View Full Version : Focus question (flowers)
09-10-2005, 08:09 AM
Took this picture today. I wanted the entire frame to be in focus, so I chose a large aperture setting and the settings below. As you can see only the middle of the frame is in focus...and I'd just like to know what you think I might have done to "achieve" this.
- Mode: Aperture-priority
- Aperture: f/11
- Shutter Speed (selected by camera): 1/350
- no flash
- Focal length: 175mm
- Autofocus: AF-A
- AF mode: Single Area (center of frame in this case)
This is using a Nikon D50 and Sigma 18-200mm lens. I'm wondering if I need to use a different AF mode in cases like this or if it's something aperture related.
Using smaller focal lengths increases the DOF, so instead of 175mm, try something wider.
09-10-2005, 06:20 PM
Hi nwpoland unfortunatly 18-200 sigma doesnt have Dof apeture scale like some lenses have a look at this scale (http://www.cofa.unsw.edu.au/units/resource/equipment_guide/still_camera/depth_of_field.shtml) Here is a calculator that may help have a play Dof calculator (http://www.dofmaster.com/dofjs.html)
In short a f22 would give you nearly twice the in focus range as f11 so try f22@1/175 instead of f11 @1/350 this should have enough shutter speed to stop shake etc. Also a lens will be in focus further behind focus point than infront of it so you could try a focus point a little closer.Next time try a several f stop settings for the same shot so you can see differance, hope this helps
09-10-2005, 10:10 PM
Thanks for the info (both of you). I'll play around with these ideas the next time out and see if I can replicate the problem and then work it out.
It makes sense, now that I'm thinking about it, that I was (1) zoomed in pretty tight and (2) focused about 1/3 - 1/2 of the way back in the frame. Should have tried it a couple of ways. I actually still like the shot...just not what I was going for.
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