The mysterious “Hutchings” filter factor for b/w landscapes

[Heroique]

…Meters are not spectrally consistent in their sensitivity; nor are films. Two allegedly similar films, TMax100 and Delta 100 differ a whole half stop in green sensitivity. The published spectral sensitivity chart gives you a clue this is true, but an actual film test more accurately tells you the filter factor.

Nice information from the field – do your film tests indicate a half-stop difference with other colors, or is green your most extreme example? And do other b/w films, in addition to Tmax100 and Delta 100, show this degree of variability?

I’m also curious if your various meters differ by this amount. Talk about complications!

Still, using filters introduces an uncertainty factor that we just have to live with, no matter what kind of methods we develop to compensate.

One might say b/w filters are “more art than a science” – or an art with plenty of field and darkroom notes plus personal testing.

[Drew Wiley]

All my Pentax spotmeters are calibrated to not only match each other, but a tightly defined industry standard. I even have shades for them. The fact is, panchromatic films differ somewhat from one another. Once you start using very deep contrast filters, these film differences become more prominent. A deep 29 filter needs just 3 stops of offset with Bergger 200, for example, but will require 3-1/2 or four with most pan films, for which a gentler 25 red makes more sense. Orthopan Acros can't deal with a deep 29 red at all without emptying the shadows, while an extended red film like old Tech Pan, or near-infrared films, will have opened up shadows. Another example would be how Pan films react to deep blue filters in different degrees. Reduced green sensitivity itself might have once be regarded as an asset for inspection development, but becomes a penalty to a more natural look, where the amount of green sensitivity has been raised somewhat in TMax films. This is apparent even with respect to light yellow-green filters. There's nothing complicated about it. You just have to test and learn one film at a time. Having a choice of films is a good thing. The specific manufacturer technical data sheets already provide you with recommended filter factor starting points, which are generally close enough for real world photography. No need to guess!

[Daniel Casper Lohenstein]

Perhaps the filter topic is inexhaustible. I need to write it down here on the forum so I can think it through logically. If we want to get a reasonable grip on the problem, we can probably only use strict measures, not ad hoc decisions.

This includes restricting the use of a specific film material from a specific manufacturer, the use of the same filters from the same manufacturer, and the consistent maintenance of a defined procedure.

An example: with my Nikons, EV corrections for TTL metering differ from the specifications given by the filter manufacturer, B+W. For a wonderful 023 dark yellow filter I get -0.6 EV (x1.5) with the camera, while B+W specifies -1.6 EV (x3). So the images are theoretically underexposed by 1 EV. In practice it is exactly this: the images are underexposed. This is less noticeable in the highlights, which are still in the printable range when underexposed. But the shadows are too dark. The filter is intended to improve the shadow drawing in the landscape ... My own tests with Ilford film in HC110 H showed that the B+W value of -1.6 EV is correct and therefore I need +1.6 EV more exposure.

But only with Ilford and HC110 H. With Kodak, Foma, Fuji, Agfa (Kentmere), Rollei it looks different. Crap, such a bad luck. Because the film emulsions react differently. Now I can test my way to Persia. - No, I'll stay with Ilford. And if I want less grain, more sharpness, higher resolution, I take 6x6 or 4x5.

But I have got larger lenses, a wonderful Symmar S MC 5.6/210. So I need bigger filters. Now, instead of buying the right BW filter for each lens - an expensive affair - I use the Cokin P system for 6x6 and 4x5. Yes, I know, other manufacturers are better. But only Cokin has the P size, which is compact and in which there is the very good, very inexpensive, highly adjustable SRB Elite bellows lens hood, which works very well in the large format context.

Cokin also gives filter factors and correction values for this filter system. I have had good results with the correction for the yellow filter, +0.6 EV (x1.5) and the red filter +3 EV (x8). The images are sufficiently dense in the shadows. I have not used the other filters since. Anyway, I now only use BW screw-in filters for the Nikons, on which I set an ISO correction of -1 EV and meter an additional loss of light of -0.6 EV with TTL, and Cokin P filters for the larger cameras, for which I set +0.6 EV on the external light meter so that +0.6 EV adds to the exposure. If I took the B+W 023 yellow screw-in filter for 4x5, I would set +1.6 EV (x3) on the exposure meter. And I limit myself to Ilford films. If you want more, you have to test more. Otherwise it's all inexhaustible guesswork.

[Drew Wiley]

All that fuss just to add yet another set of variables of uncoated filters and TTL meterings? How come I get entirely predictable results time after time, year after year, using different camera formats, different film manufacturers, different film developers, obviously many different lenses, a wide range of lighting circumstances? No guesswork involved. Filter factors aren't rocket science. No need to invent another Mars rover. A minor twist the correct amount on the scale of the spotmeter tells you everything you need.

