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Author Topic: Micro Focus and Infrared Converted dslr  (Read 1410 times)

Tim Gray

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Micro Focus and Infrared Converted dslr
« on: August 01, 2009, 11:28:06 AM »

I have a rebel xti converted to IR only by MaxMax - which I sort of like, but have a feeling that the AF isn't real friendly with the IR conversion. I'm thinking of having a 50D converted so I can use the micro focus adjustments to nail the AF, and was wondering if anyone had any experience using Lens Align in an IR converted, or more generally, experience using the micro af adjustments on an IR dslr. Thanks.
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Geoff Wittig

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Micro Focus and Infrared Converted dslr
« Reply #1 on: August 01, 2009, 09:12:52 PM »

Quote from: Tim Gray
I have a rebel xti converted to IR only by MaxMax - which I sort of like, but have a feeling that the AF isn't real friendly with the IR conversion. I'm thinking of having a 50D converted so I can use the micro focus adjustments to nail the AF, and was wondering if anyone had any experience using Lens Align in an IR converted, or more generally, experience using the micro af adjustments on an IR dslr. Thanks.

No experience per se. I have an Eos-1Ds converted by Lifepixel. I could be wrong, but I don't think micro focus adjustment will prove especially useful. Under the best of circumstances the accuracy of infrared autofocus is "ballpark". Lenses aren't optimized for IR; the focus correction varies significantly with subject distance, and with focal length setting for zooms. This hasn't been a problem for me since I use the IR body almost exclusively for landscapes, where a fairly narrow aperture covers a multitude of sins. For critical focus, like the eyes in the few portraits I've done, I confess to using the brute force approach: taking a shot, then checking focus on the LCD at max enlargement.
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JeffKohn

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Micro Focus and Infrared Converted dslr
« Reply #2 on: August 02, 2009, 01:51:06 AM »

LiveView is the way to go. Contrast-based AF off the sensor data bypasses the issues of a separate AF sensor that need calibration/compensation for IR. Or you can just focus manually, checking focus on the magnified live view.
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