I ran some informal tests of this a while ago. I shot the same scene with objects of various colors, including a red frisbee, with several films, in the same light and from the same angle. The Efke 25 did produce a darker result than most other films, but this effect was dwarfed compared to the results of Tasma MZ-3L, which produced something that looked completely black for the frisbee. Your brickwork example, by comparison, is dark gray (except for a few areas in deep shadow). Unfortunately, I don't have scans of my test scenes handy to show for comparison.
I suppose another way to test to see if a film is orthochromatic is to expose it to a red safelight and see if it fogs. I can't say that I've tried this particular test with any film, though.
Oh, and I just went Googling, and found
this page with spectral sensitivity graphs for Efke's 25 and 50 products. These shows sensitivity clearly into the red region, although without any comparison graphs for other products it's hard to draw conclusions.
Hi everybody:
It is true about EFKE 25 and KB50 - this are orthopanchromatic films, which with reduced red sensitivity, but it is still sensitive to red. Also Fotokemika - the maker of this film, claims that it is "produced with very high silver content about 2 g/sq.meter", which promises rich tonality.
And everything said is almost true.
You may take a look at my sample from this film:
http://www.flickr.com/photos/28444963@N06/2652020605/
This sample has blown out highlights due to overdeveloping, which was done in Hubl paste, but the range is good, and modulation is very different from modern films.
But there is no silver in EFKE in comparison with Tasma type 17 films. This russian films for aerial imaging have about 8g/sq.meter of silver. This combined with high resolution (about 200lines/mm) and high sensitivity (normally 400ISO, but the best results in art photo are at 200ISO).
The sample is here:
http://www.flickr.com/photos/28444963@N06/2795599061/
Take a look at skin tones and overall tonality of the image.
Considering Tasma MZ-3L - this is real ortho film, but this is film for making lithographic images or microfiches. With extremely high contrast, giving only black and only white, without gray tones. It is too hard to make it artistic. Also the sensitivity is low. For now -out of production.
Another film from this series is TASMA MICRAT-ORTHO, also ortho film, for lith negatives, ISO is only 3 (three).
For art photo there are several other Tasma films: A-2 (old, thick!! emulsion films from 50s), KN-1, KN-2, KN-3, HK-2. All of them are cubic (non-T) grain films, panchromatic, but unlike A-2, these are modern, used for movies.
I personally use type 17, which is the best thing for portraits I ever saw (it is not good for landscapes due to narrow latitude, but if you put the right exposure, the result will be outstanding). The only problem - it is available in 35mm format only. Another widths are 80mm, 190mm and 320mm. So if somebody has a machine to cut it and pack into rolls, I'll be happy to make the business out of it.
A-2 is grainy and easier to use due to it wider latitude. Better works for general shots and specific grainy images. I'm also going to try it for reversal.
AND forgot to say - A-2 gives really old looking images - it is the only old film in the production today, was developed in the end of 40s, right after WW2 under the control of Stalin, and first produced in 1950, still in production since that times. Sensitivity is 400 ISO, but many people use it up to 800 - 1000 ISO with very good results.
Also note: Svema (Ukraine) made the same types of film before, but if you see one, do not take it - quality is outstandingly bad, you may even find dust inside of emulsion or absence of the emulsion on some parts of the film. They do not produce films any more.