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Old May 4, 2007, 9:54 AM   #1
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I aquired a K mount to 4/3 adapter
mainly to try this 135mm/2.8 Rikenon that was brutaly sharp in 35mm

in this portrait, the aperture was wide open at 2.8
the DoF at this is way too tight (i had forgotten it is now 270mm)
when i checked it was just 1"

http://www.dofmaster.com/dofjs.html

it seems like with some work it will be good
I shall add a baffle and pay more attention to DoF calcs
shooting a portrait from 10-15ft is a tad weird tho
and focussing isnt so easy either

you can see the hair infront of the ears is razor sharp
yet the face is OOF

Riley
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Old May 4, 2007, 5:41 PM   #2
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Hi Riley

Thats an interesting example from that lens - it looks tack sharp on of centre but any ideas why its soft in the middle ? I would have thought it would have been the other way around. Let us know how it goes with the lens and if you can get it to work.

Cheers

HarjTT

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Old May 4, 2007, 8:22 PM   #3
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Fairly long lens with fairly large aperture means shallow depth of field. The focus is behind the face and thats the result. I don't think its broken or anything. I just looked up 135mm f2.8 on a 4/3 sensor has DOF of less than 2 inches if your 10 ft from the subject.
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Old May 4, 2007, 9:52 PM   #4
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HarjTT wrote:
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Hi Riley

Thats an interesting example from that lens - it looks tack sharp on of centre but any ideas why its soft in the middle ? I would have thought it would have been the other way around. Let us know how it goes with the lens and if you can get it to work.

Cheers

HarjTT

:? :O
hi Harj
the DoF is so narrow, in this case around one inch, that only that area one inch infront of the ears is in focus, you can see by the skin textureon the side of the face, where focus zone comes in and goes out. The face pops out of the fucussed zone.

So I need to shoot at a tighter aperture than 2.8 for more DoF. Its a film lens and its wide open so at 2.8 it whould be soft anyway, but that area that is in focus makes me think it looks promissing. I shall have another few frames at F4 - F8 and see better how it goes.

Riley
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