p.3 #1 · LensAlign Pro Plus Calibration System...my experience
To the OP, great write up.
After trying several of the DIY methods and getting inconsistent results I went with the Lensalign, quick and accurate and build quality is excellent. The time I wasted building and playing with the home made gadgets far out weighed the cost of the Lensalign. For those that are on a budget, you can rent a Lensalign at Lensrentals.com
On a side note, the "Hide Me" buttom improves the signal to noise ratio
Then look at the LensAlign ruler in the second image (Caption above the image reads: Same shot as above except I used photoshop emboss filter to highlight the focal point on the ruler. You can clearly see that the lens is back focusing). I disagree that this is back focusing.
The caption on the next image reads: Here's one of the test shots with a - 4 micro af adjusment, which put focus to the center - on "0" (i.e. corrected the back focusing issue)
The user clearly believes that DOF should center on the 0 and that is not how it works.
The way DOF works is that 2/3 of the DOF extends behind the focus point and only 1/3 in front.
For example, if you calculate the DOF for a FF camera, 50mm lens, f/4, at 25'
Near distance is 19' 2"
Far distance is 35' 6"
That is 5' 10" in front and 10' 6" behind. That seems to be exactly what the sample shot showed before adjustment. After adjustment, the sample seems to show an equal distance front and back. I define that as front focusing....Show more →
p.3 #6 · LensAlign Pro Plus Calibration System...my experience
Methodical wrote:
What lens did you calibrate using the $15 DIY tool?
Also, I don't know what agenda you speak of...as I stated $180 is not a lot of money to me and some others too but to others it is.
It's a lot of money to a lot of people and a little to a few... Goes with the normal distribution of percent of income people are willing to spend on items like this. Just like many are not willing to spend $30 on rubber band bumper (for the iphone) that cost Apple $1 to make a another $1 to distribute (if that). It's all relative. Hell, I can buy the laminated focus Genie and keep it forever for less than someone can rent a lensalign for a week. I think it's ridiculously priced but to each... etc you know the rest.
p.3 #8 · LensAlign Pro Plus Calibration System...my experience
Methodical wrote:
Whose grumpy. I told the guy that you and the other dude should be able to help and for cheap. $180 is mere pennies to me. And like I stated earlier that puny little paper thingy don't help me with my big lenses...the little ones maybe. Hell the wind will blow it away before I even set up. Besides, I knew my comment would put some fire under you to find the info...worked nicely uhh
Glad to hear that $180 is a mere pittance for you. Glad to see you are doing so well.
As you can see (maybe not, though), the concept and implementation to get this done is trivial. If you think you need to add a lot more money and fool around a lot more to get to the same result, well then that's your business. Far be it from me to tell you how to waste your time and money.
For the rest of us who understand how our stuff works and who don't desire to waste our time or money, there are cheaper and equally good (maybe even better) ways to get this done. The device from Teamspeed is one such device. One can also do the same thing with common household items (rulers and other objects that make good focus targets) with less than 5 minutes work.
p.3 #9 · LensAlign Pro Plus Calibration System...my experience
Here is what I found out about LensAlign for whatever it is worth (I don't have any relation whatsoever with that company):
1) I got repeatable and consistent results with micro-adjustment of my lenses using that device, way better than any other method I tried before. It was easy to setup with two tripods (I used a monopod that has some short spread legs to mount it on instead of a second tripod, BTW). I used it not only on my AF lenses but I have used it on my rangefinder system also with repeated accuracy. As matter of fact, I felt confident with it that I was able to evaluate some focus shift effect on selected lenses. That was enough for me to feel confident that the AF performance is optimal and it shows in the images.
2) I bought it used here on FM, if memory serves for around $120 and I know I could sell it for about the same price or slightly less. In that respect it would cost even less than the DIY method . Not that I would sell it since I intend to buy and sell lenses in the near future. You can actually rent that device to test your lenses if you don't want to spend that "capital expenditure".
p.3 #10 · LensAlign Pro Plus Calibration System...my experience
Jack M wrote:
The advantage of Micro Adjust is you can set the focus point to your taste, center, front or back focus. I prefer center, YMMV.
This is my thought as well. I want as much margin for error in front as well as behind my intended target, which means I personally adjust the focus point to be in the middle of the DOF, regardless of what the accepted definition of DOF may be.
p.3 #11 · LensAlign Pro Plus Calibration System...my experience
dwweiche wrote:
This is my thought as well. I want as much margin for error in front as well as behind my intended target, which means I personally adjust the focus point to be in the middle of the DOF, regardless of what the accepted definition of DOF may be.
