Extension tubes with 100 mm macro

Can someone give me an idea of what 58 mm of extension tubes would do to the magnification with the 100 mm f/2.8 macro? Unfortunately, the tubes that I purchased are cheap and they do not have the electronics, so I was unable to stop it down a little for a little greater DOF.

I took this particular shot today with that setup.

Neat closeup- with a non electronic setup you need to get used to focusing in low light , I did this for a while at F11- did sometimes attach a video light to my flash bracket to help.
The magnification will be near to 2:1 at min focus- easiest thing to do is take a pic of the mm scale on a ruler then the mag= sensor width/mm of ruler across width. Assuming a 1.6X crop camera the sensor width is about 22.7mm and at 2:1 you will see about 11mm of ruler scale in the viewfinder.
Brian V.

Do you mean that you were able to set your aperature to f11 when focusing in low light with a non-electronic setup? I see "00" in the aperature field in Manual (M) mode when using the non-electronic tubes that I purchased.

I did send a message to my wife last night to a link for a set of AF electronic Kenko DG tubes for Father's Day.

kwsanders wrote:
Do you mean that you were able to set your aperature to f11 when focusing in low light with a non-electronic setup? I see "00" in the aperature field in Manual (M) mode when using the non-electronic tubes that I purchased.

I did send a message to my wife last night to a link for a set of AF electronic Kenko DG tubes for Father's Day.

The lens I Had on the front was an old manual pentax 50mm - I'd managed to couple a set of pentax tubes to a canon EOS Tmount.
You should be able to preset the aperture of the lens by attaching it directly to the camera, set the aperture , turn it off and then attach the rings etc.
Brian V.

I have not tried this but I read somewhere that it was possible to stop down EF lenses by a proceedure something like;
1. put on camera, set f-stop, press and hold stopdown button
2. keeping stopdown button depressed turn of camera
3. lens is now stopped down, remove and use with non-linked tubes etc.

However Kerry it would be worth saving up for some Kenko tubes that preserve all the electrical connections. Macro is hard enough without having to deal with stopdown focussing.

I was thinking that same thing yesterday, but it did not work. I attached the 100 mm macro to the camera, set the aperture to f/8 and then reattached the tubes. I got what is in that picture.

Interesting. I just set it yesterday, turned off the camera and reattached the tubes with the lens to the camera. I will play around with this later todya and see what I come up with. I do agree with your assessment that I need to invest in a good set of tubes.

Kerry you have to hold down the depth of field preview button so that the lens is stopped down when you turn off the camera.... normally the lens sits wide open to allow you to focus.........then when you press the shutter it stops it down to your selected aperture, flips up the mirror and trips the shutter

Thanks for the tips everyone. I am definitely going to get out and give it a go this evening. I do not have to worry about rain in my area. We have officially had rain on four days during the past 30 for a total of 0.84 inches. Of course, in my area, it has only rained on two of those days.