120 vs 220

[rishij]

<blockquote>

<p>There's hope though. Your regular 'clarification' posts shows that, though slowly, you do think about what you say.</p>

</blockquote>

<p>I assume you're talking about my clarification where I say that the plane of focus might randomly change, not that (typically) MF will dip below 35mm. Well, I've got news for you: any modern detail-oriented photographer wouldn't accept that in a modern digital system. Why do you think hundreds of people complain about 'back' or 'front' focusing issues? Why do you think Canon added AF microadjustment to their line of cameras? <em>Because people no longer are willing to accept a lens element or an image sensor plane not being in the right place!</em></p>

<p>So do I think the film plane randomly moving or bent portions of film amid a frame being exposed is acceptable? <em>No! </em>Not when it can be fixed.</p>

<p>And for the record, if you're focused on infinity, using a wide aperture b/c, oh I don't know, you happen to not have a tripod today, but your film's been bent by a roller, then <strong>yes</strong> the performance of your MF system at the center of that frame can drop below 35mm. And you will experience a significant resolution drop due to the bend <strong>even at f/11</strong>.</p>

<blockquote>

<p>Another big one is the way how believing that your being scientific gets in the way of you trying to understand that the world isn't crazy, because it holds what you will qualify to be 'emotional subjective beliefs' with you being the only objective scientists in the world who holds the opposite, true belief.</p>

</blockquote>

<p>This has nothing to do with the world or me being the only objective person in it. That's stupid & you know it. I simply pointed out that some of the things you say are <strong>blatantly unsubstantiated</strong> at best & <strong>utterly wrong</strong> & <strong>mis-informative</strong> at worst. I then take the time & thought to provide you a sound framework for why I think so. And then you take about 30 seconds of your time to lazily sit there & write a response that doesn't offer <em>one</em> objective rebuttal or any evidence of your own. Only more unsubstantiated claims and 'you're wrong Rishi'.</p>

<p>...while anyone with any knowledge of signals knows that, barring infinite tonality within the dynamic range of a medium, the smaller the dynamic range of that medium (<strong>NOT</strong> the dynamic range of the scene it records, but <strong>the dynamic range as in the density range of the film</strong>) the more limited its capability to accurately represent the original signal.</p>

<p>For example, say you have a scene with a luminance ratio of 8:1. You have 8 objects in it each with relative luminance of 1, 2, 3, 4, 5, 6, 7, 8. You now have a CCD that only outputs voltages in 1v increments (of course that's silly, it'd have much finer increments, but this is for the sake of making the argument easier to understand)... this discrete nature is imposed to mimic the limited discernible density change in film. You now have a CCD that's voltage output range is 0-4v, and another one's who's output range is 0-8v. The two CCDs represent the luminosities of said objects with the following output voltages (input luminosity-->output voltage):</p>

<ul>

<li><strong>4v CCD</strong>: 1-->1, 2-->1, 3-->2, 4-->2, 5-->3, 6-->3, 7-->4, 8-->4</li>

<li><strong>8v CCD</strong>: 1-->1, 2-->2, 3-->3, 4-->4, 5-->5, 6-->6, 7-->7, 8-->8</li>

</ul>

<p>Now, let's multiply the output of the 4v CCD by 2 to make it match the output of the 8v CCD (analogous to doubling exposure in Photoshop if this were digitized data). We now get the 8 luminosities of the scene represented, by the 4v & 8v CCDs, respectively, as:</p>

<ul>

<li>2,2,4,4,6,6,8,8</li>

<li>1,2,3,4,5,6,7,8</li>

</ul>

<p>Therefore, for a recording medium (CCD or film) with finite gradations in tonality, the medium with the higher dynamic range will represent the original signal better. I.e. slides represent the signal better than negatives for a given input scene range that fits within the usable dynamic range of both mediums.</p>

<p>But hey, feel free to prove me wrong. I'm quite happy when someone proves me wrong, because it means I learned something. <strong>And learning is good</strong>. In fact I'm always open to objective arguments or empirical evidence because I'm always open to re-evaluating what I know. Lord knows I've been wrong before & I <em>will be</em>, and <em>am not afraid to be</em>, wrong again. But as far as this discussion is concerned (as well as our previous discussion on rollers bending film), I've made my points & have countered your misinformation with <em>solid evidence</em> & <em>sound arguments</em> for the sake of posterity.</p>

