DP1M versus SD1M with 20mm f1.8

Started Oct 28, 2012 | Discussions thread
Craig Philips
Regular MemberPosts: 220
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Re: DP1M versus SD1M with 20mm f1.8
In reply to rick decker, Oct 31, 2012

rick decker wrote:

Sharpness was -1.5 with both. I did several tests and then went back a day later and did the final. 20mm has slightly better edges at f11 but f8 is very close. It is not as consistent with AF as the DP1M. It is still a much better choice than the 10-20, 18-50, 17-50 zooms and if you (I) hadn't been spoiled by the DP1M, well, ignorance is bliss. This image was not a good one for upper or lower. And one was f5.6 and one f11 although the corners of the DP1M don't vary that much but I am not sure about DOF issues. Here are lower left (LL) and lower right (LR) crops. It is hard to draw any conclusions with this set.

http://www.lightreflection.com/misc/crop.jpg

Thanks for posting the lower corners Rick…

I agree there’s not a lot to chose between this second set—certainly the clear superiority of the DP2M lens your initial post demonstrates is not apparent here.

Both sets of lower corners seem somewhat out of focus and it may well be that depth of field is the main issue (with neither the slightly shorter focal length of one lens nor the much smaller f stop of the other being sufficient to overcome it).  And it may be that both lenses have a little softness at the corners.  As you say, it will take different images to verify just how well the two lenses (with the DP1M’s currently of most interest) perform at the corners and also whether curvature of field might be an issue in some circumstances.

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