M8 Pics with IR cutoff filter

[rvaubel]

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...........Are there different "strengths" of IR cut off filters?

 

Yes, there really are. In the astrophotography world. every manufacturer of filters has his own slew of special narrow pass filters. Filters can be closely taylored to compensate for the oversensitivety of the snesor in the infrared. The cheap ones are apt to be overly broad but could work OK. I have a very expensive "sharp cut" IR cut of filter made by Heliopan that I would like to try on an M8. It works great on my 20Da (infrared sensitive model)

However, I have hopes a software solution will work.

 

Putting a filter on a Leica lens is a lot like having sex with a condom; its OK but I'd rather grin and bare it.

 

Rex

[wattsy]

Are there different "strengths" of IR cut off filters?

 

While an improvement is shown in the 3rd shot, it's just not enough.

 

I've ordered a B+W UV/IR filter. Maybe that will be more effective than the Tiffen one. In any case, I'll let the forum know what difference it makes. (Maybe we will have to screw two of the damn things on to the end of each lens?)

[scott kirkpatrick]

I went back and reread the (perhaps not perfect) translation of the Solm status report on workarounds for the extra IR sensitivity. It shows a pretty complete understanding of the issues, and must represent some time working on the problem. The proposal is

 

1 an IR cutoff filter of the right strength and cutoff wavelength to bring the IR block back to the same strength as the DMR's cover glass

 

2 in-camera postprocessing of the RAW data, triggered by the lens coding and implemented in new firmware, to compensate for something, probably the overall color shift due to the filter, as the vignetting corrections would not seem to be changed.

 

This group is pretty powerful in its ability to home in on subtle M8 characteristics. I think we can assume from the RR study of the vignetting corrections that step 2 is less critical.

Click-balancing the WB with a WhiBal or the like should adjust temperature and tint to remove the small overall color, or a modified profile can be created. That leaves step 1 to be sorted out. Are there multiple mild IR-blockers on the market at varying strengths, and if so, which one works best for removing the purple cast from black nylon jackets, packs, velvet etc? Comparison with the DMR's colors would be best. Can you state the illumination (daylight should be easiest; incandescent, flourescent, and studio lamps the most relevant) and click balance to a neutral grey card, not to a sheet of white paper?

(preferably in Capture One)

 

hounds, after that fox!

 

scott

[alexr]

It might be the disappointment speaking here...but if I had seen the three test shots without the camera information, I would simply choose to buy the camera that took the first picture.

Different strenght IR filters for different materials...eydropper tool and curves...just to reproduce some decent blacks in everyday objects. It is not acceptable on a point and shoot, let alone a professional tool.

How many years do you think before the M9 comes? That seems the only solution to this.

[alexr]

I should add that i really totally respect the encomiable efforts shown by many in this forum to look into a workaround. But as fotografz says a working photographer has no time (shouldn't have any time) for this. My Leica M8 is supposed to be a tool for labour, not a labour of love.

[Guest guy_mancuso]

Scott here is my take on the whole issue i will start with the IR issue. I just bought the worlds supply of hot mirror filters but i really don't want to use them period but I have a full set for my glass. But there are some work arounds that may work , one is building a new profile and/or action in PS to control this. This is something collectively we can try and work out a best solution than the filters. Maybe some hope here on that. But the issue is blocking the IR light so anything we come up with really does not get to the root cause.

 

This whole coding thing is really got me fired up. I own the DMR for awhile now and if all this coding will do is fix the AWB than coding the lens for that is worthless to a Raw shooter. I constantly WB each group of shots in C1 as i do my raw processing and change it as i go according to the lighting changes this is really very simple in C1 and spending the money on coding just for this is frankly a waste of money.

 

Now my suggestion is AWB is always a crap shoot anyway , you really are better olf and even as Jpeg shooter to pick the right lighting setting for the conditions , use daylight for daylight because the camera will always be at a certain kelvin tempature like 5600. Tungsten pick that for that lighting. This is more important to the jpeg shooter because there is a fixed kelvin temp and won't bounce all over the place like AWB. i plan on using AWB on the M8 and on the DMR that is all i do , it really makes no difference to me because i WB in raw processsing in C1 and it works great. So if we are reading this correctly which is hard to say becuase of the translation and all it is for is AWB than coding my lenses for that alone is something i won't do. If for other reasons than we will have to look at that but i think this needs to be clarified better before i send my glass to NJ.

 

Now if you want a great card to white balance too in the field than the Whil Bal cards are very handy and just take a shot of one in each lighting change.If in daylight on a all day shoot i may take one in the morning than afternoon and late in the day or something. Or find a nice neutral white shirt, grey or black item as long as it is neutral than is can be used to WB off of. i do this a lot

[egibaud]

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Well... the good news is that there is maybe a solution, the bad news is that the temporary solution is not perfect. Let's wait for the Leica filter and firmware update.

 

really to be a good solution, black must be black and the rest must stay as it should be, the shift in the wood color is unacceptable.

 

There is also another temporary solution for wedding photographers, make your client beleive black suites are no longer in vogue, bishop color suites are the ultimate fashion

 

Eric

[pfogle]

Looking at the third picture, it seems that the reds are over-saturated. I seem to recall (before the IR issue blew up) that high red saturation was a concern with the profile supplied.

