Bobkeenan Photography June 2012 - Bobkeenan Photography

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I am not a big reading fan. I tend towards Science fiction or Historical based fiction. But non-fiction…. not so much, unless its a subject that I am currently interested in. Photography has grabbed my interest.

I am to the point where I know most of things necessary to take technically correct images with my Canon 5DMkII and 5DMkIII.

But then there is the Art or Composition part.

I think we are all pre-disposed to being naturally talented in certain areas. I think I have a talent for math and science. I also seem to be able to have good hand eye coordination. I was able to fly USAF jets, test rocket engines, sail big sail boats almost instinctually.

But ask me to do a sketch, some color matching, or organize some objects in an pleasing manner ….. I turn into a bungling idiot.

Good Photography is ART. There are those who can see and imagine a great composition of blending colors, contrasts, and subject material…..and then there are the rest of us.

The rest of us have to learn it, memorize it, experience it and then hopefully remember what we did right and what we did wrong.

But, I think, we can LEARN it…… and maybe get close to those who can do this naturally.

If you don’t have the time or money to go back to school or go to photography seminars (both of which I DO plan on doing) then you can read.

These two books are an excellent start.

The first one that I read was Michael Freeman’s: The Photographer’s Eye: Composition and Design for Better Digital Photos

I have read this book 3 times. I will probably read it again a many more times. I think every page has at lease one example image on it AND they are all great images. One warning. This book will NOT tell you how to set up your camera. It’s a book that will explain why we like to look at art and images, why certain composition works and others don’t. It turns out we are all wired to enjoy or prefer certain aspects of what we see in art. Artists have figured that out since early recorded history. I would not have believed it until it was explained in this book and then experienced on my own. For an engineer it was a real eye opener. Freeman explains, in some detail, with image examples:

How to frame an image

The elements of design (contrast, rythm, perspective, ect.)

Photographic elements ( diagonals, curves, triangles, ect.)

Light and Color

Intent (conventional, reactive, planned, etc.)

Process (Hunting, reaction, Exploration, etc.)

Most of these terms were foreign to me. But after reading and seeing the images it really opened my mind to a much better photography approach. It really improved my images.

So if you are a naturally talented artistic type maybe this book is just a good reference….. but if you are art challenged, like myself, it will change the way you look at things.

The second book was Michael Freeman’s: The Photographer’s Mind: Creative thinking for better digital Photos .

Michael Freeman’s The Photographer’s Mind

I think that Photographer’s Eye filled up most of the artistic portion of my engineering mind. Reading the Photographer’s Mind was more difficult to grasp for me. It is equally well written, like the “Eye” but the concepts and the demonstration images were more difficult to “get”. Because of this it was not an easy read for me. But I think it may be a mental exercise that I should put myself through. The book is sectioned into Intent, Style, and Process. Some of the concepts and images were brilliant and hopefully inspires my future work. Other concepts and images…… I did not like or agree with. Of course I think almost all modern art after impressionism is crap! So take what I say here with a grain of salt.

So when I meet someone who is just taking up serious photography I ALWAYS ask ” Have you read ” The Photographer’s Eye “. I usually don’t bring up Freeman’s other books ( I have them ALL) because I think they have a more specialized purpose.

So….. If you have not read Michael Freeman’s Photographer’s Eye…… go get a copy and read it….. I guarantee that you will be glad you did.

I recently got the Tamron 24-70 f2.8 VC. I also have a really neat lens cal system called the Reikan FoCal (a autofocus microadjustment system ). So as soon as I got the lens I set it up with my Canon 5D Mk III and ran a MA series on it.

Now Canon says you should run this kind of check a a distance of focal length X 50. I also have the LensAlignPro ( another autofocus microadjustment system) and it says that you can cheat on that a bit and run X 25. FoCal says you can can also run the test at a distance where you take most of your shots.

I use the full range of 24-70 (I also have the Canon) but I also like to take close up shots near the minimum focal distance. Vegetables at the farmers Market.

So I did the calibration at around 28″ from the target and got an autofocus microadjustment of 20. That’s pretty high but I checked it and it repeated.

I go to market and get some good close up (<2′ away) shots. I also take some shots of friends from about 8′ away. The later shots are out of focus. They are all the same focal length.

So I have been doing both lens align and Focal calibrations on both the Canon and the Focal for most of today.

What I am finding is that when you do a calibration for autofocus microadjustment using any system the autofocus microadjustment value is only good for the distance that you test at. It changes for distance.

What I though I was seeing was for a fixed autofocus microadjustment point, your DOF focus moves back the further from the target and it moves toward you the closer to the target.

So…… Does this make sense?

Assuming it does I think that means that if you are using AF don’t get close to the minimum focus distance. Just because you can get a focus lock does not mean it will be in focus. And if you set up your autofocus microadjustment for distances that are close to the minimum distance then you will be compromising your other shots from further away.

I think that means I need to calibrate my lens in the 25-50X range and go get a prime between 50-85mm (calibrated for closeup distances) for my vegetables.

Then I thought…. lest spend some more time on this and look at the numbers for several different cases.

So lets check this all out with a series of tests I will used my “rocket scientist” background……

Hypothesis:

Autofocus microadjustment is affected by distance. This is particularly true near the minimum focus distance.

