clarity and quality

<p><em>"In this case, the OP indicates that both images had the same field of view, so each has the same degree of enlargement in the samples and would be the same size if the entire image were printed. The comparison is valid."</em></p>

<p>It isn't.</p>

<p>It doesn't matter that both images had the same field of view. We want to know how much of what was to be seen in that field of view was captured by the two media.<br>

Finding the limit in one medium, comparing that then to the other medium set to the same final size, is not a "valid" comparison.</p>

<p>It's like testing the strength of two columns made of different types of concrete, put a load on both, increase the load gradually, and stop the test when one of them starts to show signs of imminent failure. <br>

Saying that right before that point, both columns were equally strong, because at the same load neither cracked, is like saying that this image test is valid, because they are both 100% crops.<br>

And that doesn't make sense.</p>

<p>We have found the point where one of the two media begins to show signs of failing, and stopped the test there. What the other medium would still deliver before it too starts to fail is left in the dark completely.<br>

Saying, perhaps, that the two are equal, because just before the point one of them cracked you probably could not make out a difference, makes no sense at all.</p>

<p>It got worse, even: brushing aside the difference we can see already, saying that it can be "fixed" "easily", is like saying that the cracks one of the two columns started to show can be easily fixed, and therefore - though we saw it happen - the one didn't start to crack before the other at all.<br>

Do that as an engineer, and you will sooner or later (sooner rather than later) get sued and jailed for criminal negligence.</p>

<p>And rightfully so: i don't know about you, but i certainly wouldn't want to live or work in a building build by someone using such testing methods and criteria.<br>

I rather have someone build my house who not just recognizes and acknowledges that something starts to crack, but also would then not blindly go with the other stuff without testing when it too would crack.</p>

<p>Comparative tests are fine. But they should be done properly, else they don't say much, if anything at all. We have seen where the one image started to fail. A "valid comparison" would go on testing until the other image would start to fail as well.<br>

Then and only then will you know the real difference between the two.</p>

<p>I completely agree with Q.G.: the true test would be to compare both at the 100% pixel level for the D200, and then to enlarge the Hasselblad photo until it just started to look weaker, and then print the D200 at that size, and then compare again. Comparing only one way doesn't show anything about the *relative* strengths, and thus no comparison between the two is possible, only the weak statement that both formats passed this test.</p>

Make a scan/crop of the Hasselblad image at a resolution where it just starts to go fuzzy. Make a crop of the same area from the Nikon and enlarge it in PS to the same pixel dimensions. Compare. In other words, scale to the better image and see how the worse one fares by comparison.

<p>'Film vs digital' is about as interesting as listening to my dog pass wind. </p>

<p>Focusing tricks for old eyes: (i) Find a pair of cheapass high-magnification reading glasses, like 3 diopters or more. (ii) If there's a specular highlight in an appropriate place, focus on it. (iii) Use contrast to help-- I find something black is in focus when it looks <em>blackest</em>. Works for me, YMMV.</p>

<p>Here's a pixel for pixel crop from the film scan compared to a similar crop from the D300 enlarged to the same dimensions.</p><div></div>

<p>DeBakker,</p>

<p>You make a good point - test each to the point of failure. In essence, how large could you print a scene taken with an Hasselblad on film compared to the same scene with a D300. It is one way to compare media, but not the only way.</p>

<p>The business about adjusting contrast is just quibbling. Like adjusting to match colors, you can do this without affecting resolution. You can paint bridges too - the color is not an engineering concern. If there is a fundamental flaw in the photos of the map, it is that both are well within the capability of both cameras to resolve.</p>

<p>In the comparisons between film (Ektar 100) and digital posted in my portfolio, it can be estimated that you could get about twice the enlargement from film before detail starts to fall apart. The grain in Ektar is exceedingly fine, and is not the limiting factor.</p>

<p>That said, if you can get a good 20x30 inch print from either camera, distinguishable only on examination with a 3x loupe (the effect of a 100% crop example), do you really care if you can go twice as large with the Hasselblad?</p>

<p>The following examples were not taken with the explicit purpose of making a comparison. However, I was able to select two images with approximately the same field of view, taken with good care - on with an Hasselblad (Ektar) and the other with a Nikon D2x. In order to make a 1:1 comparision, I resampled the D2x image (without sharpening) to the same resolution as the film scan - 8964 pixels. As you see, the D2x is not able to resolve details of the corrugated metal in the tower on the left, whereas the Hasselblad resolves it easily. There's nothing of interest in this image that tests film to the point of failure. Either would be useable at 20x30 inches.</p>

<p>Hasselblad/Ektar <a href="../photo/10420733">http://www.photo.net/photo/10420733</a><br>

D2x <a href="../photo/10420658">http://www.photo.net/photo/10420658</a></p>

<p>It is interesting to note that the D2x shows no signs of aliasing, which seriously detracts from shots of the same subject using a CFV digital back (also in my portfolio).</p>

<p>Edward,</p>

<p>Testing to destruction certainly is not the only way, no. But whatever way we pick, we must be aware of the limitations of the test. In every test, the test itself is in the results. And those limitations are what i wanted to point out.<br>

We see such tests all too often. Internet and paper publications are full of them. Tests in which we see that one of the things to be tested is stretched to where it still performs pretty well and is then held up to something else that also does very well.<br>

The all too easy and all too common, and incorrect, conclusion we are then presented with is that both are pretty much equal.</p>

<p>I have carefully avoided taking sides in the underlying digital vs. film debate. It is not a debate that will be decided by anything but what people want to hear and believe.</p>

<p>As Q.G. and Edward both seem to be saying at this point, I agree that it is extremely important in such comparisons to state exactly what was compared, and to state what the important bit was. For example, if it is only important to the OP that good 20x30" prints can be made, then in this case either camera is capable, and digital is of course more convenient.</p>

<p>However, this conclusion touches only on resolution. The balance would swing towards film again if it were important what it looks like when highlights are blown. Digital often fails brutally in these circumstances, with colour shifts and CA, whereas film is more graceful. If a lack of noise/grain is more important, it goes back towards digital. And so on ad infinitum.</p>