p.4 #1 · LensAlign Pro Plus Calibration System...my experience
nathanlake wrote:
The actual numbers you use for distance are also irrelevant. By forcing the camera to back focus at one distance, you will force it to back focus at all distances. As the DOF becomes smaller (such as your example of 6') the back focus is less in terms of absolute distance, but equal in terms of percentage error. You are moving the focus point back.You are creating a true back focus.
When you take that picture from 6' away, the camera is actually focusing at 6.05 feet. Everything between 5.53' and 6.56 feet will be "acceptably" in focus, but if you are doing a portrait and trying for that ultra sharp eye, it just won't happen. It is more likely the subjects ear will be in perfect focus instead of the eye.
Huh? You'll have to explain this in greater detail. If I focus the lens on the person's eye, six feet away, I'm focused at six feet, am I not? Where does your 6.05 foot dimension come from? Let's assume a properly calibrated lens/camera combination here. Using LensAlign or the calibration tool of your choice, the microadjust has been set to be maximally in focus at the zero point on the scale. This, after all, is what that depth of field calculator takes as a given. It specifies what's in focus in front of, and behind, THE SUBJECT. The subject is the person's eye, six feet away. Why do you think the ear will be in focus, rather than the eye?
Just to avoid confusion, I'm not the poster who tries to adjust the lens to be focused in the middle of the depth of field. I merely pointed out that the DOF calculator makes clear the 1/3-2/3 "rule" is not, in fact, the rule. Distance does matter.
p.4 #2 · LensAlign Pro Plus Calibration System...my experience
It's a pity about the growing number of trolls. FM used to be a great forum.
Good work OP.
BTW, I get wildly varing results with different body lens combinations. Did you find this?
The only real technique difference to what you described, was that I took 50 shots at each focal length (manually de-focusing to a random point between shots), once I'd settled on a micro-calibration setting.
For example, 1D4 + 28-70L combo is VERY bad (close to 50% front or back focused by 3" or more, with over 26% 6" or more out), but the same lens is reasonably consistant on the 5DII. The 24-70L, 35L, & 85L also show different static focus reliability results, depending on the body you use. I've used 2x 1D4's (virtually identical results) & a 5DII.
Just for comparison I received a loan of the D3s with 24-70, 70-200, and 85 f1.4 My findings were that the 24-70 was UNBELIEVEABLY more consistant at each focal length I tested it at, the 70-200 was great (though Canon's 70-200II isn't too bad either) but Nikon's older 85 f1.4 was similar to the results typical of my Canon stuff.
I haven't changed over, but it's interesting to be able to replicate on a test bench, what lots of my friends have been saying since they switched. (ie lower % OOF from a wedding) All in all, this really shows up both the flaws & strenghs of my current gear.
PS regarding value of LA Pro-
I started off with a ruler cut into a block of wood, but you can't be really sure you're perfectly square to the block, so the LensAlign Pro is a wonderful tool if you earn you living from understanding your cameras & lenses. For those who don't, put an angled cut into a block of 2"x 6", & glue in a long wood ruler with clear markings.
p.4 #3 · LensAlign Pro Plus Calibration System...my experience
PPS Another example of something useful that I found, was that both the 28-70 & 24-70 are more accurate at most focal lengths when I zoom in to focus, and then zoom back out.
By comparison, the 70-200 2.8 II changes focus slightly during zooming, so zooming in to focus like I am in the habit of doing, is a bad idea with this lens.
p.4 #5 · LensAlign Pro Plus Calibration System...my experience
shoebox9 wrote:
I haven't changed over, but it's interesting to be able to replicate on a test bench, what lots of my friends have been saying since they switched. (ie lower % OOF from a wedding) All in all, this really shows up both the flaws & strenghs of my current gear.
A number of folks are in denial of this, but the fact is Canon does have rather poor QC compared to Nikon. Can this be somewhat related to the wage discrepancy between Japanese and Thai workers?
PS: Once one's lenses are perfectly calibrated to the camera, the results are pretty incredible.
p.4 #6 · LensAlign Pro Plus Calibration System...my experience
Maybe some of you that are screaming troll should identify what you are talking about. A "troll" is a post that is meant to inflame or anger. I don't see any of those.
p.4 #7 · LensAlign Pro Plus Calibration System...my experience
Jim Levitt wrote:
Huh? You'll have to explain this in greater detail. If I focus the lens on the person's eye, six feet away, I'm focused at six feet, am I not? Where does your 6.05 foot dimension come from? Let's assume a properly calibrated lens/camera combination here. Using LensAlign or the calibration tool of your choice, the microadjust has been set to be maximally in focus at the zero point on the scale. This, after all, is what that depth of field calculator takes as a given. It specifies what's in focus in front of, and behind, THE SUBJECT. The subject is the person's eye, six feet away. Why do you think the ear will be in focus, rather than the eye?
