The Olympus 12mm field curvature vs. soft corners.

I hear time and time again negative comments about this lens. If I am to look at the front element of this lens I am confronted with one steady answer. The lens IS sharp across the frame from wide open to about F/5.6. It does get a little bit better by F/2.8 and then falls off after F/5.6 however even using it wide open leads to good results out of the camera with no additional sharpening.

The Olympus 12mm introduced a lot of things that the Olympus Pro lenses have taken on board. It has a manual clutch and a focus scale, it operates either in a simulated focus by stop to the nearest point, or in a simulated focus by graduation (small focus integers and a free spinning focus ring so that you can do follow focus for professional video shots) It is a true silent lens, no focus motor noise, and its designed to operate on video cameras such as the GH4 or E-M5II. While the zone focusing isn't completely accurate because of the hard stops it is still usable and you can get some good results with zone focusing.

The one thing it doesn't have which would suit it better for video is what the Voightlander manual focus prime has and that is an aperture ring. Trying to mash buttons, or knobs as your filming video leads to camera shake and ruined footage, perhaps the biggest fatal flaw of the Olympus 12mm for videography. A clickless aperture ring is really necessary for shooting film, unfortunately the 12/2 doesn't have one.

The drawback for photographers is the that, it focuses in stops, so you can only very roughly use the distance scale for zone focusing. A bit of a fatal flaw but not really, if you're shooting in the street you should be able to find an aperture that suits your needs for zone/scale focusing.

The 12/2 has a rather exotic optical design with 11 elements in 8 groups; one of these is aspherical, one is made of ED glass, and another two of exotic Super HR and DSA glasses. It’s a non-symmetric, telecentric design with an optical formula that honestly isn't regularly familiar. The closest similar lens design I can think of is the Zeiss Distagon. This is insofar as the Distagon use several extremely dome convex front elements and a rear telephoto group. The lens also employs Olympus’ ZERO coating to minimize flare and maximize contrast and transmission.

In the field the lens very rarely flares with some stray light creating a minor purple/blue lens flare when pointed directly into the sun. Due to the bulbous front element it suffers from some MTF drop off in the corner, but it handles this both better than the 9-18 and 7-14 from Olympus. People who don't understand this will seek to blame the lens for poor corner MTF values, they are not so much poor but the nature of the lens.

As a result the lens also has some barrel distortion, but due to the uniform nature in the curvature of the glass it is easily corrected, not so much so with the Olympus 7-14 and Olympus 9-18. Overall this is one of my favorite lenses to shoot with. It is often misunderstood because of the lens convex, but it is a very sharp lens suitable for all types of photography. It shares much with great lenses like the Zeiss Distagon, and renders very pleasantly. If anything its unconventional design and convex lenses often lead to people inaccurately claiming the lens is soft in the corners. This is not nearly the case as with the lens convex in the Olympus 9-18 and in the newly released and much more expensive Olympus 7-14.

Thank you for the review, this lens is on my shopping list but I need to save a bit as it's not very affordable, even though I guess you have to pay for quality...
--
Marco
https://www.flickr.com/marcozima
https://500px.com/marcozima

Marco Zima wrote:

Thank you for the review, this lens is on my shopping list but I need to save a bit as it's not very affordable, even though I guess you have to pay for quality...
--
Marco
https://www.flickr.com/marcozima
https://500px.com/marcozima

You're welcome Marco.

Olaf Ulrich wrote:

Nice review ... but what is all this "convex lens" babble about? You're not trying to suggest that the curvature of the field follows, or is caused by, the curvature of the front element's glass, are you?

I wouldn't be the first person to do so... This lens has substantially unusual curved front elements which cause focus issue at the edge of the lens. It's noted if you look up the lens on DXO. Ming Thein explains it also in his blog.

It's not "babble." Take a look at the curvature of the elements. There is really nothing much like this lens in terms of a prime outside of much more expensive lenses such as the Zeiss Distagon which also has a series of curved elements. You can see what Olympus's inspiration was.

Monkey see monkey do, its almost ridiculous how much this lens reminds me of a Contax G 24mm. Remarkably the Contax G 25mm Zeiss Distagon still sells for a mint and is rated as one of the most solid performers for a legacy lens.

Hithertoo wrote:

Olaf Ulrich wrote:

Nice review ... but what is all this "convex lens" babble about? You're not trying to suggest that the curvature of the field follows, or is caused by, the curvature of the front element's glass, are you?

I wouldn't be the first person to do so... This lens has substantially unusual curved front elements which cause focus issue at the edge of the lens. It's noted if you look up the lens on DXO. Ming Thein explains it also in his blog.

It is perfectly normal for any WA (including zooms extending to the WA range) with a retrofocus design (which has long been the dominant design) to have pretty stronly curved convex elements up front. There is nothing unusual about this at all.

