How do I get it tack sharp?

I've been trying to take this pic and I cannot get everything in focus.
I've been trying a focal distance of 300mm. Should I rather try the wide angle lens and get really close.
I want a bit of shallow depth of field but I want the dad and kid thorns to be tack sharp.
Where am I going wrong?

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Need a little more info. What was the aperture? At 300mm your DOF will be very small. Increasing to f/5.6 or f/8 will sharpen the background a little.

Take a look at this calculator. Enter your info and it will tell you what your depth of field will be.

http://www.dofmaster.c​om/dofjs.html

firstly a few things there glare out at me when looking at your EXIF...

1/3 shutter speed on a 300mm length That must be one strudy tripod!

Secondly you have a 40D... use the live view feature and home in on the section you want to be razor sharp and focus manually until you nail it

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You can keep your 300mm focal length, just put the camera on a triopd, mirror lock up, self timer, stopped down to about f8

The area that is in focus is fairly sharp all things considered. The depth of field is just to small. The depth of field at 300mm and f/5.6 is less than 3/4 inch. Even at f/8.0 is is just over 1 inch.

What lens are you shooting with? 75-300, 70-300, 70-300/DO, 300/2.8, 300/4?

eddarr wrote in post #5605238
The area that is in focus is fairly sharp all things considered. The depth of field is just to small. The depth of field at 300mm and f/5.6 is less than 3/4 inch. Even at f/8.0 is is just over 1 inch.

eddarr, just out of curiosity, where do you pull these numbers from?
Where did you get f/5.6 or f/8, when the aperture used for this shot is exactly f/7.1, as shown in the EXIF?
How did you calculate DoF precisly down to 1 inch, when OP never mentioned the distance between camera and the subject?

Hermeto wrote in post #5605406
eddarr, just out of curiosity, where do you pull these numbers from?
Where did you get f/5.6 or f/8, when the aperture used for this shot is exactly f/7.1, as shown in the EXIF?
How did you calculate DoF precisly down to 1 inch, when OP never mentioned the distance between camera and the subject?

I was going to say the same thing. People quote thin DOF without knowing the distances between camera and subject. At higher distance DOF is quite large even at longer focal lengths.

OP - What lens? A lot depends on that also. Also I try higher shutter speeds. At your ss, you need very nice tripod, mirror lockup, remote and good long lens technique.

I took a wild ass guess. Depending on the amount of cropping done to the image the field of view with 300mm would be 9" vertically and 6" horizontally at 10' from the subject (as found here). If 10' is reasonably close then at exactly f/7.1 the depth of field would be 1" (found here).

Based on the fact that the branch is reasonably sharp at the top and out of focus at the bottom it would be logical that the DOF is razor thin to begin with. It appears to me that the branch is leaning away from the camera or that the camera was not level when the image was taken.

I know I have made some assumptions and they may show my ignorance. But I would be willing to bet that I'm pretty close.

Used 70-300mm lens on a tripod, manual mode, manual focus +/- 1.5 m distance. It was a cloudy day. The smaller thorn is slightly behind the big thorn but I wanted that angle, as it looks like the bigger thorn is "giving a mouthful" to the smaller thorn.

What if I use some sort of plain background behind the thorns and then use a smaller aperture?

If your taking the pic tripod mounted and manual, why not stack the pics. Take 3 or 4 pics slightly adjusting the focus so that the first pic has the foremost thorn in perfect focus and the last pic has the farthest most thorn in focus and the two between about evenly spaced.

Then use a program like CombineZM to create a focus stack. You can get any DOF you'd like with little effort.
http://hadleyweb.pwp.b​lueyonder.co.uk/CZM/Ne​ws.htm

Here is what I would do. Use AF, if you need to use MF, use the live view at 10x thing like someone mentioned above. Bump up ISO to get higher shutter speeds, 1/3sec is too slow even with tripod. I would try with ss of 1/500. Start with f8, but I would think you need to stop down more like f11, or even f16. What is the distance between subject and camera?

What is the distance between subject and camera?[/QUOTE]

+/- 1.2 m

gjl711 wrote in post #5606351
If your taking the pic tripod mounted and manual, why not stack the pics. Take 3 or 4 pics slightly adjusting the focus so that the first pic has the foremost thorn in perfect focus and the last pic has the farthest most thorn in focus and the two between about evenly spaced.

Then use a program like CombineZM to create a focus stack. You can get any DOF you'd like with little effort.
http://hadleyweb.pwp.b​lueyonder.co.uk/CZM/Ne​ws.htm

I actually did that. I'll try the CombineZM. Is it quite easy to do it?
I'm downloading it now.