anybody using the kenko 1.4x with the 100 f2? i have been mulling over the purchase of a 70-200 f4 IS or a 2.8 non IS for quite some time now until i had an epiphany today. i could pick up the f4 IS and extender for the price of the 2.8. then i could have a 140 2.8 when i needed more speed. i was wondering how image quality would hold up with the extender on the 100 f/2...comparatively how it would stack up against a 70-200 2.8. a search turned up no results. hoping you guys could help.
Hi, I had the Kenko DG 300 pro 1,4x and used it with my EF 1.8 85 mm with rather poor results. The resulting "2.5 120 mm lens" was only reasonably sharp when stopped down by at least two stops. Otherwise, images were soft and showed purple fringing. The bokeh also suffer badly.
This is a typical shot lens at f 2.0 resized an slightly sharpened. Crops below.
Yeah, you'd be better off cropping and having f2 available....than trying to use a TC with that lens.
Adding 5 elements AND losing a stop of light to gain 40mm seems absurd.
I've used my Kenko 1.4X with my 100 f/2 and I've got much better results than those above with the 85 1.8.
I found center performance decent wide open (f/2.8) and quite good at f/4. AF seems the same with and without the 1.4X. You do see increased CA though.
Indeed, it seems the EF 2.0 100 mm takes the TC much better. Since autumn, I have the EF 135 L and this is really very good with my Canon EF1.4x even wide open. Obviously, the EF 2.0 100 mm is somewhere in the middle between these two.
I don't have the Kenko but in using the Canon TC 1.4 with the 24II, 90 TS-E's and 70-200/4 - the sharpness, contrast and overall IQ hold up pretty well - it's the additional CA especially in (outdoor) bright conditions that is the degrading factor.
If you're looking for IQ at 140mm go with the 135 L or the 70-200 L.
mMontag wrote:
the sharpness, contrast and overall IQ hold up pretty well - it's the additional CA especially in (outdoor) bright conditions that is the degrading factor....
True, but you can still get very decent center IQ with a 1.4X on the 100 f/2. You can see some CA in this shot, but its not that bad....This is f/3.2....
I did it once and never tried again. Under perfect lighting conditions I had to stop down to f4 resulting in f5.6.
It was quite a disappointment after having used that combination extensively with Minolta 100mm f2.