That is your choice, but consider this....DOF is really a measure of "acceptable sharpness " not perfect sharpness. Eerything within that range is acceptably sharp, but not perfectly sharp. There is only one point where the ultimate in sharpness is obtained and that is the point where 1/3 of the DOF falls in front and 2/3 behind.
By adjusting the focus so that the DOF is evenly distributed front and back, the point of perfect focus is not where the camera will go. Your images may fall within the range of acceptable sharpness, but will not be as sharp as they could be.
p.3 #12 · LensAlign Pro Plus Calibration System...my experience
I miss far more shots where an image is not anywhere in the accepted DOF versus missing a shot because it's not exactly 1/3 into DOF. Thus, why I target the center for most margin...
When I start shooting $5k L Tele-zooms on a $6k body, I may adjust my philosophy, but when that happens, it'll mean I won the lottery so to heck with you guys, I'll be living on Maui
p.3 #13 · LensAlign Pro Plus Calibration System...my experience
dwweiche wrote:
I miss far more shots where an image is not anywhere in the accepted DOF versus missing a shot because it's not exactly 1/3 into DOF. Thus, why I target the center for most margin...
When I start shooting $5k L Tele-zooms on a $6k body, I may adjust my philosophy, but when that happens, it'll mean I won the lottery so to heck with you guys, I'll be living on Maui
That may be so, but it is totally irrelevant. If the AF misses, it misses. Incorrectly adjusting your MA will not fix that.
By adjusting the way you do, you make sure the AF can never be dead on. That does not sound like good trade off to me.
p.3 #15 · LensAlign Pro Plus Calibration System...my experience
If you spend some time using the DOF calculator, you'll see that the "1/3 in front, 2/3 in back" is far from a rule. Take your 50mm lens, for example, on a full frame sensor. At f/1.4, subject at 10 feet, 47% of the DOF is in front, 53% is behind. Close down a bit to f/2.8, it's still 45% in front, 55% behind. Say you want to photograph a couple of people with your 50mm. Move in to 6 feet, close down to f/4: DOF is 46% in front, 54% behind the point of focus.
With a longer lens, and a tight shot, the DOF is even more even. 200mm, f/2.8, 30 feet, 49% of the DOF is in front, 51% is behind the point of focus. Better have your lens/camera combo dialed in pretty close.
Then look at the LensAlign ruler in the second image (Caption above the image reads: Same shot as above except I used photoshop emboss filter to highlight the focal point on the ruler. You can clearly see that the lens is back focusing). I disagree that this is back focusing.
The caption on the next image reads: Here's one of the test shots with a - 4 micro af adjusment, which put focus to the center - on "0" (i.e. corrected the back focusing issue)
The user clearly believes that DOF should center on the 0 and that is not how it works.
The way DOF works is that 2/3 of the DOF extends behind the focus point and only 1/3 in front.
For example, if you calculate the DOF for a FF camera, 50mm lens, f/4, at 25'
Near distance is 19' 2"
Far distance is 35' 6"
That is 5' 10" in front and 10' 6" behind. That seems to be exactly what the sample shot showed before adjustment. After adjustment, the sample seems to show an equal distance front and back. I define that as front focusing....Show more →
p.3 #18 · LensAlign Pro Plus Calibration System...my experience
I own LensAlign Pro. I feel that it provides me a sense of assurance if I wanna test my lens-camera AF precision. BUT, in all honesty, it is not better than any free testing procedure that is carefully carried out.
p.3 #19 · LensAlign Pro Plus Calibration System...my experience
Jim Levitt wrote:
If you spend some time using the DOF calculator, you'll see that the "1/3 in front, 2/3 in back" is far from a rule. Take your 50mm lens, for example, on a full frame sensor. At f/1.4, subject at 10 feet, 47% of the DOF is in front, 53% is behind. Close down a bit to f/2.8, it's still 45% in front, 55% behind. Say you want to photograph a couple of people with your 50mm. Move in to 6 feet, close down to f/4: DOF is 46% in front, 54% behind the point of focus.
With a longer lens, and a tight shot, the DOF is even more even. 200mm, f/2.8, 30 feet, 49% of the DOF is in front, 51% is behind the point of focus. Better have your lens/camera combo dialed in pretty close.
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.
Besides, I knew my comment would put some fire under you to find the info...worked nicely uhh
. Not that I would sell it since I intend to buy and sell lenses in the near future. You can actually rent that device to test your lenses if you don't want to spend that "capital expenditure".