focus after changing focusing screen

[j_buck]

<p>i brought my Pentax 67 to a camera tech to change my focusing screen...<br>

and now... mby its just a coincidence... what i focus through the view finder is out of focus on the negatives..<br>

mby it was bad and quick focusing from my side, but i never had this before...<br>

can it be that the tech. calibrated something wrong and if so...<br>

would it be possible that the picture is sharp through the viewfinder but not on the negative?</p>

<p>thanks</p>

[craig_shearman1]

<p>Maybe the tech put the focusing screen in upside down? Not a mistake he's allow to make often if he's doing this for a living but things do happen.</p>

[david_henderson]

<p>I know little about Pentaxes specifically, but I did use a MF slr with interchangeable finders for a decade or more, and it is possible that changing the focus screen can affect perceived focus because the light path between lens and film is not the same as between lens and eyepiece, and so its possible for one of these paths to be in perfect "focus" but not the other.</p>

<p>This could happen if the new focussing screen wasn't perfectly seated, or was upside down, or if the screen wasn't suitable in some way for your camera. I'd have thought the latter was least likely. </p>

[j_buck]

<p>i having quite bad luck with all of my cameras lately.. so tomorrow i make a test shoot and see...<br>

but damn it happened twice in a row after the focusing screen change and i never had focus problems before</p>

[SCL]

<p>Any tech worth his salt should check the screen focus and actual focus after making changes. IHMO - find a new tech.</p>

[johncox]

<p>It could also be that the camera was specifically calibrated to a previous screen. It is possible to calibrate a mirror to a screen and if that was done in the past all subsequent screens will likely be off.</p>

[rodeo_joe1]

<blockquote>

<p>"would it be possible that the picture is sharp through the viewfinder but not on the negative?"</p>

</blockquote>

<p>Entirely possible and for a number of reasons. But whatever, the monkey that changed the screen should have checked its focussing accuracy afterwards. It's a fairly easy thing to do.</p>

<p>The answer is simple - take it back to where the work was done and complain to them.</p>

[paul ron]

film plane vs viewfinder is a repair 101. not all

screens are created equally.

 

very easy to check using a ground glass on the

film plane.

 

focus the viewfinder, then check the ground glass with a loupe for sharpness.

 

the other possible mistake... the screen was put in upside down.

 

txt or email the tech asap to record the complaint, then take it back!

 

if the focus isnt corrected this time... take it to another repair shop n send the bill to this guy!