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Adapting Macro Lenses

blockend

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northern eng
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35mm
Will someone smart give the lowdown on how macro lenses perform between formats? I can't get my head around the subject at all. The size of the image circle should be the only variable, but I'm thinking image to sensor distance is going to play a part. Specifically, would a full frame 35mm macro (1:1) lens work on a micro four-thirds camera via an adapter, and still offer 1 to 1 magnification?
 
In theory yes, but I will leave the calculation about extension to those more mathematically gifted.
 
Well ...
You have to remember of course that something that fills a 35mm full frame sensor or film frame at 1:1 - say something that is 24mm x 36mm in size - will be bigger than a micro 4/3 sensor.
So if you have an original subject that is small enough to fit into a micro 4/3 sensor (or 110 frame of film ) then it should work fine at 1:1 on either format.
The only practical issue is whether the necessary adapter between the lens and the camera causes a problem with flange distance.
I have an Olympus Bellows and slide copier unit that, when combined with a 50mm macro film lens, works fine when copying slides on to film. When I try to use it with an OM-D micro 4/3 body and the necessary adapter, the physical limits built into the bellows unit result in too much magnification - the bellows don't compress enough to bring the lens close enough to allow the necessary lower magnification.
 
MattKing said:
The only practical issue is whether the necessary adapter between the lens and the camera causes a problem with flange distance.
Click to expand...
That's the part I'm unsure about. Adapters are designed to shift focus to sensor distance by the appropriate amount, so it shouldn't be an issue in theory, The practice may be different, especially regarding magnification and the physical distance limits to the front element. I'm thinking of buying the Panasonic 30mm f2.8 for digital macro work, as "60mm" works as a standard lens for me, and it would double as a film copying lens. However I also have full frame Canon and APS-C Fuji cameras, and if I can get something (classic 35mm?) that can be used for macro across formats, it would have practical and cost benefits.

My Epson scanner doesn't exhaust negative detail, dedicated 35mm film scanners and digital camera copying seem to offer much better results.
 
A lens with 1:1 reproduction ratio will reproduce a, say, 10mm object at the same 10mm size on the film/sensor. If the sensor is smaller, the object will fill a larger part of the frame.
If you want to do the same picture on a M43 sensor as you would get with a FF sensor, using the same lens, you will need a different (smaller) reproduction ratio.

Or if you want it with numbers:
let's imagine you have an object 24mm long, 36mm wide. For instance a negative you want to scan. Your sensor is 24x36.
A reproduction ratio of 1 will project the 24x36mm object on the sensor with a size of 24x36mm.
Now keep the same lens, swap the camera for another one whose sensor is only 12x18mm.
A reproduction ratio of 1 will show you the same size as you had previously, but because your sensor is half as large in each dimension, your image will cover an area of 12x18mm of your original object.
In order to see the entire 24x36mm object on your 12x18 sensor, you will need a reproduction ratio of 1/2.

Hope this helps
 
If the lens is advertised to go up to 1:1 reproduction ratio you will not need an extra adapter or bellow, which might not provide enough distance. (I had the issue using a 135mm Hasselblad on bellows adapted to my Nikon DSLR - it did not go far enough to cover the area of the picture I wanted, as I needed to go beyond 1:1 ratio).
 
etn said:
In order to see the entire 24x36mm object on your 12x18 sensor, you will need a reproduction ratio of 1/2.
Click to expand...
If I understand you correctly, that means a full frame macro lens on a M43 body with give macro x2, or an even bigger close up/enlargement. In which case moving the lens away from the subjects give 1:1 reproduction. That seems like a win-win.
 
blockend said:
If I understand you correctly, that means a full frame macro lens on a M43 body with give macro x2, or an even bigger close up/enlargement. In which case moving the lens away from the subjects give 1:1 reproduction. That seems like a win-win.
Click to expand...
The reproduction ratio of the lens remains the same regardless of whether you use a FF or a M43 body.
If you have an M43 sensor, the area covered by the sensor will be smaller than the area covered by an FF sensor. Consequently, if you want to cover a larger area you will need a lower reproduction factor - for instance 1:2 (assuming an M43 sensor length and width are 1/2 that of a full frame, which is not exactly the case). However, a lens which can do 1:1 can also do 1:2.

Macro x2, or reproduction ratio of 2:1, is needed if you want to expand i.e. photography a smaller object than the size of your sensor. This is where you need bellows/extension rings/reverse lenses etc., as very few macro lenses can go beyond 1:1 on their own.

Now I'm getting confused too, someone please correct me if I'm telling BS
 
blockend said:
The practice may be different, especially regarding magnification and the physical distance limits to the front element.
Click to expand...
The problem I have with the slide copier I have is that the intervening bellows + adapter add too much extension, and therefore too much magnification.
If the bellows was capable of more contraction than it is physically capable of, I would be able to reduce the magnification to the approximately one third life size that would suit my needs.
I am considering modifying the bellows.
 
Thanks for the replies. I'll give the subject more thought when I get a moment.
 
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