Fujinon W 210mm flange distance

**SocalAstro** · 27-Jun-2011, 12:17

Im looking for the flange distance on the older (352mm IC) fujinon W 210mm lens.
Does anyone have a source or know what this distance is?

Thanks in advace,
Leon

**Ken Lee** · 27-Jun-2011, 13:15

See http://www.ebonycamera.com/articles/lenses.html

**David Karp** · 27-Jun-2011, 13:38

Try here: http://www.willwilson.com/fujinonlc2.html

**Ken Lee** · 27-Jun-2011, 13:40

I may be mistaken, but I think flange distance may not always the same as focal length, even with "prime" lenses. The difference can be considerable in some cases.

The table on the Ebony web site actually lists both. It's the only place I could find those numbers.

**Leigh** · 27-Jun-2011, 15:10

Originally Posted by Ken Lee

I may be mistaken, but I think flange distance may not always the same as focal length, even with "prime" lenses. The difference can be considerable in some cases.

Flange focal length (FFL) is definitely not the same as the optical focal length. If they're equal it's only by coincidence.

Both optical focal length and FFL are listed on all modern datasheets. It may be more difficult to locate for vintage lenses.

- Leigh

**Leigh** · 27-Jun-2011, 15:22

Originally Posted by David Karp

Try here: http://www.willwilson.com/fujinonlc2.html

That table does not show FFL, only optical focal length, and that value is nominal not necessarily actual.

- Leigh

**SocalAstro** · 27-Jun-2011, 15:26

Originally Posted by Leigh

Flange focal length (FFL) is definitely not the same as the optical focal length. If they're equal it's only by coincidence.

Both optical focal length and FFL are listed on all modern datasheets. It may be more difficult to locate for vintage lenses.

- Leigh

Thanks for the links Gentlemen; I have those in my bookmarks. the Ebony list is indeed very helpful but does not list the FFL for the older lens I have.

FL and FFL are indeed much different and vary with lens design and such. My Grandagon 115mm for example has an FFL of 121mm which is significant when constructing fixed focus or helical focus LF cameras.

I'll just have to construct a test bench and measure it emperically I suppose.

Cheers,
Leon