Questions about B&W contrast and meter

[snommisbor]

<p>Don't know if the subject is correct but I will include examples. I shot a roll of T-Max 400 with my Leica M6 TTL and a 35 2 and a 90 2.8. I started the roll on 100 on the camera and realized that it should have been on 400 so I changed it being only a few shots had been used. Well when I got them back today I actually liked the ones that were shot at 100 and developed at 400 then the ones shot at 400 and developed at 400. The 100 had more contrast and deeper blacks and whites then just more of greys like the 400. If metering correctly at the correct film speed I would think it would have been the opposite. This is actually what I have been trying to achieve with B & W but would like to shoot at correct speed and develop the same. Is there something I have been doing wrong or is that just the way it is. All pics are like they were when scanned at the camera store.</p><div></div>

[snommisbor]

<p>Shot at 400 much less contrast</p><div></div>

[snommisbor]

<p>Another example at 100</p><div></div>

[snommisbor]

<p>last example at 400</p><div></div>

[evan_goulet]

<p>Well, the ISO 100 would be overexposed by 2 stops, which would produce some fairly dense negatives. I don't think you can use the scans from the camera store as a barometer, I think you need to look at the negatives for actual contrast.<br>

Maybe someone more familiar with a photo processor / scanner can comment on this, but does the automated scanner make levels adjustments for every single frame on the negatives, or does it just make an adjustment based on the first frame in a roll? If the first frame that was fed into the scanner was shot at ISO 100, and the scanner made an auto adjustment for the entire roll based off the first frame only, you would expect results like this. The 100 frames would look decent, and the 400 frames would look washed out.<br>

Basically I think you have poorly done scans of the frames at 400. If you evaluated them on their own, they would probably have better contrast and tonal range than the ISO 100. Of course there's always the possibility that the processor botched the development.</p>

[larrydressler]

<p>Unless you processed the film yourself you will never know all the factors. You only know 1 the way it is now and at that you don't even know if your meter is correct.</p>

<p>Larry</p>

[william_brodie_tyrrell]

<p>Agree with what Evan says - scans from a store can be terrible and many stores will auto-equalise them. If you have dark areas, they can come out grey from the equalisation as you're seeing here. You'll need to look at the negatives; specifically, it looks like maybe your dark areas are under-exposed in the 400 shots, so check if they're clear on the negatives or whether there is detail in them. If they're clear, then you have a metering problem or the store under-developed.<br>

While I think the store's scans are most likely the culprit (or maybe their development), it is possible your meter is inaccurate.</p>

[john_stockdale2]

<p>"would like to shoot at correct speed"</p>

<p>Well, "best speed" would be a better term. It depends on your metering technique as well as development and what you like. If shadow details will be important in the envisaged photo, you might set exposure while the camera's meter is pointing towards a darker area to ensure that there is enough exposure to capture some detail.</p>

<p>FWIW, I routinely set my meter on half of the box speed, and have done so for 20 years.</p>

[kari v]

<p>400 shots are just scanned / post processed incorrectly.</p><div></div>

[kari v]

<p>Where did you meter in your first shot? Shadow detail looks rather bad for two stop overexposure. If it's from the river you actually shot more or less at "correct speed".<br>

Could be contrasty lab scan too though.</p>

[doremus_scudder1]

<p>Rob,</p>

<p>It's a bit more complicated than just setting the numbers correctly (or not...), so bear with me for a while here:</p>

<p>First, manufacturers' film speeds are determined according to a rather arcane testing procedure prescribed by the ISO standards institute. They are there so you can compare films, but have little relevance to what your "actual" film speed should be (kind of like mileage figures for new cars...).</p>

<p>Your particular development process and your light meter accuracy together with a number of other variables will affect how "fast" your film will be. For good results, you really need to test for your own personal Exposure Index (E.I., that is the speed you personally rate a particular film for your individual situation). Since most personal E.I.s are generally slower than manufacturers' speeds, and since B&W film has good overexposure lattitude, many just automatically rate their film a stop or more slower than recommended and get good results (as one poster above suggested). </p>

<p>I get the feeling from your post that you are interested in getting better results, so try to absorb and apply the following.</p>

