Why you want to use an IR cut filter (sample)

[hankg]

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It's not just synthetic fabrics. Grass, leaves and various other objects can behave unpredictably. The strobes used here have UV absorbing glass covers but maybe they are still giving off more UV then daylight. So this might be worse then daylight available light. Shot with Visoflex III and 65mm Elmar.

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[Guest guy_mancuso]

Exactly Hank and been saying this since we began this journey . Nice example of it right here . Vegetation throws off IR.

 

BTW the 65mm looks very nice here

[jonoslack]

Exactly Hank and been saying this since we began this journey . Nice example of it right here . Vegetation throws off IR.

 

BTW the 65mm looks very nice here

Hi Guy

I'm going to disagree here - of course, I agree with the example of this image, but the difference in colour here represents (very roughly) an increase of hue of 16 in the red channel; if there were no issues with respect to cyan shift with filters, then it would be a no-brainer, and it's probably a no-brainer for synthetic materias and longer focal lengths. But I'm not at all convinced in terms of vegetation (and it is what I do most).

 

I think we're talking the devil and the deep blue sea here, and a simple import adjustment for correcting yellow in greens (ie with an increase in the red hue) has far fewer implications than sorting the cyan shift using IR filters.

 

Hope you're well!

[Jamie Roberts]

I agree with Jono on this too.

 

And in shots like this in particular shot you need the right profile to get the right greens (Jonathan's analysis of the channels is spot on).

 

I don't know how Hank processed these but they're not representative of the results I get without a filter.

 

Having said that, for lenses without cyan shift a filter won't hurt.

[rosuna]

It is not a question of colors alone. IR light focus at a different plane than visible light, and this affect the sharpness of the files. You can correct colors slants, but it is not the same using a IR filter or make a correction or using a different profile.

Of course, many times this IR problem is mixted with the white balance problems, and they must be separated.

[Guest guy_mancuso]

Hi Guy

I'm going to disagree here - of course, I agree with the example of this image, but the difference in colour here represents (very roughly) an increase of hue of 16 in the red channel; if there were no issues with respect to cyan shift with filters, then it would be a no-brainer, and it's probably a no-brainer for synthetic materias and longer focal lengths. But I'm not at all convinced in terms of vegetation (and it is what I do most).

 

I think we're talking the devil and the deep blue sea here, and a simple import adjustment for correcting yellow in greens (ie with an increase in the red hue) has far fewer implications than sorting the cyan shift using IR filters.

 

Hope you're well!

 

 

Yea but it still is off and for most folks that don't know this it is going to screw them up and certainly when there shooting jpegs. I mean that green pepper looks pretty enemic to me. Us raw shooters can work around some of this but we have to remember there are a lot of newbies to the M8 too. I mean newbies in a kind way here.

[Jamie Roberts]

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It is not a question of colors alone. IR light focus at a different plane than visible light, and this affect the sharpness of the files. You can correct colors slants, but it is not the same using a IR filter or make a correction or using a different profile.

Of course, many times this IR problem is mixted with the white balance problems, and they must be separated.

 

Rubén, in theory the focus issue is no doubt correct; in practice though I have not seen any lack of printable sharpness whatsoever from a filterless M8, unless the IR contamination was so thorough as to render the scene mush (think Sean's xmas light demonstration).

[Jamie Roberts]

Yea but it still is off and for most folks that don't know this it is going to screw them up and certainly when there shooting jpegs. I mean that green pepper looks pretty enemic to me. Us raw shooters can work around some of this but we have to remember there are a lot of newbies to the M8 too. I mean newbies in a kind way here.

 

Hey Guy--

 

That's very true, but I bet Hank's comparison is *not* a JPEG comparison. If it is, then I stand completely colour corrected (pun intended).

[marknorton]

You only have to look at what the M8 churns out with a daylight blocking filter to see what is being mixed with your intended image - an out of focus mush. True, it may not be much in evidence in landscape at this time of year, but the chloroplasts are hardly firing on all cylinders in the Northern Hemisphere right now so we're not seeing much IR fluorescence which is what causes IR photographers to get excited.

 

Leica did us all a dis-service by fixing in our brains that this is a problem limited to black artificial fabrics, a marketing statement made more in hope than in expectation. The problem is you don't know when it's going to be an issue, so why not keep it out of the camera in the first place?

 

The cyan correction is taking longer than expected but Scott has shown it should be relatively straight-forward once the lens type is known. The no-brainer here is to get your lenses coded.

[rvaubel]

Folks

As a dedicated filter hater, I must admit that I have come around to using them on the M8. I had visions of a flaming red cyclops calling attention to my lens and flare bedeviling my every picture. As it turns out, the filters are unobstrusive and no big deal. In situations like dimly lit backlite situations, I simply take them off. Color values are often strange in these cases anyway

 

Rex