Rokinon decentered?

**SunValley** · 11-11-2017, 12:18 PM

Just bought this morning a Rokinon 135 F2 and did a few test shots with it. The following image is taken at F2 (1/4000 iso 80). Is it my imagination or is the bottom left sharper than bottom righ? Should I return it or is this within tolerance for Rokinon? This was hand held but at 1/4000 s I doubt a tripod would have made a difference. I relied completely on focus confirmation because it's just about impossible to do it manually.

Must say I'm very impressed with CA control, a couple of those edges are just screaming for some purple fringing... but they don't get any!

Bottom left at 100%:

Bottom right at 100%:

Adam · 11-11-2017, 12:24 PM - **1 Like**

Could be hot air distorting part of the bottom-right, as there appears to be some sort of electrical equipment on top of the orange building at the bottom.

I'd say further tests are warranted, but I think your lens is OK.

DeadJohn · 11-11-2017, 12:50 PM

Originally posted by Adam

Could be hot air distorting part of the bottom-right, as there appears to be some sort of electrical equipment on top of the orange building at the bottom.

I thought the same thing before reading Adam's comment. The lower right building looks wavy from uneven air temperatures.

**SunValley** · 11-11-2017, 01:06 PM

Originally posted by Adam

Could be hot air distorting part of the bottom-right

Originally posted by DeadJohn

The lower right building looks wavy from uneven air temperatures

Nice observation, thanks to you two. Keeping my fingers crossed for clear skies tomorrow night. Shooting the stars is pretty much the ultimate test for a lens.

11-11-2017, 12:18 PM	#1
SunValley Site Supporter Join Date: Jun 2013 Location: Montreal, Canada Photos: Gallery \| Albums Posts: 574	Rokinon decentered? Just bought this morning a Rokinon 135 F2 and did a few test shots with it. The following image is taken at F2 (1/4000 iso 80). Is it my imagination or is the bottom left sharper than bottom righ? Should I return it or is this within tolerance for Rokinon? This was hand held but at 1/4000 s I doubt a tripod would have made a difference. I relied completely on focus confirmation because it's just about impossible to do it manually. Must say I'm very impressed with CA control, a couple of those edges are just screaming for some purple fringing... but they don't get any! Bottom left at 100%: Bottom right at 100%:

11-11-2017, 12:24 PM - 1 Like	#2
Adam Administrator Site Webmaster Join Date: Sep 2006 Location: Arizona Photos: Gallery \| Albums Posts: 51,597	Could be hot air distorting part of the bottom-right, as there appears to be some sort of electrical equipment on top of the orange building at the bottom. I'd say further tests are warranted, but I think your lens is OK. Adam PentaxForums.com Webmaster (Site Usage Guide \| Site Help \| My Photography) PentaxForums.com server and development costs are user-supported. You can help cover these costs by donating or purchasing one of our Pentax eBooks. Or, buy your photo gear from our affiliates, Adorama, B&H Photo, KEH, or Topaz Labs, and get FREE Marketplace access - click here to see how! Trusted Pentax retailers:

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11-11-2017, 12:50 PM	#3
DeadJohn Pentaxian Join Date: Jan 2011 Location: New York Posts: 4,834	Originally posted by Adam Could be hot air distorting part of the bottom-right, as there appears to be some sort of electrical equipment on top of the orange building at the bottom. I thought the same thing before reading Adam's comment. The lower right building looks wavy from uneven air temperatures.

11-11-2017, 01:06 PM	#4
SunValley Site Supporter Join Date: Jun 2013 Location: Montreal, Canada Photos: Gallery \| Albums Posts: 574 Original Poster	Originally posted by Adam Could be hot air distorting part of the bottom-right Originally posted by DeadJohn The lower right building looks wavy from uneven air temperatures Nice observation, thanks to you two. Keeping my fingers crossed for clear skies tomorrow night. Shooting the stars is pretty much the ultimate test for a lens.