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Macro: Magnification obtained using reversing lens

baachitraka

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Bremen, Germany.
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I got an reverse ring adapter for olympus om to reverse a 50mm lens, that gives a nice macro shots. But I couldn't figure out it's magnification though.

Also tried Helios 44-M 58mm f/2 lens and it worked too, perhaps even better because of step less aperture and aperture stop down when needed by turning the ring.This lens gives a comfortable working distance but again I couldn't figure out it's magnification.

Also tired Zuiko 24mm, 28mm and 35mm and they all worked but I presume magnification > 1.
 
As above. You will know the height of the image in the frame is about 27mm if you believe Olympus OM1 to have 100% view of the film gate size.

27 / Millimeters of Ruler Observed = Magnification
 
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Pieter12 said:
Focus on a ruler.
Click to expand...
+1 - adding something like a coin helps too.
The wide angle lenses are retro-focus designs, which does complex things with the placement of nodal points, so they might complicate using any of the calculations available for things like exposure correction and depth of field.
 
Reversed normal and wide-angle lenses produce better close-up and macro photos than reversed telephoto lenses.

I use a Nikon BR2 reverse lens adapter between the bellows and a 28mm f/3.5 Nikon wide-angle lens to capture images with a reproduction ratio up to 12:1 as compared to a reproduction ratio of 1:12 when the lens is used in its normal position.

For example, if I can fill the frame of 24x36mm image with 3mm of ruler, the magnification is 36 divided by 3 which equals a 12x magnification.


Reversed Lens for Macro by Narsuitus, on Flickr
 
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baachitraka said:
But I couldn't figure out it's magnification though.
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There is no standard answer to it. It depends of the thickness of the reversing ring and the distance from the lens filter ring to the front cardinal point and of this distance you may also put in relation to the flange-focal distance.
 
Thanks.

For 35mm focal length the mag factor is ~0.833

For 50mm the factor is ~1.388

For 58mm the factor is ~1.666

All the measurements are with a scale measures horizontally and took x/36

Perhaps a 40mm focal length could bring the ratio to ~1.00

Question: Are there any 40/42mm lens with 49mm filter thread?
 
If you specifically need to increase the magnification close to 1:1, you can use the 50mm with a short extension tube between the body and the reversing ring. If you're getting a magnification of ~1/1.4 with the 50mm as-is, then you need approximately 15mm of extension to get to 1:1.
 
Sounds like you need macro bellows, and/or a macro lens that goes down to 1:1. I see no point in buying another non-macro lens for that.
 
Pieter12 said:
I'm not familiar with any macro lenses that go to 1:1 without an extension tube or bellows. Could be.
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Indeed! The rule of optics dictates that 1:1 is accomplished with 2*FL as distance from lens node to focal plane, and correspondingly 2*FL as distance from lens node to subject. or 4*FL from subject to focal plane.

If a lens has internal focusing rack (and few do) to rack the optics out to 2* FL, it could shoot 1:1.
 
If your magnification is close to 1:1, there is no benefit to reversing the lens.
 
ic-racer said:
If your magnification is close to 1:1, there is no benefit to reversing the lens.
Click to expand...

A lens has a side intended to face a distant object, a relative long multiple of he FL, and a side which is intended to face the focal plane at roughly the FL (ignoring retrograde and telphoto optics) Reversing the lens advantage is that the subject is closer to the designed distance of that side of the optics, than using conventional lens in conventional orientation.
 
baachitraka said:
Question: Are there any 40/42mm lens with 49mm filter thread?
Click to expand...

Doesn't really matter if the lens has a 49mm thread or not .
Just get a step up or step down ring to suit .
So if the lens has a 52mm filter thread you just need a 52mm to 49mm step down ring .

Moving the lens away from the camera a bit more just increases the magnification ratio slightly .

But to answer the question my "SMC Pentax-M " 40mm f/2.8 Pancake lens has a 49mm filter thread .

I've never tried it reversed as I have macro lenses for each of the systems I use plus a Tamron Adaptall 100mm macro lens ( that's 1:1 without an extension tube or 1:1 dioptre adapter ) , that's a very nice , sharp and versatile lens .
 
The magnification does not matter. What matters is does it give you what you want?
 
Just how much magnification are you looking for?

As I understand it, reversing the lens not only gets you more magnification but also gets you flatter plane and supposedly better image?

Unfortunately I didn't document this image well and don't remember other then I used a macro on a bellows and reverse the lens to get even more magnification.

Untitled by Les DMess, on Flickr

And you can stack bellows and extenders.

Fuji 100-23 LX-35 by Les DMess, on Flickr

Of course if you need more magnification then microscopes might be even ore useful.

Microscope by Les DMess, on Flickr

Biggest problems with getting more magnification is applying proper lighting on the target as well as having a bright finder and using a focusing screen with no split image as it will be such a nuisance when it blacks out. If you are using one of those split image screens that never black out - like the ones used on a Canon New F-1 and Nikon FM3A, it will be impossible to focus as everything looks in focus even when they are not.
 
There are several macro lenses for 35mm that focus to 1:1 without needing bellows or an ext tube. I think the Vivitar 90/2.8 is one. Anyway, extension tubes are cheap.

Most or all normal lenses for 35mm SLRs are slightly retrofocus in order to clear the mount and mirror. This means the principal planes are not symmetric about the center of the lens. A consequence is that greater useful magnification can often be obtained by reversing the lens, and macro performance may be better when reversed. However, if you want to do a lot of photography around 1:1, a purpose built macro lens is worthwhile.
 
Sirius Glass said:
The magnification does not matter. What matters is does it give you what you want?
Click to expand...

Yes. From 24mm to 58mm it gives a nice magnification and working distance (longer the focal length, far the distance from the camera to subject)

I should try zuiko zooms 28-48, 35-70, etc., to see how it goes.
 
ic-racer said:
If your magnification is close to 1:1, there is no benefit to reversing the lens.
Click to expand...

I would not say so in general. Depending on lens design a reversing already may affect image quality
 
Oh, dear. Lenses optimized for general out-and-about use are designed to have a large subject in front of a small sensitized surface. This is also true of most lenses sold as "macro" -- the exceptions are optimized for magnifications greater than 1:1 and very few are offered for 35 mm still cameras -- and for enlarging lenses (small negative behind, large print in front). When a lens designed for large front - small behind is used at magnifications > 1:1 (small front, large rear) it should be reversed. At magnifications < 1:1, it should not be reversed.
 
Well, my remark was referring to situations close to 1:1.
 
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