October 25 2009 - Photo Jottings

October 25 2009


The first installment of my new random lens comparisons is below.  I like doing this just for kicks, as it doesn’t take up too much time.

 I’ve been playing with the Tamron 17-50mm F/2.8 XR Di II for the last week or two, (thanks to Richard in CA), and noticed it was pretty sharp across the entire frame when stopped down at 50mm, so I decided to do some quick comparisons with the Sony 50mm F/1.4 lens using apertures of F/2.8-8.0.
Now then, when you look at the comparison crops below, (now located here at the bottom of the page), you may just notice the Sony is sharper than the Tamron, so big deal.  If this is your reaction,
then you’re missing something important.  If you really look at the F/8 crops, you’ll see they’re almost the same in the centers, with the Sony just a bit sharper when comparing the corners.  If you’re still saying to yourself “big deal,” then consider this; the Sony is a full frame compatible lens, (meant for 36x24mm sensor or film) consequently, when used on an half size sensor APS-C camera, you’re only using the middle portion of the lens, which is the best part. The Sony is also a fast prime lens, meaning it is designed around that specific focal length only, and to give fairly good results at very large apertures, like F/1.4, and really good results stopped down to F/5.6-8.  There are few sacrifices involved since there is no zoom capability.
The Tamron lens is designed for APS-C cameras, meaning the entire imaging circle is used, which includes normal contrast problems around the image periphery.  The designers must also contend with making a zoom lens perform good at all focal lengths, and make appropriate compromises. The crops below are part of an image that would print out about 45″ (1.14m) wide as you see it on your computer screen, and the actual crops come from about 200-300 pixels from the corner!  I’d say off the cuff the Tamron would make a good landscape lens at that focal length, but I think I’ll hold my thoughts on everything else until I’m completely done with the review.
The Tamron 17-50mm F/2.8 XR Di II review will probably be ready sometime around the first week of November.
go to the lens comparison page
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