<p>Overexposing more than necessary to bring the film up to speed (like you probably did) has the advantage of improving separation in the shadows. Some large-format users routinely do this to increase the quality of their negatives. The downside of this is 1.) that the negative is overall more dense and therefore grainier (not an issue for large-format users, but certainly a concern for 35mm users) and 2.) if overexposed too much, many films lose highlight detail to "blocking," i.e., the increased exposure in the highlight areas does not result in adequate highlight separation, just blank white. </p>

<p>The "ideal" E.I. is one that maximizes separation in both highlights and shadows but minimizes graininess. In your case, you were probably underexposing your film a bit (by using box speed) so your mistake likely resulted in only about 1-stop overexposure. This would yield good blacks and shadow detail, but cause a bit more graininess (which may not be apparent in small prints). </p>

<p>In looking at the scans you post, one can see that the blacks are stronger in the "overexposed" prints and that the shadow detail is good (the boy's camo jacket is nicely rendered even though it was in the shade). In the pictures exposed at 400, the blacks are not black, rather dark grey, and the detail is lacking (e.g. in the shadow under the fountain, etc.). This latter situation, despite the unreliability of judging from camera store scans, is classic underexposure.</p>

<p>One could view your mistake as a test and analyze the results thusly: E.I. 400 appears underexposed. You should probably use a slower film speed overall for the way you meter and the way your film is being processed. The E.I. 100 negatives look good as far as exposure goes, but <em>may</em> be overexposed (there is no way to tell at this point). Your ideal E.I. will likely be closer to 200, but you need to zero in on it yourself.</p>

<p>For your next "test," take a few more different exposures of the same scene. A scene such as the first scan you post is ideal, since there are sunlit highlight areas and detailed shadows (the boy's camo jacket again). You know that E.I. 400 is too little exposure so start a couple of numbers down the scale, say E.I. 250 and make several exposures. I would use E.I. 250, 160 and 100 to start with, skipping every other setting. </p>

<p>Send these in and get them developed and examine them using the same criteria as above, i.e., look for good, deep blacks and excellent detail in the shadows. The minimum exposure that gives you the desired results can be your provisional E.I. Then, just keep an eye on things in the future: if your shadow detail is suffering, maybe slow the film down a notch, if the shadows are always wonderful, maybe you are overexposing a notch, so try bracketing at a higher E.I. and compare results. Again, the minimum exposure that gives you the results you want is what you should use. (Keep in mind that very contrasty scenes will mess up your testing and evaluation process, so in the beginning, disregard shots made in very harsh light.)</p>

<p>Once you are getting consistent results, I would recommend you note the difference between your personal E.I. for this film and the box speed. This can be applied to other films you shoot as a starting point (e.g., if your 400 speed film works best for you at E.I. 200, then rate all other films one-stop slower to begin with as well).</p>

<p>Now to the final step: As I mentioned above, contrasty scenes often do not work well using the above parameters. They present a problem for most in-camera metering systems. This can be overcome by learning to recognize contrasty situations and then overexposing. I recommend simply overexposing by one stop for most contrasty situations (extreme situations can be overexposed by two stops). This ensures shadow detail, and the contrast is dealt with in the (scanning and) printing process. This seems counter-intuitive, but is really soundly based in photo science. It may be, if the scenes you posted were very harshly lit, that this is precisely what you have done by accidentally rating your film at 100. It is hard to tell from the scans exactly what the original lighting was like.</p>

<p>I hope I've given you some food for though and a quick "down-an-dirty" way to get better results from your present exposure/processing situation.</p>

<p>Best and good luck,</p>

<p>Doremus Scudder</p>

<p> </p>

[AJG]

<p>Doremus has it covered pretty well--one other thing you might consider doing is checking your meter against the "sunny 16 rule." Set your f/stop to f/16, take a meter reading of an average sunlit (sun over your shoulder) scene between 10 AM and 2 PM and see what shutter speed your meter indicates. The meter should tell you to set a speed that is the same as the ASA/ISO, or very close to it. (1/500 for 400 speed film, for example) If it tells you to set 1/1000, then reset the film speed setting to 200. As someone who teaches beginning photography classes at a community college, I can tell you that this is a common problem with many cameras, especially cameras with a needle readout, as a slight knock against a wall can disrupt the tiny bearing that the needle rests on.</p>

[bernard_lazareff]

<p>Siding with John Stockdale's short reply and to some extent with the longer one by Doremus Scudder (I admire writing such a detailed response).And not discarding that the shop scans are probably crummy.<br>

