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Lens focus The place to talk about your camera's glassware.

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Old 20th October 2012
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Macro with m4/3 12-50mm or OM 50mm 3.5

I was about to splash out on an OM 50mm f3.5 macro lens, but when I looked at the size of the OM adapter I realised it wouldn't be much smaller than the 12-50 and certainly not lighter, so I had a check of what it would get me in magnification - it's rated at 0.5 according to this site, and the 12-50 is rated at 0.36.

According to the spec, in macro mode the 12-50 is meant to focus down to 200mm, but I found it would focus at 170mm. Here's a composite of a centimetre scale taken at 200mm and 170mm.


By my reckoning, at the closest focussing distance of 170mm that's nigh on 0.5 magnification. To get that on the OM 50mm I'd need to be at 114mm - the lens would be just about touching the subject!

Here's the sums, sensor 13mm high:

At 200mm we get 34mm in shot = 13/34 = 0.38
at 170mm we get 26.5mm in shot = 13/26.5 = 0.50


So have I got this all right? Assuming equal quality of glass, is the 12-50 a better bet for macro?

Anyone tried this OM lens for macro on m4/3?

Just as a little aside, why on earth does the 12-50 focus closer than it's spec?
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Old 20th October 2012
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Re: Macro with m4/3 12-50mm or OM 50mm 3.5

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Originally Posted by jdal View Post
why on earth does the 12-50 focus closer than it's spec?
I don't know, but it does do better than the specs. I did it on the long side with 35mm of the ruler in the screen & divided that into 17.3(mm) & that's about 0.5 magnification. Well, don't tell everyone. They might want one too.

Edit:
Here's my photo to prove it.


If you really want macro though, get the 60mm lens & then the Kenko extension tubes might be a goer with it too for greater magnification.
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Lenses: M.ZD12-40mm f2.8 PRO Lens, M.ZD40-150mm f2.8 PRO Lens, MC-14, MC-20, M.ZD12-50, M.ZD60 Macro, M.ZD75-300 Mk II, MMF-3, ZD14-54 II, Sigma 150mm F2.8 APO Macro DG HSM.
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Old 20th October 2012
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Re: Macro with m4/3 12-50mm or OM 50mm 3.5

I use Ross' method as it works equally for all lens and sensor sizes and is a reliable calculator for magnification.
Your calculations are correct, I think, as measuring image height or width and comparing to sensor dimensions is bang on.
I don't worry about distance, though, as the magnification/distance relationship varies with focal length.
Longer lenses, properly extended, give good working distance. The 70-300 is a example that, though the elements need a lot of internal travel (150mm) to achieve .50x magnification at 300mm.
The closer focus you mention might be a function of aperture?
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Old 22nd October 2012
Footloose1949 Footloose1949 is offline
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Re: Macro with m4/3 12-50mm or OM 50mm 3.5

I'm betting the you will not be able to focus as close on the larger end of the zoom as you will on it's shortest focal length. One of the benefits of using a longer focal length, is that because your subject will be further way from the lens on the longer focal length setting (when both used at the 1:1 ratio) which will make lighting the subject and tracking it - if it is moving, a bit easier.

Whist the zoom may give you more flexibility in relation to the distance between the lens and subject, being a zoom, the image quality will undoubtedly be better with a prime lens. As for the issue regarding the extra size of the lens due to using a 4/3rds to m4/3rds adaptor, it's in my opinion, a wholly irrelevant issue and certainly nothing to get your 'Knickers' in a twist about!

Last edited by Footloose1949; 22nd October 2012 at 12:05 PM. Reason: Additional clarification.
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Old 22nd October 2012
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Re: Macro with m4/3 12-50mm or OM 50mm 3.5

Quote:
Originally Posted by Footloose1949 View Post
I'm betting the you will not be able to focus as close on the larger end of the zoom as you will on it's shortest focal length. One of the benefits of using a longer focal length, is that because your subject will be further way from the lens on the longer focal length setting (when both used at the 1:1 ratio) which will make lighting the subject and tracking it - if it is moving, a bit easier.
The 12-50 is a fixed 45mm focal length when in macro mode. So not far off it's longest focal length and not far off the the OM lens.

Quote:
Originally Posted by Footloose1949 View Post
Whist the zoom may give you more flexibility in relation to the distance between the lens and subject, being a zoom, the image quality will undoubtedly be better with a prime lens. As for the issue regarding the extra size of the lens due to using a 4/3rds to m4/3rds adaptor, it's in my opinion, a wholly irrelevant issue and certainly nothing to get your 'Knickers' in a twist about!
Ah well, you see, for me size does matter, since I bought into 4/3 because of the size, and with my cheapo adapter the OM would be about 50% heavier. The quality may well be a bit better, but remember that the 12-50 is a prime when in macro mode - so maybe not. Having said that I had a go with my brothers 50mm 1.4 OM and it was very good, better than the 12-50 I'd say.

ps.. re primes vs zooms I can show you a 14mm prime where the 7-14mm zoom knocks spots off it for quality Mind you there's nigh on a grand price difference!
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Old 22nd October 2012
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Re: Macro with m4/3 12-50mm or OM 50mm 3.5

I definitel don't doubt the quality of the 7-14mm zoom; I've owned the Zukio version since 2006-7 and it's a stunner, marginalised by some for being 'too expensive' and ignored in group tests because until recently, there hasn't been a lens in the APS-C format to compare it to, and 'they' probably hate being reminded that this is one area where 4/3rds, and m4/3rds otics rule the roost. I've also used Voightlander's 12mm f5.6 FF RF lens, but it suffers from a 3 f-stop difference between the centre and the edge of the frame, and the only satidfactory way of correcting that, is by purchasing a circular ND filter which reduces it's working apeture down to around f11-16.
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