About bounce flash with K-5 to K-5 II(s)

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Kerusker Senior Member • Posts: 1,349
About bounce flash with K-5 to K-5 II(s)

Lately I replaced my K-5 II with a used K-5 IIs as my main PENTAX camera (kind of retro).

During my 'K-5 revival' I found two interesting posts regarding the famous 'K-5 flash problem':

KPM2 in Sept. 2020: https://www.dpreview.com/forums/post/64329919

I only use not a zoom lens, which has not a constant aperture, because that the flash results are under or overexposed depending on the zoom position (and there changing full open aperture) All in all, that was for me the bug in the K5 flash system.

PentaxianDan in March 2013: https://www.pentaxforums.com/forums/115-pentax-k-5-k-5-ii/208119-k-5ii-p-ttl-overexposure-tilted-flash-test-analysis-8.html (last post)

I'm feeling really guilty but try as I might, I can't get my K-5, AF-360FGZ combination to fail the P-TTL bounce flash tests!!! ......... LensType: smc PENTAX-DA 18-135mm F3.5-5.6 ED AL [IF] DC WR.

After doing some TTL bounce flash testing with my K-5 IIs my result is:

K-5 to K-5 II(s) TTL bounce flash assumption:

  1. Body <-> Lens communication is key for correct functioning.
  2. Zooms with variable aperture may only function correctly with focal value at largest aperture (but with all apertures there). Usually this is the smallest focal length value.

I didn't test very much but I used a K-5 II with DA* 16-50mm 1/2.8 and Metz 58 AF-1 in 2014 on a birthday party without any bounce flash problems.

In the last days I tested my K-5 IIs with the Metz 58 resp. Godox 350TT with bounce:

  • no problems with lenses having constant aperture f.ex. DA* 16-50mm 2,8; Tamron AF 28-75mm 2.8; FA 50mm 1.4; DA 35mm 2.4; Sigma 28mm1.8 II;
  • no problem with these zooms having variable aperture: DA 18-135mm 3.5-5.6; DA 50-200mm 4-5.6; DA 18-55mm 3.5-5,6 AL II;
  • but problem with Sigma 10-20mm 4-5.6 DC at focal lengths not equal to 10mm.

I'm not a flash systems expert so others will know a lot more or better than me - nevertheless this hopefully is interesting for some Pentaxians.

Thanks for reading.

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 Kerusker's gear list:Kerusker's gear list
Sony RX10 IV Pentax K-1 Pentax smc DA 15mm F4 ED AL Limited Pentax K-5 IIs Pentax smc FA 50mm F1.4
Pentax K-5 Pentax K-5 II Pentax K-5 IIs
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