How to use extension tube ?

[locksley]

Hi All,

My friend just passed my a set of extension tubes (12mm ,20mm, and 36mm)

May I know how to use it for marco shoot ?
And how to do the calculation ?

THanks

 

[rainman]

It simply reduces the mimimum focus distance...thats mean u go nearer to the object. So when u go nearer to shoot ur object becomes bigger loh!

a 50mm lens need a 50mm extension to reach 1:1 magnification
Think should be a ratio calculation...let other experts enlighten u..keke

 

[locksley]

Thanks Rainman

 

[Echo22]

a 50mm lens need a 50mm extension to reach 1:1 magnification
Think should be a ratio calculation...let other experts enlighten u..keke

can anyone enlighten me the distance you are from the object and the different zoom will give you wat kind of magnification ratio, how to calculate?

thankz

 

[Terence]

You want formulas? Here's one to mull on...

http://kenmcvayphoto.clymbers.com/articles/extensiontubes.html

Some picture examples...

http://www.toledo-bend.com/gallery/index.asp?request=ExtTube

 

[behyx]

1 more question: does extension tubes affect the amount of light entering the lens?

 

[Adzz]

1 more question: does extension tubes affect the amount of light entering the lens?

I guess not, but since light travels a longer distance in the lens, the light quality is somehow affected.