Archived posting to the Leica Users Group, 2016/08/31

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Subject: [Leica] IMGS: IR Attempts
From: hlritter at twc.com (Howard L Ritter Jr)
Date: Wed, 31 Aug 2016 21:24:53 -0400
References: <dzpu1t01807g8Sg01zpwaV> <faf2188d-203b-b67c-fd85-6fc199c51fe0@cox.net>

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
> 
> 
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In reply to: Message from kcarney1 at cox.net (Ken Carney) ([Leica] IMGS: IR Attempts)