Extenders: does brand really matter?

c h u n k wrote:

gardenersassistant wrote:

c h u n k wrote:

stevendillonphoto wrote:

I have the Kenko, but I don't use them much. I did an entire session with the 36mm last year, but it caused a good bit of vignetting that I didn't care for. I got a 500D this year and I'd much rather use that over a tube because 1) there is no light loss and 2) no vignetting.

The "light loss" is a non issue because its due to the effective fstop changing. There is no difference with tubes vs closeups for light relative to fstop...or very little.

for the avoidance of doubt (I know it is implied by the previous sentence, but it might not be obvious to everyone): "There is no difference with tubes vs closeups for light relative to effective fstop...or very little".

And the effective f-stop increases as you add tubes, but doesn't increase with a close-up lens. (I've never been able to find definitive documentation of this, but my experiments have been consistent with it being true, or as nearly true as my comparisons can't distinguish otherwise.)

Correct. So just change the Fstop on the camera. Bam. Problem fixed.

As long as you have the f-stops available. As you will know, but others may not, as magnification increases past a certain point (which depends on the kit being used) you can get a smaller effective aperture (with the accompanying larger depth of field but greater loss of light) with macro lenses/tubes etc than with close-up lenses.

This can of course have consequences that may seem counter-intuitive. For example, people often associate large depth of field with small sensors, but with for example an MPE-65 from 2:1 up wards I could get greater depth of field with a full frame camera than I could with my 1/2.3" sensor bridge cameras using close-up lenses to frame the same scene size (even though the MPE-65 only goes down to f/16 while the bridge cameras go to f/45 full frame equivalent). With the MPE-65 on APS-C I could get greater depth of field from 1:1 upwards than with my small sensor bridge cameras, and at less magnification than that with a macro lens that goes to f/22, and at any magnification with an f/22 macro lens on micro four thirds.