Why is MF film typically slow?

[zack_zoll]

<p>Another reason for fewer MF films over 400 is that newer film designs (both colour and black and white) take to push-processing much better than the old stuff. TMax 400, if developed using TMax or another push-friendly developer, is almost as good at 3200 as actual TMax 3200. I've been told that the new Portra 400 is still pretty usable at 1600 ISO as well, but I wasn't happy with it past 800.</p>

<p>The advantage of MF, as mentioned, is negative quality. If you do out all the math, there's almost never a good reason to shoot high ISO MF these days. A 645 with an 150mm f/4 lens at 800 ISO will yield similar DOF to a 35mm camera with an 85 f/1.4 at 200 ISO, and the smaller grain on the 35mm film means the enlargements won't be much worse. You could probably even shoot 100 ISO with the 35mm camera, since the lens is shorter and less prone to camera shake at slow shutter speeds.</p>

<p>As far as I'm concerned - and I make a lot of big prints - if you need to shoot over 400 ISO, then you probably shouldn't be using medium or large format.</p>

[q.g._de_bakker]

Camera shake is mass related. The more of it, the harder it is to set it in motion. So that favours the heavier MF cameras. (Until, that is, the weight of the camera is that great that it puts enough stress on you that you begin to shake harder. Something you are on the brink of using a Mamiya RB/RZ, while a thing like the Fuji 680 will 'comfortably' make you do.)<br><br>The lens being shorter does not matter: it's the ratio of the angle of view to the angle of shake. Assuming your shake does not depend on what camera you are holding (and ignoring the fact that lighter cameras are easier to shake), and given the same angle of view, the effect of shake on the image will be the same.

[sfcole]

<p>The question isn't really relevant for B&W because of the success with which films like T-max 400 can be either pushed or pulled. The iso is really up to you.</p>

[ondebanks]

<p>I think the rate of disappearance of fast medium format films is similar to the rate for 35mm films. In most cases, the whole emulsion was cancelled in all its formats. Among the fast films I've used, the 120/35mm dearly departed included Konica SRG 3200, Agfachrome 1000RS, and Konica Centuria 400/800/1600. It's good that Ilford 3200 is still going in 120 format, but there's nothing above ISO 800 anymore in 120 colour (unless I missed something and even Porta 800 & Pro 800Z are now gone as well?). </p>

[zack_zoll]

<p>QG, I was under the impression that angle of view had nothing to do with the film format. A 150mm lens, while three times 'larger' on 35mm than 4x5, is still a 150mm lens, and still magnifies as much as a 150mm lens magnifies. Since the magnification is the same, it will 'magnify' your body's shaking the same amount, regardless of what camera you hold in your hands. Obviously an OM-1 is a little thing, but in theory an F5 will be as likely to show camera shake as a 645, assuming similar shutter speeds and lenses.</p>

<p>The difference in lens formats, if I'm not mistaken, is the amount of coverage, and not the angle of view. Using an adaptor to put a Hasselblad lens on your Nikon will give you the same photo as if you had shot it on your Hasselblad, and then masked off everything but the middle part of the negative. By the same token, putting a 10-24 on a full-frame body will give you a true 10mm angle of view; it's just that you'll only get the middle section of the frame, as the lens isn't designed to cover the entire sensor.</p>

<p>The angle of view, magnification, compression, and all the oher tech specs remain the same, since those are determined by the lens, and not the camera.</p>

[philip_wilson]

<p>The "effective" focal length of the lens is (in my opinion) a better estimator of camera shake than the actual focal length. thus an 80mm lens on M4/3 is an effective 160mm, on Canon APS-C is 128mm, on Full frame is 80 and on my GX680 would be only 37mm. Thus when handholding the m4/3 would need a higher shutter speed than the GX680. That said there are other factors at play of which the mirror and body design seem to be the key ones. Holding the body to your eye with elbows tcked in seems to be more stable than holding it at your waist with a WL finder. the bigger factor in my opinion is the mirror. I find that my Rangefinders (Leica and Contax G) are very easy to handhold at slow speeds (no IS here) but my GX680 is almost impossible. Q.G. with the GX680 the big issue is the mirror - you have to use MLU as the mirror causes seismic shocks. I used to think my old RZ67 (which the Fuji replaced) had a mig mirror but the GX680 can make the earth move!</p>

[craigd]

<blockquote>

<p>QG, I was under the impression that angle of view had nothing to do with the film format.</p>

</blockquote>

<p>It has to have something to do with the film format, for two reasons: (1) a lens is designed to project an image circle suitable for a specific format, and the image circle diameter, along with the focal length, defines the lens' innate angle of view; (2) the only "angle of view" that matters to a photographer is the part that gets into his pictures, which is obviously affected by the film format.</p>

