Archived posting to the Leica Users Group, 2016/09/01
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]Hi Howard, Yes, that is correct. In my initial tries with digital IR I thought a wide-angle at infinity would make things simple, but as you note there are different infinities for the wavelengths. With regard to autofocus, I can't offer a technical explanation. Since the autofocus is based on contrast differences, I just assume those work as well in the IR as they do in normal light. Here is a more complete explanation from Lifepixel.com: https://www.lifepixel.com/focus-calibration-options Here are some samples mostly all taken with the Fuji XE-1 or XE-2 and a Hoya R72 IR filter (and autofocus): http://www.kencarney.com/infrared The Fuji cameras have a weak IR filter. The downside is long exposure times and a tripod or monopod (as much as 1/2 second). I will probably soon have a third Fuji XE body which I will probably have converted to IR only, and take advantage of normal exposure times. Ken On 8/31/2016 8:24 PM, Howard L Ritter Jr wrote: > Ken? > > If you think you can't focus IR because you can?t go beyond infinity, > you?re going in the wrong direction. IR focuses as though the subject is > CLOSER than it is, so you want to use a DOF marker that focuses the lens > at a shorter distance than the subject actually is. For my lens (same as > Tina?s) the best ?distance" for a subject at infinity is 2-3 meters. Even > there I can?t get as sharp an image as with visible light. > > No, this 21mm f/2.8 Elmarit doesn?t have an IR index. I?ve seen them, and > would have sworn that my older Leica glass did, but not so my vintage 50 > ?lux, DR ?cron, or 5cm ?cron. I have no idea where I used to see them, but > clearly IR is out of fashion now. > > I?m intrigued to hear that you can get properly focused IR images with an > AF lens. Are you shooting digital? I?d have thought that the IR filter > routinely used as a sensor cover glass in digital photography (except for > the M8!) would have prevented this. Or are you using film? If digital, > what camera? And what filter are you using? > > ?howard > > >> On Aug 31, 2016, at 8:50 PM, Ken Carney <kcarney1 at cox.net> wrote: >> >> Looks like you're pretty close. I think the key to IR is autofocus, not >> an option here. You might try a few shots at different focus settings to >> see what works with the M8/21. I know my Fuji X 14mm is OOF when it is >> at his hard stop infinity setting, with a 720nm filter, but autofocus if >> fine. Also in LR I like to pump up the whites and decrease the blacks >> some. It is great that you can make IR images at those settings, freeing >> you from the tripod. I take it that the 21 does not have an "infrared" >> focus mark? >> >> >> On 8/31/2016 6:49 PM, Tina Manley wrote: >>> LUG: >>> >>> After seeing the great IR photos posted here lately, I finally dug out my >>> old M8s (the ones that fell in the river but are still working fine), >>> charged up the batteries, and found a B+W 092 filter in the drawer that >>> fit >>> my 21/2.8 Elmarit. I went out around the farm and photographed a few >>> things. Lots of problems. Nothing looks sharp. What am I doing wrong? >>> None of the EXIF is right. Most of these were made at ISO 160, around >>> 5.6, >>> and usually 1/30 or more exposure. >>> >>> http://www.pbase.com/tinamanley/image/163998663 >>> >>> and the next 5. Is there a trick to focusing with the dark filters? I >>> do >>> like the tones so I would like to learn how to do this, but it has to be >>> in >>> focus to work for me!! I got some great photos of the cat yawning that >>> are >>> so out of focus I won't bother to post them!! >>> >>> TIA >>> >>> Tina >> >> _______________________________________________ >> Leica Users Group. >> See http://leica-users.org/mailman/listinfo/lug for more information > > _______________________________________________ > Leica Users Group. > See http://leica-users.org/mailman/listinfo/lug for more information