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10-14-2011, 07:22 AM   #16
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QuoteOriginally posted by boriscleto Quote
No they do not. The macro ratio is independent of sensor size. All that 1:1 means is that 1mm covers 1mm of the sensor. It doesn't matter if the sensor is 36mm across or 24mm across. A 2:1 ratio lens would be double life size. 1:2 would be half life size.

Rio beat me to it again!
If you make a print that is the same size as your negative/sensor, then yes, the reproduction ratio does not change. But who makes prints that small? At full magnification the digital image will frame a smaller portion of your subject. If you enlarge the negative to 8x10 and enlarge the digital image to 8x10 and put them side by side, isn't the subject larger on the digital print? That is what I am talking about. So, in practical terms, the digital camera "magnifies" the image by the 1.5 factor. Just as a 200mm lens is still a 200mm lens on a Pentax Digital SLR but produces an image that is equivalent to a 300mm lens on a film camera.

10-14-2011, 01:38 PM - 1 Like   #17
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Magnification is defined as the ratio of recorded image size to subject size. If the image recorded on the film or sensor frame is the same size as the subject, it's 1:1, period. No, we don't normally print frame-size images from miniature-format cameras. We enlarge those. Such enlargements are totally separate from the lens magnification.

Forget about crap.factors. Moving lenses between cameras doesn't change their focal length, and magnification ONLY depends on focal length and extension. A lens with a focal length of 100mm, whose optical center is 200mm from the frame, has 1:1 magnification NO MATTER WHAT THE FRAME SIZE IS! Could be 4x5in, 6x9cm, 645, 135/FF, APS-C, m43 / 110, whatever -- that doesn't matter. Only focal length and extension matter.

Last edited by RioRico; 10-14-2011 at 05:51 PM.
10-14-2011, 03:23 PM   #18
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QuoteOriginally posted by jeverettfine Quote
So, in practical terms, the digital camera "magnifies" the image by the 1.5 factor.
Please hold to the magnification definition. The definition is there so everyone could know what is the lens doing. If you start presenting some lens as doing effectively 3:1 magnification, f5,6 and 300mm on some crop camera, no one will know until he searches for the specific camera senzor size. And recently we got some new sizes never seen before on the market.
You could say 1:1 is like 5,5:1 on the Q, but what if you only crop tiny part of the middle of hypotetical 1Gpix medium format? Does it count as well?
10-14-2011, 07:35 PM   #19
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It is true that macro ratio is independent of the sensor size, as is focal length. One thing that's not independent of the sensor size is the lens classification as tele, normal, wide, etc., because a 33mm lens on APS-C operates like a 50mm lens on a 35mm camera in terms of field of view. An analogous correspondence can be established for how close you need to get to a subject for it to fill the whole frame. In this sense, a 50mm 1:1.5 macro lens on APS-C operates like a 50mm 1:1 macro lens on 35mm. Just don't call it "1:1 macro equivalent" or anything like that. People owning true 1:1 macro lenses will take offense. ;-)

10-14-2011, 08:26 PM   #20
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IMHO what's important, especially for the less experienced, is learning how a lens works on THEIR camera, not comparing with how it might work elsewhere. That includes learning how to fill the frame at various focal lengths, i.e. learning the FOVs. A lens projects an image; different frames crop more or less of that projection. How we work with these differences of frame size, focal length, distance, and perception, greatly affects perspective, DOF, and the degree to which we enlarge the image for presentation. Any equivalences are rough at best.

How about a test, with comparative shots using a 100mm at 1:1 on APS-C vs a 150mm at 1:1.5 on 135/FF?
10-14-2011, 09:36 PM   #21
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This article makes it all crystal clear. The example in the section about perspective is especially elucidating. There is no difference whatsoever in perspective between the shot with a 135mm lens on a full-frame camera, vs. the 28mm lens on a compact camera with a crop factor of 4.8.
10-14-2011, 10:30 PM   #22
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QuoteOriginally posted by Ikarus Quote
This article makes it all crystal clear.
Very thorough article, and it echoes (even with some of the same citations) what I've been writing here awhile. Especially note the conclusion:

QuoteQuote:
IMHO, the notion of an “equivalent” something (e.g. macro factor, focal length, etc.) when discussing the effects of using sensors of different sizes should be avoided, Whatever pedagogical qualities such as an approach may have, there is also a lot of evidence that this approach leads to a lot of confusion among those mistaking equivalence for actuality. It is much better to use the actual value – and to educate oneself and others to understand what this entails.
10-15-2011, 12:31 AM   #23
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All those who try to see incorporate FOV, the crop factor with magnification, are unnecessarily confusing the issue.

