4x5 vs 6x7 crop
This has likely been discussed in the past, but I could not find a clear answer in all the debating.
My Mamiya RZ67 Pro ii produces beautiful negatives, but after scanning, I am not exactly clear on how I should be cropping. I, foolishly, entered 6 and 7 into Photoshop's custom constrain field, and while I love the ratio that gives me, I am loosing quite a bit on the edges. Meanwhile, if I go with 4x5, 8x10, etc. I get a ratio that fills the frame with the ability to go ALL the way to the edges on all four sides. This seems like the 'ideal format' in truth, but I can't help but wonder where 67 comes from, if that crop is such a slice on the sides. I'd love some history, or input. What do you guys do?
So-called designations 645, 6x6, 6x7 are approximations.
- The real frame width on 645 depends upon brand, but about 42mm x 55.5mm or 1:1.32 aspect ratio. (Mamiya and Pentax 41.5mm x 56mm, or 1:1.35; Bronica 42.5mm x 55mm, or 1:1.29) ,
- The real frame width on 6x6 is actually 56mm x 56mm.
- The RB67 actual frame size is 56mm x 68.4mm, or 1:1.22 aspect ratio.
The print size on enlarger paper varies a bit due to borderless 1:1.25 vs. bordered print 1:1.26, also, although nominally 1:1.25 aspect ratio.
Don't forget that few enlarger negative holders showed the entire frame, in an effort to prevent contrast destroying stray light leakage at the edges of the image area. And to account for brand-to-brand variances in frame dimensions.
'the ideal format' is a bunch of marketing ploy. One might argue that Bronica's 645 format printed on bordered 8x10 paper is really more 'ideal' than Mamiya 6x7 on 8x10 paper borderless!
Last edited by wiltw; 08-17-2014 at 10:54 AM. Click to view previous post history.
The format of a Fidelity, Lisco, or Riteway 4” x 5” film holder is about 95mm x 120mm due to the edges used to retain the film in the holder. So in this case the 4” x 5” format has the aspect ratio 24:19 = 1.26.
The 6 x 7cm format can vary depending on the make and model. The Mamiya RZ67 uses 56mm x 69.5mm with aspect ratio 1.24.
Although they aren’t identical, the aspect ratios of the RZ67 and the Fidelity, Lisco, and Riteway 4” x 5” film holders are quite close to each other.
Yeah, the 6x7 designation is rather unfortunate from that perspective. On my Pentax 6x7 the actual film gate ratio is pretty darn close to "ideal format" proportions (1.25 aspect ratio), and I think I have read that it was designed for those proportions. Maybe all 6x7 cameras are designed to be close to ideal format? I am sure others will chime in with a better history, but all I know is that 120/220 film is 60mm wide, so it seems that the "6" part of any 6x? format is just a convenient but very rough approximation to the image dimensions. The actual image width (edgewise) is typically more like 56mm.
Last edited by jnanian; 08-17-2014 at 11:11 AM. Click to view previous post history.
Reason: misread/misunderstood question sorry ..
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I think wiltw is right, the sizes are approximate.
4x5 negatives fill up 8x10 and 11x14 inch paper with a minimum of cropping (or in my case no cropping). Being able to get all of a negative on a print is great when you like what you see, and don't want to waste a drop. (I can easily get carried away discussing black borders and no cropping, if you want to hear more, you could dredge up an old thread)...
I think 6x7 was intended to carry on that proportion with 120 roll film.
It's not only about maximizing the quality (although you do maximize the quality)...
I recently noticed that Kodak Pocket Instamatic frames (110 cartridges) also fits 11x14 inch paper nicely, and I enjoy the two prints that I made for the Monthly Shooting Assignment "Cheap Camera"...
So based on this information, 6x7 is not a useful figure to the artist, but more of less a marketing classification. I am cropping these images at 4x5, as it maximizes what I get out of the negative.
Sounds like a good idea to maximize what you get.
In case you are wondering whether or not you should crop... I dredged up an old thread for you, where I reveal some of my thoughts about the crop/no crop position...
I am happy with the 4x5 crop, since it allows maximum inclusion of detail and space. I take my time when composing shots, despite the fact that I have a huge negative to work with, I am very stingy when it comes to frame real estate. I strongly dislike cropping an image to get rid of something in the bottom corner. Here's a shot from my first RZ roll, cropped edge-to-edge at 4x5.
You're not the only one who thinks 6x7 cameras produce images with a 6:7 aspect ratio. It is a common misconception.
Originally Posted by LMNOP
The 6x7 format was developed as a roll-film version of 4x5 and 8x10 view cameras and all of them produce images closer to 4:5 than to adjacent aspect ratios. The difference between 6x7 and 6x6 images substantial - a 6x7 frame is 25% larger than a 6x6 frame and prints without meaningful cropping to the typical papers that are also 4:5 (8x10, 11x14, 16x20, etc.).