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(0 votes) 5:23 pm
July 25, 2012
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Hello! I was trying to make some AF fine adjustments based on Lesson 18, with my 18-105 lens, because I noticed that sometimes the AF-S with one single point it’s in the place I want, but the subject in that point is not focus, but few inches a side is in focus. This happened at 22mm zoom. So I learned very well the lesson, put my camera on 45 degrees etc, and noticed that at 18mm the camera is focusing on spot but at 105 it has a problem of few inches from the reference point that should be in focus. I turned to -3 in AF fine tuning, but the problem is that for 105mm it’s ok, but for 18mm is much worst. In the class you mentioned that this fine tuning is better for prime lenses, and Nikon also recommend on prime, not on zoom lenses. But what should I do about it? Another important question, and I believe I’m doing this exercise wrong, is that I don’t know the high that the camera should be from the meter-tape. The high the tripod should be regulated you know? This is important because it determinates the perspective errors on the lens, because one surface is flat like the table and the other is 45 degrees and not 90 degrees has we take the photos, is this correct?
Thank you for your guidance.
it is hard to tell on which hight to put your camera from the tape, because it would be different for different lenses. As long as it is 45 degrees and as long as it is at expectable focusing distance you are file.
This is the problem of zoom lenses. They can be a bit different on different focal length. I would sugest to fine tune your lens on the longer end, since you will use a longer focal length with wider aperture (shallower DoF) more often I would assume. If you know you lens well and you know that it is back-focusing or front-focusing at sertain focal length, you can fine-tune it on the spot depending what focal length you use. It is a bit crazy and an extra work so. But precise focus only matters, if you should with very shallow DoF, like macro for example or some portraits. For macro I would use manual focus so.
There is also a devise called Datacolor SpyderLensCal SLC100 (http://amzn.com/B0041L3JS4), which lets you to test your focus more precise.
4:22 pm
October 11, 2012
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I have read on other forums that a software program called focal works really well for micro adjusting AF. As my camera doesn’t support micro adjust I have not used the program but others have found good success with it.
http://www.reikan.co.uk/focalweb/#
6:12 pm
July 25, 2012
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Well I read all the article of http://photographylife.com/how…..cus-issues and the other article about AF-fine tuning and I discover that my lens 18-105mm sucks. I just made the test of the focus chart in a vertical wall with that lens and a 105macro 2.8, and the second lens is ok and the kit lens is too bad. When taken in liveview mode it seems sharp at 18mm, but then I took the samples with the viewfinder at 1/30 sec and f/ 3,5 ISO 100… and the results were horrible. I believe it’s because the slow shutter speed , I had few ambient light…need to test it with 1/125 at least in a saturday morning. I tested with 1/20 and the results were even worst. At that point I was blaming the camera, but when I tested the macro and the result were very sharp I finally must agree with some reviews that the 18-105mm is a crap, not for architecture and wide things but for precise photography in low light situations, I mean wildlife, portraits and so…
1:23 pm
July 25, 2012
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Here goes a test of a zoom lens 18-105mm (kit lens) ranged at 18mm on AF-S, and those are the settings:
-tripod
-mirror up mode
-cable shutter release
at: F3.8 at 1/30 sec ISO 100
The difference between the two photos is only that the SECOND was a test shot with LiveView turned on, and the 1ST is with LiveView off and using the viewfinder. I made the first shoot according to recomendations of the site posted below.
My 1st problem is:
Why the photo with liveview (LV) is better in colors and sharpness than the one with viewfinder more red and bad focus?
I read the article but still dont understand.
8:18 am
November 22, 2012
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Daniela said
Here goes a test of a zoom lens 18-105mm (kit lens) ranged at 18mm on AF-S, and those are the settings:
-tripod
-mirror up mode
-cable shutter release
at: F3.8 at 1/30 sec ISO 100
The difference between the two photos is only that the SECOND was a test shot with LiveView turned on, and the 1ST is with LiveView off and using the viewfinder. I made the first shoot according to recomendations of the site posted below.My 1st problem is:
Why the photo with liveview (LV) is better in colors and sharpness than the one with viewfinder more red and bad focus?I read the article but still dont understand.
Hi daniela:
Here another interesting and good article on autofocus not expensive and simple as usually shall be. It can be done in any camera.
How to use the AF Fine-Tune function
https://nikoneurope-en.custhelp.com/app/answers/detail/a_id/51633/related/1
8:29 am
November 22, 2012
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Daniela said
Here goes a test of a zoom lens 18-105mm (kit lens) ranged at 18mm on AF-S, and those are the settings:
-tripod
-mirror up mode
-cable shutter release
at: F3.8 at 1/30 sec ISO 100
The difference between the two photos is only that the SECOND was a test shot with LiveView turned on, and the 1ST is with LiveView off and using the viewfinder. I made the first shoot according to recomendations of the site posted below.My 1st problem is:
Why the photo with liveview (LV) is better in colors and sharpness than the one with viewfinder more red and bad focus?I read the article but still dont understand.
To help you, in the issue you have to let the metadata in the picture, Eyes alway can be mislead, that is why the photometer was invented and a teodolito too.
12:03 pm
July 25, 2012
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Hi Patrick. The exif of both pictures are: F3.8 at 1/30 sec ISO 100, the only difference is that the upper is the true photo taken with the viewfinder in order to test the lens and the bottom was taken with Liveview (is a base for the test) according to the steps on site you recomended once: http://photographylife.com/how…..cus-issues
I don’t understand why the photo taken in liveview is better than any photo taken in viewfinder mode… On the site is given the following explanation:
“Before we analyze the captured data, let me explain exactly what you are doing here. First, you captured an image in Live View mode, then you captured an image normally, as you would if you were taking pictures. Why are we doing this? All DSLR cameras rely on a “Phase Detect” autofocus sensor located inside the camera (see my article on phase detection autofocus). The good news is that the Phase Detect system is very fast. The bad news, is that the Phase Detect sensor itself and lenses must be properly aligned and calibrated for this system to work. And that’s exactly what we are trying to test here. When using Live View mode, the mirror inside the camera flips up and the Phase Detect sensor can no longer be used to acquire focus. Therefore, the camera relies on a different focus method called “Contrast Detect” to acquire focus. The camera forces the lens to focus back and forth until the image looks sharp, which is why this method is very slow in comparison. However, because focus confirmation happens electronically through the camera sensor, it will always be accurate. That’s why we are using the first shot captured through Live View as a reference image.”
Read more: http://photographylife.com/how…..z2LqgJrAcW
Well the problem is … if the picture taken in Liveview mode is that sharp…why we dont take every picture that way?
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