self lens calibration Q

KIPAX

KIPAX

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KIPAX Lancashire UK
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Its late me head hurts..

-20 is the camera
+20 is the subject

no calibration is 0

currenty set on +7

focus is slighty towards me.. eg two people (quite a distance away) one in front of the other.. i focus on the person at back but the person in front is more in focus .. I need to adjust by 1 but is it +1 or -1

waddaya fink?
 
The camera focuses further away with every + adjustment - closer to the camera with every - adjustment.

Put another away + adjusts for front focus and - adjusts for back focus.
 
CT said:
The camera focuses further away with every + adjustment - closer to the camera with every - adjustment.

Put another away + adjusts for front focus and - adjusts for back focus.
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6 or 8 ? :)
 
Well. First thing to say is have you noticed a problem which you think needs this calibration?

Even using a proper test setup with fine detail, these are actually very tiny adjustments and you can go nuts looking at images and trying to decide if there's an improvement. I wouldn't have thouight using a test image of two people one behind the other is ideal for trying to do the set up.

If you actually have a setting now of +7 and it looks like you need to adjust by another 6 or 8 + increments it would indictate that your lens is back focusing out of the box at around 15 or 16 which is quite a lot (the max is only 20). I'd think that's unlikely though not impossible. You really need to use a proper controlled setup though, I'll try to find a link.
 
I did explain :)

Its at 7 now.. it needs a fine tune of 1 but 6? or 8? .. you should notice they are 1 either side of 7 :)


simple question.. if i focus on one spot but the focus is slightly towards me do i need to + or -

? :)
 
KIPAX said:
I did explain :)

Its at 7 now.. it needs a fine tune of 1 but 6? or 8? .. you should notice they are 1 either side of 7 :)


simple question.. if i focus on one spot but the focus is slightly towards me do i need to + or -

? :)
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LOL. Ah right ... then you need +1 which moves the focus one setting further away.
 
Cheers... i thought i knew... then i had a thought.. then i confused myself....its been a very long day with three matches photographed and sending pics off and i ahve to be up and out early for more so my heads spinning... sorry :)
 
CT said:
LOL. Ah right ... then you need +1 which moves the focus one setting further away.
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I'd have thought that was pretty clear in my first post.
 
CT said:
I'd have thought that was pretty clear in my first post.
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Nope not at all... what you wrote and a simple.. +1 .. miles different so thanks for the simple one :)

i did -1 because its more in focus nearer to me i thought it had to come back to me.... i did this a yr ago and managed.. today i struggled oh hum
 
i just know I am so so close... it also changes over distance... things close to you look pin sharp.. then using a 300 lens stuff a whole football pitch lenght and some more away look right on f2.8.. crowd for example..

But crowd half way down the pitch i took loads of shots at different points... where the focus point is just the right size to fit someones head.. and all of them the person ever so slightly in front is sharper... but at that distance its not that big a differnce..

same lens was +6 on the mk3 and a peach.. absoloutly perfect evrywhere i ponted it... i need to get it like that on the 4.. has to be bob on :)

using a crowd at distance is good for calibrating a long lens because the crowd is layered.. so pick someone and the row behind or in front will give you a good indication of calibration...
 
I've just farted about with two lenses and two bodies so I know it's a pain. Canon recommend that the test target should be at 50X the focal length of the lens and that you manually focus the lens to infinity before each test shot to keep AF focus travel consistent.

When you have more time that method of Tim's I posted is pretty good.
 
CT said:
..... Canon recommend that the test target should be at 20X the focal length of the lens and that you manually focus the lens to infinity before each test shot to keep AF focus travel consistent.
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Did you mean 50X the focal length....that's the only reference I've ever seen.

Bob
 
Get your gear fixed instead - if it really needs adjustment, its broken.

You can't calberate non par-focal zoom lens with one setting, as one size doesn't fit all focal lengths or distances. Why compromise with fine tune, when it needs to be brought up for specs (aka warranty service)
 
puddleduck said:
Get your gear fixed instead - if it really needs adjustment, its broken.

You can't calberate non par-focal zoom lens with one setting, as one size doesn't fit all focal lengths or distances. Why compromise with fine tune, when it needs to be brought up for specs (aka warranty service)
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this is very true,
but can be pricy, i had a siggy 150-500mm in pentax mount, it was way off focus more than -20, i sent it back to the place i brought it online at my cost £25 they sent it back to sigma who calibrated it, got it back and it was just as bad as originaly, also the optics wear marked and covered in crud, then had to send it back with my k20d at my cost £50 as they said it would need calibration to the camera body. got it back and it was just the same,
so sent it back again at my cost £25 for them to finaly send me new lens(which was better) :bang:
 
puddleduck said:
Get your gear fixed instead - if it really needs adjustment, its broken.

You can't calberate non par-focal zoom lens with one setting, as one size doesn't fit all focal lengths or distances. Why compromise with fine tune, when it needs to be brought up for specs (aka warranty service)
Click to expand...

What tosh.
 
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