my new Canon 25mm f3.5 help needed - aperture issue?

[harpofreely]

Hello all,

I've just taken possession (via EvilBay) of a nice-in-a-user-way Canon 25mm f3.5 (the little chrome one).

Overall it's in decent shape, but wide open (3.5), the aperture blades are still visible and the opening is still hexagonal. The aperture at 3.5 _is_ larger than at 4.0, but there is not the round, bladeless opening that pretty much every other lens I've ever seen has when set wide open.

Is this normal for this lens? I've googled a but, didn't find much except a photo that kind of looks like this is not normal.

Thanks much!

 

[kermaier]

My Canon 25/3.5 and 28/2.8 are that way too -- it's normal.
If your 25/3.5 has clean glass, you have a real gem of a lens to enjoy!
Cheers,
Ari

 

[harpofreely]

Ari,

Thanks much & glad to hear it - the glass looks at least as good as most of what I have from that era.

Best,
-Paul

 

[Livesteamer]

Mine is the same way and I regard it as a very nice lens whether on my IIIc or M6. I love the small size also. Enjoy. Joe

 

[roundg]

It's normal and it's a great lens on film and digital. No color shift at all on my M9.

But be careful to use a filter. A filter can easily generate dark corner in the pictures.

 

[mdarnton]

It's not uncommon for designers to design a lens and then throttle it back a bit until it gives the results they want. I have a lens that's f12.5, and if you fold back a tab internally, it actually opens to f6.8, but the maker didn't want it ever to be used there. On really old lenses, they used a plate in front of a half-way decent lens to stop it down so that it started out being a decent lens.

Here's an example: https://lh5.googleusercontent.com/-...%21r%21FCTe%2ClJIcBQlIk7TU6%21%7E%7E60_57.JPG

 

[iphoenix]

be careful to use a filter. A filter can easily generate dark corner in the pictures.

Does this apply if you use the original thin Canon RF filters?
I have a set which I haven't used on the 25mm yet.

 

[Nokton48]

Does this apply if you use the original thin Canon RF filters?
I have a set which I haven't used on the 25mm yet.

You will need the Canon Slimline filters if you are shooting 35mm film. When I tried anything else I got vignetting with this lens.

 

[kbg32]

If you're careful, I used regular filters on my Canon Serenar 28/3.5. I used a file to file down the retaining rings making it a slimline. Didn't take very long.