<blockquote>

<p>A 150mm lens, while three times 'larger' on 35mm than 4x5, is still a 150mm lens, and still magnifies as much as a 150mm lens magnifies. Since the magnification is the same, it will 'magnify' your body's shaking the same amount, regardless of what camera you hold in your hands.</p>

</blockquote>

<p>Yes, but a larger negative will not need to be enlarged as much as a smaller negative to make a print of any given size, so shake will be more noticeable in a print from a smaller negative.</p>

<blockquote>

<p>The difference in lens formats, if I'm not mistaken, is the amount of coverage, and not the angle of view.</p>

</blockquote>

<p>Those are, for all practical purposes, the same thing. If a lens is projecting an image circle larger than my film needs, the extra part is wasted and irrelevant. (With a shift lens, you can choose what part of the larger image you want to use, but the unused part of it is still wasted.)</p>

<blockquote>

<p>By the same token, putting a 10-24 on a full-frame body will give you a true 10mm angle of view...</p>

</blockquote>

<p>Even ignoring the importance of film format, considering the lens itself in isolation, there is still no such thing as a "true 10mm angle of view", since angle of view is affected by the size of the image circle, and not all 10mm lenses project the same image circle.</p>

[leighb]

<p>Angle of view is strictly a function of lens design. <br /> It has nothing to do with film format or lens focal length.</p>

<p>For example... <br /> The Zeiss 150mm Sonnar, designed for the Hasselblad, has an angle of view of 29°.<br /> The Rodenstock 150mm Apo-Sironar Digital has an angle of view of 53°.<br />The Rodenstock 150mm Apo-Sironar-S for large-format cameras has an angle of view of 75°.<br>

The Nikor 150mm SW, also for large-format cameras, has an angle of view of 103°.<br>

<br />These numbers were taken directly from the manufacturers' data sheets.</p>

<p>- Leigh</p>

<p> </p>

[craigd]

<blockquote>

<p>The "effective" focal length of the lens is (in my opinion) a better estimator of camera shake than the actual focal length.</p>

</blockquote>

<p>I think what you really mean is that the angle of view of any given lens/camera system is the most useful predictor of shake -- which is what QG said.</p>

<p>You can do yourself and everyone else a great favor by banishing the incorrect and confusing notion of "effective focal length" from your mind. Focal length is a physical property of a lens; if you use a 50mm lens on a full-frame camera and a crop-frame camera, it remains a 50mm lens either way. What does change is the angle of view in your pictures, because the smaller sensor uses a smaller portion of the image produced by the lens.</p>

<p>It would really be nice if more people understood how focal length and sensor format combine to produce an angle of view. Then they could intelligently discuss how angle of view varies between formats rather than confusing themselves and others by implying that a camera somehow magically transforms a 50mm lens into an 75mm, 80mm, or 100mm lens (for Nikon DX, Canon APS-C, and Four-Thirds bodies respectively).</p>

[craigd]

<blockquote>

<p>Angle of view is strictly a function of lens design. <br />It has nothing to do with film format or lens focal length.</p>

</blockquote>

<p>The angle of view of a lens is not the same as the angle of view of a lens/camera system. You're confusing two separate issues. To a photographer, the angle of view of a lens approaches total irrelevancy, because the only part of the image that matters is the part recorded by his camera.</p>

<p>If you tell me that a given lens has a 90 degree angle of view, but I can't stand at the corner of a square and see two sides of the square leading away from me, what good does that 90 degrees do me? What I care about is what I can see in my photographs, not some lab measurement of a lens taken in isolation from a camera.</p>

[leighb]

<p>Hi Craig,</p>

<p>You're correct that the 'effective' angle of view depends on the film/sensor format, so to be more precise...<br>

The effective angle of view = the minimum of (the subtended angle of the film diagonal) and (the design AoV of the lens itself).</p>

<p>If you put the 150mm Sonnar that I mentioned above on a 4x5 camera, it will still only cover 29°.</p>

<p>- Leigh</p>

 

[craigd]

<p>Right, well, of course a larger film/sensor format can't result in a wider angle of view than the lens produces. I don't think anyone meant to suggest that it did.</p>

[q.g._de_bakker]

