use of kenko mc7 macro tele 2x on pentax k-30

Started Feb 9, 2013 | Questions thread
audiobomber Veteran Member • Posts: 5,568
Re: use of kenko mc7 macro tele 2x on pentax k-30

HawaiiMike wrote:

I have the macro/tele with contacts for metering, but no autofocus. I have a couple of questions:

I'm looking at getting a DA 50mm f/1.8 as an inexpensive fast indoor lens. Can I couple this with the teleconvertor? Do I simply set camera body on manual focus and Av?

Yes, that would work, but note that a 2X TC delivers quite a large performance hit. You will notice the difference in image quality.

I read somewhere to use caution with coupling macro/tele to zoom lenses. Is this only a concern with very short focal lengths ? Is it ok to couple with a 50-200 lens? Same settings as above?

The concern is not with mounting a TC on a zoom. Plenty of good quality zooms work just fine with a TC. The concern is that a TC causes image quality to deteriorate, and consumer level zooms have none to spare. With most consumer teles, you will have better results by shooting without the TC and cropping to the same field of view.

A 2X TC leads to more severe degradation than a 1.4X. The DA 50mm may deliver acceptable results. I think you'll find that fringing, coma and loss of sharpness will discourage you from using the Kenko on the 50-200. Note that a 2X TC loses two stops of light, so your f4-5.6 apertures become f8-f11. And that's shooting wide open, that lens should be stopped down for better IQ. You will need a lot of light or a tripod for the shot.

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