focusing problem

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billozz

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bill
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not sure whats wrong with my setup, i have a 7d and took the following with a sigma 70-200 2.8 fitted. i was focused on the number 5 on the rule and as you can see the focus is way off, i have followed instructions on the vid in the link to do a micro adjustment to the focus and it doesnt matter which way i adjust it doesnt allow me to get the number 5 centrally in focusits soft one way or the other( not sure if that makes sense lol)
is there something i am missing? i have just bought the lens from this forum, does it look like it might have a fault?
thanks
Bill
 
It's back focusing as I see it!
 
Bill.

If you are trying to check for focus accuracy I would suggest that you use a slightly better set up than you are using here.

Have a look at the way a Lens align is set up. I'm not suggesting you buy one but make a similar set up. Flat target with good contrast to focus on and the ruler at 45 degrees with the 6 on the ruler level with the plane of focus. You need to have your camera on a tripod at around 25 times the focal distance of the lens you're checking. The camera should be at the same height as the focus target and parallel to it.

Then use one shot AF and take several images refocusing the lens between each one. This should give you an idea of whether it is front or back focusing and then you can try the micro adjust from there.

To get the best results you need to have a set up that is repeatable and accurate.

And have a search on Google for front and back focusing. Plenty of info out there regarding micro adjustment.

Hope this helps
 
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I had a d7000 and that body was notorious for being out! All of my Nikon lenses were -20 out! So if you're only moving a couple of numbers either way it won't make much difference! The number could be microns! Put it at +20 and see what difference it makes! And then gauge it back or forwards to get it perfect.... Are you shouting at 2.8?
 
thanks for the replies, yes Gary you are right i do need to set something up a bit better, this was done very quickly based on the vid i posted just to see if it would make a difference, having noticed that a coule of recent pics were a little soft when i was sure that i had focused accurately. having said that surely if i am focusing on the number 5 and its obviously soft there must be something wrong somewhere, either camera or lens, i tried the micro adjustment in the hopes that it would correct the problem, there doesnt seem to be enough adjustment to accurately focus on the number 5.
i have read that there are a number of different methods to micro adjust or match a camera to a lens (i have to say i am surprised there are a NUMBER of methods) if anyone knows of others i am happy to give them a try. i know i could send them to canon and ask them to do it but having just bought the lens (second hand) i think i will try to rectify it myself first, with a lot of help from places like this.
thanks again for any replies
Bill
 
I did mine with the back of a washing powder packet set at 45 degrees and focusing on a particular word or letter and sorted mine out! Made a big difference
 
yes thanks Mark, i have to say that was my way of thinking maybe not technically a perfect setup but good enough to help me a little, but like i said having tried the micro adjustment i cant get the focus to move far enough over to get the number if the middle of the focus area
 
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