It's not "babble." Take a look at the curvature of the elements. There is really nothing much like this lens in terms of a prime outside of much more expensive lenses such as the Zeiss Distagon which also has a series of curved elements. You can see what Olympus's inspiration was.

Have a look at for example the 7-14/4 or the 7-14/2.8 PRO for some even more drastic examples of curved and convex front elements.

That wasn't really my point but OK. What I was talking about is how this effects focus, particularly on the Olympus 9-18 but also the 7-14 now in the mean time. Most recently a number of people here have been having a discussion about how this affects focusing on these lenses, I was pointing out that it is the same theory with this lens.

Anders W wrote:

Hithertoo wrote:

Olaf Ulrich wrote:

Nice review ... but what is all this "convex lens" babble about? You're not trying to suggest that the curvature of the field follows, or is caused by, the curvature of the front element's glass, are you?

I wouldn't be the first person to do so... This lens has substantially unusual curved front elements which cause focus issue at the edge of the lens. It's noted if you look up the lens on DXO. Ming Thein explains it also in his blog.

It is perfectly normal for any WA (including zooms extending to the WA range) with a retrofocus design (which has long been the dominant design) to have pretty stronly curved convex elements up front. There is nothing unusual about this at all.

It's not "babble." Take a look at the curvature of the elements. There is really nothing much like this lens in terms of a prime outside of much more expensive lenses such as the Zeiss Distagon which also has a series of curved elements. You can see what Olympus's inspiration was.

Have a look at for example the 7-14/4 or the 7-14/2.8 PRO for some even more drastic examples of curved and convex front elements.

I should add here that the front elements of the lenses mentioned, while convex on the front surface, are nevertheless concave (negative rather than positive) as far as refraction is concerned.

Hithertoo wrote:

That wasn't really my point but OK. What I was talking about is how this effects focus, particularly on the Olympus 9-18 but also the 7-14 now in the mean time. Most recently a number of people here have been having a discussion about how this affects focusing on these lenses, I was pointing out that it is the same theory with this lens.

Yes, but I don't understand what you mean by that either. What's special about the focus of the 12/2 according to you? And in what way do you think that has anything to do specifically with the convex outer surface of the front element(s)?

Anders W wrote:

Hithertoo wrote:

That wasn't really my point but OK. What I was talking about is how this effects focus, particularly on the Olympus 9-18 but also the 7-14 now in the mean time. Most recently a number of people here have been having a discussion about how this affects focusing on these lenses, I was pointing out that it is the same theory with this lens.

Yes, but I don't understand what you mean by that either. What's special about the focus of the 12/2 according to you? And in what way do you think that has anything to do specifically with the convex outer surface of the front element(s)?

As I said above it is the field curvature of the lens that determines the slight MTF drop off in the corners with this lens and lenses like it. It causes the image to be very sharp in the centre with sharpness drop off closer to the edges. There isn't a flat image plane as such as a result the sensor is sampling a part of the image that is created in front of the lens curvature and getting a sharp result but in the mean time this is causing a loss of MTF in the corners which aren't focused at the same point.

Hithertoo wrote:

Anders W wrote:

Hithertoo wrote:

That wasn't really my point but OK. What I was talking about is how this effects focus, particularly on the Olympus 9-18 but also the 7-14 now in the mean time. Most recently a number of people here have been having a discussion about how this affects focusing on these lenses, I was pointing out that it is the same theory with this lens.

Yes, but I don't understand what you mean by that either. What's special about the focus of the 12/2 according to you? And in what way do you think that has anything to do specifically with the convex outer surface of the front element(s)?

As I said above it is the field curvature of the lens that determines the slight MTF drop off in the corners with this lens and lenses like it. It causes the image to be very sharp in the centre with sharpness drop off closer to the edges. There isn't a flat image plain as such.

Based on my own rather extensive experience with this lens (I have tried three copies), I am inclined to agree that it has a slight (but only slight) degree of (Petzval-type) field curvature. However, as Olaf Ulrich already pointed out, that has nothing to do with the pronounced curvature of the front element(s). How much field curvature a lens has depends on the optical formula as a whole, not the curvature of specific elements. For example, the 7-14/4 (which is another lens I am personally familiar with) has front elements that are even more strongly curved than those of the 12/2, yet shows no field curvature.

But it is, or at least it is a series of elements in this particular design including the front element more specifically that causes the MTF drop off. The original point is now lost that this slight aberration is an issue where people say this lens is "rubbish" while at the same time they are willing to put up with worse corner sharpness results from the Olympus 9-18 or 7-14 Pro lens.

I find this funny is all.

You seriously need to calm down sometimes Anders, your pedantry ruins good discussions. This isn't the first time I've seen you enter into arguments with multiple people on this forum just to be a pedant.

I don't really care about what shape the front element has, all I care about is the rearmost element - the sensor and what it creates. I've used this lens a bit for a couple weeks, in Times Square, Coney Island, in woodsy areas while hunting for my lost cat, and my brother-in-law's back yard.

