optyczne reviews the Olympus 25/1.8

dhazeghi

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Full lab test of the 25/1.8 is now up at optyczne. Text is in Polish, but the charts (sharpness, CA et al.) are pretty self explanatory. Lenstip will probably have an English translation in a few days.

EDIT: English translation is now up at lenstip.

Sharpness look very good at wider apertures:
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The Panasonic 25/1.4 for comparison:
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If only the Olympus were 2/3 stop faster...
 

napilopez

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Nice to see that supports my own experience; it's sharper wide open, a little less sharp in the center when both are at F1.8/F2, but still sharper in the corners. Again, the drop off of sharpness across the frame for the Panasonic is much more noticeable than any loss in center sharpness in the Olympus. But of course, the Olympus doesn't do F1.4, and has different rendering qualities. That's some pretty steep drop off at smaller apertures though. F22 looks barely useable.
 

Jay86

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Looking at these charts it makes me wonder, where's about does diffraction kick in on most M43 lenses? F/8?
 

dhazeghi

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That's some pretty steep drop off at smaller apertures though. F22 looks barely useable.
I guess in theory it could be valuable for certain macro shots, if focus stacking were not an option. Personally, I've never shot past f/16, and that only rarely. Just remember that f/22 on this sensor is like f/8 on a 1/1.7" compact...

Looking at these charts it makes me wonder, where's about does diffraction kick in on most M43 lenses? F/8?
Diffraction is a function of the sensor, not the lens, and yes, it is fully recorded around f/7.1 on a 16MP m4/3-sized sensor. That said, there are some lenses where the gains from stopping down will still outweigh the losses to diffraction (like the 14-150 at the long end). As a rule of thumb, most m4/3 lenses seem to achieve optimal sharpness around 2 stops down from wide open, though it certainly varies.
 

FlyPenFly

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Interesting to note that at peak sharpness, the PL25 is noticeably sharper across the frame. It is of ourse noticeably much larger as well with hood. You can see a 9-10 lpmm in mtf50 easily.
 

BigTam

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Interesting to note that at peak sharpness, the PL25 is noticeably sharper across the frame. It is of ourse noticeably much larger as well with hood. You can see a 9-10 lpmm in mtf50 easily.
Am I missing something? I don't see a 9-10 lpmm difference anywhere on the graphs. At peak sharpness, maybe 1 or 2, definitely not visible.

Edit: sorry, edge sharpness at f4 better on the Panasonic, sorry. Probably visible in landscapes.
 

dhazeghi

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One interesting comparison is the sharpness of the 25/1.8 and the 17/1.8.

17/1.8:
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25/1.8
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jnewell

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Full lab test of the 25/1.8 is now up at optyczne. Text is in Polish, but the charts (sharpness, CA et al.) are pretty self explanatory. Lenstip will probably have an English translation in a few days.

Sharpness look very good at wider apertures:
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The Panasonic 25/1.4 for comparison:
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If only the Olympus were 2/3 stop faster...
Interesting. That seems rather different than the graphic at SLRGear.com would seem to indicate. (Not arguing, just thinking out loud.)
 

orfeo

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It's look like a logical F1.8 sharpness lens curve. Noting that the summilux being faster and sharper in the center is quite an achievement whilst being poorer on the edge is physics laws.
 

dhazeghi

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Interesting. That seems rather different than the graphic at SLRGear.com would seem to indicate. (Not arguing, just thinking out loud.)
I'm rather suspicious of SLRGear. In addition to refusing to standardize their test camera (for a given mount), they manage to get substantially different results with lens designs that are nearly or exactly identical. They're also not measuring MTFs, so it's possible that whatever they are recording follows different patterns.

It's look like a logical F1.8 sharpness lens curve. Noting that the summilux being faster and sharper in the center is quite an achievement whilst being poorer on the edge is physics laws.
True - it's easier to make an f/1.8 design that sharpens up than an f/1.4 one that does. All things considered, I'd probably recommend the Olympus to most people (especially with the recent price increases on the Panasonic), but for my purposes, f/1.4 is still quite valuable, at least until our sensors get another stop better at high ISO.
 

jnewell

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Actually, lack of corner sharpness is only a definite disadvantage if you are photographing brick walls or other planar surfaces. :smile: It is sometimes an advantage in real life photography (although that is random chance rather than by design). :wink:
 

FlyPenFly

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Actually, lack of corner sharpness is only a definite disadvantage if you are photographing brick walls or other planar surfaces. :smile: It is sometimes an advantage in real life photography (although that is random chance rather than by design). :wink:
Wishful thinking.
 

dhazeghi

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lenstip.com has the English version now.
Yes, it's there now.

Looks like they only found two items to complain about in their conclusion: noticeable vignetting and astigmatism up to f/4.0. Contrast that with the very lengthy list of things that are done right - they clearly think it's a winner.
 

FlyPenFly

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Lenstip measurements also raise my eyebrows sometimes. For example the 12-40mm review, the lens is sharpest at 12mm F2.8 then degrades even stepping down. Certainly a very unusual performance
 

jnewell

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Wishful thinking.
Not at all. Although it's random and unpredictable, you can have a photo of a group of people with people at the edges closer than the subject who's been focused on. In terms of predictability, it's a whole lot more likely that I'll have "curvature of subject" than that I'll have a planar-flat subject.
 

FlyPenFly

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Not at all. Although it's random and unpredictable, you can have a photo of a group of people with people at the edges closer than the subject who's been focused on. In terms of predictability, it's a whole lot more likely that I'll have "curvature of subject" than that I'll have a planar-flat subject.
I've sold a few landscape photos where edge to edge sharpness is part of the aesthetic of the image.

If you only take pictures of individual objects, corner sharpness may not be critical but for a lot of uses it is.
 

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