[vincenzomiceli]

Hello folks,

I just finished my rev 1 of an article that describes how to find the optimal focus offset for lens\cameras WITHOUT the ruler/scale method.
The article describes a workflow were a 2D target's focus is evaluated by software. So no need to see how many millimeters your camera\lens combo is front focusing or back focusing. Have a look and let me know what you think...
The method is explained in details and may seem cumbersome but really is very simple and easy to perform. I got my offsets for each lens within 10 minutes.

URL is:
http://sites.google.com/site/vincenzomiceli/quantitative-micro-focus-adjustment-for-dslrs

Ciao,

Vincenzo

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Last edited by vincenzomiceli; 01-12-2012 at 07:28 PM.

[vonBaloney]

Fix the link.

[vincenzomiceli]

Oops... fixed.

[panoguy]

Nice description and method, Enzo! I personally enjoyed how you avoided too much techspeak and made it very practical.

Might give it a try and compare it to my subjective LensAlign settings...

[vonBaloney]

This method also looks intriguing: AF microadjustment for the 1Ds mark III, 1D Mk3, 5D Mk2, 7D

[wlachan]

This method also looks intriguing: AF microadjustment for the 1Ds mark III, 1D Mk3, 5D Mk2, 7D

The problem with this method is that it won't work on all monitors. I have a 24" with LG H-IPS panels which shows different pattens at slightly different focus. AF will sometimes pick this pattern, and sometimes that pattern. Also, calibrating focus at such short distance is never as accurate as virtual infinity target.

[vonBaloney]

The problem with this method is that it won't work on all monitors. I have a 24" with LG H-IPS panels which shows different pattens at slightly different focus. AF will sometimes pick this pattern, and sometimes that pattern. Also, calibrating focus at such short distance is never as accurate as virtual infinity target.

Yeah, I haven't tried it but I figured as much. Looks easy enough if it does work with the monitor you've got though. Could also try it on a big flat-screen TV I guess. I don't want to hijack the thread though -- the OPs method looks good.

[derekkite]

Very interesting. I will try it.

[Pa. Patriot]

Thanks a lot for posting this.
My first K5 body was defective, FF and BF all over the place, and after many frustrating hours with various focus charts/methods it was returned and replaced. According to the charts, the new body seems to be good at default, (+/- 0), but I will definitely be using this method to confirm.

[Groucho]

Not a bad idea. I'll have to give that a shot, especially for my pesky 50mm F1.4 which is a bit off.

Thanks a lot for posting this.
My first K5 body was defective, FF and BF all over the place, and after many frustrating hours with various focus charts/methods it was returned and replaced. According to the charts, the new body seems to be good at default, (+/- 0), but I will definitely be using this method to confirm.

There's no need to return the whole thing, that is an adjustment that they will make under warranty, it doesn't mean that the body is defective.

It does seem to drift over time though; after about a year and ~12,000-15,000 photos, I've had to send in my K20D, K-7, and K-5 for focus adjustment. The ol' *ist DL and K100D seemed to stay spot-on, but that may have been partially due to the lower resolution making it harder to notice.

[Pa. Patriot]

There's no need to return the whole thing, that is an adjustment that they will make under warranty, it doesn't mean that the body is defective.

True, but it was quicker. Given the choice, which I had in this case, I chose to not to wait weeks but rather get a replacement from the place of purchase and let them deal with the slow repair. One of the reasons that when I buy online, I buy from Amazon. No BS returns/replacements. Had replacement in my hands within a week from shipping the defective body out.

It does seem to drift over time though; after about a year and ~12,000-15,000 photos, I've had to send in my K20D, K-7, and K-5 for focus adjustment. The ol' *ist DL and K100D seemed to stay spot-on, but that may have been partially due to the lower resolution making it harder to notice.

I had read that, and experienced it with my K10. The K5 wasn't drifting, it initially seemed OK with some AF adjustments. Within 1000 clicks it was not even adjustable anymore and it swung wildly between FF and BF. Something may have been easily fixed, I dunno, got my replacement and an extended warranty just in case

[imtheguy]

Shucks, I wanted to play with this technique but I am a lowly Elements user and it does not appear to have an equivalent tool for import files to layers. Of course if someone corrects me on this I will give it a whirl.