extension tubes

[Aschlaman@comcast.net]

I was wondering if someone could tell me how extension tubes work? Is it something that is used with a macro lens? If you use an extension tube with a macro lens doe it allow you to get better magnification? I have always wondered about this.

Thanks

Art Schlaman
Downers Grove, Illinois USA

[tim]

An extension tube is just a hollow tube with pass-thru electrical connectors. It works by moving the lens further from the sensor.

[foxbat]

If you use an extension tube with a macro lens doe it allow you to get better magnification?Yes it does. For example, if I set my Sigma 105mm macro to 1:1 magnification then add 67mm of extension an object that previously filled approx 50% of the viewfinder now fills approx 100%. So now I have 2:1 magnification at the expense of lost light, working distance and extreme sensitivity to movement.

[cmM]

it changes the focus distance, that's all. (at the expense of some light loss, as mentioned by foxbat)

[willg]

it changes the focus distance, that's all. (at the expense of some light loss, as mentioned by foxbat)
canon makes two the 12mm and the 25mm..i have the 12mm because the 25mm was too much to handle..VERY sensitive to movement..0 dof

[Aschlaman@comcast.net]

Thanks for the information.

Art Schlaman

Canon 20D, 35mm f 1.4L, 50mm F1.4. 85mm F1.8, 18-85mm IS, 17-40MM f4L,
300mm F4L, 70-200MM f2.8L IS, 100-400mm L,
Tamron 28mm-75mm f 2.8, Tamron 180mm f2.8 macro, 580 EX flash

Epson RD-1 with Zeiss ZM 35mm f 2
Epson P2000 storage device