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PostPosted: Wed May 19, 2010 11:22 pm 
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A recent purchase for use with an adapter on the E-P1.

It is a really tiny lens. It makes the Panasonic 20mm f/1.7 look huge in comparison.

The body is made of metal. One ring sets the aperture continuously from f/1.4 to totally closed over about 1/4 turn. The other ring adjusts the focus. As it was supplied this wasn't fitted properly, and turned loosely and roughly. After a bit of messing around it caught on whatever it was supposed to and now feels as expect. It is nicely damped, turning about 3/4 of a turn end to end. In practice, 1/4 of a turn is beyond infinity, leaving the remaining half turn going from infinity to MFD measured around 60cm. This is quite off from the specified MFD of 30cm, so I have to assume the focus stop isn't correct on mine given the excess amount beyond infinity mentioned earlier. After taking some test shots, I started taking it apart and... its bed time so it wont go back together tonight.

Bear in mind the following bokeh shots are set at about 60cm focus distance, so it could be bigger if it was set correctly at 30cm.

The aperture is round when fully open, but goes into a complex shape turning rectangular then onto a slit when almost closed.

Image
Resized pic, flare at f/1.4

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Resized pic, cat's eye effect at f/1.4

Image Image
100% crop, f/1.4 - the "whiter" light on the right shows colour fringing.

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100% crop, f/1.4

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100% crop, f/2 to 2.8-ish

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100% crop, f/8-ish

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100% crop, almost closed aperture

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f/1.4 vignetting

Tomorrow I'll finish dismantling the lens, then I have the fun of assembling it correctly again. It seems quite simple so an interesting learning exercise.

I don't have any real sample pics uploaded, but at f/1.4 I'd describe it as artistically soft. Not like a bad lens blurry, but more like soft focus.

_________________
Canon DSLRs: 7D, 5D2, 1D, 600D, 450D full spectrum, 300D IR mod
Lenses: EF 35/2, 50/1.8, 85/1.8, 135/2+SF, 28-80 V, 70-300L, 100-400L, TS-E 24/3.5L, MP-E 65, EF-S 15-85 IS
3rd party: Zeiss 2/50 makro, Samyang 8mm fisheye, Sigma 150 macro, 120-300 f/2.8 OS, Celestron 1325/13
Tinies: Sony HX9V.


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PostPosted: Thu May 20, 2010 6:47 pm 
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"artistically soft": Nice description of what we might find as soon as you dare post some "real" images, popo :wink:
Hope you can assemble it correctly!

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Thomas (beware: Nikon-fanboy and moderator!) My Lens Reviews, My Pictures, My Photography Blog
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PostPosted: Fri May 21, 2010 11:34 pm 
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I finally got the lens reassembled. The way it goes together, it is a bit hit and miss if I get the focus stop in the right place. The range stop could go in one of 6 orientations, so I just fiddled with that until I got close enough. Now at one end I get infinity-ish, and at the other I get a MFD of just under 40cm, working distance of 33cm.

I only took a few more test shots since then. I noticed two things I didn't before: field curvature and spherical aberration. Point sources don't get resolved to a point, but a sharp-ish bit and a lighter blur around it. That I guess explains the soft focus.

The field curvature was most noticeable when I pointed the camera at a textured surface at close focus. The plane of focus wasn't a plane, it was round. At a perpendicular angle you get a ring of focus.

I don't think I put the lens out of alignment by my disassembly, as it is very simple. The front element unscrews out, allowing access to the aperture ring. The core itself holds the remaining elements. Adjusting focus moves the whole lens away from the sensor.

I'll really have to take some serious samples tomorrow.

_________________
Canon DSLRs: 7D, 5D2, 1D, 600D, 450D full spectrum, 300D IR mod
Lenses: EF 35/2, 50/1.8, 85/1.8, 135/2+SF, 28-80 V, 70-300L, 100-400L, TS-E 24/3.5L, MP-E 65, EF-S 15-85 IS
3rd party: Zeiss 2/50 makro, Samyang 8mm fisheye, Sigma 150 macro, 120-300 f/2.8 OS, Celestron 1325/13
Tinies: Sony HX9V.


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PostPosted: Sat May 22, 2010 9:31 am 
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A quick example of the funny focus field:

Image
Focus set to the middle. Actually I'm possibly slightly off, with focus just fractionally behind the middle as there was a faint colour shift. On a normally corrected photographic lens, we would expect to see a horizontal band in focus as the screen is tilted slightly.

Image
Focus set back a bit, note the ring region in focus.

Image
Here's an improvised spot test. The spot is actually a single white pixel displayed on my monitor. I didn't control the exposure so on the left is f/1.4 with levels adjusted, right is somewhere between f/4-f/8 straight out of the camera.

Image
And finally, a quick shot sample.

Image
100% crop from above. I manually focused so the eyelashes were in focus.

Finally, a quick observation on the corner vignetting. There is quite a bit of metal on the subject side of the front element forming a kind of hood. I suspect this is causing the corner vignetting, so I might try to sand off parts of it at the corners to see if that helps.

_________________
Canon DSLRs: 7D, 5D2, 1D, 600D, 450D full spectrum, 300D IR mod
Lenses: EF 35/2, 50/1.8, 85/1.8, 135/2+SF, 28-80 V, 70-300L, 100-400L, TS-E 24/3.5L, MP-E 65, EF-S 15-85 IS
3rd party: Zeiss 2/50 makro, Samyang 8mm fisheye, Sigma 150 macro, 120-300 f/2.8 OS, Celestron 1325/13
Tinies: Sony HX9V.


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PostPosted: Sat May 22, 2010 9:40 am 
Sorry if this is an unrelated question, but how much of a pain, if at all, is manual focus on the EP-1 without a viewfinder? Will it let you "zoom in" to confirm focus as many DSLR's do?

Nice lens though, could make some nice portraits Im sure!


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PostPosted: Sat May 22, 2010 9:53 am 
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I find using the screen without magnification to be no worse than an optical viewfinder for MF, in other words, not good for shallow DoF. I often tend to end up in mm of DoF... In those applications there is nothing better than magnified live view. I've optimised my E-P1 for MF assist as far as can be.

One of the live view display modes is a zoom toggle. In that mode, pressing "ok" button toggles between full view and 7x or 10x magnification which can be selected by the roller. I turned off other info screens so that my only two live view modes are normal and zoom. Unfortunately in the zoom screen you can't change most settings.

Other info screens include live histogram, level (tilt) meter and assorted gridline overlays. I don't really use any of those normally.

_________________
Canon DSLRs: 7D, 5D2, 1D, 600D, 450D full spectrum, 300D IR mod
Lenses: EF 35/2, 50/1.8, 85/1.8, 135/2+SF, 28-80 V, 70-300L, 100-400L, TS-E 24/3.5L, MP-E 65, EF-S 15-85 IS
3rd party: Zeiss 2/50 makro, Samyang 8mm fisheye, Sigma 150 macro, 120-300 f/2.8 OS, Celestron 1325/13
Tinies: Sony HX9V.


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