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help!

Posted: 13.02.2009 04:24
by peteschick
Can someone help me figure out how to get better results?
I either get a halo (method B) or blurry areas (method A). Am I doing something wrong?
I'm using a Canon xsi 450D and taking about 14-20 pictures of each subject, exporting the raw files into Helicon, using a radius of 4.....?

Need more lens - distance info

Posted: 23.02.2009 13:55
by BrianS
Hi,

Most likely culprits are:
a) not enough frames taken, however without knowing what lens/aperture and the approx starting focus distance it's hard to know.
b)the combo of lens, distance and aperture might not be optimum for sharpness.

The following is best guesses based on the remaining exif in your files.

Your exif details tell me the focal length is 55mm, and you used about f5.6
I'm also guessing this is not a dedicated macro lens, but maybe a zoom with 'macro' focussing yes?

All lenses will have a sharpness 'sweet spot' at a certain distance, and through an f stop range - dedicated macro lenses aim for optimal at closer distances. I would suggest you do a sharpness test using different f stops, although I think you'll find you'll get the best results around f8

If these shells are very small, and you're at close to minimum distance than depth of field will be very small. At f5.6 even more so

For example when I shoot diamond rings using a a Canon 100/2.8 macro lens on a 50D, I get close to min distance i.e. 1:1.

Shot from a steep angle above, I need approx 25-30 shots - for an object only about 20mm deep.

BTW if you use apertures smaller than f11 then you will start to see diffraction degradation, definitely by f16 and by f22 any depth of field increase is offset by diffraction damage. I tend to stay between f8 and f10, which is the sweet spot for my lens.

If you can supply more lens details, and how close you were this could help.

Cheers

sweet spot

Posted: 07.03.2009 15:08
by peteschick
Hi Brian,
I was re-reading this post -- were you referring to the Canon 100/2.8 when you said your lens's sweet spot is between f8 and f10?

Thanks,
Nancy

yes it was the 100 2.8

Posted: 08.03.2009 00:58
by BrianS
Hi Nancy

Congrats on getting the Canon 100 2.8 macro.

Re sweet spot, yes between f8 and f11 is the optimum range, by 5.6 I can see a little softness creeping in (but still quite sharp - better than normal lenses), and by f16 I can start to see diffraction issues - not a lens issue - just a physics issue.

Cheers
Brian