K-7 focus adjustment

Hi All,

I'm off on hols in a couple of weeks, I don't really "do" sunbathing so thought I'd sit down and test/check all of the focussing on my K-7 with the small arsenal of lenses I'll be taking on my travels.

Can anyone with some experience of using the in-built focus correction tools give me a little advice please?

1./ A good/useful link to download a test chart
2./ What lighting conditions are best for doing the tests?
3./ Can I get away with using the screen on the back of the camera to do the tests? I was hoping not to take a laptop with me.
4./ Do I need to test at a variety of apertures? Or is the widest Av the one to use?

Thanks!

Hi Will,

1.)
You might find this link useful link
There are quite a few different ones but I have found this one fairly easy to use and gives reproducible results.

2.)Probably daylight is best

3.) Yes you can get a pretty good idea from the screen on the camera.

4.) Best to test at widest aperture. Small apertures result in such a depth of focus that they are difficult to interpret.

Whether you should test at different focal length with zooms is more arguable. I tend to stick to the longest focal length.

Archie

I find something slightly odd in the concept of going on holiday and taking a test chart to photograph...there might be better subjects! :

Indeed... it does seem odd but in the middle of the day when only mad dogs and SWMBO will be out in the midday sun, I thought I might find the odd spare moment to kill! It's not a bad job to do sat on the balcony with a pina colada in my hand!

Pretty sure the rest of the time there will be plenty to train my lens on!

Now I understand.

Pentax user and blogger Yvon Bourque has a good set of charts.

Odd thing to do on your hols, but each to his own.
As long as you end up using the stack of lenses you are taking with you, for more than just adjusting the camera.

I use one of these ...






I AF on a chosen number at an oblique angle, and then zoom in on the preview and check whether it's front or back focussing

Presumably after several tries, focusing in both directions to make sure a good average is arrived at. It may also vary with focal length, even temperature, so being 100% precise won't be possible.

I prefer Richard Day's method. Possibly more holiday friendly than a test chart too!

K.

Thanks for the link Kris - no wonder I couldn't find that thread title using the search function, knew it had been discussed before!

As to my "odd" choice of holiday activities... believe me, I'll be out there taking pics as much as is possible, even dusted off the underwater housing to my old 5MP canon compact! It's just that I know for certain that there will be those odd hours to kill when doing focus tests is more productive than reading a book!

Good idea.

Richard Day's method is no doubt extremely thorough, but I wouldn't have the patience.

G

I've done similar to Richard Day on occasion and it does take an awful lot of patience. The tape measure is the quick and dirty method and works most of the time.

Law of diminishing returns!

I have found differing AF accuracy at different subject distance on some lenses so when I get time ( and the energy ) I will do a Richard Day on them.

Will,

I used same method as Smeggy. Shoot wide open with each lens, so minimum DOF.

A 12 inch ruler set on edge (here comes the blue tac again), on a table top, near a window, with the ruler at about 30 degrees to the camera and set about 3 feet in front of camera (on tripod), focus on the 6 inch mark. Use zoom feature on LCD to assess the point of sharp focus and adjust accordingly.

cheers S.M.

by far the easiest method i've used is the one on this webpage:

http://www.northlight-images.co.uk/article_pages/cameras/1ds3_af_micoadjustment.html

Hmmmm... I might give that a go here and now, got an hour or so to spare this evening. Thanks for the link...