First time beyond 1:1 reproduction ratio for C&C

[Marc-Etienne]

I recently purchased extension tube (total length 68mm). I coupled those extension tubes to my Sigma 105mm macro and my ring flash and went on the "hunt" for those guys (from the family of Chironomidae for the entomology interested people about 3mm (0,118 in) long by 1mm (0,04 in) wide). It wasn't really a "hunt" because those guys are everywhere! They come in cloud and copulate on every surface they can find including yourself...:er:

Anyhow... These are my two best shots (I didn't shoot for long, I was turning into a giant fly orgy...) both shot taken at 1/200s, ISO 400, f16 and flash output 1/8. #1 as a light crop on the left and bottom and #2 is not cropped at all. PP included a bit of sharpening, color saturation and very light exposure correction.

#1

#2

As usual, I'd like to know what you guys think.
Also, if anyone knows how to approximate reproduction ratio when adding extension tube to a macro lens (or any lens) It would be nice to know. I found some "equation", but according to those, these shots would represent a reproduction ratio of around 1.2, sounds hard to believe. Thanks

 

[ChrisA]

You've got some good sharpness from the tube addition. Not overly interesting pictures to me, mainly the dull surface etc, I'm sure you'll get some better ones soon. I believe that the reproduction ratio with an extension tube depends on 3 things - the length of the lens, the size of the extension tube, and the size of the sensor used. So maybe the equation needs reworking ?

 

[Marc-Etienne]

You've got some good sharpness from the tube addition. Not overly interesting pictures to me, mainly the dull surface etc, I'm sure you'll get some better ones soon. I believe that the reproduction ratio with an extension tube depends on 3 things - the length of the lens, the size of the extension tube, and the size of the sensor used. So maybe the equation needs reworking ?

Thanks ChrisA! I'm hoping as warmer weather quicks in, I'll be able to see more interesting creature in more interesting environment. Thanks for the encouragement! These two matting couples were taken on the hood of a white pick-truck (Not much texture to it...).

As for the equation, I had:

Reproduction ratio = (Length of tube + Master lens advance volume) / master lens focal length
Master lens advance volume = (master lens focal lens)^2 / (master lens distance reading - master lens focal length)

That gives me a reproduction of about 1.15... Seems really small to me... I'll see if I can find something else like you say that includes size of sensor too.

 

[ChrisA]

I wonder if this reproduction ration should really be read as magnification. I maybe wrong, but if you say have a 1.6 crop sensor anyway your effective mag ratio would be 1.2 x 1.6 : 1 = roughly 2:1 (when compared to the same image on a full frame sensor).

But I could be barking completely up the wrong tree. I'll have to have a read around.

I did see this out there on reproduction (quick google earlier)...http://savazzi.freehostia.com/photography/reproratio.htm