I was surprised to see how out of focus this fellow's nose is compared to his shoulder where I focused. I should have been fine according to an on-line DOF calculator. Could this be a bit of motion blur (mine, not his, he wasn't moving at all) combined with a bit of DOF (since the nose is likely a foot closer than the shoulder where I focussed)? Or does this mean that I need to buy a D800 with 70-200 ASAP All ideas welcomed.
35ft away with D300s and 18-200 at 90mm using iso200, 1/125, f/5.6
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#1. "RE: DOF?" | In response to Reply # 0RABaker Registered since 30th Sep 2003Mon 17-Sep-12 04:49 PM
It is a little hard to judge from the relatively small image posted here, but it appears to me that both fawns and the plants slightly beyond the fawns are within the DOF. Since I would judge the farthest fawn and the plants to be more than 5.3 feet behind the buck, I would guess that your lens actually focused on a distance somewhat farther away than his shoulder. If I'm correct, it would explain why his nose is more out of focus than would be expected. Check your original file and try to determine how far back the DOF extends; you can also attempt to judge the near limit of the DOF from the grasses in the foreground. Once you think you have determined the front and back limit of the DOF range, you should (hopefully) be able to estimate where in the frame the lens actually focused.
#2. "RE: DOF?" | In response to Reply # 1Wed 19-Sep-12 06:35 PM
I am going to have to run a test I think. As you can see from the red square, the focus point was on his shoulder, but I have to agree that the actual focus seems to be a bit behind that. Thanks for looking.
#3. "RE: DOF?" | In response to Reply # 2
#5. "RE: DOF?" | In response to Reply # 3Fri 21-Sep-12 02:47 AM
That had not occurred to me Sheri, interesting thought. He had just walked into view as I was tracking the small ones with their mum and I did not want to take the time to reframe or move the focus point to his head, so I just focussed and shot. I am going to run a test with a subject 35 feet away. If the focus is spot on, then your theory may well be right, there really isn't much to focus on, thanks for the idea.
#4. "RE: DOF?" | In response to Reply # 0
>I should have been fine according to an on-line DOF calculator.
Keep in mind that the DOF calculator is based upon making an 8x10 print viewed at about 18 inches.
When looking at this image on my monitor (about the size of 8x10) at my normal seated position (about 22 inches), the nose of the stag looks acceptably sharp.
It also is important to remember that DOF is an illusion. There is only a single plane of focus, and as you move away from that plane the detail will get progressively softer. How soft it will appear is dependent upon the captured CoC, amount of enlargement of the capture, and the distance at which it is viewed. So with the deer’s head turned, even if the focus is on the shoulder, the nose is probably around 2 to about 2.5 feet in front of them. With a front DOF of 4 foot that places the nose near the edge of the DOF. So if you look at it with an enlargement greater than the designed calculation, it will look even softer. Add a little back focus to the mix, and the nose will look even softer.
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#6. "RE: DOF?" | In response to Reply # 4Fri 21-Sep-12 02:58 AM
I didn't know that . . . an 8x10 at 18inches, good information, thanks. You certainly can exceed that on a monitor very easily and I did see that the nose looked fine when viewed at smaller magnifications as you would expect.
Needing f/8 to keep a nose in focus is more than I expected!
#7. "RE: DOF?" | In response to Reply # 0
First of all, Great Shot! It's nice to be in the right place at the right time.
I agree with Pete's comments. It's is also important to realize that each lens has a "sweet spot" in regard to f-stop where you would achieve the greatest sharpness. This is typically in the middle of the range (f8, f11) but can vary by lens. You can check technical reviews of your lens since they usually provide this information.
Additionally I would recommend to do a focus test. I did one on my D300 after finding that my focus point seemed off. You can make and store corrections in your camera for each lens.
Here is a link to a site with downloadable test patterns that I have used. http://regex.info/blog/photo-tech/focus-chart
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#8. "RE: DOF?" | In response to Reply # 7Mon 24-Sep-12 02:04 PM
Thanks Paul, yes I think it is time for a focus test if for no other reason than to rule-out equipment issues. That site will help, thanks.
I resist using higher f-stops because I have to raise the ISO. In this case I did have enough light and I should have raised the ISO but he just appeared out of nowhere. Next time
If I do raise the ISO and work at f/8 or higher I get the added benefit of a deeper DOF as well as the sharper lens performance.