I understand one can use a yardstick at a 45 degree angle to calibrate lens focus, using the maximum focal length and widest aperture -- but I don't know the formula for the correct distance from the camera for the lens in question. I'm checking my new Tamron and several Canon zooms on a MKII and a 70D. Any suggestions would be appreciated, as I'ver never tried this before.
cjc2
Loc: Hellertown PA
There is a decent article you can access from the SIGMA site that may help. You might also try the info on the sites of the two popular devices that are sold by B&H for this. Although you don't absolutely need a focus adjustment device, you may find, after doing some further research, that you might find one helpful. Just a few suggestions.
SnappyHappy
Loc: Chapin, SC “The Capitol of Lake Murray”
I would think the minimum focus distance of the lens at 600mm to a point near the center of your yard stick.
I think MT shooter could answer your questions if you want to get in touch with him. He was about to demonstrate this procedure to us while we were in Yellowstone and then suddenly we were chased away buy an elk in rut! Very exciting!
I've read two different things;
1- 25xfocal length, which at 600mm leaves you at about 50 feet. Might be tough to find a good place to do that indoors.
2-at a distance you would typically use the lens.
I was able to calibrate mine using the 25x formula. I have a ranch style house with a straight shot from one end to the other.
Nalu
Loc: Southern Arizona
plessner wrote:
I think MT shooter could answer your questions if you want to get in touch with him. He was about to demonstrate this procedure to us while we were in Yellowstone and then suddenly we were chased away buy an elk in rut! Very exciting!
I'd bet that Elk adjusted your focus for you!
This is the one I used with great success.
http://regex.info/blog/photo-tech/focus-chart#featuresgary northrop wrote:
I understand one can use a yardstick at a 45 degree angle to calibrate lens focus, using the maximum focal length and widest aperture -- but I don't know the formula for the correct distance from the camera for the lens in question. I'm checking my new Tamron and several Canon zooms on a MKII and a 70D. Any suggestions would be appreciated, as I'ver never tried this before.
gary northrop wrote:
I understand one can use a yardstick at a 45 degree angle to calibrate lens focus, using the maximum focal length and widest aperture -- but I don't know the formula for the correct distance from the camera for the lens in question. I'm checking my new Tamron and several Canon zooms on a MKII and a 70D. Any suggestions would be appreciated, as I'ver never tried this before.
I would calibrate it at a distance you are most likely to be using AND at 600mm setting unless you will be using 550mm more instead.
I used focustune on my Tamron. Made a world of difference.
gary northrop wrote:
I understand one can use a yardstick at a 45 degree angle to calibrate lens focus, using the maximum focal length and widest aperture -- but I don't know the formula for the correct distance from the camera for the lens in question. I'm checking my new Tamron and several Canon zooms on a MKII and a 70D. Any suggestions would be appreciated, as I'ver never tried this before.
+++++++++++++
I have used the Tamron on both my 7D and 5D mark II for over a year now (got it in Feb 12th 2014).
It worked great out of the box on both cameras.
gary northrop wrote:
I understand one can use a yardstick at a 45 degree angle to calibrate lens focus, using the maximum focal length and widest aperture -- but I don't know the formula for the correct distance from the camera for the lens in question. I'm checking my new Tamron and several Canon zooms on a MKII and a 70D. Any suggestions would be appreciated, as I'ver never tried this before.
to answer your question with the formula.......
600mm @ f5.6 @ 30' will give you 0.24' DOF, {about 3"}
600mm @ f5.6 @ 60' will give you 1' of DOF
{in the app store "setmycamerapro"} it is a handy app to have
good luck!!
not to discredit anyone, but I did a lot of reading on calibrating zoom lenses and what I deciphered , was to calibrate your lens in the center of the focal length, for a general calibration {unless a person shoots at ,say 450mm or 600mm then cal. it there}
JUST "my" $0.02!!
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