M8 plus B+W 092 IR

[KEH]

I was inspired by an earlier thread on taking advantage of the high IR sensitivity of the M8 sensor. So I have tried a few shots with the 092 (deep red) filter. Works pretty well - in bright light you can shoot at ISO 320 handheld with a reasonably wide lens. Here is a first example from my gallery with the Elmarit 28/2.8 asph:

http://www.rangefinderforum.com/photopost/data/500/medium/20080224-L1000685.jpg

I pretty clearly have to experiment with focus - as I understand it, the different diffractive properties of IR light means that you are usually front-focusing if you just focus using the rangefinder.

I am not sure that anything is in sharp focus in the experimental shots that I took - is just a fact of life with IR? Any advice appreciated.

Cheers,
Kirk

[infocusf8@earthlink.]

Kirk,
Use F8 and hyperfocal you'll be fine.

[KEH]

Kirk,
Use F8 and hyperfocal you'll be fine.

Thanks, that's useful. Can't always use F8 unless I want higher ISO / more noise. But going hyperfocal will cure some of the front focus for sure. Older lenses used to have an IR marker, as I recall.

Cheers,
Kirk

[etrigan63]

Zeiss ZM lenses have the marker as well. Here is one I took using the Zeiss 50mm Planar:

http://farm3.static.flickr.com/2325/2276062895_cc5eda6aa4_b.jpg

[jaapv]

Thanks, that's useful. Can't always use F8 unless I want higher ISO / more noise. But going hyperfocal will cure some of the front focus for sure. Older lenses used to have an IR marker, as I recall.

Cheers,
Kirk

The IR marker is the 5.6 DOF mark. That is correct for the type of lenses which one will use for most of the time for this kind of work. Apochromatically corrected lenses (at least by Leica) will have virtually no focus shift under IR.

[infocusf8@earthlink.]

Thanks, that's useful. Can't always use F8 unless I want higher ISO / more noise. But going hyperfocal will cure some of the front focus for sure. Older lenses used to have an IR marker, as I recall.

Use a tripod to keep ISO down. If you start using any of the IR filters you'll have to. Keep in mind when using an IR filter that high ISO's can produce a grain effect similar to Kodak HIE. The M8 mimics this grain incredibly well, another positive side effect of no IR blocking filter. Different IR filters also produce different effects. Have fun!

[DaveB]

The wide lenses like your 28mm are wondersful for IR specifically because of the great DOF they offer. I have a 15mmCV lens dedicated to IR with a B+W filter wedged into the shade.

Longer, faster lenses can be fun too as they allow for a selective focus that is different under IR as compared to visual light.

http://i27.tinypic.com/160r9lh.jpg
(http://i27.tinypic.com/160r9lh.jpg)

[Brian Sweeney]

The Collapsible Summicron and Type I Rigid Summicron have IR marks that are just outside of F2's DOF, well within F4. This is unusual for fast lenses: many require F8 for good correction in IR. Apochromat's are well corrected for IR. Mirror lenses do not require adjustment either, I've used a 500mm Mirror lens with my Nikon Mount IR camera.

[semrich]

Here is a shot I took playing around with the B+W 093 IR filter, ISO 1250, 1/30 sec. hand held.

De-saturated in CS3.

[Ronald M]

Focus with the RF, then move the spot you found to the right to 5.6 on debth of field scale.

This will be accurate for a 092 or 093 or other deep ir filter. A red that allows more visable light to pass will be different .