If angle of view has nothing to do with focal length, why is it that longer focal length lenses have a smaller angle of view? ;-)<br><br>If you frame a subject a certain way using a lens of focal length X mm on a MF format, then change to a smaller format (35 mm format) and want to frame the subject the same way, the focal length will have to be reduced proportionally (that "equivalent focal length" thingy).<br>(You're wrong once again, Leigh: the angle of view in our pictures is a function of both focal length and frame size. Not of the focal length alone. Manufacturers do know that, and specify the angles of view of their lenses for a given frame format. They also, as was mentioned, restrict the angle of view by making their lenses for a given maximum format.)<br><br>Yes, X mm will be X mm and not change. But the smaller crop produced by the smaller format also means that the angle of view will be smaller.<br>So to counter the reduction in angle of view caused by the smaller crop, you will need a lens with a larger angle of view (i.e. with shorter focal length) to make sure that the frame still covers the same angle of view.<br><br>Now, the important thing (as far as shake goes) is that using a shorter lens to get that same shot on a smaller format does not mean that, as was suggested, there is less chance for shake. The only thing that matters is the ration of the angle of shake to the angle of view.<br>Both images, on MF using a long lens, on 35 mm using a proportionally shorter lens, have the same angle of view, say Y degrees. If you shake the camera for, say, Y/2 degrees, the size of the blur caused will in both cases be half of the frame.<br><br>Or: reducing the effect of shake by using lenses with a larger angle of view (i.e. shorter) only works when the ratio between that angle of view and the angle of shake changes too, i.e. when you don't reduce frame size as much as you reduce the focal length.<br>There is nothing to be gained by changing to a smaller format. Only by changing to a wider angle of view across any format.<br>(And - before anyone would suggest that - cropping later will of course also not help.)

[q.g._de_bakker]

There is a limit to the angle of view somewhere, set by geometrics.<br>But there's no reason why a 150 mm lens could not be made to have an angle of view that is double (or triple) those 29 degrees.<br>For instance: a Schneider Super-Symmar 150 mm has an angle of view of 105 degrees.<br>And that's the angle the lens' physical design restricts the angle of view to. Not the very limit of what a 150 mm lens could produce.<br>To make full use of it, you will have to use a bit of film of appropriate size, obviously. In this case it's 8x10".<Br><Br>Now shake that camera for 29 degrees, and the blur in the image will not be as bad as when you would shake a 6x6 camera through the same angle with that Super-Symmar, or any other (!) 150 mm lens on it.<br><br>That was the important bit re benefits of a smaller format. None.<br><br>As far as that angle of view thing goes: a 300 mm lens made the same way will have (about) half the angle of view compared to that 150 mm lens, on any frame of any size. Angle of view is a focal length related thing.

[leighb]

<blockquote>But there's no reason why a 150 mm lens could not be made to have an angle of view that is double (or triple) than those 29 degrees, Leigh.For instance: a Schneider Super-Symmar 150 mm has an angle of view of 105 degrees.</blockquote>

<p>Hi Q.G.,</p>

<p>I did mention the Nikor SW 150mm in my earlier post, with an AoV of 103°.</p>

<p>I have no Schneider lenses in my database.</p>

<p>- Leigh</p>

 

[leighb]

<blockquote>

<p>If angle of view has nothing to do with focal length, why is it that longer focal length lenses have a smaller angle of view? ;-)</p>

</blockquote>

<p>They don't in the general case. Most lens families have a uniform AoV, selected to provide the desired performance.</p>

<p>For example, all Rodenstock Apo-Sironar-S lenses from 100mm through 300mm have the same AoV, 75°. The 360mm (the longest one in that family) has an AoV of only 68°, which still yields a huge IC of 468mm, large enough to cover 8x10 with very ample movements.</p>

<p>They could have made the 360mm with the same 75° AoV as its brethren, but it would have increased the size, weight, and cost, with no benefit.</p>

<p>You'll find that all LF lens families have consistent AoVs in almost every case, regardless of focal length.</p>

<p>Lenses designed for use on single-format cameras (35mm, 6x6, etc.) are meant to cover that format and none other. Economics dictate that the AoV should be the minimum that will cover the film adequately. That's a design decision based on a specific application.</p>

<p>- Leigh</p>

[ant_nio_gomes]

<p>Coming back to MF film ISOs, and specially color film, I'd like to raise a question on the effect of speed on resulting negative, namely color saturation as film curve response is not the same as on digital (on the other end we have the reciprocity issue).<br>

This together with grain and definition makes higher ISO films less appealing for most uses and offer and demand laws may drive manufacturers to cut them off their product lines, and for both 135 and 120 formats as a trend, even if some don't do it at the same time.<br>

I leave this question for the more experienced ones to says if it makes sense. Thanks vm.</p>

[q.g._de_bakker]