<p>So I rest my case.</p>

<p>-Rishi</p>

<p>P.S. Funny how you still won't admit you were wrong about medium format film holders bending film. Whose obsessed with thinking he's right, even in the face of pictorial evidence to the contrary?</p>

[rishij]

<p>To sum up my slide vs. negative argument in one sentence:</p>

<p><em>It just boils down to the fact that slides use a larger # of dye clouds to represent a finite tonal change in the original scene than negatives do.</em></p>

<p>-Rishi</p>

[rishij]

<p>Earlier we were talking about graduated ND filters. I just tried spot-metering with my camera's meter through a clear vs. the darkest portion of the filter, & got -2 to -2 1/3 stop drop in exposure. This is a 3-stop reverse graduated ND filter. </p>

<p>Which got me to thinking -- is it not actually a 3-stop grad ND filter, or is it just that, since I can't use stop-down metering on my Canon EOS film system, maybe the metering is wrong/unpredictable for any given scene at some given aperture smaller than the widest aperture? Which might then make the whole metering through the filter process non-productive or inaccurate.</p>

<p>Either that or the 3-stop filter is not actually a 3-stop filter. </p>

<p>This requires some further investigation so I will test which method works better:</p>

<ul>

<li>Metering the foreground & determining the amount of overexposure of the sky then placing a graduated ND filter close to the ∆EV (or 1 stop less than ∆EV for skies)</li>

<li>Metering through the filter to determine optimal exposure.</li>

</ul>

<p>As you can see, Q.G., I'm always willing to have my understanding re-evaluated. When valid, logical points are made.</p>

<p>-Rishi </p>

[q.g._de_bakker]

Yes, Rishi. But as soon as you get a true and sensible answer, you go off in a huff, rather than think about it and see why it is true and sensible.<br>Will it happen again, now you're once more asking for input on something you will run your scientific test 'on', with which you then will fly in the face of sense and reason again? ;-)<br><br>Anyway, It's not impossible that that '-3' stops filter indeed is not exactly that.<br>But metering through the clear part should not produce a -2 stops drop, even with a not-so-precise filter. So probably something indeed has gone wrong in metering (the metering spot, for instance, could be not that small that it will only meter through the clear part).<br><br>The first method you will test is the one that will lead to the best results with the least effort.<br>Most work using grads is spend trying to determine how the density should change (fast or slow) whether you have a filter to suit the need, and how to place the straight line gradient across a usualy not so straight scene. Today, with digital capture or scanned film, using HDR-software in post-processing is the easiest way to get things as good as they can be. In optical printing, dodging/burning will also provide more control than a grad before the lens. But only, of course, if the negative contains enough data (which it often will - not so with those hopless slides. ;-) ).<br><br>By the way, have we now not strayed quite a bit too far from the 120 vs 220 topic?

[rishij]

<p>Go off in a huff, rather than think about it? Between you & me, the only one recurrently exhibiting an absence of thought is you. Your unsubstantiated claims on, e.g. film flatness & how negatives are better than slides & slides are useless, still go, well, unsubstantiated. </p>

<p>But you're right, we're off topic. I've taken the slide vs. negative debate in relation to negatives being noisier over <a href="../digital-darkroom-forum/00YfoI">here</a>; feel free to join that discussion if you have something objective & constructive to say.</p>

<p>Rishi </p>

[greg_peterson3]

<p>I liked using 220 just because it cut the number of times I had to stop to reload in half. </p>

<p>I do lots of aerial photography and when he meter for the helicopter is running at $350 an hour you don't want to waste time juggling film backs or, worse yet, actually loading film inserts. (I use a Mamiya 645 AFD)</p>

<p>But the first sentence is in the past tense because I now have a digital back for the Mamiya that gives me better images (in most respects) than I could get from film and my Nikon CS9000 scanner. So, if anyone would like to buy some 120/220 Mamiya film backs...</p>