« on: April 30, 2013, 06:31:20 PM »
There is no quality loss when using tubes. It is only air inside of them and no glass. You loose 1-2 stops, and you have an extreme narrow depth of field, but you will get youre macro.
Lenses are generally optimised optically at infinity. I have the 50/2.5 macro. It has a floating element system, which means it changes optically as it focuses closer, so at 1:2 its not the same as at infinity. It is better when focused to 1:2, than focused at infinity with the EF25mm. It is also better at 1:1 with the life-size adapter that has glass than with my EF25mm extension tube. Simple lenses such as the nifty fifty simply rack the entire optical system further from the focal plane.
However, the (slight) reduction in optical quality may be acceptable. This will vary between lenses. My 70-200/4 (non-IS) is definitely less sharp than my 200/2.8 when used with the EF25mm extension tube. Indeed, I suggest that for the OP, extension tubes would meet his needs optically and financially, but a close-up lens would be easier when busy on the job.
I'll do some comparison shots in a few hours of the 50/2.5 with extension tube, life-size converter and with 250D closeup lens.
TY man...the more images I see from each option the better informed I am as I move forward!