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Micro Adjustements

nicolas claris

OPF Co-founder/Administrator
I’ve been following Bart Van der Wolf technique for many years it is amazingly accurate but one needs to have a camera with a live view…
Since I use the Pentax 645D, one missing feature of this camera is… live view.
During every day work, this is not a real issue, but to achieve a precise micro adjustment of all my lens, I had to find a very reliable method.
Then I remembered Michael Tapes (a fair guy who worked with Asher and I to set-up OPF years ago. Unfortunately for us, but we did understand the « whys », he had to leave us and focus (pun intended) on his own business.
As far as I remember, Michael started with a pretty good grey card (I still use it when needed) and then spent months to elaborate a reliable technique to achieve precise micro-adjustments.
So I bought his software FocusTune and the LensAlign target, not a heavy investment!
I won’t explain here how I used it, it’s much more simple to read Michael’s website and information Center
I just wished to testify, that it is really simple to use, you just have to be precise, use with methodic approach, step by step and you’ll be set!
ONLY avoid any low voltage lighting (such as LEDs), otherwise you’ll get crazy with the random results…
Before using Michael’s tape focusing tools, I did my own settings by try and guess, and there were quite precise, but now… wow ! I have almost a new camera…


Visit Michael's website.



PS I paid the full price to Michael, this post is absolutely for your information, only.
 

Asher Kelman

OPF Owner/Editor-in-Chief
I'm pleased, Nicolas, that you make this post. We have a lot to be thankful to Michael Tapes for his hard work in helping us set up OPF when Rob Galbraith's forum ended as it did.

This tool my Michael has involved a lot of iterations and that it works as it should is simply Michaels devotion to detail and his honesty. But the extra special payback is that it helps you in your mission-critical work, (where Bart's methodology can't work), and you get such a precise adjustment that the camera seems perfect. This is a completion of a circle and very satisfying!

Asher
 

Doug Kerr

Well-known member
Hi, Nicolas,

I have an earlier version of this instrument. I do not use it for micro adjustment of AF, as I have no cameras that offer that. But I do use it for AF accuracy testing.

I was very impressed by the clever and meticulous engineering and the nice construction.

The latest model has some nice new features.

Best regards,

Doug
 
I was very impressed by the clever and meticulous engineering and the nice construction.
Hi Doug,

I agree, based on an earlier LensAlign version that was part of my beta testing it shortly before final release. Further refinements have been made since. It is obvious that a lot of thought has gone into such a deceivingly 'simple' (as in 'angled ruler') looking (to the casual observer) device. Small things like how the hinge point of the ruler retains a relatively close correlation between the ruler and the plane of optimal focus reveal that attention to detail. It all helps to reduce the number of variables involved in honing in on an optimal AFMA setting.

I had a look earlier at the pre-release version of FocusTune, and it seemed to do what was advertised, also for those cameras/lenses that do not offer fully automatic evaluation.

One observation though, I've noticed that the light quality (spectral composition or color temperature) at which the focus optimization is determined, can have an influence on the optimum one arrives at.

That may have to do with the fact that the AF sensors of some cameras may be sensitive to a spectrum that differs from the sensor sensitivity itself. The sensor is usually filtered for IR, and for most (non-Apochromatically corrected) lenses the focus plane for e.g. tungsten weighted light sources is at a different position than average daylight requires to correct for. The AF sensor in an SLR may not be filtered the same way as the imaging sensor.

Cheers,
Bart
 

Doug Kerr

Well-known member
Hi, Bart,

Hi Doug,

I agree, based on an earlier LensAlign version that was part of my beta testing it shortly before final release. Further refinements have been made since. It is obvious that a lot of thought has gone into such a deceivingly 'simple' (as in 'angled ruler') looking (to the casual observer) device. Small things like how the hinge point of the ruler retains a relatively close correlation between the ruler and the plane of optimal focus reveal that attention to detail. It all helps to reduce the number of variables involved in honing in on an optimal AFMA setting.
Indeed.

One observation though, I've noticed that the light quality (spectral composition or color temperature) at which the focus optimization is determined, can have an influence on the optimum one arrives at.

That may have to do with the fact that the AF sensors of some cameras may be sensitive to a spectrum that differs from the sensor sensitivity itself. The sensor is usually filtered for IR, and for most (non-Apochromatically corrected) lenses the focus plane for e.g. tungsten weighted light sources is at a different position than average daylight requires to correct for. The AF sensor in an SLR may not be filtered the same way as the imaging sensor.
That very well might be.

Thanks.

Best regards,

Doug
 

nicolas claris

OPF Co-founder/Administrator
Good to see you guys commenting into this thread!
Yes the lighting is very important, as I wrote in the OT low voltage lamps bring aberration in the analysis by ttypohe SW. Best, of course is to use daylight. AFAIK Michael is talking about this in his site, but I can't remember where…
 
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Michael Tapes

OPF Administrator/Moderator
Thanks and hi!

Hi Guys,

Good to be back. Looks familiar. Same faces :>)

Thanks for the kind words. Yes, have been busy with further development on both LensALign and Focustune. WhiBal got a complete overhaul (redesign) a few years back and are still going strong. I have been able to very much optimize LensAlign and FocusTune to work with each other. Where the earlier versions of FT just read the face of the target and selected the sharpest one and so forth, the new FT v3 now can read the ruler in space, and properly determine the relative back/front position of each shot in the test series. This now gives a much fuller picture (pun) of the Af performance and how best to adjust it. Also, did a lot of work on target design, and created a new Generation 3 target that can slip onto any existing MkII LensAlign. Turns out that the Af system are quite fussy about the target, and will focus to a different plane based on the target design. I think my design is the appropriate solution. I have not seen a target as "neutral" in terms of AF consistency and proper resultant plane of focus.

Anyway, enough with the ad. Thanks again, and allow me to wish all at OPF a happy holiday season and a great 2014.

Photographically I have been shooting micro-4/3 for most things, but D800E for birds in flight. You can take a look here if you like. Comments always welcome. http://mtapesphotos.com. (The flight gallery is not yet posted, but will be soon).

See you all next time.
 

Doug Kerr

Well-known member
Hi, Michael,

So nice to have you visit us again.

I have not been very active in the AF poking and tweaking field for a while, but I'm excited to learn of the thoughtful and well-crafted advances there you bring to us.

Happy New Year.

Best regards,

Doug
 

Michael Nagel

Active member
Hi Michael,

I have been watching the development of this sort of tool for some time. The help your tool provides for correct alignment is a big plus.

There is however one thing the user of the tool has to think of and add to the setup (this mainly applies to phase AF):
The correct light.

From my experience AF modules do not behave the same depending on the light temperature.
A correct focus at 5500K is unfortunately no absolute guarantee for the same behavior at 2700K.

What are your experiences on this?

Best regards,
Michael
 
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