p.25 #2 · Dot-Tune: Autofocus Fine Tuning in under 5 minutes
coolyota wrote:
Hello, trying out the tuning method and I get two different results on my Tamron 24-70mm.
Do you suggest tuning at the widest end, or the longest zoom?
Thanks.
If you're using a newer Canon body (5DM3/6D/1DX/70D) you enter two AF tune values, one for either end of the zoom, and Canon's firmware will interpolate for focal lengths in between. Otherwise if the two tune values are close enough you might be able to make do by using the average of the two. I actually had to send my Nikon-mount 24-70mm to Tamron because the AF tune spread between 24mm and 70mm was over 10 points and Nikon bodies don't support two tune values; it came back perfect (I sent my body in as well and they tuned the lens to it).
p.25 #3 · Dot-Tune: Autofocus Fine Tuning in under 5 minutes
I really love this method.. Good stuff..
Just curious though on three things.
1. Is it normal for the range to be say +10 through -10?
2. I notice when I let go of the half shutter press that no any zoom lens I can hear the motor engage and disengage and then when I press the shutter again it will reengage again (hopefully that makes sense).
3. Are the results similar if I am shooting in dimly lit room (I.E Iso 200 2.8 1/20th?)
p.25 #4 · Dot-Tune: Autofocus Fine Tuning in under 5 minutes
RyanGphoto wrote:
1. Is it normal for the range to be say +10 through -10?
I currently have a total of 84 AFMA registered settings, between my four Canon DSLR and sixteen tested lenses (plus two Extenders). My outer bounds for AFMA are +10 to -6. Forty-two of the values are zero, and all but two of the remaining values are within +5/-5.
RyanGphoto wrote:
2. I notice when I let go of the half shutter press that no any zoom lens I can hear the motor engage and disengage and then when I press the shutter again it will reengage again (hopefully that makes sense)
There are at least two things that might be going on here. If you have AF controlled by the shutter button (instead of a back button), this might be activating and deactivating the AF, although it probably shouldn't make a 'new' noise if you release the shutter button when it's already in focus. Also, if it's a lens with IS, then that will turn off and on, with some time lags between pressing and releasing the shutter button.
RyanGphoto wrote:
3. Are the results similar if I am shooting in dimly lit room (I.E Iso 200 2.8 1/20th?)
The AF accuracy in low light will vary widely with the camera you're using. My 1DX and 6D are about the best you can get from Canon, and generally work pretty well, especially if you can find a convenient light/dark transition line near where you want to focus, and you're using a relatively fast lens. IOW, I don't think the AFMA values will vary in low light, rather the overall accuracy of your AF will vary, sometimes considerably depending on the camera and lens.
p.25 #5 · Dot-Tune: Autofocus Fine Tuning in under 5 minutes
I am about to try Dot-tune for the first time. I just downloaded a few different test charts as was wondering if it's best to print them or can I just have them displayed on my laptop and use it that way.
One of the lens I'll be checking is a 600 f4 IS. Any suggestions for the distance from lens to test chart for a longer telephoto?
p.25 #6 · Dot-Tune: Autofocus Fine Tuning in under 5 minutes
Distance suggested is 50x the lens mm. This needs to be done in bright light such as on a sunny day with no wind. The 600mm would equate to approx 98ft.
p.25 #7 · Dot-Tune: Autofocus Fine Tuning in under 5 minutes
I do all of my AFMA tests indoors, with a spot light on the target. The longest 'run' I can get is about 13m. This lets me test anything up to 200mm at the 50x distance (10m for 20mm lens). I test my longer lenses at 12m, and do a few spot checks outside at longer distances. So far, all of these spot checks at longer distances have been spot-on. The LensAlign II instructions suggest you should test at 25x focal length, which means even my 500mm lens 'fits' for indoor tests, using this criterion.
I like to use high-res targets, and so use a 600 dpi laser printer to make them, and I have a Lens Align II target, as well. It's critical to have high res targets when you're measuring lens resolution (e.g. USAF 1951 target), but it's probably not so important when you're just using the target for AF lock.
p.25 #17 · Dot-Tune: Autofocus Fine Tuning in under 5 minutes
Joshua J. Ahern wrote:
on my 1DX the AFMA range is from -8 to +8
solid green confirmation
The 1DX supports a range of -20 through +20. If you're getting a solid confirmation from -8 to +8 then your lens tunes at 0, which means it's perfect and doesn't require tuning
