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-   -   12mm is 12mm is 12mm.....or is it? (https://forums.steves-digicams.com/olympus-micro-four-thirds-103/12mm-12mm-12mm-209806/)

Greg Chappell Jan 23, 2014 1:00 AM

12mm is 12mm is 12mm.....or is it?
 
I noticed a comment over in the Micro forum at DPReview about the 12-60mm four-thirds Zuiko being noticeably wider at 12mm than the new 12-40mm f2.8 M. Zuiko.

I no longer have the 12-60mm Zuiko that was my standard zoom when I was shooting with the Olympus DSLR's, but I do have the 12mm f2 M. Zuiko, 12-40mm f2.8 M. Zuiko and Panasonic 12-35mm f2.8 to compare, just to see if there was any noticeable difference and was surprised to see the results.

First, no comments about the bland, need to be cleaned apartment kitchen scene, but there were some good items on each side of the image to better judge the difference between the three files.

Tripod-mounted E-M1 with stabilization turned off. In-camera superfine JPEG with all the other default settings so all of the in-camera corrections are happening with all three images.

First, the "widest" of the three, the 12mm f2..

http://gmchappell.smugmug.com/photos...VjC5gGX-X2.jpg

Then, second and the widest of the two zooms, the 12-35mm f2.8 Panasonic..

http://gmchappell.smugmug.com/photos...Fh5NqNb-X2.jpg

Last, and the "least-wide" of the three at 12mm is the 12-40mm f2.8 M. Zuiko..

http://gmchappell.smugmug.com/photos...BQZq7Pk-X2.jpg

Didn't bother taking any other comparison shots like I could have with a lens such as the 9-18 zoomed to 12mm, but there you go. If my three units are an accurate indication of the field of view each model captures, if you want the widest view in a standard high-end zoom, you'll want the Panasonic. If the widest view is the most important regardless of lens type, the 12mm f2 prime is what you want.

ramcewan Jan 23, 2014 6:42 AM

interesting, I found similar things were true when comparing the Lumix 14mm f2.5 to the Zuiko 14-54mm MK II at 14mm. Some of it could be due to the distance between the front element to the subject?

Greg Chappell Jan 23, 2014 7:59 AM

Who knows for sure. I know focal lengths can be different from maker to maker and the digital world has now added auto corrections to the mix so there are a lot of variables and probably few hard and fast rules when it comes to lens designs and how close being "in the neighborhood" is to being able to call a lens a certain focal length.

SammyKhalifa Jan 23, 2014 8:58 AM

Could it be something as simple as number rounding? Maybe one is 11.5mm and another 12.3 or something.

EDIT--Though yeah, like you said the distortion correction could be a lot of it. And that would make sense as I'd assume a zoom would have more distortion (and therefore more removed) than a lens dedicated to 12mm.

chiPersei Jan 23, 2014 11:22 PM

Very interesting indeed. I would have thought 12 was 12 was 12. Perhaps the industry needs to move to Field of View like binoculars. You've likely seen it stamped on a binocular in one of two formats; FOV 347 feet @ 1000 yds or sometimes it's written FOV 4.5. At least that way we can do a fair comparison. BTW - It's usually the more expensive bino that has the wider FOV. A 7x35 with an FOV of 6.5 is more expensive than the 7x35 with a 5.0 FOV. Usually.

Biro Jan 25, 2014 9:07 AM

How about the built-in distortion correction of the camera? Perhaps the native micro four-thirds lenses need a bit more of this than the original four-thirds glass. And maybe some MFT lenses need more correction than others. Just a theory. But you could probably investigate this by shooting raw and not applying any correction in post. I'm assuming that these images were taken as jpg's to begin with.

Greg Chappell Jan 25, 2014 9:33 AM

I've already done that with raw files captured with the 12mm f2 using raw therapee. Comparing uncorrected files to the same image shot using the four-thirds 9-18 the 12mm f2 images come out between 10-11mm so, at least on the case of that one lens, it captures well wide of 12mm and the corrections bring the image back to 12mn.

Biro Jan 25, 2014 12:11 PM

I guess that mZuiko 12mm f/2.0 is a better deal than it first appears.

Steven R Jan 25, 2014 7:54 PM

Quote:

Originally Posted by SammyKhalifa (Post 1366628)
Could it be something as simple as number rounding? Maybe one is 11.5mm and another 12.3 or something.

EDIT--Though yeah, like you said the distortion correction could be a lot of it. And that would make sense as I'd assume a zoom would have more distortion (and therefore more removed) than a lens dedicated to 12mm.

Yes, I think that you are correct. In the typical major lens tests in Pop Photography, when you read the technical specs, the actual measured is always a little less or more than the listed mm. So it is common for a 12mm lens to be something like 11.9 or 12.1, etc.

ramcewan Jan 26, 2014 11:14 AM

for comparison sake;

here is the Zuiko 14-54mm MK II @14mm and f2.8

http://farm4.staticflickr.com/3808/9...5b572556_b.jpg
P8041646 by ramcewan, on Flickr

and the Lumix 14mm f2.5 @ f2.5
http://farm8.staticflickr.com/7312/9...e9557b6e_b.jpg
P8041648 by ramcewan, on Flickr

I think these are a lot closer, well except for the fact you can see more of the back of the laptop on the Lumix which might be a result of the difference in where the front element is, but otherwise very close.


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