) and I have a puzzling problem. The lens' filter size is 40.5mm and my B&W UV filter threads on perfectly. My vented lens hood from Heavystar also threads on perfectly. My problem is that the B&W UV/IR Filter I recently acquired doesn't thread on correctly. Yet, the lens hood threads on the front of the uv/ir filter perfectly.

 

Can anyone enlighten me?

 

My suspicion is my new uv/ir has the filter pitch used on 40mm Summicron lenses, but then why would my other 40.5 accessories thread on the front of the filter correctly?

 

Thanks in Advance

 

Richard in Michigan

 

My new 40.5mm B+W XS-PRO Digital MRC Nano 010M UV Haze threads perfectly to my lens. Did you try to back thread the filter first and to then try to mount the filter?

 

Rich

[pgk]

My suspicion is my new uv/ir has the filter pitch used on 40mm Summicron lenses, but then why would my other 40.5 accessories thread on the front of the filter correctly?

From what you say it does sound as though front and back threads of the filter might have different pitches.

 

If so I suppose that this might make sense if the filter is a uv/ir filter specifically designed for using on the two Leica CL lenses with the oddly pitched 40.5mm thread (I think it is the 40mm & 90mm lenses which utilse the non-standard thread), as it will then allow for other readily available accessories to be mounted on the front which have a standard thread. Given that the only other accessory available to fit the non-standard thread would be the, now long discontinued, rubber lens hood, then this is fairly reasonable logic if it is correct. I assume the Rokkors use a stadard thread pitch.

[WestMichigan]

Thx Rich,

I did try to backwards rotate the filter a couple of times so it would "seat up" better in the lenses threads, but no improvement. To be honest I am 99% certain the B&W Uv/ir filter I bought has the odd thread pitch for the Leica C lenses on one side and standard pitch threads on the front. I think this because it snugs up about 3/4 of turn in the way I've seen described here on the forum.

 

RW

[jdlaing]

The Rokkors and the Leica 40mm have different thread pitches. There is an adapter available.

The Leica rubber hood for the 40mm had those threads.

[naturephoto1]

No Richard has an M-Rokkor lens and it takes a 40,5mm filter thread. At this point, I am not sure what is the issue with the one filter that Richard has. Maybe you should try to get another filter to check the problem.

 

Rich

[pgk]

Advertisement (gone after registration)

it snugs up about 3/4 of turn in the way I've seen described here on the forum.

The pitch difference is apparently 0.5mm and 0.75mm so you do get only about 1/2 to 3/4 of a turn before locking the differing threads up. It would be interesting for 40mm Summicron owners if B&W still make the 'adapter/filter' that you appear to have (might be worth emailing them - I'm impressed at how many German companies respond well to English language queries) and I'm sure that someone will take it off your hands if you replace it:).

[lct]

All 40.5mm filters have a thread pitch of 0.50 normally, including those made by Schneider (B+W).

Given that the M-Rokkor 50/2 has a 0.50 thread pitch as well, the only explanation i can think of is that the OP's filter has a wrong external thread pitch, probably 0.75 instead of 0.50.

BTW the filter diameter of Leitz C lenses (40/2, 90/4) is not 40.5mm but 39mm with a thread pitch of 0.75.

[lct]

I meant that the M-Rokkor *40/2* has a 0.50 thread pitch, not 50/2 sorry.

[WestMichigan]

Well,

I want to thank everyone for their responses to my issue. By experimental testing I am 99.9% certain that this lovely filter has two different thread pitches. The one on the back which won't screw into a Rokkor 40mm f2 C lens fully and threads in the front which exactly match the my lenses threads. My Minolta UV filter screws right the heck into front of this uv/ir, but the uv/ir won't screw into my uv filter. My aftermarket lens hood also screws right into front of the uv/ir same way it screws into the lens.

Sincerely

Richard in Michigan

[WestMichigan]

Hi PGK,

contacting the Manufacturer would be a good idea. I'm going to leave a reminder in my iCal to write something up and maybe post a writeup in here &/or the M8 Forum.

R in Mi.

[01af]

The E39 filter threads is 39 × 0.5 mm. The Series 5.5 threads for the filter-retaining ring (such as the Summicron-C 40 mm's hood) is 39 × 0.75 mm. The E40.5 filter threads is 40.5 × 0.5 mm.

 

Generally, regular filter threads' pitches are 0.5 mm for small diameters up to and including 41 mm. They are 0.75 mm for diameters between 43 mm and 82 mm. They are 1.0 mm for diameters of 86 mm and beyond.

[Joe S]

There are adapters available with the 39 × 0.75 mm male threads to screw into your lens. They have 39 x .50 female threads to allow use of standard Leica filters and lens caps to match other Leica lenses.

[lct]

The diameter of the Rokkor's filters is not 39mm but 40.5mm folks.

[Joe S]

The diameter of the Rokkor's filters is not 39mm but 40.5mm folks.

 

I stand corrected on the size but the adapter for this lens to standard 39mm Leica is available and the best way to deal with a filter on these goofy threads.

[lct]

Joe, the Rokkor has no goofy theads either. 0.50 IINW.

[Joe S]

My definition of goofy is that it is unlike all my other Leica lenses that nicely take a everyday 39mm filter. The adapter solves that problem.

[lct]

So you envision to put a 39mm filter on a 40.5mm lens really? No vignetting then? Just curious.

[Advertisement]

Hallo,

Look here: Interesting Leica gear

[Joe S]

No vignetting problems. The glass elements are tiny by comparison with the lens od. I don't think the 40.5 was chosen of necessity but rather was part of Leicas attempt at segregating the lesser priced product from the M line.

[lct]

Leica C lenses are 39mm but their 0.75 thread pitch has been chosen for the reason you mention most probably.