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Pentax lenses on Sony Full Frame

Malcom Knight , Oct 25, 2013; 09:06 p.m.

I was reading an article (http://briansmith.com/sony-a7r-field-test/) on a field test of the new Sony FF A-7R.
It came to my attention that you can use Pentax lenses via an adapter on Sony cameras. Has anyone tried this?
The adapter isn't expensive (http://www.amazon.com/RainbowImaging-Pentax-mount-Camera-Adapter/dp/B003X19WZC/ref=sr_1_cc_1?s=aps&ie=UTF8&qid=1329283364&sr=1-1-catcorr)

Responses

Hin Man , Oct 25, 2013; 09:42 p.m.

Malcom, you should look into this adapter as it has 5 steps aperture adjustment that can work with DA type of lens that are without aperture ring. The one you posted only work with lens that have aperture rings. I have the adapter with aperture control for 5 steps. Both Pentax K to NEX adapters are a bit bulky. There is a similar adapter for the M42 lenses and it is even bulkier with a cylinder shape. I don't have the A7 but you can visit my blog page and see how I use Pentax K mount/M42 mount lenses with Sony NEX cameras.

An alternative way to use the Pentax Full Frame capable FA mount lenses with current nex E mount is with Zhongyi Lens Turbo that is a focal reducer that cancels out the 1.5 crop factor on aps-c and the focal reducer adds 1 extra light of stop. The caveats lie in degradation on corner performance. The advantages are FF field of view and gain of 1 stop of light. You can look up Metabones speedbooster and the Chinese knockoff Lens Turbo. The reason that I mention Lens Turbo is that the adapter is almost like half the length of the Pentax K to NEX adapter.

Using the FA 77 and 43 with the lens turbo is great on my nex 5n and so are the inexpensive SuperTakumar 55mm f/1.8, 35mm f/3.5 and 28mm f/3.5. The gain of 1 stop of light work especially well with slower lens as in f/3.5 and f/2.8.

Hin Man , Oct 25, 2013; 09:57 p.m.

The Pentax K to NEX adapter is not small and you can see this picture with a FA 43mm for reference
DSCF2886

And the Leica M, LTM, Pentax Auto 110, Konica AR to NEX adapter are thinner in comparison
DSCF2884

They all work well in the NEX system and they should work with full frame lenses on A7/A7r in the FE mount. If you mount any DA lenses onto the A7/A7r (the FE mount), a crop mode is required if you don't want the vignette on corners.

Out of all the traditional SLR lenses, the smaller adapter that I know are the Canon FD and Konica AR. The others are similar in size to the Pentax K adapter.

Hin Man , Oct 27, 2013; 02:49 p.m.

Hin Man , Oct 27, 2013; 07:47 p.m.

I am studying the two adapters that come out with A7 and A7r. They will work with AF with Sony Alpha lenses in

  • Sony LA-EA3 $199 -- Use this adapter to attach Alpha A-mount lenses to your Alpha E-mount full frame camera body. It includes Auto Exposure support with aperture mechanism and a detachable tripod attachment.

  • Sony LA-EA4 $349 with built in SLT -- Attach Alpha A-mount lenses to your E-mount full frame camera body and enjoy full-time continuous Phase Detection AF while capturing stills and video with world's first full frame mount adaptor to be equipped with Translucent Mirror Technology™. Plus, aperture drive mechanism enables Auto Exposure with compatible A-mount lenses3.

The latter will work with faster AF with phase detection. It is analogous to the LA-EA1 and LA-EA2 that work with Sony NEX (aps-c cameras).

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