How To Test Your Lens At Different Apertures

[a900_dw73]

I recently tried performing a test of all the apertures on the Zeiss 24-70 lens on the A900. I just had the camera on tripod focused on my bookcase. I used 2 sec. drive mode to take each shot, but I left the Super Steady Shot On. Should I always turn SSS Off when using a tripod and 2 sec. Drive mode? Also, I noticed that certain apertures on the 24-70 were more prone to being out of focus - for instance, F16 took several tries to get in focus, where F18 was easy to get in focus...

The purpose of my test was to see how much resolution loss there will be in the lens once I go past F8, F11, so that when I'm out in the field I can shoot with confidence with any given aperture...

Lastly, generally speaking, if I would like to perform future lens tests like this, could you please let me know anything else I might be doing wrong? For instance, I auto-focused the very first test shot, and then for all subsequent test shots at the different apertures, I switched to Manual Focus, so that I wouldn't be focusing slightly differently each time, i.e. sometimes some of the different red focus points light up in the ViewFinder signifying the auto-focus might be slightly different each time - in other words, how do I reduce all amount of variation from shot to shot, when I perform these lens tests.

Thanks in advance for any input here...

Dave

[David Kilpatrick]

First, don't use wide are focus, just switch to centre point focus. Get a good focus lock, and set the lens the manual. Use the lowest ISO possible, turn off SSS, and use the mirror pre-lift self-timer with a cable release (the remote IR trigger does not permit this) - or with great care without a cable, as long as the tripod does not vibrate.

It will not look very sharp at f/16 or f/22, all other apertures should be OK.

David

[sury]

First, don't use wide are focus, just switch to centre point focus. Get a good focus lock, and set the lens the manual. Use the lowest ISO possible, turn off SSS, and use the mirror pre-lift self-timer with a cable release (the remote IR trigger does not permit this) - or with great care without a cable, as long as the tripod does not vibrate.

It will not look very sharp at f/16 or f/22, all other apertures should be OK.

David

David,
I thought we can do 2 sec using IR remote control supplied by Sony and 2 sec. always deploys MLU.
Am I wrong?

Sury

[a900_dw73]

Thanks David,

I just tried a tripod test shot at F16 with SSS turned Off - and the result was tack sharp on the first try.

I never understood why we must turn SSS Off when using a tripod and long timed exposures - could you explain?

Thanks,
Dave

[David Kilpatrick]

SSS tries to correct for movement which is not there! It just is not needed when you have a solid tripod.

David

[David Kilpatrick]

David,
I thought we can do 2 sec using IR remote control supplied by Sony and 2 sec. always deploys MLU.
Am I wrong?
Sury

Yes, you are wrong. The 2sec on the remote does not use the mirror lockup. It's very annoying. You must fit a wired electric cable release for that. That's why my macro kit includes a release.

David

[sury]

David,
Thank you for the clarification. I do have R1000 so I am covered too.

Sury