pavel_l. Posted September 25, 2015 Share Posted September 25, 2015 <p>Hi all.<br> I have a question for the owners of CZ Planar f/2.8 80 mm. I noticed that the depth-of-focus catch button does not work if f-stop set to between f4 and f2.8 (same behavior as during f2.8 position.) I can't find any reference describing this functionality. Is this normal?<br> Cheers.</p> "... Our perception of the world is a fantasy that coincides with reality." Chris Frith. Link to comment Share on other sites More sharing options...
rodeo_joe1 Posted September 25, 2015 Share Posted September 25, 2015 <p>Does the lens stop down any if the shutter is actually fired?</p> Link to comment Share on other sites More sharing options...
pavel_l. Posted September 25, 2015 Author Share Posted September 25, 2015 <p>Yes the lens stops down on all f-stops.</p> "... Our perception of the world is a fantasy that coincides with reality." Chris Frith. Link to comment Share on other sites More sharing options...
rodeo_joe1 Posted September 26, 2015 Share Posted September 26, 2015 <p>In that case I wouldn't worry about it. The difference in Depth-of-field between f/2.8 and f/3.5 is insignificant and practically invisible on a tiny 6 x 6cm viewing screen.</p> Link to comment Share on other sites More sharing options...
pavel_l. Posted September 26, 2015 Author Share Posted September 26, 2015 <p>Thank you Joe. My main concern was to make sure that my lens is not defective.<br> Cheers.</p> "... Our perception of the world is a fantasy that coincides with reality." Chris Frith. Link to comment Share on other sites More sharing options...
francisco_disilvestro Posted September 27, 2015 Share Posted September 27, 2015 <p>That is normal, I have a couple of CZ lenses (C T*) and the depth of field catch button starts to work from 1 stop from fully open (i.e. f4.0 for the 80 F 2.8, 5.6 for the 150 f 4.0).<br> Having said that, you can just close one more stop, between f5.6 and f4, press the depth of field button and then open one stop to f 3.5 and you will be able to evaluate the effect, which I presume will be insignificant, as Rodeo Joe said previously.</p> Link to comment Share on other sites More sharing options...
pavel_l. Posted September 27, 2015 Author Share Posted September 27, 2015 <p>Thank you Francisco. I always use DOF brackets on the barrel of the lens to check estimated DOF.<br> Cheers. </p> "... Our perception of the world is a fantasy that coincides with reality." Chris Frith. Link to comment Share on other sites More sharing options...
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