What do orange and green B&W filters do on the Leica M10 Monochrom?

[Godfrey]

What do orange and green B&W filters do on the Leica M10 Monochrom?

To evaluate what an orange or green filter does on B&W film, I'm accustomed to doing a couple of test exposures of the Xrite Color Checker—one without a filter, and one each with the two filters—and then comparing them. I've become so accustomed to looking at test exposures this way it makes sense to me.

But I realized that trying to see exactly how the filterless exposure compared against the two filtered exposures, and how they differed from each other, was a bit difficult given the Color Checker's distribution of the color tiles.

I got the idea in my head that I could take a color image of the CC and the three exposures, mark each tile as to its position on the grid, and then decompose it into three sets of 18 tiles. I then ordered the tiles take by the M10-M without a filter from dark to light, and rearranged the colored tiles and the two sets of tiles made with the orange and green filters the same way next to each other.

The result, I think, gives me a better feel for what the M10 Monochrom sensor is actually seeing and how it changes with the orange and green filters. Here's the graphic I created to display it:

Leica M10-M : Color to Grayscale ​

(The full resolution image of this graphic is the size of my 27" computer display and can be downloaded from Flickr.com. Just click on the image to get there... )

What do you think?

G

 

[Paratom]

Interesting; for me a little theoretic. I would rather look into typical scenes subjects and see how they change with those filters. Is the M momo much difFerent from film?
imo orange should work to give skies more rendering and make them darker. When I had. A m246 i had a dark yellow and left it on the camera nearly all the time.

 

[Paul Spinnler]

The conversion should be not much different than what the Leica M10 sees when shooting color and you convert it to B&W via C1 or PS. I think it is a standardized B&W conversion as how typically these software packages do it, no? I remember comparing the output of an achromatic back and a colour back once and they matched perfectly by converting the colour image in PS via B&W adjustment layer.

 

[Godfrey]

Interesting; for me a little theoretic. I would rather look into typical scenes subjects and see how they change with those filters. Is the M momo much difFerent from film?
imo orange should work to give skies more rendering and make them darker. When I had. A m246 i had a dark yellow and left it on the camera nearly all the time.

The conversion should be not much different than what the Leica M10 sees when shooting color and you convert it to B&W via C1 or PS. I think it is a standardized B&W conversion as how typically these software packages do it, no? I remember comparing the output of an achromatic back and a colour back once and they matched perfectly by converting the colour image in PS via B&W adjustment layer.

This chart is, in some ways, an exercise in "proof of theory." ...

B&W films have a pretty broad range of differing spectral response curves, I wanted to see how the M10-M behaved against a color calibration standard like the ColorChecker, because I've been using the ColorChecker for decades to test and evaluate B&W films and filtering. The issue that I was confronting was that if I want to see what several different filtering options do in comparison to each other, the way the CC is arranged makes it a little difficult to get the gestalt of those differences in a glance. In addition, I have been doing B&W rendering from color raw files with a whole host of cameras for years. I created a small set of my own pathological B&W rendering presets to use as starting points, and I wanted to see what filtration on the M10-M would give me similar starting points. The M10-M has more dynamic range and more resolution than most of my previous cameras (including the M10-R); the only other camera I have with similar dynamic range and resolution is the Hasselblad 907x ... I wanted to use the CC's standardized color swatches as a baseline rather than just picking scenes and shooting them with different filters because the CC color swatches provide a more controlled reference.

I didn't post the whole magilla here as it is too complicated to assemble the images and graphs in a properly readable way, but I also did tests with two Yellow filters, two Red filters, a less dense Green filter, and a couple of Blue filters. The 2 stop orange and 2.5 stop green filters on the M10-M gave me the closest match to my preferred two B&W rendering start points (and I honestly don't care for Adobe's "standard" B&W conversion at all...), so I chose to present those.

I also did a couple of CC exposures with Ilford XP2 Super and HP5 to compare ... processed my standard way (not Ilford's recommended way...), the grayscale conversions from those films are a pretty close match to the M10-M native capture, and the filtered exposures are also pretty close. My summary of the filtering behavior is that the orange filter is good at upping the contrast and lowers the number of discernible gray tones, where the green filter helps separate out a number more tones than the M10-M will produce without it. I've taken to using the deep green on the camera for most of my daylight photos as I like the expanded tonalities. The darker of my yellow filters nets tones quite similar to the deep green, with just a little variation on the orange-red range of swatches.

G

 

[asnapper]

Thank you for doing this, Do you have a wratten 44a filter which mimics ortho film, it would be interested to see how it performs on the M10-M

 

[Godfrey]

Thank you for doing this, Do you have a wratten 44a filter which mimics ortho film, it would be interested to see how it performs on the M10-M

I don't have a Wrattan 44a, unfortunately because I was hoping to find something like that. I've heard that an 80B can do a similar job ... I think I have one of those somewhere. Or I'll find a Wrattan 44a somewhere...

G

 

[asnapper]

The 44a filter certainly made a difference with film

 

[Godfrey]

Someone on the largeformat forum posted a graph of the blue-green filter transmission curves some time ago. I've edited it to highlight the 44a and 80a filters:

Looks like a 44 will do a decent job too. But i can only find 44a or 44 in gel filters, so far. And they tend to be very pricey. An 80a is not as efficient in reducing red-end wavelengths, but they're only $16 or so in 46mm threaded mount... I have one on order now. The one I thought i had has disappeared... sigh.

G