Filter F-1734

[tony_cunningham]

I have a 77mm filter I obtained some years ago with a Pentax 67 75mm

lens. It is marked F-1734 77x0,75. It looks clear and is probably a

UV filter. The only other mark on it is a logo that looks like a bird

flying over a trapezium. Ca anyone identify what this is please? The

x0,75 is strange, it can hardly be the filter factor!

[NetR]

Hello

 

The 0.75 refers to the pitch of the thread, i.e. one thread per 0.75mm. At the larger diameters the standard thread pitch changes from 0.75mm up to 1.0mm, (e.g. my Hasselblad 93mm is 1.0mm pitch) so it is useful to be able to check that a specific filter will fit your lens. Another example is the T2 thread, which is 42mm diameter by 0.75mm thread, whereas the Pentax screw thread is 42mm diameter by 1.0mm thread.

 

I can't help with the F-1734. Take some photos of standard colours (Macbeth colour checker or similar) with and without the filter, on slide film, and see what difference it makes.

 

Regards, Ross

[stepan_benda]

Hi Tony,

 

may be I can help You. It`s just an ordinary sky-light filter . 77mm its diameter 75 it`s so called "Steigung" in metric system.

 

The "Bird" You are talkin about is a sign of a russian filters used originaly for 16mm Movie-Camera "Krasnogorsk". I habe 4 different pieces of them. Y-2x, Y-1,5 and N-4x (gray).

 

The filter are not bad and not expensive.

 

Stepan