Focus Test Shots – Advice please (2 IMG)

I tried taking some focus test shots with Tim Jacksons test chart to night….I’m not sure what to make of them. Attached are links to 2 results….. the full resolution versions are on my Picasa site for thorough viewing.

http://picasaweb.google.com/john.karen.rob/FocusTest#

The 1st shot is from my 14-54 and all looks well, although it is at f3.5 and 54mm (will try a different set up in daylight for shorter focal length and f2.8).



The 2nd shot is puzzling me.



Its from my 50-200 and it is at f2.9 and 112mm….I noted that while the rhs of the image looks tack sharp on the focus line, the lhs is not…..is this simply because I was not set up truly perpendicular to the test pattern in the horizontal or is something amiss ?

Any assistance in interpreting this would be appreciated.

Thanks
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Best Regards;
L. John K.

Doesn't look like you are perpendicular (you are using a tripod, right?) - and especially with the 200 make sure you are at a proper distance from the chart.

If you can setup somewhere that you have a tile floor for reference, that makes it easy to get to true perpendicular if it's difficult to eyeball it.

Gidday John

In both shots you have shot the chart from the side. I do not think that this is how it works.
Read the instructions.
I suspect you must shoot from straight on , but I don't know.

In the first shot the L/H side is in better focus than the R/H side, but shot from the side at an angle.

In the second shot ditto.

Also remember that the 50~200 has almost no DoF at this distance, FL and f-stop ...

[edits] sorry, got the sides mixed up ... [end edit]

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Regards, john from Melbourne, Australia.
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Yes, I really need to do this in daylight and I suspect I was not straight on enough....I'll give it a more thorough set up Sunday and repost.

Thanks guys;

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Best Regards;
L. John K.

You mentioned it in your question.

The pattern isn't aligned even remotely correctly. Not close. Not close by a mile. Your focus test is completely worthless...and that's GOOD.

I suspect your lenses and camera will likely be just fine.

But I'm curious as to what you were doing. The pattern is so clearly out of whack that you must have been aware of it. It's a precision test capable of measuring fine focus and I don't understand how you could take these images and expect any result other than what you got.

I've been using the same test chart.

One thing is puzzling me. We know the middle af point isn't actually the square in the middle. I mean effective measuring area is little bit bigger than the square. So how can you be sure that af hits the right level of the chart?

I really rdidn't realize how bad they were aligned
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Best Regards;
L. John K.

degree vertical correct, I really didn't realize how bad they were aligned in the horizonal until I viewed them on screen.

Then I looked at the instructions and the sample there was not dead perpendicular and it got me thinking....how far off is to far off.

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Best Regards;
L. John K.

it makes alignment easy and gives your AF a flat surface to work with.

(I bought it after trying the very same web based PDF and finding it not worth the hassle given the number of lenses and cameras I needed to adjust)

Anyway - when you use it, there are red dots that you align which makes it simple to get the alignment perfect.

I did use the pdf one you are showing there to find my just bought E3 was front focusing. I got it exchanged for an E30 which you can adjust.
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John Mason - Lafayette, IN

http://www.fototime.com/inv/407B931C53A9D9D

If I was to do this with my E510 & 70-300 that I suspect being a bit off focus & proved that it was could I actually do anything about it? I'm pretty sure it doesn't have any adjustments.
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Phill D

The 510 does not have any end-user per-lens adjustments, nor any end-user focus adjustments at all for that matter. As you may have seen from my thread from yesterday at http://forums.dpreview.com/forums/readflat.asp?forum=1022&thread=33360478 , it is possible (although not recommended) to adjust the entire camera's focus; however, if your 14-54 is working, adjusting things will break that.

Apparently Olympus can adjust focus on a per-lens basis, but you need to send in (pretty sure you need to pay for shipping) your camera / lens (and if it is not under warranty, you will pay for the actual service) for calibration. I have seen reports from people on this forum that this has worked well for them, but not being in the US I felt that international shipping was too much of a hassle for me to try.

Cheers
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--Wyatt
http://photos.digitalcave.ca

You must use tripod and very good light for focus test. You can use flash, but not direct flash. Don't use that chart because it is worthless. Use an ordinary ruler, or any known subject instead, as long as it is stable. Books are very good test objects.
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http://www.olyflyer.blogspot.com/

To answer one question posed with part I.....I realize the E510 is not adjustable, but I have suspected that my 50-200 front focusses...I haven't used it that much, but when I have my 70-300 seems to be much sharper.

Hence I was trying to test two lens to rule out the camera as the cause and I think I have.

Please have alook at these (full res are on the main site)

http://picasaweb.google.com/john.karen.rob/FocusTest#

14-54; f3.5 & fl 54....looks good



14-54; f3.2 & fl 33....looks good



Now the questionable results:

50-200; f3.5 & fl 200....seems a bit front focussed



50-200; f2.8 & fl 50....seems way front focussed



The only proble was that due to minimum focus length of the 50-200, it was hard to set this one up to "fill the frame"...does anyone know how crucial that is....would'nt seem to be critical to my thoughts as long as perpendicualr and 45 are on.

Comments/suggestions again would be appreciated.

Thanks
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Best Regards;
L. John K.

Don't use that chart. The target is wrong, especially for Olympus cameras, so the camera has a hard time to find focus. Use real objects instead which would give a more accurate results and would in a better way emulate how lens/camera manufacturers test focus. That chart is totally useless, no matter what the guy says on his own web page about it.
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http://www.olyflyer.blogspot.com/

...I'll try some real world stuff, thats what really matters anyways !....sometimes I overcomplicate the obvious.

Cheers;

Best Regards;
L. John K.

LJohnK said:

...I'll try some real world stuff, thats what really matters anyways !....sometimes I overcomplicate the obvious.

Click to expand...

John, it doesn't have to be "real world objects" like dogs, cats or people. Mainly what I mean is that no camera is created to catch the line with any great accuracy, except from close range in very good light. The chart gives practically no information about how severe the focus error is. Also I found that focusing down slope with Olympus is difficult and that's not the way they test focus, so even if you'd complain about your camera or your lens, the images can not be used as a proof of anything. When I discussed focus issues with Olympus I used an aluminium ruler because that gives them (and you) enough information about how serious the problem is. You can read what I have written on my blog about how I test focus accuracy.

http://olyflyer.blogspot.com/2009/05/blog-post.html

I don't know if the above is any help but that's the way I tested my cameras and lenses. Olympus has a far too large sensitive area for the AF, so focusing on the black line of the chart especially at the angle, is quite a bit of a hit and miss for any Oly. That chart is for some reason widely spread without having any real value in my opinion. Testing focus isn't that difficult, and according to me, more informative if done the way I do than using that chart. Of course, I know not everyone will agree with me, but if you look at the DPR article about a visit in the Leica factory and the focus test rig you will see what I mean. I don't remember the link, but I know it wasn't a very long time ago they published it and it is really interesting to look at it.

BTW, I don't think you overcomplicate things, quite the opposite; it is something I am good at.
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http://www.olyflyer.blogspot.com/