More precisely. ASA/ISO setting and meter "accuracy" are the answer only for a standard subject. Or for a camera with matrix metering. Case in point: pictures #1 and #2. Sunlight from above or maybe part backlit on vast expanse of water and grass. But... people (indirect lighting only), while a significant element of the scene, occupy a small area: negligible for meter.<br>

So, you have to look at the scene and decide what you want to do with the various parts. Even if you don't buy into the Zone System's "expansion" and "contraction", what they call "placement" is worth understanding. In this thread we are discussing a 2-stop difference between 100 and 400 ISO. The difference between sunlit and open shade (same day, same subject) is 3 stops.<br>

Having an M6 you might have a few dollars left to buy, e.g. Ansel Adam's "The Negative". <br>

My 2¢ of advice. Sunlit with interesting parts in open shade: Meter from the palm of your hand, oriented similar to the open-shade subject (i.e. open shade also). The open shade values will be recorded one "zone" down from what they would be if metered exclusively. Better than three zones down if metering from the dominant sunlit surrounding.</p>

[snommisbor]

<p>Thanks for the tips, especially Doremus, you should write a book. Kari I understand the whole level adjustment that was what I did to correct those. I just prefer to get it right with the camera and not have to do that. Sort of why I have gotten back into film. It pushes me to take my time and get it right not just shoot now and PS it later. Nice to have PS to fall back on but I'm just trying to hone my craft to make it the best. Heading to Africa in less then 2 months via London so the Leica will be burning through the rolls along with my D300. Thanks again to all who responded. If anyone else have something to add feel free, thats why we are here to get better.</p>

<p>Rob</p>

[CosteaM]

<p>I think Doremus and Bernard gave very good advice but ultimately you know what you want from your negs: prints or digital files. If you need silver prints then you can get better only if you develop your films and establish your personal EI. For example on Kodak Tri-X 400 ISO I work with EI of 160 ISO and my negs have detail in shadows and highlights and good contrast. When you exposed for ISO 100 by coincidence you possibly run into a light situation that brought you close to your pers EI (so far unknown). Knowing your pers EI must be connected with controlled development in order to preserve detail in the highlights. Expose for the shadows and develop for the highlights is the way to go. Getting a good negative helps the printer to do a better job.<br>

If you aim at showing your pictures on monitors then you can continue shooting at the box speed and adjust the leves and curves in post processing.</p>

 

[john_stockdale2]

<p>"Knowing your pers(onal) EI must be connected with controlled development in order to preserve detail in the highlights"<br>

Absolutely spot-on.<br>

Having your black and white film developed by a lab is very often inconsistent. It has been said a million times, and here I go again, if you develop your film yourself it will be better. There is not one standard and correct way to dev b+w film.</p>

[stephen_benskin]

<p>"First, manufacturers' film speeds are determined according to a rather arcane testing procedure prescribed by the ISO standards institute. They are there so you can compare films, but have little relevance to what your "actual" film speed should be (kind of like mileage figures for new cars...)."<br>

I have to disagree with this part of Doremus' response on principle. While a primary aspect of the ISO standardization is film to film comparison, it is also based on real world results. The change in the standard in the 1990s changed some of the more questionable practices in order to reflect real world use. In addition, the ISO standard was founded on psychophysical testing which unquestionably reflect real world conditions.<br>

How you use your light meter and other personal working methods have a higher degree of influence to how you expose than the actual film speed. I agree with Doremus that you should find what works for you based on your personal methods. Before coming to any conclusions, you must first carefully investigate all the potential variables that can influence the final results. Many people misinterpret such things as over processing as over exposure. Confirm what your lab is doing.</p>

[doremus_scudder1]

<p>Stephen, </p>

<p>You are, of course, correct that ISO testing is done more practically now than in the past. I didn't mean to imply that the ISO numbers were somehow "off" or completely inapplicable.</p>

<p>That said, the ISO tests for determining film speed prescribe exposure, metering technique, developer, agitation, development to a certain contrast index, etc., etc., most of which are not duplicated by photographers in real life. Again the analogy to the mileage figures for new cars is appropriate. If you drive exactly as the tests are done, then you will likely get the advertised mileage. If not, you won't.</p>

