Extension tube insanity

[Kretch]

OK maybe I'm an idiot or doing something wrong. But I bought some extension tubes (the manual ones). I had heard you lose a few stops of light, but no matter what I do, the viewfinder is almost pitch black. Even using the #1 smallest tube. Why is that. Any help?
These things are absolutely worthless. What am I doing wrong?
Thanks

PS, this happens with ALL my lenses. Even my fastest glass.

[Kretch]

Never mind, I found the answer

[WVCoalMiner]

OK What was the answer???

[Kretch]

LOL, sorry.
I actually figured out the answer myself.
The problem is, those cheap $7 extension tubes work great, but not on gelded lenses.
You must have lenses with an aperture ring to set because unlike the more expensive tubes ($100) they don't have contacts for auto focus and aperture setting.
In other words, they won't work on my 70-200vr, but shine on my older 85mm.

[OsmosisStudios]

Originally Posted by Kretch

they don't have contacts for auto focus and aperture setting.

They actually lack the small arm that moves the tab on the lens to control aperture (it's move physically by the body when the lens is mounted, not electronically within the lens). Just fyi.

[ravncat]

You can use a small wedge, (I`Ve used a plastic bag even) to adjust the position of the aperture on gelded lenses. Unfortunately, you have the choice of - wide open , or somewhere wider than closed down to work with via this method - but it`s one way to use castrated lenses.

just be very careful about making sure you can remove whatever wedge you find to hold the aperture wide.

[Kretch]

Originally Posted by OsmosisStudios

They actually lack the small arm that moves the tab on the lens to control aperture (it's move physically by the body when the lens is mounted, not electronically within the lens). Just fyi.

Right!, thanks for that. It makes sense.