My own focus test woth 10D & 24-70 f2.8

[jd_D60]

I've been using this combo for a while and in the studio (say f11) the results are great but when shooting outdoors I often get software images, so today I shot a few test images at f2.8 and was quite surprised at the dof of 2.8 on the 10D.

http://johndavies.pwp.blueyonder.co.uk/florida/piccies/lottie_full.jpg

shot of my daughter slightly off centre

RIGHT EYE

http://johndavies.pwp.blueyonder.co.uk/florida/piccies/lottie_right.jpg

& LEFT EYE

http://johndavies.pwp.blueyonder.co.uk/florida/piccies/lottie_left.jpg

Well I was quite surprised at the difference in sharpness.

No adjustments have been made to RAW image other that crop for Web

PS first time linking photos so fingers crossed

[maderito]

Looks like you're quite close to your pretty subject:

At 70 mm, f/2.8 on the 10D

Camera to subject 3 ft: DOF = 2.97 to 3.03 ft.
Camera to subject 5 ft: DOF = 4.92 to 5.08 ft.

At 3 feet, the DOF extends about 1/3 inch in front and beyond your focal point.
At 5 feet, it's about 1 inch.

I read frequently that you should stop down to at least f/5.6 to get adequate DOF for portrait-type shots.

I became so concened with this issue that I plugged the DOF formulas into an Excel worksheet. The actual formulas and online DOF calculator (not mine!) are at: http://dfleming.ameranet.com/dofjs.html

[Tom W]

Looks like you're quite close to your pretty subject:

At 70 mm, f/2.8 on the 10D

Camera to subject 3 ft: DOF = 2.97 to 3.03 ft.
Camera to subject 5 ft: DOF = 4.92 to 5.08 ft.

At 3 feet, the DOF extends about 1/3 inch in front and beyond your focal point.
At 5 feet, it's about 1 inch.

I read frequently that you should stop down to at least f/5.6 to get adequate DOF for portrait-type shots.

I became so concened with this issue that I plugged the DOF formulas into an Excel worksheet. The actual formulas and online DOF calculator (not mine!) are at: http://dfleming.ameranet.com/dofjs.html

There's some that might use a somewhat larger or smaller Circle of Confusion for the calculation, but I agree that your DOF is very shallow at f/2.8 at relatively close range. I think that this is one of the reasons that people think that they have a focus issue, when they are really dealing with a very shallow DOF as well as the false expectation that a camera can lock focus within a 5 mm range repeatedly.

That's a very good example, JD!

BTW, Manderito, do you happen to have the Excel Spreadsheet available as an e-mail attachment? I'd be interested in it if it is. Don't worry if you can't though, I can understand. PM me if you can.

[Sendide]

--------------------------------------------------------------------------------

maderito wrote:
Looks like you're quite close to your pretty subject:

At 70 mm, f/2.8 on the 10D

Camera to subject 3 ft: DOF = 2.97 to 3.03 ft.
Camera to subject 5 ft: DOF = 4.92 to 5.08 ft.

At 3 feet, the DOF extends about 1/3 inch in front and beyond your focal point.
At 5 feet, it's about 1 inch.

I read frequently that you should stop down to at least f/5.6 to get adequate DOF for portrait-type shots.

I became so concened with this issue that I plugged the DOF formulas into an Excel worksheet. The actual formulas and online DOF calculator (not mine!) are at: http://dfleming.ameranet.com/dofjs.html



I'm interested too in getting this Excell file, great idea, is it possible to post it? or as tom mentionned , if you don not mind emailing it to me as well.
regards
KHalid

[Sendide]

--------------------------------------------------------------------------------

maderito wrote:
Looks like you're quite close to your pretty subject:

At 70 mm, f/2.8 on the 10D

Camera to subject 3 ft: DOF = 2.97 to 3.03 ft.
Camera to subject 5 ft: DOF = 4.92 to 5.08 ft.

At 3 feet, the DOF extends about 1/3 inch in front and beyond your focal point.
At 5 feet, it's about 1 inch.

I read frequently that you should stop down to at least f/5.6 to get adequate DOF for portrait-type shots.

I became so concened with this issue that I plugged the DOF formulas into an Excel worksheet. The actual formulas and online DOF calculator (not mine!) are at: http://dfleming.ameranet.com/dofjs.html



I'm interested too in getting this Excell file, great idea, is it possible to post it? or as tom mentionned , if you don not mind emailing it to me as well.
regards
KHalid