[Leica] How IR filters affect M8 B&W

[kididdoc at cox.net (Steve Barbour)]

On Jun 17, 2008, at 12:06 AM, Geoff Hopkinson wrote:

> Well done Peter, a very useful and practical illustration of the  
> points that
> you made. With a close up, wide open and all tungsten lighting you  
> have a
> worst case, certainly though. My initial impression on the extra  
> 'light'
> gained by removing the filter is that it would be slightly defocused  
> less
> useful light. I don't understand any benefit for not using the UV/ 
> IR, except
> of course where you are deliberately seeking to simulate an IR  
> effect as
> though it was an IR film emulsion. The other exception might be if  
> you had a
> problem with reflection of specular light sources made worse by the
> additional glass?


what started all this is the vague memory of several of us (or was it  
confabulation?) that without IR filters,  bw on the M8 is in fact  
slightly improved, sharper, more contrasty thanks to the IR rays,

anybody know about this?

Steve
>
>
> Cheers
> Geoff
> http://www.pbase.com/hoppyman/e
> http://gallery.leica-users.org/v/gh/
>
> -----Original Message-----
> Subject: [Leica] How IR filters affect M8 B&W
>
> Steve Barbour wanted to see an A/B comparison of an M8 shot with and
> without an IR filter.
>
> My newly-acquired VC 35/1.2 arrived today (yeah, I bought one).  
> While I was
> checking it out, I took the same wide-open shot without an IR filter  
> (left)
> and with the filter (right).  Tungsten lighting, three 40w bulbs  
> above my
> bathroom mirror.
>
> http://users.2alpha.com/~pklein/temp/IRNofiltVsFilt.jpg
>
> Here's the whole frame of the IR filtered shot, uncropped but greatly
> reduced, for reference.
> http://users.2alpha.com/~pklein/temp/IRFiltFullFrame3382.jpg
>
> I stood on the exact same spot with both feet, and focused on my  
> eyeball
> for each shot.  Shot RAW, converted in Capture One with the JFI  
> Plain BW
> profile.  Identical exposures, 1/360 at f/1.2.  Default Capture One
> settings, so the same amount of sharpening was applied to each.
>
> Notice the differences in tonal rendition and contrast, not to  
> mention the
> sharpness of my eyelashes and receding hair line...   :-)  This is
> completely consistent with other test shots I've made with other  
> lenses on
> a tripod. Since it shows a real person rather than cereal boxes or  
> soup
> cans, I thought it would be a reasonable real-world demonstration of  
> what
> happens.
>
> The IR makes the skin a little lighter, and reduces the sharpness and
> contrast a little.  You might be able to play with local contrast  
> and get
> back some of the crispness of the filtered shot, but the differences  
> in
> rendition between the filtered and unfiltered shots remain.
>
> All other things being equal, I prefer to use the IR filter while  
> shooting
> B&W with the M8.  However, I have noticed that you can often gain a  
> half
> stop more exposure without the filter, especially in reddish tungsten
> light.  So if I was shooting at 1/15 or slower, I might remove the IR
> filter, figuring that the half-stop faster shutter speed I'd get  
> might gain
> me more in clarity than the IR smearing would take away.
>
> --Peter
>
>
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