<i>"They don't in the general case."</i><br><br>They do, Leigh. They do. Without fail.<br>It's the only reason lenses come in a variety of focal lengths.<br><br>Ignoring everything else (which we must to get out of this apparent confusion) the difference in focal length between otherwise similar lenses is that the one magnifies more than the other. Given any format you wish to put behind the two (and that really means any, i.e. format does not matter as long as it is the same in both cases), the longer lens will not be able to cram as much in as the shorter lens. Angle of view is a function of focal length.<br><br>I see and understand the way of thinking that created this confusion. It's like saying that whether something is big or small depends on what you compare it to.<br>However true that may be, the actual size of the thingy itself matters too. Saying that it doesn't is, plain and simple, wrong.<br><br>So yes: though the angle of view of a given lens varies with what you compare it to, i.e. with what format you put behind it, it primarily (and fundamentally) depends on the focal length. Longer lenses have a smaller angle of view.<br>It's all perfectly fine what is said about angles of view and formats. But saying that the angle of view does not depend on, is not a function of focal length is a fundamental error.<br><br>See?

[q.g._de_bakker]

Antonio,<br><br>A slippery slope your question puts this discussion on.<br>Film is not the same as digital in many ways. But one major way is the way in which digital is the result of image capture and in-camera image processing that takes a lot of the imperfections away before you even get to see an image. And that accounts for the best part of the greater appeal of high ISO digital compared to high ISO film.<br>Still: it is what you get, so real enough.<br>But not something that sets 35 mm format apart from MF, or vice versa, is it?

[ant_nio_gomes]

<p>Q.G.<br>

Actually I don't think it is, as 135 and 120 are just different "cuts" of the same emulsion.<br>

And if some MF lenses have limited shutters speeds it would not be a major problem if you use ND filters when needed. This considering you would not choose a high ISO film to shoot under sunny days light, but as you have both a limited number of frames per film and in most cases the option to change magazines you could most likely change to a lower ISO film when the conditions ask for settings that go beyond your lens speeds.<br>

On the other hand, in B&W I used Tri-X 400 pushed to 1600 with very good results if combined with an ultra-fine grain developer, therefore nominal ISO doesn't mean everything when choosing a film (color films are another story). </p>

[ondebanks]

<blockquote>

<p>image capture and in-camera image processing that takes a lot of the imperfections away before you even get to see an image. And that accounts for the best part of the greater appeal of high ISO digital compared to high ISO film.</p>

</blockquote>

<p>Oh, no. This is a very dangerous myth. I used to believe it myself before I got into the theory and practice of digital sensors and cameras. The problem was that I assumed that digital ISO ratings were the same as film ISO ratings, i.e. based on shadow detail (minimum signal to detect something, above the base + fog density in the case of film, and above the readout noise in the case of digital). I therefore reasonably believed that exposing a camera with say ISO 1600 film, on something with a lot of dim shadow detail (the starry sky is perfect), would give the same results as a modern DSLR set to the same ISO 1600, same lens, same f-stop, same exposure time. But it doesn't; by a shockingly large margin, the DSLR will detect <em>far</em> more shadow detail (far more stars, nebulae, milky way detail etc.). And it's all there in the totally unprocessed RAW files, not just the manipulated jpegs. You can scan and manipulate the film image as much as you like too, and it won't even come close.</p>

<p>The reason for this is that digital ISO can be defined in different ways, but the standard in use is with respect to the highlights, rather than the shadows. Normally this means establishing the exposure at which the sensor images an 18% grey card in full sunlight at 18% of its full well electron capacity. One can quibble whether it's 12%, 16% or 18%, but that doesn't matter; the manufacturer might even use 5% so as to build in a safety margin against overexposure saturation clipping...it doesn't matter. The point is that it is a certain fraction of the <em>maximum </em>signal the sensor pixel is capable of, not a certain multiple of the <em>noise floor</em> at the other end of the brightness scale altogether.</p>

<p>This changes everything. It totally decouples digital ISO value from image quality, in the signal to noise sense (when comparing cameras, not when comparing different ISOs on the same camera). It also explains why little pocket digital cameras can claim the same high ISO ability despite sensors which may be 100 times smaller in area. Their tiny pixels collect far less photons in a given exposure time, but 18% of their tiny full well capacity occurs at about the same exposure time as with a big sensitive pixel. So they meet the ISO definition, but at crappy signal to noise.</p>

<p>Had I known earlier that digital ISO specs have nothing to do with shadow image quality and detectability, that a modern CMOS DSLR at say ISO 800 murders both pocket digicams and film at ISO 800, I would have had a much greater respect for DSLRs, much sooner.</p>

<p>Had I also known earlier that even amongst similar-area, similar pixel-size digital sensors, the same applies - their ISO ratings tell you <em>nothing </em>a priori about their shadow performance, and you have to dig down to their readout noise and unity-gain ISO to get the real story - I would have had a much greater respect for Canon's DSLRs in particular, much sooner.</p>

