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09-29-2016, 09:10 AM   #1
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K-1 focus adjustment

Was wondering, is it possible to do it accurately (enough) without getting a product such as LensAlign? Not really feeling coughing up 150$ if I can avoid it
Maybe there's a free chart I can just print out and try to adjust to it? I think my focus point is a bit off, not sure by how much. Using a K-1 + SMC 50 1.8 combo for now.

Thanks!

09-29-2016, 09:47 AM   #2
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Short answer is yes it can be done with homemade charts. I suggest an internet search and you will find a number of charts and you should also find a method using moire patterns on a monitor screen.

However, free or homemade does not mean that the test can be done casually. Doing it with a homemade method is IMHO much harder (though cheaper) than using a device built for the purpose. You need to be extremely precise in alignment in both planes as well as taking care to mount the camera on a secure tripod and use a remote. We are talking very, very tiny adjustments here. Quite often the margin for error in the test exceeds the actual error we are trying to correct. So repeating the test numerous times (say 10 iterations) throwing out the outliers and averaging the remaining results would be good practice.

IMHO if all you do is print a chart, take a few snaps and make a correction you are basically just adjusting your camera randomly. Keep doing that and eventually you might hit on a setting that works. So take the time to do it right. I usually spend about 2 hours minimum on testing a new lens.
09-29-2016, 10:04 AM   #3
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Ok thank you! Yeah, I didn't think it'd be as easy as pointing it at a sheet of paper and pressing the shutter button. If I'm saving more than a hundred bucks I'd be investing that into time I spend on the longer and more cumbersome dyi process, which is fine.

I'm wondering, could it be that the lens itself is not doing a very good job? I haven't tried a D FA lens on my k-1 yet, so I don't know if this is a normal behavior, or its slow and inaccurate. I get in focus shots sometimes, but I had way more keepers with my previous oly em1 + panaleica 25 1.4 setup, and I was always under assumption that af wise dslrs are still ahead (plus em1 is a 2013 body).
09-29-2016, 10:19 AM   #4
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Fine adjustment

The test photos have to be taken through the viewfinder.
AF Live View doesn't need to be adjusted.

09-29-2016, 10:50 AM   #5
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Another option. Check eBay. Some sellers offer high quality printed test charts on card stock - usually printed in China and slow shipping.
09-29-2016, 01:42 PM   #6
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Focus Test Chart option

Here's something that might be worth trying. I've used it previously and found it to be accurate enough to save you the $150. The chart is at the back after the instructions/guide.

Tas
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File Type: pdf focus21.pdf (267.2 KB, 65 views)
09-29-2016, 02:46 PM   #7
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I've used this the last two times I cal'd my lenses. Works well.
https://www.amazon.com/gp/product/B012F8G1DO/ref=oh_aui_detailpage_o03_s00?ie=UTF8&psc=1

DSLRKIT on Amazon, about $5.

Definitely use a heavy tripod for your camera and a cable release. Use lowest ISO (100 ON K-1). Use off camera flash.Use viewfinder, spot focus. Spot focus square should be slightly smaller than target area square.Please note that, for manual lenses, a light touch is a must. Try not to move or bump the camera. For both manual and auto-focus lenses, first place lens at infinity, then adjust manually or auto-focus from there. Repeat 2-3 times. Verify correct adjustment by re-checking in 1-2 days. See AF adjustment tool procedure on this forum.

Last edited by dfp771; 09-29-2016 at 03:03 PM. Reason: added more info.
09-29-2016, 04:03 PM   #8
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What would be the proper distance to the chart? Is there some formula to calculate based on focus distance?

09-29-2016, 04:19 PM - 1 Like   #9
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Why not focus at something 25-50x the focal length on a tripod, with a 2 second timer, and start at AF adjustments -10 all the way to +10 in groups of 2 (so -10, -8, -6, etc)

So set the camera -10 AF adjustment (ensuring the camera starts at min focus), take a photo, set the camera to -8 AF adjustment (ensuring the camera starts from minimum focus back to what it perceives as correct focus), take a photo, -6 AF adjustment etc etc

Then cycle through and see which one is best in focus? It is admittedly a bit tedious, but surely it would work no?

of course set the lens to the max aperture possible. If you shoot at f/5.6 or f/8 it is going to be very impossible to dial it in correctly.

Also would take a Live view shot as baseline for correct focus before going back to PDAF to conduct the test.
09-29-2016, 04:55 PM   #10
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The process outlined above by mee is indeed the cheapest, easiest and a very reliable way (if you are patient) to do an AF calibration. I'd also add:

- choose a sharp test target (newpaper page will often do), place it perfectly flat on a board, light it very well with bright, even lighting, and stand it perfectly vertical;
- put camera on tripod, at a useful distance for the lens you are testing, align camera/lens exactly 90 degrees to the test target.
09-29-2016, 07:33 PM   #11
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QuoteOriginally posted by dfp771 Quote
I've used this the last two times I cal'd my lenses. Works well.
https://www.amazon.com/gp/product/B012F8G1DO/ref=oh_aui_detailpage_o03_s00?ie=UTF8&psc=1

DSLRKIT on Amazon, about $5.

Definitely use a heavy tripod for your camera and a cable release. Use lowest ISO (100 ON K-1). Use off camera flash.Use viewfinder, spot focus. Spot focus square should be slightly smaller than target area square.Please note that, for manual lenses, a light touch is a must. Try not to move or bump the camera. For both manual and auto-focus lenses, first place lens at infinity, then adjust manually or auto-focus from there. Repeat 2-3 times. Verify correct adjustment by re-checking in 1-2 days. See AF adjustment tool procedure on this forum.
Hey! That's what I bought on Ebay. Mine was about $3 including shipping. But it took a long time to get to me.
09-29-2016, 09:35 PM   #12
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You only need a normal ruler with high contrast, best black marks on white. Put it on 45 degree angle in the appropriate distance and you can simply save 150 Dollar. There are also a lot charts available to be printed on paper to do the same without any cost.
09-30-2016, 04:08 PM   #13
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Thanks guys, a lot of good info. I'll get to calibrating my lens when I have few spare hours.
09-30-2016, 06:54 PM   #14
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Btw if you ever have to calibrate a zoom, since we only have 1 AF adjustment per lens, I'd adjust for the focal length you use the most. Some sites recommend the longest end. But that seems out of whack if you use the widest end most often. I'd just go for widest in that case.
10-01-2016, 01:21 AM   #15
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QuoteOriginally posted by mee Quote
Btw if you ever have to calibrate a zoom, since we only have 1 AF adjustment per lens, I'd adjust for the focal length you use the most. Some sites recommend the longest end. But that seems out of whack if you use the widest end most often. I'd just go for widest in that case.
Since you only have one adjustment - compensation for the lens flange thickness tolerance - it is pretty futile to spend inappropriate time and effort messing around with expensive targets. In the end you have to rely on whatever data the manufacturer put in the lens rom. Adjustment at infinity had always worked for me with APS-C bodies and I can't see why FF should be any different.
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