Ok. 50mm 1.4 Test Shots on Book For Focus Check

kevingeary · April 20, 2011

This is pretty unscientific, but it's the best I can do right now:

All of these are shot wide open (1.4) using the CENTER focus point on the "24".

These are large images so I'm just posting links.

Here is a shot with zero recomposition:

http://kevingeary.smugmug.com/photos/1258651260_3NGrVgV-X3.jpg

And here are various shots WITH recomposition:

http://kevingeary.smugmug.com/photos/1258650145_zh9n2QG-X3.jpg

http://kevingeary.smugmug.com/photos/1258652573_VC963qR-X3.jpg

http://kevingeary.smugmug.com/photos/1258652062_PkHKcvq-X3.jpg

What say you?

lanaer · April 20, 2011

Um... which part of the 24 were you trying to focus on? It looks like the images are all focused towards the bottom/nearest part of the 24.

kevingeary · April 20, 2011

lanaer wrote: »

Um... which part of the 24 were you trying to focus on? It looks like the images are all focused towards the bottom/nearest part of the 24.

The 24 is about the size of an eye.

I always focus to the center.

lanaer · April 20, 2011

Then it looks to me like your lens is focusing a tad too far forward.

Scott_Quier · April 20, 2011

Something you may or may not be aware of .... there is only a little correlation between the size/position of a focus point (in your viewfinder) and what the camera actually focuses on. This is even more the case when you are asking the camera to focus on something at an angle to the focal plane (your sensor) and in less then optimal lighting conditions.

If your are attempting to test how well your camera/lens combination is achieving critical focus, you might be better served by:

Taping a sheet of printed paper to a wall in a well-lit location
Mounting your camera on a tripod
Set to Av, shooting RAW format (JPG will apply sharpening and all sorts of other processing)
Un-focus your lens and actuate the AF mechanism (for most shooters, half-press the shutter button). Don't take the shot
Release the shutter button
Half-press the shutter button again.
Slowly continue to press the shutter button to release the shutter
Repeat the process at least two more times.
Review your RAW conversions in Photoshop or LR, without applying any corrections.

Once you've convinced yourself that your camera/lens combination can acquire critical focus under the best of conditions .... now you have starting point from which to experiment with the focus-recompose issue. Even then, I would recommend you use a focus target the is parallel to the sensor so you are working from a well-understood known.

zoomer · April 20, 2011

Well if your equipment is anything like mine....I could take this same shot 20 times refocusing each time and it would focus slightly differently in quite a few of the shots. I think this is in agreement with what Scott said.
This is a huge problem with my 85 1.4. And occurs especially often in low light or with scenes of low contrast.

I know this to be true because I did extensive testing to fine tune the focus of my lenses to my cameras.

More and more I have taken to focusing using continuous focus and giving the focus just a micro second to settle before following through and fully depressing the shutter.
I seem to get much more consistent focus that way.....especially when using very thin depths of field which I usually am.

NeilL · April 20, 2011

zoomer wrote: »

Well if your equipment is anything like mine....I could take this same shot 20 times refocusing each time and it would focus slightly differently in quite a few of the shots. I think this is in agreement with what Scott said.
This is a huge problem with my 85 1.4. And occurs especially often in low light or with scenes of low contrast.

I know this to be true because I did extensive testing to fine tune the focus of my lenses to my cameras.

More and more I have taken to focusing using continuous focus and giving the focus just a micro second to settle before following through and fully depressing the shutter.
I seem to get much more consistent focus that way.....especially when using very thin depths of field which I usually am.

Yes, my experience too.

Good technique tips!

Neil

Qarik · April 20, 2011

your 1st shot seems in focus to me. The other attempts slightly less so.

Ok. 50mm 1.4 Test Shots on Book For Focus Check

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