Question on using Lens Align tool - micro-adjust

The directions for Lens Align say to use a working distance of between 25x and 50x the focal length. That means to calibrate my 80-400 f/5.6 lens at the 400mm, f/5.6 setting I’m looking at a Dof of about 7.9 inches at the minimum working distance of 33 feet. The lens align tool with the standard ruler is all but useless with such a large Dof - what would be the downside of using a much closer working distance, say 10 feet, to chop the Dof down to 1.5 or 2 inches so I can see where the zone of focus falls on the standard Lens Align ruler?

I think your depth of field calculation is off by quite a bit. It looks like the depth of field is about only 1 inch acording to this calculator.
http://www.dofmaster.com/dofjs.html

Dan, I suspect you entered a wrong number, but I'd still like to hear from any of the tech savvy folks if they know why  such a high minimum working distance is recommended. Any input would be appreciated.
Thanks

Dan the distance lens align suggests is to ensure an improvement over all distances for general use of that lens, it wont be perfect at every distance but it should be improved. This is because AF adjustment can only be perfectly accurate at one distance. If you shoot most of the time at say 20ft then calibrate at 20ft but remember you may not get the best results when you then shoot at 40ft.

Hope that helps

Good question re minimum distance for calibration. I always thought we were supposed to calibrate at the most used working distance.

Thanks Trev, that makes sense. I wonder how much difference 10 or 20 feet in calibrating distance will make - only one way to find out! Thanks.

The other thing to consider is that there is really only one truly sharp plane, the one you've focussed on. DOF is just a zone of acceptable sharpness. I found that out the hard way doing astrophotography. You would think using a ultra wide angle lens focussed at infinity would be simple as our DOF tables may suggest, but there is only one spot where it's in focus. DOF is of no help.

Scott is right and that is exactly why the small ruler works just fine with a 400mm lens at the recommended distance of 25 times the focal length or 10 meters. You will clearly see the image going soft in front of and behind the plane of critical focus.

EJ,. would you be happy with this? (80-400 at 400mm,  f/5.6, 10meters, 100% view, -02 micro adjustment)

Nothing seems sharp to me , maybe try using flash?

I wonder what the result would be if the same shot was taken in live view mode using contrast detection AF.

Not nearly big enough to make a judgement. I would have to see the original file. It looks to me like some camera shake kept the whole thing from being sharp.

If you are a wildlife shooter at what distance should you use to adjust a 300mm f/2.8 lens?(subjects are at different distances), and should you include your teleconverters in the adjustments?

Each combination of TCs and lens and lens alone should be done individually.

Joe

So for the 300mm it would be 7.5 meters or at the distance you are mostly shooting at ?

Here's my take. This notion that you have to go out and microadjust every lens and TC combo that you own is both incorrect and a complete waste of time! I've owned multiple copies of a number of Canon supertelephoto lenses and quite a few different bodies, and there's only one time that I've had to microadjust a camera-lens combination. Reserve microadjustment for times when you're having reproducible problems with focus. Almost every other pro photographer I know feels exactly the same way I do.

Doug Brown wrote:Here's my take. This notion that you have to go out and microadjust every lens and TC combo that you own is both incorrect and a complete waste of time! I've owned multiple copies of a number of Canon supertelephoto lenses and quite a few different bodies, and there's only one time that I've had to microadjust a camera-lens combination. Reserve microadjustment for times when you're having reproducible problems with focus. Almost every other pro photographer I know feels exactly the same way I do.

Your right Doug, I guess most assumed that there has been an issue in the focusing hence the test to see if there is a problem. If your getting the results you want, like you say why bother testing it. My 500mm plus extender needed a bit of calibrating but the 500mm by itself is fine.

Trev wrote:

Doug Brown wrote:Here's my take. This notion that you have to go out and microadjust every lens and TC combo that you own is both incorrect and a complete waste of time! I've owned multiple copies of a number of Canon supertelephoto lenses and quite a few different bodies, and there's only one time that I've had to microadjust a camera-lens combination. Reserve microadjustment for times when you're having reproducible problems with focus. Almost every other pro photographer I know feels exactly the same way I do.

Your right Doug, I guess most assumed that there has been an issue in the focusing hence the test to see if there is a problem. If your getting the results you want, like you say why bother testing it. My 500mm plus extender needed a bit of calibrating but the 500mm by itself is fine.

+1.

I just adjusted my 500+1.4TC because that combo is clearly useless without the adjustment. Using pretty much the method that Roger suggests on his webpage, I got a result that, IMO, is good enough for all practical purposes.

Doug Brown wrote:Here's my take. This notion that you have to go out and microadjust every lens and TC combo that you own is both incorrect and a complete waste of time! I've owned multiple copies of a number of Canon supertelephoto lenses and quite a few different bodies, and there's only one time that I've had to microadjust a camera-lens combination. Reserve microadjustment for times when you're having reproducible problems with focus. Almost every other pro photographer I know feels exactly the same way I do.

You probably own newer Canon gear or if not you may be lucky or you may just not be as critical as some.  The latest Canon gear from the 1Dx on and the new Mk II telephotos rarely need much adjustment at all although usually 1 or 2 points one way or the other does maximize sharpness but granted that's minimal and in real world photography situations doen's make that much difference.  But the generalization that it's a waste of time is not accurate:  Older Canon lenses tend to need quite a bit of adjustment.  Also newer cameras with higher pixel density tend to be more critical of focus in order to get the most out of the sensor (just wait until those 50mp Canon bodies come out).  On the Nikon side, life is nowhere near as good with almost all lens/camera combos needing some adjustment and many needing drastic adjustment.  The 500 f/4 VR with a 1.4x with any Nikon body, for example, in the vast majority of cases is completely incapable of making sharp photos without a huge adjustment, often right to the edge of what can be done in camera and sometimes the combo would still need more adjustment.  Almost all third party lenses need a very significant amount of adjustment to be able to render sharp photos on either the Canon or Nikon platforms.

Totally agree with what EJ is saying. On my D800, my 500 VR needs to be near +20 and with the previous TC-14E II it needed to be above +20. My Sigma 150 Macro is -15 and my Tamron 24-70 is +17. The 300 f4 AFS is +7. If I tried to shoot all these lenses at zero, the results would be drastic.

Larson, with regards to the Lens Align, my test images come out close to what you are seeing. I find it extremely difficult to determine between -8, 0 and +8. To me it seems to be a guessing game using that tool.