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# Thread: phase one + 28mm, distortion?

1. ## phase one + 28mm, distortion?

Hi, I never owned a medium body and looking into moving from FF/35mm to medium format.
The 28mm lens on Phase one body = 17mm on 35mm body.
My question:
Does the 28mm has a distortion of 17mm(35mm body) or distortion of 28mm(35mm body)?

Regards,
Evgueni

2. ## Re: phase one + 28mm, distortion?

sample (P1 28mm)

3. ## Re: phase one + 28mm, distortion?

Thank you, Shlomi,
It feels like 28mm but hard to say because of tilt.
Thanks, again

4. ## Re: phase one + 28mm, distortion?

There is some inevitable distortion.
You can see the distortion lines clearly in the structure lines in the photo - shooting against the lines will make the image look very distorted.

Sharpness however is much better than any 35mm 17mm I know.

5. ## Re: phase one + 28mm, distortion?

Originally Posted by strok
Does the 28mm has a distortion of 17mm(35mm body) or distortion of 28mm(35mm body)?
If you mean the geometric distortion resulting from the angle of view, then it's going to be the same as a 17mm on 35mm.

6. ## Re: phase one + 28mm, distortion?

Originally Posted by Graham Mitchell
If you mean the geometric distortion resulting from the angle of view, then it's going to be the same as a 17mm on 35mm.
Thank you.

7. ## Re: phase one + 28mm, distortion?

Be careful not to interchange "distortion" two casual usages:
- the relative size of objects near and far away from the lens
- parallel lines being bent outwards

The former is a combination of focal length and sensor size and the later is an optical-design issue.

Concerning parallel lines being bent outwards the 28mm D, when using Capture One's built in lens corrections has effectively zero distortion.

Concerning the feeling that foreground objects are disproportionally larger than background objects the distortion is the same as the 17mm when using a full frame dSLR.

There are other subtle differences though regarding the feel of certain lenses on different formats. The draw of out of focus areas, the steepness of sharpness fall off, micro-contrast, edge detail, and color can all have significant impacts on how a wide angle feels. Handling differences, aspect ratio, and ergonomics also often change the way you handle composition, framing, and lens choice thus further creating a difference (neither universally better or worse) in the effect your asking about between different sensor sizes.

In particular composing for a 4x3 frame rather than a 3x2 frame can significantly effect your lens choice for some kinds of subjects (notably small rooms and tall buildings).

Best way forward is always your own hands-on testing with subject matter and shooting styles typical to your needs/desires.

Doug Peterson (e-mail Me)
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8. ## Re: phase one + 28mm, distortion?

Some reading in relation to this topic:

http://en.wikipedia.org/wiki/Angle_o...f-view_formula

http://en.wikipedia.org/wiki/Perspec...n_(photography)

Read the above articles, and the question is thoroughly answered. Perspective distortion, particularly "extension distortion," is a prominent part of wide-angle photography, no matter the format.

9. ## Re: phase one + 28mm, distortion?

Have there been any formal tests of the lens? Any barrel, pincushion, mustache distortion? ...rather useful info if you plan spending \$5000 on a lens. How does compare to the other ultra-wide solutions for medium-format?

We need a crazy person to do some serious measurebationing for us!

10. ## Re: phase one + 28mm, distortion?

Some pin cushion but easy to correct with lens correction in C1. Have done a lot of interiors with it to perfection. Actually a really great lens. Wish I still had mine but needed something else.

11. ## Re: phase one + 28mm, distortion?

It's a great lens - especially when used with C1 Pro. I'm addicted to mine!
Bill

12. ## Re: phase one + 28mm, distortion?

I agree w/Bill - great lens; I got some great images using it and would still have it if I hadn't gone the tech camera route.

13. ## Re: phase one + 28mm, distortion?

These are all from the 28mm with a P25+ processed in C1.

14. ## Re: phase one + 28mm, distortion?

BTW there is no corrections going on here except for the slight pincushion. All my lines are straight.

15. ## Re: phase one + 28mm, distortion?

Lines look straight to me. It will be interesting to compare to the Pentax 25mm lens when it comes out.

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