I am an optics junkie like Rio except on a far smaller scale, and I like to play around with my lenses, extension tubes, bellows and etc. When I am playing around with macro related stuff, I use 1:1 magnification ratio as a benchmark of sort, I don't always have a metric scale handy so I looked around for an object that I could shoot to gauge the magnification ratio and that perfect object happens to be a Canadian quarter, whose diameter is 23.89 mm (American quarter is probably the same). Pentax APS-c sensor is 15.8 x 23.6 mm (K20D). Shooting the quarter at 1:1 magnification (K20D + Tamron SP 72B, 90/2.8). I capture about 99% of the coin across the full width of the sensor. A full frame SLR is 24x36 mm. I mounted my Tamron 72B on my Pentax PZ-1 and focused on the quarter at 1:1 magnification, the quarter fills the full height of the PZ-1 focus screen; 24mm. A mm is a mm, whether it's viewed through an APS-c DSLR or a full frame SLR or any other camera for that matter.

10-15-2011, 10:58 AM   #24
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QuoteOriginally posted by excanonfd Quote
Shooting the quarter at 1:1 magnification (K20D + Tamron SP 72B, 90/2.8). I capture about 99% of the coin across the full width of the sensor. A full frame SLR is 24x36 mm. I mounted my Tamron 72B on my Pentax PZ-1 and focused on the quarter at 1:1 magnification, the quarter fills the full height of the PZ-1 focus screen; 24mm.
Are you saying you shot the coin with the same lens at the 1:1 setting on both APS-C and full frame and had the coin fill 100% of the the field of view on either? That would be surprising.
10-15-2011, 11:38 AM   #25
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QuoteOriginally posted by Ikarus Quote
Are you saying you shot the coin with the same lens at the 1:1 setting on both APS-C and full frame and had the coin fill 100% of the the field of view on either? That would be surprising.
Why? 1mm is 1mm, 24mm is 24mm. If a quarter is ~24mm across it should fill a 24mm sensor.

This isn't in mm, it's 15/16"

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10-15-2011, 11:50 AM   #26
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QuoteOriginally posted by Ikarus Quote
Are you saying you shot the coin with the same lens at the 1:1 setting on both APS-C and full frame and had the coin fill 100% of the the field of view on either? That would be surprising.
Hmm, I thought I had explained myself fairly clear... What I am saying is that with an APS-c DSLR the coin fills the sensor frame horizontally, and vertically in full frame. APS-c measures 24mm horizontal, full frame is 24mm vertical.
10-15-2011, 08:42 PM   #27
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I get the point of the technical discussion. Yes 1:1 is 1:1 regardless of the camera format. I'll try and hold to that standard in future discussions.
I have photographed with 4x5 and 8x10 view cameras for decades, doing natural close-ups as well as commercial product shots etc. There are no convenient 1:1 markings on a view camera lens. You just have to know what focal length you are using and measure your bellows extension to calculate magnification and extension factors for exposure. Sometimes I have had to do an exact reproduction ratio, but that is pretty rare for me. More common is the need to keep framing and the lens to subject relationships (i.e. perspective) constant such that you need to focus and frame with the rear standard (one of the great advantages that view cameras have in macro photography).

I still say that once you enlarge a 35mm film negative or a digitally captured image, in a print or on a computer screen, reproduction ratio is pretty much meaningless in practical pictoral photography.
10-15-2011, 11:24 PM   #28
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QuoteOriginally posted by excanonfd Quote
Hmm, I thought I had explained myself fairly clear... What I am saying is that with an APS-c DSLR the coin fills the sensor frame horizontally, and vertically in full frame. APS-c measures 24mm horizontal, full frame is 24mm vertical.
My mistake. For some reason I was under the impression that you were trying to contradict what I said here. It seems we all agree that a 1:1 macro on full-frame produces the same (identical, equivalent, matching, whatever term one finds least offensive) FOV as a 1:1.5 macro on APS-C. Can we move on then?
10-16-2011, 09:19 AM   #29
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yes please

Indeed, let's move. We can all agree that we love the macro world in our own particular way.
11-21-2011, 04:27 AM   #30
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I have an old Rokkor 50/4 enlarger lens. I am wondering what kind of adaptor I need to fit it to a K-mount bellows. (I also have a m42-K adaptor.) The Rokkor lens has a thread that is about 38.8mm OD, but I cannot deterine the thread pitch. I used to use it on a Lucky II-C enlarger.
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