650D (t4i) and Kenko teleplus pro 300 DGX 1.4 xT/C

Started Nov 20, 2012 | Discussions thread
WilbaW Forum Pro • Posts: 11,454
Re: 650D (t4i) and Kenko teleplus pro 300 DGX 1.4 xT/C

alan e jones wrote:

WilbaW wrote:

alan e jones wrote:

the KENKO wins !!

haeve alook at these shot and see and judge yourselves !

Mm, not in the upper left, which suggests there may be focus or DOF differences. A perpendicular target focussed using CD AF would be ideal.

the Kenko shot retains more defined detail...

Look at the dribble(?) at the base of the chrome handrail. See the spot a few mm to the left of the dribble, about 20mm down from the edge of the deck? In the crop of crop shot it's sharp and clear but almost disappears in the crop of Kenko shot. Elsewhere, like the "a" of "special", the kenko shot clearly looks better, so the differences aren't even across the frame. We'd need to control for that for a valid comparison.

also what you are forgetting is the pixel count for printing the Kenko verison has double the pixels ! (there is hardly any left on the 300 shot)

It's about 40% more linearly, which is what matters for resolution.

I saw some interesting things while looking at some fresh test shots. If I just look at the pixel level, I'd chose the TC shot every time, but at the image level, an equivalent crop of the non-TC shot always looks sharper, clearer, better contrast... right across the frame. That's with images equalised for white balance and brightness. It might be different if I gave them a full post-processing treatment, including resizing and sharpening. The TC also introduces noticeable barrel distortion.

So that adds a level to what I've always thought - use the TC if I really need as much focal length as I can get (and I can do without the centre PD AF point), but if I wouldn't be significantly cropping the TC shot I'm better off without the TC (both for IQ and AF). That's for electronic display. I don't know what would be better for large prints.

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