Film-Tech Forum ARCHIVE: ADJUSTING ISCO KA298 LENS

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Posted by Matthew Bailey (Member # 601) on 10-31-2000, 04:34 PM:

I need help in adjusting the feet/meters
NOT FOCUS on an ISCO MODEL KA298 2X
anamorphic lens. How do I adjust it?
I have all the necessary jewler screwdrivers
to do the work.

Posted by Frank Prete (Member # 627) on 11-08-2000, 04:54 AM:

Dear Matthew,

First of all you need a loop of RP40 test film. Thread this up and start running it.

Loosen of the locking nut that holds the adjustment ring in place. On some lenses the ring pushes forwards or backwards to release. On others it has locking screw, and on others there is a locking knob that tigtens onto the mechanisim.

Get the lense into its best focused position using the normal focus control. Start to rotate the 'distance' control. You should see a change in the image on screen (it will squash in or strech outwards). Keep moving the ring until you find the best overall focus. The lense should now be optimised.

This procedure is sometime overlooked when lenses are installed, resulting in a sub-standard scope picture. Other times, the install engineer will count roof tiles or just guess the distance and set the lenses there. I find that setting them up using test film and your judgment gets better results.

Frank

Posted by John Pytlak (Member # 331) on 11-08-2000, 05:40 AM:

Check out the "Focusing Anamorphics" article in the "Tips" section of Film-Tech. Setting the distance ring to the measured throw gets you close, but final adjustment using the SMPTE 35-PA (RP40) test film to bring both vertical and horizontal targets into focus at the same point is essential to completely eliminating any astigmatism.

------------------
John P. Pytlak, Senior Technical Specialist
Worldwide Technical Services, Entertainment Imaging
Eastman Kodak Company
Research Labs, Building 69, Room 7419
Rochester, New York, 14650-1922 USA
Tel: 716-477-5325 Fax: 716-722-7243
E-Mail: john.pytlak@kodak.com