<p>Similarly, if you do not meter, expose and develop precisely as prescribed by the ISO tests, you will likely not get the same film speed for your individual purposes. Fortunately, the ISO tests are a lot closer to reality than they once were, but one should still be aware that the published speed of films will often be different (usually faster) than in practice. The response I gave described a generalized and somewhat simplified approach to quickly achieve better results. Often, nothing more is necessary.</p>

<p>Best to all,</p>

<p>Doremus Scudder</p>

[stephen_benskin]

<p>The almost universal tenet that ISO film speeds are faster than in practice is most likely attributed to a flawed concept with the Zone System. While the statistical shadow placement falls 4 1/3 stops below the meter reading, the ISO speed point falls 3 1/3 stops. Why? Flare. Average flare adds at least a stop to the speed of the film. The Zone System doesn't factor this in and its assumption that the shadow falls four stops under the meter reading creates a 2/3 stop difference in speed. When you consider experimental error and a slight influence of flare from the testing (80 percent of flare is produced from the subject), this can make for a difference from 1/2 to 1 stop slower film speeds than the ISO speed. Since this discrepancy is almost universally observed with ZS testing, the difference between the ISO speed and the "personal speed" can't be attributed to laboratory verses practical testing. In fact, because of the consistent difference, it actually verifies the validity of the ISO speed. <br /> <br /> ZS testing actually produces results comparable with the pre 1960 speed standards which produced film speed one stop slower than the current standard. Films such as Tri-X were rated at 200 and Plus-X was rated at 50. Without any changes to the films and only a change in the standard, film speed doubled over night. According to the “first excellent print” test which was the psychophysical test that established the criteria for modern film speeds, the perceived quality of the results increased with increased exposure up to a certain point than there was no increased perception of quality with increased exposure. The practical conclusion was to pick the point where the minimum of exposure produced the best results or the first excellent print. This would produce faster film speeds allowing for faster shutter speeds and shorter printing times. It doesn’t mean that any “over exposure” wouldn’t produce equally good looking prints (although it will tend to increase grain and decrease sharpness). So, any slight “over exposure” like that produced with the flawed ZS concept will still produce excellent results. BTW, the reason why the speeds dropped by one stop after 1960 is because there was a safety factor attached to the prior standards. There still is a slight safety factor but it is dependent on the degree of flare from a given scene.<br /> <br /> In addition, another misconception of film speed comes from a misinterpretation of the ISO standards fixed density method. Although the ISO standard uses a fixed density point as the speed point (0.10 over fb+f), it is only valid when the contrast parameters of the standard are followed. This is because under those conditions, the fixed density point fits into a formula that will approximate the fractional density method, which is considered to be the most accurate speed determination method. If the contrast conditions are different than the delta 0.80 density differences at a range of 1.30 log-H from the speed point, then an additional equation must be used to calculate the film speed. This method is known as the Delta-X Criterion. The reason the Delta-X Criterion isn’t discussed in the ISO speed standard is because standards don’t generally deal with theory. The ISO speed standard is designed to instruct how to determine the ISO speed of black and white film and a discussion on why a certain method was chosen or how to determine speeds that don’t adhere to the chosen method aren’t pertinent. Generally, a paper will be published concurrently with the new standard that contains all the background.<br /> <br /> According to the Delta-X Criterion and in accord with the fractional gradient method, density isn’t the primary factor in the determination of the quality produced. The contrast or curve’s gradient is the most important factor. It was determined that most consistent results producing the highest quality reproductions were produced when the speed point was at a gradient of .3 times the overall curve gradient. Using the Delta-X Criterion incorporated into the ISO standard, when adhere to the standards conditions, this point will fall 0.28 log-H units below the 0.10 fixed density point. As the processing changes, this will change the overall curve gradient as well as the gradient of the shadow. This tends to change the relationship between the fixed 0.10 density point and the Delta-X Criterion point. This, in effect, tends to negate film speed changes associated with developmental changes. In other words, within a certain range of development (approximately -1 to +2), there is only a single film speed. The variability that most people experience using the fixed density method of 0.10 over fb+f without the incorporation of the Delta-X equation doesn’t exist.<br /> <br /> Let me be clear, I am making a distinction between film speed and pragmatic method of making an exposure. What most people attribute to film speed is more about personal working methods. Film speed is about scientific methodology. When it comes to making an exposure, you do what works for you.</p>