It does great. I did buy a hood at B&H while in NYC (as I was obviously there). Only once, with the hood off, could I coerce some chromatic abberation from a low bright sun peeking through some trees. The flare was non-existent.

This is a damn good lens and I'll post some samples when I get home.

I won this new on eBay, with my lone opening bid of $400, so I can't say it was too expensive. I find it sharp from center to edge. Curiously, the edges were only sharp when they were in focus, duuh. Sure, it distorted in Times Square when pointed up but that's what I expected.

I did read a few very positive reviews on this lens, and only a few negative ones where I didn't think the reviewer(s) knew how to test wide angle lenses: focusing on the center and expecting edges to be in focus (despite the greater distance), angling it up and expecting undistorted results, etc.

This thing has great colors and is sharp. Just shot 150 keepers of 170 pix with it at my sister's birthday party Saturday. Cropped, a little white balance, a few vibrance and tonal adjustments, and I had a slideshow to surprise her with Sunday ready in a couple hours.

What serious criticism have you seen?

Bassam Guy wrote:

I don't really care about what shape the front element has, all I care about is the rearmost element - the sensor and what it creates. I've used this lens a bit for a couple weeks, in Times Square, Coney Island, in woodsy areas while hunting for my lost cat, and my brother-in-law's back yard.

It does great. I did buy a hood at B&H while in NYC (as I was obviously there). Only once, with the hood off, could I coerce some chromatic abberation from a low bright sun peeking through some trees. The flare was non-existent.

This is a damn good lens and I'll post some samples when I get home.

I won this new on eBay, with my lone opening bid of $400, so I can't say it was too expensive. I find it sharp from center to edge. Curiously, the edges were only sharp when they were in focus, duuh. Sure, it distorted in Times Square when pointed up but that's what I expected.

I did read a few very positive reviews on this lens, and only a few negative ones where I didn't think the reviewer(s) knew how to test wide angle lenses: focusing on the center and expecting edges to be in focus (despite the greater distance), angling it up and expecting undistorted results, etc.

This thing has great colors and is sharp. Just shot 150 keepers of 170 pix with it at my sister's birthday party Saturday. Cropped, a little white balance, a few vibrance and tonal adjustments, and I had a slideshow to surprise her with Sunday ready in a couple hours.

What serious criticism have you seen?

I've been around a while to see the comparisons, inevitably to the Olympus 12-40 and Panasonic 7-14 which do not have such aberration at 12mm, but neither lens option offers a sharp enough frame not to care at 12mm. At print size even as large as 30" prints which I've tested you can't notice the MTF drop off. I suppose you might be able to if you were sticking your nose up against it with a loupe, but who even really is that much of a pedant?

The other complainants seem to raise the issue of price. I raised the issue of this aberration on the basis that the now highly expensive Olympus 7-14 pro lens has a worse aberration to the corner of the frame so it can't really be said that this is a bad lens in that regard based on price. In the context I think some people just want to complain.

If you wait around you can find this lens for around $500, I did, so I don't think it is priced outside affordability. There is some degree of sample variability with this lens, but as I keep saying even when buying on ebay there is the toss it back option of INAD (item not as described) so you can't really lose.

It's a damned good lens, the distortion that it does have is easily correctable as there is a slight barrel distortion with no pillow top. DXO has an auto correcting profile for this lens also to save the hassle.

It's fast enough to shoot into the twilight zone or at night with good lighting and maintain solid shutter speeds even at ISO100 and sharp past good MTF results all the way from F/2 to around F/5.6. I have no complaints what so ever with this lens.

Some people will walk past it, it's their own loss.

Wonderful Review and I agree with your assessment on the quality of the 12mm f/2.0 wholeheartedly . Through years of film shooting, my favorite lens has always been 35mm, 17mm for us and the widest lens I ever owned was a 28mm, 14mm for us. When I went to buy my E-M10, I didn't want a kit with the zoom and asked for a 17mm f/1.8. They were out at my dealer so I bought the 12mm f/2.0 and it has become my favorite lens ever since.

When I was still doing a lot of street shooting, which I don't do all that often any more, I would use zone focus with the 12mm all the time. The distance scale has clear mark at 3-meters. I like to use the 3m mark at f4 or f5.6 which puts almost everything in focus from 3-meters out to infinity.

Here are the promised pictures. Playing with a new lens and learning to tame the beast!

Nothing serious so please, waste no time on critiques...

Cat Hunting, decent vertically and no sun induced CA

Sharp edges, nice colors, little CA on the "C" in Coney

OK, forgot I used it in the Bronx Zoo. My son with face hidden. Super colors, right arm stretched - is that a surprise?

Times Sq. Poor framing, held camera overhead. OMG, the buildings distort!!!

Left side only, cropped to protect innocent children. Super chromatic aberration. Sun is just to the left.