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Old 16th June 2019
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Re: New MC 20 announced.

Originally Posted by Phill D View Post
Like you Ross I always leave my 1.4x tc on the 40-150. I didn't think it was much worse in IQ either although I don't think I've ever done a back to back direct comparison. Has anyone else done one? Maybe when I get the MC20 I'll do all three options. I'd certainly like to do a back to back with a Panasonic 100-400 if anyone is up for it and maybe a 300mmf4 too?
When I got the 300 a couple of years ago I did a brief, rough and ready comparison of it and the 40-150 with and without my MC-14. Hand held, and framing only approximately the same field of view in our back garden.

Scarcely scientific, therefore, but at 100% on screen I couldn’t see consistent resolution degradation on adding the converter to the 300, but I could to the zoom. There’s no way the effect even on the zoom was worryingly visible for real-life image uses, though, and since I don’t produce 20x30” prints I ignore it.

Of course there are various issues with a test like that - aerial perspective (ie much longer air path between target and sensor at 420(840)mm than 40(80)mm) being just one. There are also various potential effects on resolution, microcontrast, CA, distortion, flatness of field etc that are lumped together, and i took a pragmatic view on image stability: ie I was going to be handholding all 4 combinations in real life, so that was how I’d test them.

Is it better in real life to use the 300 alone and crop? Very hard to answer, and it probably depends hugely on exactly what you’re photographing, how fast it moves and how skilful/practiced you are at holding focusing points over the target. i wouldn’t give much credence to any results obtained with the rig on a tripod, or not tested by anyone who wasn’t very experienced with the gear.

I’d add that the effect of adding the Nikkor 1.4 converter to the 70-200 f2.8 VRII I used to have 8-9 years ago was most definitely visible at real-life image output sizes. Like the new Sony converters, the technology has improved a lot in recent years.

The great advantage of using converters these days I’d say is that you can take them off when light levels are low: apart from the magnification the major impact I see is on focusing speed and accuracy in dim light. Having an f2.8 150(300)mm option available is really useful for a lot of wildlife photography, for example.

I can’t find them via a quick web search, but one of the review sites has published MTF charts of the 300 +/- the converter that unsurprisingly do show measurable degradation, but (as with most of this stuff) worrying too much about it borders on measurbation...

Too much Oly gear.
Panasonic 12-32, 12-35, 15. Laowa 7.5.
Assorted legacy lenses, plus a Fuji X70 & a Sony A7S.
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Ross the fiddler (16th June 2019)