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Old Apr 1, 2010, 9:28 AM   #41
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Thanks A.C...... the 'adaptor' isn't at all like the MMF-2 - it's simply a 52mm thread with micro-four-thirds mount, sold as a product for reverse mounting any lens with a 52mm thread onto a micro-four-thirds camera.

I read loads of material (obviously not enough though!) discussing reverse mounting a lens as a great way to get greater than 1:1 magnification without investing in a dedicated macro lens. I saw some great images of the results too, which looked like fun and made me want to explore shooting macro myself.

All of the material I read (and all the setups I saw pictures of), were discussing DSLR (and SLR) cameras - not m4/3, which is why I wonder if this is an issue.....

What I really don't understand though, is when I look through my 50mm lens backwards, subjects are only in focus when they are very close to the other side of the lens - i.e. I can see my finger-print huge and very clearly if my finger is only a centimetre or so from the back of the lens, with my eye looking through the front - the same way as the camera 'sees' the lens. Why when I mount the lens (backwards) does the point of focus move way back to 25/30cm..?

Confused, and frustrated!

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Old Apr 1, 2010, 2:09 PM   #42
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Remember when you're looking through the lens while holding it in your hand image focused by another optical system (your eye) as opposed to an image formed on the camera sensor. Maybe I was clear on using the 4:3 to m4:3 adapter. If you interposed that adapter between your 52mm to 4:3 adapter it would move the lens further away from the sensor and perhaps result in a more useable image that covered the full sensor. In the "old days" reversing adapters were generally used in conjunction with focusing bellows or an extension tube set (three extension tubes of different lengths that could be used individually or stacked to vary the focus.)

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Old Apr 7, 2010, 10:21 AM   #43
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Just offering a quick update for those interested.... I returned the 52mm>m43 reversing ring adaptor, as it obviously wasn't what I was looking for.

Since my FD adaptor arrived today, I've been able to confirm by hand holding my 50mm in reverse against the adaptor, that the problem was indeed one of distance to the sensor - it would seem reversing the lens this way (i.e. after the FD-m43 adaptor) will work. It doesn't look like 1:1, but is certainly focusing much closer than when the 50mm is mounted the correct way.

Since starting this thread, I have won some FD extension tubes (set of 3 for 10!), so will give "right-way-round" macro a go with the 50mm shortly, and let you know how it works out.
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Old Apr 8, 2010, 7:02 AM   #44
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Default First GH1 extension tubes test....

Following the arrival of my FD-m43 adaptor yesterday, the FD extension tubes I won also turned up this morning!

I was keen to try them out to see what kind of magnification was possible. Suffice to say, stacking all 3 tubes gets you in quite close, and it quickly becomes apparent how much use image stabilisation is. Yes, this is where those of you with Olympus bodies can feel quite smug , however, it is still perfectly possible to get the shot, and I'm really looking forward to trying this in the field!

For what it's worth, here are examples of the kind of magnification possible with the various tubes fitted. I hope these are useful...

GH1, Massa FD->m43 adaptor, Canon FD50mm only @ f2.8


...with 12mm tube


...with 12mm & 20mm tubes (+32mm)


...with 12mm, 20mm & 36mm tubes (+68mm)


I'm really not sure what the actual achieved magnification numbers are I'm afraid, although I guess with all 3 tubes, it's beyond 1:1 - perhaps someone can clarify the maths please...?
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Old Apr 8, 2010, 7:50 AM   #45
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... Suffice to say, stacking all 3 tubes gets you in quite close, and it quickly becomes apparent how much use image stabilisation is. Yes, this is where those of you with Olympus bodies can feel quite smug ...
Actually, sensor shift image stabilization (from Olympus, Pentax, Sony, or anybody else) doesn't work with extension tubes. Sensor shift image stabilization uses the focal length reported by a lens to determine the angle of view, and the amount of shift that must be employed to counter the effect of shake. As you increase the distance between the lens and the image sensor, the angle of view changes. The path light takes when it exits a lens headed for the image sensor is almost never parrallel to the optical axis of the lens, so the angle of view changes, so the stabilization system can't determine the appropriate amount of correction to apply. And since every lens is different, the system can't ever know. (Lenses that have a light path that is parrallel to the optical axis are called Telecentric Lenses.)

Since optical image stabilization (from Canon, Nikon and others) projects a stabilized image out the rear of a lens, the image is stabilized even when using extension tubes.

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... I'm really not sure what the actual achieved magnification numbers are I'm afraid, although I guess with all 3 tubes, it's beyond 1:1 - perhaps someone can clarify the maths please...?
Since most lenses aren't telecentric, and since the degree to which lenses are not telecentric varies from lens to lens, the amount of magnification can't be determined mathematically. The only way to do so is to compare the actual size of the object in the image to the size of the image sensor. Since your GH1 has a 17.3x13mm image sensor, an object that size that fills the image will be represented 1:1.
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Old Apr 8, 2010, 8:27 AM   #46
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Thanks for the clarification about sensor-shift technology TCav!

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Since most lenses aren't telecentric, and since the degree to which lenses are not telecentric varies from lens to lens, the amount of magnification can't be determined mathematically. The only way to do so is to compare the actual size of the object in the image to the size of the image sensor. Since your GH1 has a 17.3x13mm image sensor, an object that size that fills the image will be represented 1:1.
...so I'm not even getting 1:1 then? It doesn't really matter, I was just interested - and it's useful information for others who are looking into this area - to know what kind of magnification this combo was producing.

Correct me if I'm wrong here.... I had read that using the same amount of extension as the focal length of the lens would render 1:1 magnification - i.e. a 50mm lens with 50mm of extension would be 1:1. Presumably the 2x multiplier comes into effect here - since the 50mm lens acts like a 100m lens on a GH1 (or any other m43 camera for that matter), it would therefore need 100mm of extension for 1:1 - is that right?

Ignoring the 40 I spent on an FD adaptor (as it isn't only to be used for macro), considering I've spent 20 on the lens and 10 on the tubes, I reckon that 'macro on a budget' is just about possible!

If I'd gone for a 28mm FD lens (may well still get one anyway), this along with the 68mm of extension tubes should give more than 1:1 if my hypothesis about the 2x factor above is correct? Equally, I guess it could be reverse-coupled with the 50mm I now have for even greater magnification.
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Old Apr 8, 2010, 8:30 AM   #47
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IIRC, the newer Pentax offerings allow one to set FL for lenses which don't report FL, and use the IS feature. Not sure of the other makers.

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Old Apr 8, 2010, 9:43 AM   #48
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The E-620, and I presume other Olys allow manually entered focal lengths for IS. I suspect since macro involves higher than normal magnifications (small physical movement = large angular change) as with long telephoto lenses it might be best to enter a focal len much longer than the actual focal length for best results.

A. C.

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Old Apr 8, 2010, 9:52 AM   #49
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IIRC, the newer Pentax offerings allow one to set FL for lenses which don't report FL, and use the IS feature. Not sure of the other makers.
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The E-620, and I presume other Olys allow manually entered focal lengths for IS.
But even at that, as the distance between the lens and the image sensor changes, the angle of view changes, so you would have to guestimate what focal length to enter in order to correctly compensate for camera shake. And each lens is different, so you can't just apply a rule-of-thumb either.
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Old Apr 8, 2010, 10:02 AM   #50
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...so I'm not even getting 1:1 then?
My guess is that, in your last photo, you're actually getting a little bit better than 1:1, though it's obviously a crop and I've no way to determine how much you cropped it.

A simple way to judge would be to take a photo of a ruler. Like this.
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