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Sharpness


SlowSong Plus
12 9.3k 30 England
28 Jun 2012 5:47PM

Quote:Well, here's a good way of depressing yourself. ....then you post on ePz about it and we seem to depress you even more!! Wink
Well that's guaranteed; I expect nothing less. Wink


Quote:Have a very large glass of G&T - great antidote for photography-induced depression.

I need no inducement to drink gin. Smile Thanks for the new recipe. And the OH buys the booze, so no depression! Win win situation. Smile
avacreates 9 448 1 United Kingdom
29 Jun 2012 4:43AM
I have a question for Gareth Robinson - how do u fine tune a lens?
ge22y 12 115 12 Wales
29 Jun 2012 8:05AM
To do it yourself you need a camera which has a function in the menu called something along the lines of AF fine tune, it's usually only found on higher spec camera's, I know it's on the Nikon D7000 and above, my mate also has it on his Canon 5DII and 1D mk4.

On the Nikon it allows you to make 20 adjustments either forwards or backwards, I think it basically moves the sensor either forward or backward adjusting the focus point (it doesn't actually adjust the lens)
User_Removed 10 4.6k 1 Scotland
29 Jun 2012 9:31AM

Quote:To do it yourself you need a camera which has a function in the menu called something along the lines of AF fine tune, it's usually only found on higher spec camera's, I know it's on the Nikon D7000 and above, my mate also has it on his Canon 5DII and 1D mk4.

On the Nikon it allows you to make 20 adjustments either forwards or backwards, I think it basically moves the sensor either forward or backward adjusting the focus point (it doesn't actually adjust the lens)



Don't know about Canons but, on Nikons, it will "remember" your fine tuning settings for each of your lenses and automatically apply them when you mount a lens.

Having said that, I have never had to use the facility - guess I have just been lucky.
avacreates 9 448 1 United Kingdom
29 Jun 2012 2:42PM
Thanks heaps ge22y for that info. I have a Nikon D5000 which means I won't have that setting Oh well - I still love my camera, we have bonded.
Ava
mikehit 11 8.0k 13 United Kingdom
29 Jun 2012 3:46PM

Quote:

Don't know about Canons but, on Nikons, it will "remember" your fine tuning settings for each of your lenses and automatically apply them when you mount a lens.

Having said that, I have never had to use the facility - guess I have just been lucky.



Canons do as well. But you calibrate only one particular focal length for each zoom lens.
It is surprising how many people obsess over this AF calibration and then sometime later realise they actually preferred overall lens performance before they adjusted it so reset to zero.
keith selmes 17 7.4k 1 United Kingdom
29 Jun 2012 8:03PM

Quote:Instead of going out in the hot sunshine
the what ? no danger of that, not without a long aeroplane ride
avacreates 9 448 1 United Kingdom
30 Jun 2012 3:09AM
That was funny Keith, it's the same here in Victoria, Australia, we have to endure it for at least two more months coz its winter here. This morning was bright sunshine so I planned a photo day at the beach, but some dark clouds are presenting themselves to me - in mockery - oh well, I'll have to put my imagination to good use in-doors, hope the sun is shining brightly warming up your part of the world.
Ava
LenShepherd 12 4.2k United Kingdom
30 Jun 2012 9:58AM
There are 3 things to think about.
The first is, if using AF, most test targets to not include a completely reliable AF target area. This can lead to unexpected softness. Comparing manual LiveView with ordinary AF can help clarify if this is part of a sharpness issue.
The more you magnify the faster the shutter speed needs to be to compensate for camera shake at big magnifications. Viewing at 100% is a big magnification. Some use a flimsy tripod on a thick carpet in relatively low light without thinking about mirror vibration issues - and do not get the sharpest results.
Viewing at 100% can be the equivalent of a print as big as an internal house door, often viewed on a monitor with less than 100 dpi resolution. Even with a Nikon 36 MP D800 you are more than pushing your luck expecting a critically sharp image in a 6.5 foot print viewed at about 15 inches on a relatively low resolution monitor.
Interpolation and sharpening post processing can help a bit. Even so a 6.5 foot, high quality print at 300 dpi viewed at 15 inches ideally needs 24,000 pixels on the sensor long dimension. The D800 has less than 8,000.
Viewing at 33% or 50% often gives a better indication of image sharpness than viewing at 100%.
EDIT
Most web reviews base their findings on the number of lines resolved on a target, which rarely shows any improvement between about 33% and 100%.
As far as I know only Amateur Photographer uses results viewed at 100%. I have yet to see AP find anything sharp enough to resolve 50 lpm at 100%. In "absolute terms" 50 lpm is quite a low resolution - and the AP results do not look critically sharp at their chosen 100%. The merit of AP is it makes sensor progress easy to compare, having gone up from the mid 20's 2-3 years ago to about 40 lpm with the very latest high MP introductions.
colin beeley Plus
17 1.2k 10 England
30 Jun 2012 11:09AM
that is one of the reasons i bought the 1d mk3 so i could do micro ajustments. i have had to set all my lens's except one. i was not that happy with my 1d mk IIn I HAD TO TAKE IT TO CANON TO DO :-(

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