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Zenitar 16mm f2.8 fish-eye focus
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PostPosted: Tue Nov 14, 2017 9:41 am    Post subject: Zenitar 16mm f2.8 fish-eye focus Reply with quote

Hello everyone,

First post from a Romanian manual lenses/Pentax SLRs fan. Smile

I've just purchased a Zenitar 16mm fish-eye, which has the "lack-of-infinity focus" problem. Started to adjust it, and I encountered some issues:
- if infinity-focused "properly" using the split-view viewfinder on the Pentax ME Super (on a house roof vs sky, 50-75m away), then the Ricoh KR10x and the Pentax K-R are out of focus at infinty (have to focus closer to get the viewfinder to align/the DSLR pictures to appear sharp at infinity)
- to make things funnier, lenses that I considered to have no infinity-focus issues (Pentax 50mm f1.4 FA, Vivitar 28-90mm f2.8-f3.5), seem to need "back-focusing", but just on the Ricoh KR10x; the others are just fine
- so... is there something I'm missing? can the old SLR viewfinders be "slightly intolerant"/be lying to me?

All the best,
Mihai Toma


PostPosted: Tue Nov 14, 2017 4:35 pm    Post subject: Reply with quote

Welcome MihaiToma

This lens requires the rear uv filter to get infinity focus. Or, removal of rear filter if lens has had focus adjustment. Mine didn't need the filter, which is preferred mode imho.

There are plenty of focus adjustment guides for this lens online.


PostPosted: Tue Nov 14, 2017 10:10 pm    Post subject: Reply with quote

Sorry, maybe I wasn't clear - I did adjust the focus properly... It's just that I'm not too sure which camera "to believe" of the three at hand.


PostPosted: Tue Nov 14, 2017 10:53 pm    Post subject: Reply with quote

My sorry!

Adjustment for wide angle lens is finer than for normal through telephoto lens, so, yes the three cameras could easily show different for 16mm wide lens.

If not too much different of course you can adjust lens to go to Infinity on the farthest focusing body, thus infinity can be reached on other bodies using lens'focus adjustment.

Need a calibrated wide lens to check which body, if any is correct.


PostPosted: Wed Nov 15, 2017 8:06 am    Post subject: Reply with quote

I hardly believe that the dslr has a focal flange distance or a ttl path adjustment issue if it wasn't tempered with it.
So first , on the film cameras, I would check if any viewfinder diopter correction is used, then I would compare the image focused through the viewfinder with the image in the film plane. There are online tutorials about how to check the focus in the film plane as it's also the main method to calibrate rangefinders.
If I had to guess I would say a focusing screen it's wrongly installed or needs adjustment, but you'll have to check it yourself.


PostPosted: Wed Nov 15, 2017 8:39 am    Post subject: Reply with quote

Thanks to the both of you! Will investigate further, as per you advice... Come to think of it, the first film that I shot with the Ricoh KR10x was sliiiightly out of focus, even though the viewfinder had much better visibility then the K-R viewfinder (and I always use manual focus on that too, as all my lenses are manual focus).

Looks like I'll have to shoot some "focus test rolls" with my two cameras. Now I've been reading that the focus shown by the viewfinder might be different than the focus on the actual photo, in case there are issues with the mirror. Fun. Smile

Fully unrelated, it looks like my third camera (I'm a cheap-and-cheerful-old stuff buff), the Olympus XA2 seems to have the tendency to underexpose by a stop or so. This film stuff is much more fun than anticipated. Wink


PostPosted: Wed Nov 15, 2017 9:22 am    Post subject: Reply with quote

Quote:
Looks like I'll have to shoot some "focus test rolls" with my two cameras. Now I've been reading that the focus shown by the viewfinder might be different than the focus on the actual photo, in case there are issues with the mirror. Fun


I wouldn't waste film if in doubt. Good film is expensive at f64 Wink. Put a ground glass in the film plane or a piece of transparent cd case with transparent adhesive tape on it (matte surface/tape towards the lens) and check the focus with a magnifier.

Quote:
the Olympus XA2 seems to have the tendency to underexpose by a stop or so.
.
CdS meter cells tend to deteriorate. One can compensate changing the iso 1 stop down in your case.

And yes, I find the film nice too . I've recently re-started to shoot and process BW film and even I'm not much of an photographer it is so fun and rewarding at least at a personal level.


PostPosted: Wed Nov 15, 2017 10:17 am    Post subject: Reply with quote

Thanks!

Would you mind posting a link to a more in-depth tutorial on how to achieve what you proposed, above?

P.S. Acum remarc tara similara. Smile Stiti pe cineva care se ocupa de reparatii/verificare/intretinere aparate/lentile SLR vechi?


PostPosted: Wed Nov 15, 2017 11:45 am    Post subject: Reply with quote

Strangely enough after a quick search I could not find a detailed tutorial. I'll keep looking when the time will allow me to. Meanwhile maybe someone else here can point to an usable guide. If not, as I plan to check the focus on a rangefinder before loading film, I will post some photos of the process.

Quote:
Stiti pe cineva care se ocupa de reparatii/verificare/intretinere aparate/lentile SLR vechi?


I'm located north-east of Romania and I don't know any camera repairman in this area, so I maintain my small collection myself, taking the eventual risks Smile . I'm pretty sure there are repairmen in Bucharest, that can do film cameras and manual lenses. There are a few other romanian members here, maybe they can recommend someone.


PostPosted: Fri Nov 17, 2017 12:56 pm    Post subject: Reply with quote

Thank you. Will have to do some more digging. In the meantime, I'm building myself a DIY automated "Jobo" photo development processor. Again, fun. Happy Dog


PostPosted: Fri Nov 17, 2017 1:29 pm    Post subject: Reply with quote

There's a DIY section in the forum: http://forum.mflenses.com/diy-f60.html . Maybe you can share there your film processor project. I'm quite interested ... especially about the temperature control and agitation part Wink