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Forum: Pentax SLR Lens Discussion
10-10-2016, 07:51 PM
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No, the hood is fine on FF. In theory I think there could only be vignetting in the 60-75mm range on FF (since it's the same hood on the DA* 50-135), but even there I have not noticed to make any difference
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Forum: Pentax SLR Lens Discussion
05-16-2016, 09:48 PM
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I've cut it to be exactly the same length as the original and the same diameter as the mount opening (after the original was removed from there). I think it was just too shiny as images looked sort of washed out with it.
Probably a tube made of real flocking material instead - like this one for example Scopestuff FLK1SA Black Flocking Material Self Adhesive Sample Size 3" x 4" | eBay (just a random search) will work better.
OK, it was a busy day at the office and I could only take a few random shots before the sun went down, so excuse the boring pictures / high iso. Still they should give a good idea what to expect. I've added also some shots of a white wall to show how's the worst case vignetting at different settings. Here's the link https://www.dropbox.com/sh/nyyq6egj5hn4e8n/AABz3aYsH7ix0YFK-MjSxllWa?dl=0 |
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Forum: Pentax SLR Lens Discussion
05-13-2016, 07:19 PM
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No, I have not seen any bad effects so far - I kept using it on K5IIs meanwhile. Did not use it much on FF since it was kind of front heavy on A7R and I don't really like the adapters for DA lenses.
In theory it can reduce the contrast in some situations due to reflections from the sensor (with felt on the outside, etc I assume that was its main purpose on APS-C since the rear element is anyway oversized for APS-C) but I have not really noticed any bad side effects . However, I've tried to replace it with some black tube I've made from cardboard initially and that made it noticably worse - material was not suitable for this I guess.
I will be off the grid ths weekend but I'll try to post some FF raws on Monday
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Forum: Pentax SLR Lens Discussion
05-12-2016, 03:07 PM
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Forum: Pentax SLR Lens Discussion
05-11-2016, 08:16 PM
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Attachment 309637
This is what it looks like when removed from the lens. The white spots around the rim are the glue that used to hold it in place.
I've just removed it from the lens for now and use it like this - but ideally the part that looks like a felt ring inside the tube should be cut out as it causes the vingetting (so the piece basically becomes just a tube ) and the remaining "tube" then glued back in place.
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Forum: Pentax SLR Lens Discussion
05-11-2016, 01:59 PM
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I finally got my K-1 yestarday and the lens works great on it! (Just remember to set the crop mode to FF not auto :) ).
Looks like Gutta Perka's approach to the mod is much safer/easier to do - I didn't know how the internals are back then so I removed the whole mount but then I had some hard time putting it back together with all the little pins and springs.
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Forum: Pentax SLR Lens Discussion
09-18-2015, 11:52 AM
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To my knowledge they put them to prevent reflections form the sensor and other shiny metal parts inside the lens and camera bodies (In a way, similar to what the lens hood is used for on the other side).
Proper solution would be to replace the baffle with one with a larger diameter - which sould be easy as it is basically a short tube with a little ring to glue it to the mount. But so far I did not notice any problems with reflections.
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Forum: Pentax SLR Lens Discussion
09-18-2015, 10:44 AM
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I guess everyone has seen the samples where DA* 60-250 "almost" covers FF with some dark corners.
But Pentax has a patent for a FF 60-250 lens so I thought maybe it is just the baffle at the back causing the dark corners.
So I finally got some time and disassembled mine to remove the baffle - and tested it on sony a7r. The results are pretty good! Dark corners were gone at all focal lengths.
I've noticed some light vingeting on some focal lengths wide open but no more than what I expect from any lens.
Resolution outside the APS-C zone is good as well, except maybe at 250 (but generally mine is somewhat worse at 250 than for example at 200 even on aps-c).
It is a pretty easy mod to do - just unscrew the mount (and make sure you dont loose those spring-loaded contact pins). The baffle is just a black tube that is glued (!?) with some spots of white glue to the back of the mount.
(I find it litte weird that the baffle is just glued that way - almost like it was not part of the original design and they just figured a way do add it later.)
Apparently the glue is not strong so you should be able to easily pry it out of the mount and re-assemble the lens without it. - And you'll have your FF lens ready.
Mod is fully reversible, as you can just glue the baffle back in its place. I guess it's purpose is to reduce internal reflections but I did notice any problems in that regard while testing.
I tested without the hood but I guess it should be fine at least in the 90-250 range.
Anyway, it looks like the FF camera is delayed again but I thought someone might find this information useful.
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