Kenko tubes

[sting]

Hi my tubes arrived today but the instructions are in German, I can see how to use them but wondered how to choose which ring to use and why? I have the 12mm 20mm and 36mm so when do you use each one? I put all three on my 70-200 and went in the garden seemed to go ok but not as close as I imagined it would be. Also these bugs are just so fast and never stay still I have lots of blurry shots lol.

 

[Mud]

The longer the lens, the more tubes you'll need. The more you want to reduce the minimum focusing distance, the more tubes you'll need. The more tubes you use, the more light you'll lose.

 

[sting]

Hi thanks for the reply is there a calculation to work out this out?

 

[Canon Bob]

Hi thanks for the reply is there a calculation to work out this out?

Mag with tubes = Native mag + ( Tube length / actual focal length )

Be aware that the focal length of your lens is specified when focussed at infinity and it will be less when focussed at minimum focus distance.

Bob

 

[adsayer]

also you'll find you'll get more magnification at 70 mm rather than 200 mm. And even more magnification with decreasing focal length.

I used a 17 -35 mm with the extension tubes and managed to adjust the zoom (and essentially the focus) so that I was focusing on the front element - which was pointless but I was adjusting between a fly at 10 mm away from the element