 

I think that, since IR will affect all the colors to some degree (though, admittedly, most obvious in 'black' fabrics), it's a dead-end job to try to correct this by selective color correction. You might get a close match, but for pro photogs who *need* accurate rendition, it's a non-starter.

 

IMO, a lot of the sniping that has been going on is because we don't always recognise that other peoples requirements are different to our own, and just as valid. So this camera may be perfectly acceptable for a lot of users, and totally useless for others.

 

As an aside, the old Olympus 2020 had a very similar response, which was corrected in later models by a new IR (internal) filter. They are now cult items for IR photographers! To be honest, I wasn't particularly surprised at this issue surfacing when I saw the color space diagram for the M8 in the Luminous Lanscapes review. There's an obvious IR spike in there...

[Vivek Iyer]

Are there different "strengths" of IR cut off filters?

 

Marc,

 

Look for the Baader Planetarium filters (there is a 2 inch version that is the largest) for UV/IR cut variety. You would need to get them mounted into a thread of your choice (as dictated by you lens' filter thread size). Vignetting wouldn't be a problem because of the crop.

[wizard]

The top picture may look more 'black' but the 3rd image overall has a lot more life

 

Funny, those were my thoughts as well. While the blacks are "deeper" in the first shot, the third shot looks the most natural to me.

 

Andy

[Vivek Iyer]

I am very sorry to break this to you folks but it has to be said.

 

The proposed solution of adding an UV/IR cut filter to the lens by Leica WILL NOT WORK for wide angle lenses since the hot mirror filter's efficiency depends on the incident angle of light.

 

For longer focal length lenses, it will be alright (longer the better). For the new Tri-Elmar, simply FORGET IT.

[scott kirkpatrick]

Won't work because it's dichroic, and depends on wavelengths matching glass thickness? Then the effect of the filter would depend on the angle of the object away from the midline of the lens, and give rise to a radial correction like the vignetting correction which is already done for the coded lenses. That would make sense as the objective of step 2.

 

scott

[gseitz]

As to software fixes, I found:

 

1. Select offending tinted black color with eyedropper

2. Select "color range" from PS "Select" menu - fuzziness varying, but 20-40 somewhere - this selects that particular dark magenta everywhere in the image.

3. Hue/Saturation/Lightness - desaturate overall about halfway, with additional half-desaturation for magenta, blue, red and green individually (to avoid taking neutrals too far to the green side), plus a slight lowering of lightness because the IR is raising the shadow exposure artificially.

 

But as fotografz says - not something one can do with 300-400 shots per week.

 

Wiht Greg's permission I'll attempt it on his unfiltered M8 shot and post it here.

 

Hi, feel free to modify them.

 

By the way, I tweaked the color temp and balance in capture one a bit and was able to get rid of some of the color cast introduced by the filter. Here it is...

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[carstenw]

I am very sorry to break this to you folks but it has to be said.

 

The proposed solution of adding an UV/IR cut filter to the lens by Leica WILL NOT WORK for wide angle lenses since the hot mirror filter's efficiency depends on the incident angle of light.

 

For longer focal length lenses, it will be alright (longer the better). For the new Tri-Elmar, simply FORGET IT.

Do you have any links to more information about what range of lenses we could expect to work with hot filters?

[adan]

Here's my "fix" of the original shot selecting the magenta/black tint globally that is the signature of IR-stained blacks and desaturating overall and for magenta, red, blue, and green.

 

Problem is that the IR will stain other things - green grass and gray-green cloth and foliage - but it can save some pix where black is the only obvious problem.

 

It's also obviously not ideal for folks who need to move a lot of pictures in a short time - it only takes a minute or so - but a minute x 200?

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[rvaubel]

I am very sorry to break this to you folks but it has to be said.

 

The proposed solution of adding an UV/IR cut filter to the lens by Leica WILL NOT WORK for wide angle lenses since the hot mirror filter's efficiency depends on the incident angle of light.

 

For longer focal length lenses, it will be alright (longer the better). For the new Tri-Elmar, simply FORGET IT.

 

Yikes!! I forgot about that. What's worse, the same angle of incidence problem would also effect the ability of the filter in front of the sensor to do its job, especially for wide angle lenses.

 

Rex

[carstenw]

Yikes!! I forgot about that. What's worse, the same angle of incidence problem would also effect the ability of the filter in front of the sensor to do its job, especially for wide angle lenses.

 

Rex

From what focal length is the IR-cut filter no longer effective?

[MP3]

From what focal length is the IR-cut filter no longer effective?

 

I just read the BW 486 UV-IR Cut Filter desciption on their site.The description said the 486 filter is effective regardless of the angle of light incidence. And the filter is an ideal 1.0.

 

here

 

&

 

here

 

Best

Matthew

[pierovitch]

Lets not get into rash generalizations the technical data on angle of incidence of dichroic bandpass filters from a reputable source can be found here http://ssc.spitzer.caltech.edu/irac/documents/quijada2004spie.pdf A 5% variation does not make it unuseable

 

Cheers Pierre

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Hallo,

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