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Strange issue... But not really?

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    Strange issue... But not really?

    I use a sigma 1.4x teleconverter on my 150mm f2.8 os macro lens, it gives me a little more distance, which is great for flighty insects etc in the field...and obviously I lose 1 stop... But I'm usually at f8... So no issues.... Recently purchased the sigma 70mm f2.8 macro.... Fabulous lens by the way, for inside work, flowers etc. I took the teleconverter along for its first outing in the field, as I'd read that there is no noticeable drop in quality, and I agree... But my camera (5d3) still registered the fstop all the to f2.8? What gives? No other issues.... Apertures all worked, lens was pin sharp etc.... No issues on any other lens and the lens works faultlessly with or without the teleconverter attached?
    Ideas on a postcard please....

    Sent from my Mate 10 Pro using Tapatalk

    #2
    Re: Strange issue... But not really?

    Have seen something similar with my Sigma 150-600 when zooming to long end the 5D3 thinks aperture is still f5 and not 6.3. Doesn't seem to affect the images though as they seem correctly exposed.

    Only happens now and then, can't recall it happening with my 7D2.
    Canon 5D3, 7D2, 60D, Canon 70-200L f2.8 IS II, Canon 300 f4L IS, Canon 16-35 f4 L, Canon 24-105mm f/4L IS USM, Canon 1.4 MkIII extender, Sigma AF 10-20mm f/3.5 EX DC HSM, Sigma 150-600 Contemporary, Tamron SP AF 70-300 F/4-5.6 Di VC USD, Canon EF-S 18-55mm 1:3.5-5.6 IS
    https://www.flickr.com/photos/16830751@N03/

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      #3
      Re: Strange issue... But not really?

      Originally posted by supergeeman View Post
      I use a sigma 1.4x teleconverter on my 150mm f2.8 os macro lens, it gives me a little more distance, which is great for flighty insects etc in the field...and obviously I lose 1 stop... But I'm usually at f8... So no issues.... Recently purchased the sigma 70mm f2.8 macro.... Fabulous lens by the way, for inside work, flowers etc. I took the teleconverter along for its first outing in the field, as I'd read that there is no noticeable drop in quality, and I agree... But my camera (5d3) still registered the fstop all the to f2.8? What gives? No other issues.... Apertures all worked, lens was pin sharp etc.... No issues on any other lens and the lens works faultlessly with or without the teleconverter attached?
      Ideas on a postcard please....

      Sent from my Mate 10 Pro using Tapatalk
      Do you mean the that when you change aperture the readout in the viewfinder always reads f2.8 or do you mean that the file data always reads f2.8 regardless of the aperture used?

      Teleconverters can do odd things. I have two Teleplus 2x converters; 1 is the standard , black, MC7 while the other is the fancier, white, Pro-300 type. With my 70-200 f4L the black version always shows the maximum aperture as f4 and records the nominal aperture rather than the effective aperture. The white one on the other hand actually displays the effective aperture aperture in the 'finder - so the maximum aperture is displayed as f8, f5.6 becomes f11 etc. On my 40D the white version shuts off the AF - because the 40D isn't designed to focus at f8 - while the black versions allows the camera to keep on focusing because the camera thinks the combination is still an f4 lens.

      I suspect in this instance that the black version simply connects the lens to the camera while the white on has a microchip that does the effective aperture conversion calculation before passing the lens data to the camera.

      If you're getting odd values from your combo it may be that the lens firmware is not fully compatible with the cameras - not enough to trigger an Err99-type message but enough to misreport the facts...
      Nigel

      You may know me from Another Place....

      The new ElSid Photogallery...

      Equipment: Far too much to list - including lots of Nikon...

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        #4
        Re: Strange issue... But not really?

        Sounds about right... On my 150 f2.8 it shows the correct 1 stop loss and max f4.... On this lens its as if its not connected... opens to f2.8... No issues with quality etc, just not seen that before

        Sent from my Mate 10 Pro using Tapatalk

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