How to calibrate focus on folder lens - Adox Stelo with Anastigmat 6.3

[steve_kraft]

<p>Hello,<br>

I have an old Adox Stelo, 6x9 camera. The lens is an Adoxar Anastigmat f/6.3, 10.5cm.<br>

In removing the front lens plate, and cleaning the lens elements, I have put it all back together, but don't know how to ensure that the focusing ring is accurate. The outer lens ring is held down by two screws on the front plate, but this ring can move independently around the front element, until it is tightened down - thus giving some play to where the focusing marks will end up. <br>

So, I don't have any ground glass and wondered if there was some way to do this properly?<br>

Thanks!</p>

[sw12dz]

<p>"Scotch Magic Tape" will work almost as well as ground glass. Place it across the film rails.</p>

[mike51664877339]

<p>As Stuart says. I mount the camera on a tripod, open the lens, and aim it at my computer monitor, which displays a foot-high letter "R." (Darken the room.)</p>

[John Seaman]

<p>I have used a piece of the opaque white plastic from a simple carrier bag, taped in position. You need a good magnifier to see the image properly, a loupe or similar.</p>

[Gus Lazzari]

<p>To add to the "scotch tape" method previously described by Stuart & Michael, but with more accuracy:</p>

<ol>

<li>I would <strong>make an X</strong> with a permanent marker on the <strong>sticky side </strong>& then apply the tape to film rail,</li>

<li>Mount the <strong>camera on the tripod</strong> like Michael indicated,</li>

<li>Have a bright light on the film side such as a window or lamp as the <strong>backlight,</strong></li>

<li>Open shutter and use an<strong> SLR with a 200mm or longer</strong> lens to peer in to the Adoxar lens,</li>

<li>Find the tape/mark which you placed in the center of the film plane & <strong>focus the Adoxar</strong> to get a sharp <strong>infinity</strong> image.</li>

</ol>

<p>Now you can tighten those two screws with the knowledge that you have a correct infinity.<br /><strong>FYI:</strong> 200mm or longer assures that you magnified the image enough to see the subtle grain of the scotch tape.</p>

[bernard_lazareff]

<p>Not so fast!</p>

<blockquote>

<p>use an<strong> SLR with a 200mm or longer</strong></p>

</blockquote>

<p>The SLR's focusing (whether split image or microprism) makes a compromise between using large effective base and remaining usable with "slow" lenses. The minimum aperture being around f:4.5 or f:5.6, fixed by the angle of the microprism or the split prism, independent of the lens focal length.<br>

But, the longer the focal length, the further apart (at the lens aperture) the pencils of light that are brought together to verify focus. So, if you choos too long a lens on the auxiliary SLR, the two (or three) rays will not fit within the aperture of the lens under check. Especially if it is slow like the:</p>

<blockquote>

<p>Adoxar Anastigmat f/6.3, 10.5cm.</p>

</blockquote>

<p>Make your own experiments, keeping the above in mind.</p>

 

[Rob_the_waste]

<p>What I've done successfully has been to take an old cd "jewel case," run a few strips of the Magic tape on one side, and put the tape side against the film rail. Lock the shutter open on "Bulb," and aim the camera at a distant target. Use a loupe to see the sharpest image on the tape while adjusting the focus. Reset the focus ring to infinity. I'm sure all of the suggestions you've seen here work quite well. There's more than one way to skin a cat (and I've got three).</p>

[Gus Lazzari]

<p>Bernard, I didn't mention the microprism or split image as the focus device. If you set this up properly, you'll see the target image in the matte (brighter) portion, sufficiently to gain the proper focus.</p>

<p>200mm or higher for obvious reasons, it magnifies the target.<br>

Just try it, it's easier than trying to target an infinity object while squinting through at the clumsy 'film plane' lupe... </p>