Focus and Micro Adjsut - front or rear

[mikew09]

Pruchased my 50D about a month ago and have had a play with the micro-adjust on the 70-200L but to be honest didn't really find there was much in it. Luv the 50D by the way...

However; I did some testing with my Tammy SP AF 17-50 2.8 today and have found that the best focus point appears to be about 10 - 15 mm in front of the focus point - this is quite noticeable when zoomed to 100%. Hence the lens is sharp as a tac but when I viewing I notice that the best focus point is in front of the actual point of focus.

My question is - out of interest and rather than taking a load of photos with groups of + & - micro adjusts, which way do I adjust for off set of front focus?

Thanks in Advance,

Mike

[Tricky]

Gee, now you're asking. OK, I think that the way it works is that "+" increases the distance at which focus occurs, so if you're front focusing (ie focusing too closely to the camera), then dial in some "+" to push the focus point away from the camera.

I guess I've got a 50:50 chance in getting this right, but I think "+ means increase distance" is how I made myself remember it.

There's a few past threads on AP about the various ways you can do a micro-adjust test and correction.

[mikew09]

Gee, now you're asking. OK, I think that the way it works is that "+" increases the distance at which focus occurs, so if you're front focusing (ie focusing too closely to the camera), then dial in some "+" to push the focus point away from the camera.

I guess I've got a 50:50 chance in getting this right, but I think "+ means increase distance" is how I made myself remember it.

There's a few past threads on AP about the various ways you can do a micro-adjust test and correction.

Thanks Tricky, yea did a quick search ealier but didn't seem to come across a thread that specific. I did try the micro-adjust with the charts as described in one thread but did not seem to work to well for me. Did the adjustment on my 70-200L by shooting a detailed object and it worked better or seemed too as it needed very little adjustment.

Will try winding a couple clicks + and see how it goes tomorrow. Just interested and at the moment no serious time to good through the process.

Thanks again,

Mike

[Riverlander]

I can't remember which way it went on my 50D, but on the 7D there is a "person" and a "mountain" icon instead of a + and a -. The person is towards the left.

In this post I show the "system" I use to do the adjustment - it is so easy. I set the camera to what I most often use when taking shots - ie 500mm af f/8 on my new 50-500. Get that one as close as I can (spot on normally) and do not fiddle with other settings.
http://www.ausphotography.net.au/for...t=41426&page=2

[mikew09]

I can't remember which way it went on my 50D, but on the 7D there is a "person" and a "mountain" icon instead of a + and a -. The person is towards the left.

In this post I show the "system" I use to do the adjustment - it is so easy. I set the camera to what I most often use when taking shots - ie 500mm af f/8 on my new 50-500. Get that one as close as I can (spot on normally) and do not fiddle with other settings.
http://www.ausphotography.net.au/for...t=41426&page=2

That looks like the way to go for me - excellent. Only one issue, I only have Tassie's finest will it work with them :-).

I will give this a go this week with the Cascade line up.

Thanks again.

[mikew09]

Well finally got around to having a true shot at micro adjust on my two lenses - the 70-200L f4 and my Tammy 17-50 f2.8.

In my initial go at micro-adjust the method I used did not appear to show much different but trying another method used by one of the members I found different.

Tammer adjust +4
70-200L adjust -2

Does not seems like much but it really does make a difference and after this activity it is easy to understand the problem of back and front focus.

It is not that the either lens was not sharp, but the sharpest point which is generally where you choose with the focus point was off on both my lenses. So after some testing and observation I can micro adjust the lens so that it is at its sharpest at the point of focus I choose.

Actually, I did not find there was much of an issue with the 70-200L but there is definatley an improvement in sharpness. Though happy with the Tammy; I have been just a little disappointed with as it did not always seem to live up to expectations. Now is a whole new lens, not an L series but a still a very nice lens to use.

For those with a new 50D, spend some time and experiment with the micro-adjustment feature. Seems to me that all lenses can be improved to a degree.

Mike

Why canon would choose to not include micro adjust int he 60D is behind me - once understood, it is an invaluable tool.