De-Centered Lens

**jrpower10** · 02-10-2015, 06:23 PM

I just received a 67 55-100 lens. I also just bought a Zeiss test chart to double-check all my lenses. When I set up the 55-100, focus on the centre circle, then start to throw the lens out of focus, the centre circle begins to separate and turns into 4 distinct circles at the extremes of the focus throw. I think I know the answer but want to confirm that this is an indicator of a de-centered lens. If so, does anyone have an idea of what it would cost to correct? My first instinct is to return it, but I got a good deal on it and I might be willing to negotiate with the seller if it can be fixed.
Thanks

osv · 02-10-2015, 07:47 PM

maybe post some pics of the issue.

i usually think of decentering as being softer on one side than the other.

**UncleVanya** · 02-10-2015, 09:01 PM

LensRentals.com - Testing for a Decentered Lens: an Old Technique Gets a Makeover

Maybe try the methods on this site before you go any further.

**jrpower10** · 02-10-2015, 09:19 PM - **1 Like**

OK, don't I feel like a numnuts. The reason the image is splitting when out of focus is because I have it dead center of the focusing screen (it's doing what it's supposed to do). When I move the center of the test chart outside the center of the focusing screen and check, everything is fine. Guess I can keep the lens after all. Gotta get used to focusing screens again.

---------- Post added 02-11-15 at 02:22 PM ----------

Originally posted by UncleVanya

LensRentals.com - Testing for a Decentered Lens: an Old Technique Gets a Makeover

Maybe try the methods on this site before you go any further.

Yeah, reading that is what made me buy the Siemens chart I'm using. Just wasn't thinking the test thru. Turns out the lens looks fine, but thanks.

02-10-2015, 06:23 PM	#1
jrpower10 Site Supporter Join Date: Sep 2011 Location: Richland, Washington, USA Posts: 935	De-Centered Lens I just received a 67 55-100 lens. I also just bought a Zeiss test chart to double-check all my lenses. When I set up the 55-100, focus on the centre circle, then start to throw the lens out of focus, the centre circle begins to separate and turns into 4 distinct circles at the extremes of the focus throw. I think I know the answer but want to confirm that this is an indicator of a de-centered lens. If so, does anyone have an idea of what it would cost to correct? My first instinct is to return it, but I got a good deal on it and I might be willing to negotiate with the seller if it can be fixed. Thanks

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02-10-2015, 07:47 PM	#2
osv Veteran Member Join Date: Mar 2007 Location: So Cal Photos: Gallery Posts: 2,080	maybe post some pics of the issue. i usually think of decentering as being softer on one side than the other.

02-10-2015, 09:01 PM	#3
UncleVanya Loyal Site Supporter Join Date: Jul 2014 Photos: Gallery \| Albums Posts: 28,464	LensRentals.com - Testing for a Decentered Lens: an Old Technique Gets a Makeover Maybe try the methods on this site before you go any further.

02-10-2015, 09:19 PM - 1 Like	#4
jrpower10 Site Supporter Join Date: Sep 2011 Location: Richland, Washington, USA Posts: 935 Original Poster	OK, don't I feel like a numnuts. The reason the image is splitting when out of focus is because I have it dead center of the focusing screen (it's doing what it's supposed to do). When I move the center of the test chart outside the center of the focusing screen and check, everything is fine. Guess I can keep the lens after all. Gotta get used to focusing screens again. ---------- Post added 02-11-15 at 02:22 PM ---------- Originally posted by UncleVanya LensRentals.com - Testing for a Decentered Lens: an Old Technique Gets a Makeover Maybe try the methods on this site before you go any further. Yeah, reading that is what made me buy the Siemens chart I'm using. Just wasn't thinking the test thru. Turns out the lens looks fine, but thanks.