I would be happy to know the filter aperture diameter of the Ektar 203mm f/7.7

[Color and Cielo]

I got a Kodak Ektar 203mm f/7.7 lens mounted on a Sychro-Compur #1 labeled Graphic. I like it because it has more character than modern lenses and is easier to handle than vintage lenses, but I don't know what size filter will fit this lens. The same lens I see often on Ebay today will fit Kodak series filters, but this seems to have a different thread. The unique number on the lens is marked OY, so this was probably the last production lens shipped in 1960. I initially assumed this was a 37mm, but it could not be mounted, then I tried a Kenko 36.5mm, which also could not be mounted. I have asked people who are familiar with filter calibers in Europe and the U.S., but to no avail. At one point I considered having S.K. Grimes in Rhode Island make a conversion adapter to 52mm. However, airfares from Japan are too expensive these days, and I have decided not to pursue this plan. I imagine that perhaps this has an unusual thread, but I would appreciate it if someone with more knowledge could enlighten me. I do a lot of outdoor shooting and I don't want to inadvertently damage the lens.

[MartyNL]

Hello, my Ektar 203mm is in a different mount and takes a 2 part slip-on filter that accepts different glass.

There are 2 older threads that I hope will help:
https://www.largeformatphotography.i...tar-203mm-lens

https://www.largeformatphotography.i...er-thread-size

However, I hope someone here can tell/confirm the answer for your exact set-up, if you can't find it above.

[rfesk]

I made my own adapter for my Kodak 203mm lens

1) Measured the outside diameter of the lens.
2) Purchased an appropriate Kodak slip-on adapter ring to series filters. (In my case it was a 1 15/32" to series VI slip-on adapter.)
3) Measured the inside diameter of this slip-on adapter (in my case it was 44mm.)
4) Purchased a 43mm to 67mm filter step up ring.
5) Epoxied the step up ring into the Kodak slip-on adapter ring.

Cheap, elegant and it works

[Steve Goldstein]

I made my own adapter for my Kodak 203mm lens

1) Measured the outside diameter of the lens.
2) Purchased an appropriate Kodak slip-on adapter ring to series filters. (In my case it was a 15/32" to series VI slip-on adapter.)
3) Measured the inside diameter of this slip-on adapter (in my case it was 44mm.)
4) Purchased a 43mm to 67mm filter step up ring.
5) Epoxied the step up ring into the Kodak slip-on adapter ring.

Cheap, elegant and it works

15/32 seems small. Did you omit the inches and write just the fractional part?

[rfesk]

I wasn't thinking. It is marked 1 15/32 also 37mm. I have edited my post.

Those dimensions are for my lens which is of European origin. The original poster's may have different dimensions.

The method of making the filter adapter remains the same.

[peter brooks]

Some of the 203mm f7.7 Ektars made here in the UK say 'Mount 370' on the beauty ring. I would imagine that this refers to the filter size.

I have several 'Mount 370' push-on filters and a push-on hood for my 203mm, all use a simple method of clamping (the rim is split, making a primitive spring / clamp), and are not threaded. They are stackable.

I also have the red filter shown which marked Size 370 "Kodak" Red Filter Made in England. This has a solid rim, no thread, and appears to be a drop-in filter that would require some kind of retaining ring (like Hasselblad ones).

[Conrad . Marvin]

I have a similar lens. Mine is from 1961 with the same type of shutter. I found an adapter ring made by Kodak which fits fine and gives you a series 6 thread. It’s a number 27 adapter ring made by Kodak. I will measure the threads and get back to you later or tomorrow. By the way, the threads will be some inch number as the lens and adapter were both manufactured in the US. Hope that this helps.

[Color and Cielo]

thank you! I also referenced these threads. However these are a bit small for my Ektar and don't seem to work.

[Color and Cielo]

Such a challenging spirit is wonderful. It's great to create something instead of an off-the-shelf product. Given the true purpose of the filter, this may be the most rational method.

[Color and Cielo]

Is the Size 370 "Kodak" Red Filter still available? Is it listed on Ebay or something?