Just to avoid confusion, I'm not the poster who tries to adjust the lens to be focused in the middle of the depth of field. I merely pointed out that the DOF calculator makes clear the 1/3-2/3 "rule" is not, in fact, the rule. Distance does matter. ...Show more →
No....the whole point of MA is to move the true point of focus away from where the camera thinks it is. If you are exactly 25' feet from the subject and you adjust the MA so that half the DOF is in front and half is in back, the camera will actually be focusing at 28.7 feet away...not 25 feet.
p.4 #8 · LensAlign Pro Plus Calibration System...my experience
nathanlake wrote:
Maybe some of you that are screaming troll should identify what you are talking about. A "troll" is a post that is meant to inflame or anger. I don't see any of those.
I would identify those calling the OP a 'sucker' for purchasing Lens Align rather than just reading the thread and moving along as an indication of a post meant to inflame or anger.
p.4 #9 · LensAlign Pro Plus Calibration System...my experience
nathanlake wrote:
No....the whole point of MA is to move the true point of focus away from where the camera thinks it is. If you are exactly 25' feet from the subject and you adjust the MA so that half the DOF is in front and half is in back, the camera will actually be focusing at 28.7 feet away...not 25 feet.
Now I think you're misinterpreting what most of us are talking about. Only one person here has suggested microadjusting his equipment to place the focus point at the midpoint of the DOF. The rest of us - and the instructions the come with LensAlign are directed at this end - seek to calibrate the electrical-mechanical system of our cameras and lenses so the focus motor drives the lens to focus on the spot that we see in the red box in the viewfinder. If our red box is located on a subject 30 feet away, and our lens/camera consistently gives us images focused 29 feet away, something is out of calibration. Are we really disagreeing about this? This is a maintenance issue, no different than the numerical control techs having to dial in the accuracy on precision machining equipment.
Once the camera and lens are calibrated so the real focus point corresponds to the focus point we've placed under the red square in the viewfinder, the amount of depth forward and behind that accurate focus point in the resulting image will correspond to what's on the DOF charts.
In short: if we are exactly 25 feet away from our subject, we want to adjust the MA so our focus is exactly 25 feet away. This has nothing to do with the 1/3-2/3 "rule." Look at the DOF calculator. With a properly calibrated lens/camera combo, the percentage of depth fore and aft of the actual focus point varies depending upon camera to subject distance. This is an entirely different issue than microadjusting a lens accurately. The OP wrote up a nice report of his experience with LensAlign, describing how it helped get his equipment properly calibrated. How we got here in this discussion, I do not know.
p.4 #11 · LensAlign Pro Plus Calibration System...my experience
dwweiche wrote:
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Finally, this past weekend, I discovered the Emboss Filter in Photoshop. I knew about it, but never really tried it. It almost seems like it was made for focus testing
I made a wooden version of the Lensalign this weekend and will use it this week. Can someone post the steps for applying the emboss filter for us PS rookies please?
p.4 #12 · LensAlign Pro Plus Calibration System...my experience
Jim Bau wrote:
I made a wooden version of the Lensalign this weekend and will use it this week. Can someone post the steps for applying the emboss filter for us PS rookies please?
Very easy. It's in the 'Filter' section of PS, maybe one more layer down in the drop-down menu. Just take a minute to look for it. I just use it w/ whatever the default settings are.
p.4 #13 · LensAlign Pro Plus Calibration System...my experience
thw2 wrote:
A number of folks are in denial of this, but the fact is Canon does have rather poor QC compared to Nikon. Can this be somewhat related to the wage discrepancy between Japanese and Thai workers?
PS: Once one's lenses are perfectly calibrated to the camera, the results are pretty incredible.
Nikon forum seems to have plenty of people talking abotu duds over there too. The Canon lenses I have were made in Japan, and I though Japanese workers made more than Thai workers?
p.4 #14 · LensAlign Pro Plus Calibration System...my experience
Here is a link I picked up from POTN that looks like a very promising method of MA without having to purchase any tools. Haven't tried it, but really worth trying as it makes sense.