<p>My own preference for medium format cameras over "small format" 35mm kept me away from DSLRs for a long time, but my belief in this myth was an even bigger factor in delaying my addition of a DSLR to my arsenal. I regret that, and I feel obliged to help others avoid similar regrets arising from the same mistaken beliefs!</p>

<p>Conclusion: the "best part of the greater appeal of high ISO digital compared to high ISO film" is not due to processing trickery to make the digital image look better. It really, really is (can be) better, quantifiably and unmanipulated, to a degree which depends totally on the camera/sensor underlying performance and not on its ISO ratings.</p>

<p> </p>

[craigd]

<p>Q.G.:</p>

<blockquote>

<p>If angle of view has nothing to do with focal length, why is it that longer focal length lenses have a smaller angle of view? ;-)</p>

</blockquote>

<p>Leigh:</p>

<blockquote>

<p>They don't in the general case. Most lens families have a uniform AoV, selected to provide the desired performance.</p>

</blockquote>

<p>Q.G.:</p>

<blockquote>

<p>They do, Leigh. They do. Without fail.<br />It's the only reason lenses come in a variety of focal lengths.</p>

</blockquote>

<p>You guys are still talking about different things. Leigh's point is that within an LF lens family, the image circle size varies with focal length so that the angle of view of the lens itself remains fairly constant. Q.G. appears to be talking about the angle of view obtained in a photograph by capturing images of the same physical size (e.g. 4x5" film), which I referred to earlier as the angle of view of a lens/camera system. Naturally you're going to disagree if you insist on talking about two different things as if they were the same thing when quite obviously they're different.</p>

[q.g._de_bakker]

Craig,<br><br>We (Leigh and i) are not talking about different things. I explained, (or so i had hoped ;-) ), that whatever you say about one thing, you must not mistake that for the begin all end all of the matter.<br>That Leigh's <i>"Angle of view is strictly a function of lens design. It has nothing to do with film format or lens focal length."</i> is fundamentally wrong (in two ways), no matter what you may say about how the angle of view differs when you change the format of the thing behind the lens. No matter what you say about how lenses are made.<br>Angle of view is a function of focal length. The only reason they make lenses in different focal lengths is to change the angle of view.

[ondebanks]

<p>No Q.G., Craig is right, you are talking about two different things. You're holding the film format constant, Leigh is holding the lens design constant. You are both right - for the different things you are talking about!</p>

[ant_nio_gomes]

<p>Ray,<br>

I take the tone of your last post to say exactly the same regarding the way you questioned Q.G.s statement on "in-camera image processing" and your believes about the old "film versus digital" discussions that seem to be over for a long time now as people did realize that it is not a matter of "one or the other" but of two different ways to achieve results.<br>

As a matter of fact you "can not see" the data gathered and recorded in a RAW file (and lets forget that the signals were already subjected to some kind of treatment to produce the RAW) as those have to be converted to information and to a format that you can "see", either on a screen or printed on paper.<br>

And, either in-camera processing or RAW file conversion will show you just one of the possible images you can extract from the file, depending on the algorithms used by the software and the adjustments you choose, either ways.<br>

And, as you said, image quality doesn't depend only on ISO. You're completely right, as real digital ISO changes from manufacturer to manufacturer and sensor technology, trying to track the response to light to give a certain result but being just an electric (lets call like this) adjustment to the signal sensitivity of the sensor. But there are other factors going on that will influence the final result, some of them you referred and others you did not indicate.<br>

For instance, take the captured signal distribution across the light spectrum and the number of levels of grey resulting from the bit deepness. When you make an exposure these will have a major influence, as you're supposed expose to the right to avoid "burnouts" of the highlights and will determine how far you can go to the left without generating too much digital noise.<br>

The information can be there but mixed noise can make it not viable to recover, and you have to use processing to try. However, all this is changing when we get new sensor technology and more powerful software and certainly more important than the "megabytes race" marketing tries to keep us on.<br>

And we also need to take into account that not all sensors are the same or work according to the same rules (take Foveon, for instance), the same applying to filter arrays and so on.<br>

Therefore, it is great that you did realize the potential of DSLRs but I don't think it means people start to look at MF or film photography as something "inferior" or of the past. As a matter of curiosity you can look at the increasing use of very old photographic processes from the 19th century by the Fine Art circles and the prices these images are reaching.<br>

Digital and film are just different tools.<br>

(sorry if you find some errors of typos, but I'n in a hurry and I can not revised the text)</p>

<p> </p>