[Michael R]

How come I get entirely predictable results time after time, year after year, using different camera formats, different film manufacturers, different film developers, obviously many different lenses, a wide range of lighting circumstances?

Because you don’t. Nobody does.

[Heroique]

An example: with my Nikons, EV corrections for TTL metering differ from the specifications given by the filter manufacturer, B+W. For a wonderful 023 dark yellow filter I get -0.6 EV (x1.5) with the camera, while B+W specifies -1.6 EV (x3). So the images are theoretically underexposed by 1 EV. In practice it is exactly this: the images are underexposed. This is less noticeable in the highlights, which are still in the printable range when underexposed. But the shadows are too dark. The filter is intended to improve the shadow drawing in the landscape ... My own tests with Ilford film in HC110 H showed that the B+W value of -1.6 EV is correct and therefore I need [+1 EV additional] exposure.

This experience caught my attention because Ilford + HC110 H is a favorite combination with my Nikon 35mm cameras – F100, FM3a, N90s, and EM. So I’m naturally curious which cameras are giving you this TTL -1 EV underexposure?

Also, does it happen with all your b/w filters, or just the 023 yellow?

I’m not sure by your description, but are you saying the 023 reduces highlight values less than it reduces the shadow values? If so, this may very well be the “more-blue-light-in-the-shadows” phenomenon which the Hutchings factor tries to remedy.

[Drew Wiley]

I absolutely do get consistent totally predictable results, Michael, just as long as it's a quality control film like Kodak, Ilford, or Fuji. I can't speak for emulsions poured out of the Bubba Gump shrimp gumbo kettle. And not if I trusted TTL metering! - too many unrelated internal variables. Once I started using true spot meters over forty years ago, I never looked back. Just today I was doing some practice with my Nikon FM2n, and just for fun comparing the kind of exposure assessment it would give me, versus the handheld Pentax spotmeter itself. Of course, I already knew the answer. Not everything in the world is a giant gray card; and besides, I want to know where small deep shadows land on the scale, and bright highlights too - not just an averaged stew!

But if the issue of filter factors gets confused with just plain not understanding how a particular film curve is going to behave under a set of exposure and development circumstances, and how it will print, well, then it's best to learn those skills first, before applying a filter. Films can sometimes behave like chameleons in relation to very long exposures and strong contrast filters. But that can be tested for too, and predictable filter factors determined, if someone happens to do that kind of work.

As far as more blue in the shadows under an open blue sky ... duuuh .... I'm a color photographer too.

[Daniel Casper Lohenstein]

This experience caught my attention because Ilford + HC110 H is a favorite combination with my Nikon 35mm cameras – F100, FM3a, N90s, and EM. So I’m naturally curious which cameras are giving you this TTL -1 EV underexposure?

Also, does it happen with all your b/w filters, or just the 023 yellow?

I’m not sure by your description, but are you saying the 023 reduces highlight values less than it reduces the shadow values? If so, this may very well be the “more-blue-light-in-the-shadows” phenomenon which the Hutchings factor tries to remedy.

Why so complicated? Imagine the zone system scale. If the structured shadows are in III and the structured highlights are in VII, then at -1 EV underexposure the shadows fall in II and the highlights in VI. The structured shadows are no longer in the printable range from III to VII. They turn black on paper. The highlights still remain in the printable range. They are darker, but still in VI. You might not notice anything if the darkest shadows are only in IV and the highlights are in VII, but with higher contrast scenes you get problems. You might not notice anything if the darkest shadows are only in IV and the highlights are in VII, but with higher contrast scenes you get problems. Especially with short focal lengths, i.e. a lot of sky and many objects in the image field. If you use long focal lengths to clean up the image, to eliminate background or sky areas, you tend to work with little contrast. Perhaps Bruce Barnbaum's placing shadows in IV is a reminescence to this problem, as a result of using filters in every exposure.

The F100 is a very good camera with a useful light balance in third stop resolution. It has been every Nikon I have used so far. For a while I thought I had to have one camera each for color and black and white, and because Nikon cameras are so good, another backup. So I used the F2, F3, FM2n, F100, F4, F5. With each camera I achieved a TTL measured reduction of -0.6 EV with B+W 023. But the manufacturer says x3, so -1.6 EV, which is why I should actually expose +1.6 EV. I set that on the exposure meter, and the negatives turned out much nicer than the pictures with the Nikon TTL. Sure, it could have been a lazy shutter on the large format camera. But the pictures become better with every lens, with every light meter, and, what really convinced me then, when I started using a Sekonic incident light meter to do macros with the Micro-Nikkor 3.5/55 (with additional macro prolongation faktor): also with the Nikons. That is why I always set +1 EV on the light meter with 023 filters, 64 instead of 125 ASA for HP5+ in HC110 H, 16 instead of 32 for FP4+ in HC110 H. The remaining +0.6 EV is done by the Nikon.