1. Canon 5D Mark II

2. Canon 5D Mark III

3. Tamron 24-70mm f2.8

4. Canon 20-70mm f2.8 I

5. Reikan Focal Calibration system ver 1.5 beta

6. LensAlign Pro

7. Tripod

8. Two 6500K CLF lights

I will get the best autofocus microadjustment at three distances for both lenses on both cameras at 70mm at f2.8 in Av mode at 100 iso. The distances I will use are

My favorite distance for close up shots 28″ ( minimum focus distance is 1.25′)

5 feet ( close to 25X as recommended by LensAlign)

9 feet ( close to 50X as recommended by Canon- 50x is really about 11′ but my room has limitations)

So I will do both cameras and lenses at each distance on the Focal system. Then I will repeat that on the lensAlignpro system. Sounds like fun…… well its raining outside and my wife has a bunch a women over for an exciting domino’s tournament…..so this is what I can do.

Hang on ….. there are 12 of these things. The summary and conclusions are at the end.

5DMk II Canon Lens 28″

Comment: Decent curve fit with most points together at each autofocus microadjustment

5DMkII Canon Lens 5′

Comment: fairly wide spread of points for the near autofocus microadjustment’s…. not sure why

5DMkII Canon Lens 8′

Comment: Really nice tight curve fit.

5DMkII Tamron Lens 28″

Comment: Except for -20 a pretty good tight fit

5DMKII Tamron Lens 5′

Comment: This was rated, by the software, as a poor cal. The points are all over the place. But there were a predominance of points around 6 0r 7.

5DMKII Tamron Lens 8′

Comment: Fairly good fit with some stray points

5DMKIII Canon Lens 28″

Comments: Again fairly good fit with some stray points

5DMKIII Canon Lens 5′

5DMkIII Canon Lens 8′

Comment: Better fit of points

5DMkIII Tamron Lens 28″

Comment: Lots of spread at the high negative range but then tight after that

5DMkIII Tamron Lens 5′

Comment: Decent fit except for a few places

5DMkIII Tamron Lens 8′

Comment: Really nice fit

I did not include images of the results of these tests. There is a fair amount of subjective judgement with this system in determining the middle of the depth of field. Its pretty straight forward at close distances and is easy to see. So I have I lot of confidence in those results. The more distant readings at 8′ were subjective in that the DOF was almost as wide as the ruler. I will have to get the longer ruler that they sell. The autofocus microadjustment’s that I did come up with are shown below with the FoCal numbers from above.

Here is a summary of all of the AF

Focal Method

Distance

5DMkII

5DMkIII

Canon

Tamron

LensAlign Pro

If you compare each camera and lens combination between the FoCal and LensAlignPro, they are all pretty close except for the combination of the Tamron and the 5DMkIII. If you look at the calibration curve it looks like it almost requires an adjustment of greater than 20, which is not possible. But it does not behave that way on the 5DMkII.

There is a small tendency to require Higher autofocus microadjustment adjustment, in the FoCal sytstem, near the minimum focal distance. This is most noticeable in the Tamron lens near the closer 28″ test.

It was satisfying to see that the LensAlignPro test showed that the Tamron/ 5DMkIII combination a MA adjustment of only 12 was required and not the 20+ that the FoCal system showed.

Most of the tests with the FoCal system at 8′, closest to the recommended 50X, seemed to have the best curve fit

DSLR AF systems are NOT 100% repeatable. Stray bad focusing happens

If you are going to be taking photos of images close to the minimum focus distance you DOF may not be where you think it should be. I am thinking that several shots, with the focus point a slightly different distances, may help to insure you get the focus where you want. At least that is true with my lenses on these cameras.

Its probably best to set your AF MA at the 25-50 X distance.

For the most part Focal agrees with the Lens Align systems. Note that I was using a FoCal beta version.

There is something odd going on with the Tamron Lens that you can see in both cameras. I may try to get my hands on another Tamron and see what results I get.

How to drop a DSLR – Brand New Canon 5 D Mark III November 30, 2012

Bags, Bags, Bags, My Journey to the best DSLR Camera Bag October 30, 2012

FocusTune by Michael Tapes Design- Review October 27, 2012

My Microstock Sales October 26, 2012

How to Buy DSLR stuff September 23, 2012

Sigma 70mm f2.8 Macro Lens and my journey to get there September 7, 2012

Blowing Dust away with the KOH Hepa Jet II Air Blower September 2, 2012

Zoom Lenses Make you Lazy July 14, 2012

Book Review: Michael Freemans Photographer’s Eye and Photographer’s Mind June 18, 2012

Autofocus Microadjustment Epihany June 6, 2012

How to drop a DSLR – Brand New Canon 5 D Mark III

Bags, Bags, Bags, My Journey to the best DSLR Camera Bag

FocusTune by Michael Tapes Design- Review

My Microstock Sales

How to Buy DSLR stuff

Links | GFC Photography Blog on Reikan’s Focal System- DSLR Autofocus Microadjustment Calibration

bobbyk on Reikan’s Focal System- DSLR Autofocus Microadjustment Calibration

Mitch on Reikan’s Focal System- DSLR Autofocus Microadjustment Calibration

David on Reikan’s Focal System- DSLR Autofocus Microadjustment Calibration

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