Search results for 'back focus' - page 640
Leica 39mm - K mount adapter. Does it exist?
Hi, I understand what John says about DOF, The 12 and 15mm CV lenses are not RF coupled for this reason and rely on Zone Focussing. However, I don't think mounting a CV lens without a special adapter like the Nikon one will work. The movement in the Pentax 15mm is a couple of MM's at most. The diff...
Posted by Kim C on 20/10/2005 - 09:36
Leica 39mm - K mount adapter. Does it exist?
Yes the BessaL is a great wideangle photo machine... brought me back to photography some years ago (and to rangefinder cameras) The body plus 4.5/15mm Heliar weights the same as a 3.5/15mm SLR lens alone! The BessaL 4/25mm combo is also great for street photographing. have fun, Frank
Posted by Sonnar2 on 21/10/2005 - 08:29
New Member...Quick Zeiss Question...
Hi all, The East German factory was run by the Russians and was an 'un-official' factory and nothing at all to do with the Carl Zeiss from before the war and nothing to do with the Contax/ Zeiss brand we now know. The Russians simply inherited the four walls of the old Zeiss factory in Jena, as t...
Posted by Sonnar2 on 27/10/2005 - 22:30
Why not a 50-135mm zoom lens?
The reason is optics. My example was grossly simplified to make the point, and your extension of the concept to 200mm is logical, but only in the same basic way. Lenses are more complex thatn this, especially zooms, so there are many more design factors involved. Even something like focal leng...
Posted by johnriley on 26/10/2005 - 08:09
Why not a 50-135mm zoom lens?
To get back to the original subject: woo-hoo!! I found one of the 45-125 lenses at KEH in Atlanta, Geogia. It is in "excellen"condition (which at KEH means pretty much mint, I buy "bargain" equipement all the time and it's fully functional and totally clean. Just some brassing, nothing to effe...
Posted by Arthur Dent on 27/10/2005 - 03:10
Why not a 50-135mm zoom lens?
Sorry to disagree, but a vari-focal lens is one which has a variable focal length. This is subtely different from a zoom. The zoom is supposed to maintain it's point of focus as you change the focal length (essential in a movie, useful for still photography) but a vari-focal has to be refocused afte...
Posted by johnriley on 27/10/2005 - 07:49
FA 28-200mm IF-AL Lens
I wrote a review of this lens for photo.net a few years back. You can see it at http://photo.net/equipment/pentax/smc28-200
Posted by niblue on 17/12/2005 - 19:23
Tokina AF205 28-105mm F/3.5-4.5
Has anyone had this lens? Can anyone comment on it? On digital and film (i.e. on APS-C or full-frame)? What is your general experience with Tokina lenses? People here seem to prefer Tamron after Pentax, and Sigma seems to have the good (EX?), the bad, and the ugly! :) But I rarely hear about Tokina....
Posted by Flink on 27/10/2005 - 16:03
It's out
(Back on thread) Park Cameras have listed the 12-24mm. At a pinch under £700. Big ouch! That really smarts, especially as the Sigma 10-20mm can be had for around the £300 mark... but isn't available in PAF mount :( Just hope the street price lowers (a lot!). Matt
Posted by MattMatic on 24/11/2005 - 09:02
Just ordered the Tamron 70-300 Macro
I've a number of Tamron lenses but they're all the older Adaptall2 manual focus models but I think they're great and I'm sure you'll be pleased with your purchase. Do let us know how you get on and what camera you'll be using it with.
Posted by Kimbo on 14/11/2005 - 14:40
Asahi M42 35mm 1:2.3 lens from 1959
Hi Mac, It does not take a screw in filter but a funny 70mm clamp on one which fits in the middle of the 2 part hood. An interesting lens which is a genuine true retro focus and one of the first. If you unscrew the front element, you can use it as a macro lens! It was a very good performer for it's...
Posted by Kim C on 09/11/2005 - 09:13
Super Multi Coated Macro-Takumar Question
Oh Joy! Mac's got a new toy, and here come the stupid questions.... I've just downloaded another of Kim Coxon's wonderful manuals - this one dealing with Super Takumar lenses. In it, they refer to the two 50mm Macros - one with fixed diaphram and the Auto version. Pre TTL, there was considerab...
Posted by Anonymous on 10/11/2005 - 11:00
Help! Lens with back-focus?!
Yes, it can happen. I've read reports of some Sigma lenses showing this (on both Canon and Nikon). Most of the problems can be fixed with a chip-change in the Sigma... ...but now you come to mention it I'm slightly puzzled as to how you can get focus errors when the body is doing the control?! I'...
Posted by MattMatic on 15/11/2005 - 21:42
Help! Lens with back-focus?!
Can someone help me with this one? Is it possible for a lens to have back-focus? I mean, with the body in autofocus, the lens focuses consistently further away than the point the body marks as focused. I tried several lenses on the same body, and only this one exibits this characteristic... I ...
Posted by Flink on 15/11/2005 - 21:40
Help! Lens with back-focus?!
I am so baffled by this that I didn't even describe the culprit! I'm talking about my new Tokina AF205 28-105mm F3.5-4.5. The body is my *ist DS. In fact, the first time I used the lens at an event (my mother-in-law's birthday) all the photos taken with the Tokina had bizarre focus points... I th...
Posted by Flink on 16/11/2005 - 08:19
Help! Lens with back-focus?!
This is very interesting and certainly something that I've never heard of before. Basically I think you're saying that the autofocus system is choosing a point slightly behind the subject, do you get focus confirmation (correctly on the subject) when you focus manually? If you don't, then I suspect...
Posted by Kimbo on 16/11/2005 - 14:01
Help! Lens with back-focus?!
Just remembered something ;) (Lightbulb! Ding!) Apparently the *ist-D firmware was designed to focus to the hyperfocal point. It uses information from the lens (aperture and length) to determine where that point is. Now, if the lens inaccurately reports either the aperture or focal length then...
Posted by MattMatic on 16/11/2005 - 16:07
Help! Lens with back-focus?!
Looks like we're thinking along the same lines Matt but you're more technically knowledgable than myself. BTW, it's a Tokina lens not a Tamron!
Posted by Kimbo on 16/11/2005 - 16:18
Help! Lens with back-focus?!
Thanks for the correction Kimbo ;)
Posted by MattMatic on 16/11/2005 - 17:12
Help! Lens with back-focus?!
Kimbo and Matt, Yes, I get focus confirmation on manual focusing (on the wrong place), either by slowly focusing from back to front or from front to back. I'm using Select Focus Point (on the center, and I've tried Single Center, it's the same). And I kept my fingers on the (generous) focus ring;...
Posted by Flink on 16/11/2005 - 22:35