But these are all subjective values, from comparison with unfiltered Nikon shots, which also all came much denser in the shadows than the filtered shots. I'd have to put in the Stouffer card sometime. But as Drew Wiley already indicated: you can also test yourself into madness.

[Heroique]

Imagine the zone system scale...

That’s a nice analysis of your metering experience, a great testament to personal testing in field and darkroom.

However, I was asking if your meter might have reduced highlights less than they reduce the shadows, due to the higher proportion of blue light in the shadows, and the filter’s removing more of this part of the total spectrum than other colors. That is, a non-linear change. (The type of change, Simmons says, that the Hutchings factor specifically means to help.) It sounds like you haven't run into this phenomenon.

I've seen this happen at very high altitudes in my region on sunny days, about 1/2 or 2/3 stop, and more noticeable the more complete the shadow is.

[Daniel Casper Lohenstein]

That’s a nice analysis of your metering experience, a great testament to personal testing in field and darkroom.

However, I was asking if your meter might have reduced highlights less than they reduce the shadows, due to the higher proportion of blue light in the shadows, and the filter’s removing more of this part of the total spectrum than other colors. That is, a non-linear change. (The type of change, Simmons says, that the Hutchings factor specifically means to help.) It sounds like you haven't run into this phenomenon.

I've seen this happen at very high altitudes in my region on sunny days, about 1/2 or 2/3 stop, and more noticeable the more complete the shadow is.

Oh, sorry if my statement was unclear. We Germans tend to yak other people to death with big and extensive statements about any of our motives for doing anything ....

I assumed that blue is made darker by a yellow filter, while yellow is lightened. So yellow filter darkend blue shadows would have to be considered even darker in the exposure than the metered shadows in a measurement. Which should cause the exposure meter to expose more, if they were mesured through the filter glass. My TTL Nikon does the opposite. Perhaps because yellow is made brighter? Which causes the light meter to expose less?

The Hutchings problem is another issue. As you have presented it, it would say metrologically that a yellow filter changes the color brightnesses in different ratios, non-linearly. That is, the light meter's response to blue is less than to yellow. Therefore, the darkness of the blue is not sufficiently compensated. Which leads to underexposure. Sure, the blues vary anyway, as do the yellows. Especially in the mountains, as you say. Depending on the time of day, weather conditions, etc. But I don't know wether Hutchings or you meant this.

If I understood Simmons correctly, who doesn't report that much on him, Hutchings was concerned with the problem of shadows, which he tries to save by exposing more abundantly - but what becomes of the highlights? - Simmons wrote that Hutchings was concerned with yellow, orange and red filters, not with green filters, which lighten blue, and not blue filters, which lighten blue a lot. They are his personal filter factors for his personal process, with which he photographs the sceneries typical for him at times of day that are typic for him. Like Drew Wiley, see above, who seems to have a photographic process and practice clarified over long years, where things just come out well, while we are still in the process of learning and understanding.

- Simmons said: it's best to measure through the filter, then you'd have shadows and highlights in the ratio or relation that the filter sees them. Absolute values are not yet obtained, only contrast ranges of the sceneries. Then you still have to decide absolutely how much light this contrast scale should receive, so that the contrast scale falls within the desired range, e.g. between III and VII. To do this, one could also measure the given contrast scale without a filter. One would then have to extend the exposure value found without filter by a certain factor, e.g. the filter factor, as a starting point. This is what Simmons suggests, p. 28. "Take your light readings through the filter by holding it in front of the exposure meter." Be aware that this only affects the contrast relation, not the absolute exposure value, which must be adjusted with the filter factor.

I think it gets complicated when you do a relative contrast measurement with the yellow filter, and an absolute measurement without the filter, then do a prolongation of exposure with the filter factor, and add a 1/4 Hutchings obulus to that for the darkened blue. I wouldn't be able to reproduce that so accurately with my process anymore ...

Why don't you take some comparison shots with 35mm film and see which you like better in the end. I took pictures this morning without a filter, because the darker yellow also kills some of the haze in the morning. Without haze, the image lacks depth. Yellow filter images are often more brilliant, but less atmospheric. Especially in the mountains. A filter turns them into abstract and flat patterns, while without the filter they develop air and aerial perspective. Why give up atmospheric haze just for those stupid clouds? https://flickr.com/photos/miloniro/2...7658837001681/ Here's an image from a photographer that would be lost with a yellow filter and even with panchromatic film.

Ansel Adams: Natural Light Photography - this book describes filters very extensively.