Autufocus errors

[nikonian]

This tweaking business reminds me when I was a hi-fi buff. I purchased a stereo open reel tape recorder. Had very good specs and I was pleased with it. I applied to the makers who then sent me gratis the full worksheets for this model. I thought I would tweak the angle of the heads for a higher frequency responce. Spent a day on it through the whole adjustment. When I finihed, tested it I was amazed at the top end sound. It proves that makers of cameras etc do not have the time to minutely adjust the item.

[KeithT]

Originally Posted by SieSmith

Just to pick up on a point that Keith raised:-

I tend to do this also, Keith, but can't this lead to problems as well, if not done correctly and with care? If someone focuses then recomposes with the narrow DoFs we've been discussing, it could appear to them that the focus on the lens is out, even though it is really their technique that is at fault?

Cheers, Sie

Yes, Si you do need to be careful using this off focusing method, but after years of practice with it, it becomes part of the routine. In general, most focal points are at the centre of the frame, so that's where I like to concentrate my lens. Exposure is another thing and I often check out various areas of an image for the best exposure. In many instances I am happy for the camera to make those decisions (but not always of course). Narrow dof will always be frought with danger whatever method you use.

[SieSmith]

Originally Posted by SieSmith

Now the original point was about front and back focus and tweaking the focus point to "calibrate" the lens. What I would like to ask is "What settings do you use for this calibration?".
Etc, etc, .........

Any advice at all about the best way to do this?
Any takers?

Cheers, Sie

[cosmicma]

you could try this method
http://regex.info/blog/photo-tech/focus-chart

had a go myself one day out of curiosity and it seems to work

[nikonian]

Originally Posted by cosmicma

you could try this method
http://regex.info/blog/photo-tech/focus-chart

had a go myself one day out of curiosity and it seems to work

My effort is similar to this. If I knew how to put a link on this thread I would post it.

[ap4a]

Originally Posted by nikonian

My effort is similar to this. If I knew how to put a link on this thread I would post it.

Just type the URL in in the same way as you would any other text, so long as there's a http:// or www. at the start of it the forum will autolink it. Alternatively if you want to change the link text to be descriptive then you can highlight text in your post and then click the globe + chain link icon above the message box to add in the URL.

[nikonian]

http://cdn.mos.photoradar.com/files/...tam-175050.jpg
Hope this is OK .The slide on the left runs from - to + with zero in the centre level with board. 0 should be the sharpest with a tail off at both ends. The B/W squares are just for focussing.

[SieSmith]

Thanks folks, will take some time and go through the info.

Cheers , Sie