Re: quick test with extension tubes
jim mij wrote:
Following my rant last night about extension tunes I did a quick test with each of the extension tubes to see if i'd ever use them again or consign them to the garage
Canon apsc camera on tripod, canon ef-s60 lens, natural light, F8 throughout,
Lens Distance to subject MAX DoF extra magnification
efS60 95mm 3mm n/a
+12mm 85mm 2mm <17%
+20mm 80mm 2mm >17%
+36mm 75mm 1.5mm 38%
Note :
Distance measured from ring of lens to the 10 marker on ruler
Pics are sooc jpg
Some thoughts :
Quality does drop off, look at the grain of the ruler / paper at 100%
12 & 20 tubes are very similar, difficult to differentiate
As the extension tubes were added the angle did change, but reflects actual usage. If the subject was parallel to the lens DoF issues are reduced
Conclusion:
Big question is would I use tubes again, or just crop in ?. The 36 is a definite no. I've tried it a few times in real life and been greatly disappointed. Given the quality is bad that implies the 20 is less bad, and the 12 not so bad. The trade off is getting some magnification, but working distance is a tad closer, light and DoF deteriorate. For me its not worth it, I'll crop in
Hope this helps
Jim
lens
+12mm
+20mm
+36mm
It would be more obvious if you had the ruler horizontal and aligned an edge for reference. You're getting a major increase in magnification with the 36mm tubes, but you aren't parallel to the subject matter.
That's roughly the native 1:1 with a micro 4/3, so it's not that extreme. If you don't pick up glares within the tubes, they shouldn't degrade the image. Even at 1:2, you have to be very aware of the angle or you'll never get enough dof.
I can barely tell the difference between tubes with a standard lens and a macro lens at the same image size, so I don't think the extension tubes alone are the problem.