6x4.5 vs 6x7 Film Size

[glen_h]

<p>Seems to me what hasn't been said is that other things are rarely equal.</p>

<p>For now, ignoring the costs (larger lenses cost more), compare 24x36 to 56x68 (the size above for a 6x7 image).</p>

<p>Consider a shutter speed fast enough that we can handhold (subject not moving) and aperture for sufficient depth of field. To simplify the calculation, the area is about 4x, so about 2x linear. We need about 2x the focal length lens with the larger format.</p>

<p>For actual numbers, consider the 35mm camera with ISO 125 film, shutter at 1/125, and aperture at f/8. Now what happens for 6x7?</p>

<p>We want equivalent shutter speed for handheld photography. Since the enlargement at printing will be 1/2 as much, the same shutter speed is fine. (The 2x from the focal length cancels the 0.5x less enlargement.)</p>

<p>https://en.wikipedia.org/wiki/Depth_of_field<br>

indicates that for the same depth of field, and same field of view, we stop down two stops, to f/16, with 2x the linear dimension and focal length. For the same shutter speed, we need 4x the film ISO. Seems to me that the larger grain, at reduced enlargement, just about cancels.</p>

<p>As well as I know, the original transition to 35mm photography came when higher quality lenses could be made at affordable prices, to get enough resolution into the smaller format. As we know, medium format cameras with cheap lenses stayed around for a long time.</p>

<p>Also, I didn't consider diffraction, which I suspect is more of a problem at the smaller format.</p>

[ilya_inov]

<p>I'm in the same situation as the original poster was, i.e. considering which medium format camera to move to from my 35mm, will it be a 6x4.5 or 6.6/6.7? And while image quality is certainly affected by the negative size, I'd like to point out that another huge factor is your<strong> scanning method</strong>. I have found that using a dedicated film scanner like Nikon Coolscan offers a huge improvement in both detail and colors obtainable from a negative, as compared to a flatbed scanner. So while you gain more negative size with MF, you certainly lose in the scanning quality from a flatbed.<br /> And going to a larger negative size, you get the added issue of keeping the negative flat at the time of scanning, which also takes quality away. (there are aftermarket film holders out there that may remedy it somewhat). Then there's scanning software as well: most people also agree that using 3rd party scanning software like Vuewscan offers additional benefits compared to standard software that comes with the scanner.<br>

So if you compare a 6x7 negative scanned on a flatbed to a 35mm negative scanned on a good dedicated scanner, the improvement in quality may not be as huge as comparing negative sizes will suggest. <strong>Only comparing apples to apples</strong>, in this case a Coolscan/Frontier scan of both, <strong>will give you the true indication of the improvement in quality</strong>. But how many people have access to a medium format Coolscan or Fuji Frontier?<br />Lots of things to consider!</p>

[barry_r]

<p>ilya: private message sent</p>