EOS 70D shoot without lens

[DocksideDave]

I'd like to use my 70D with my microscope but I may need to trick my shutter into releasing without "focus acquired" message from the (absent) lens. What's the accessory needed, to complete the electrical data so that I can use the T-mount?

Other cameras have this function "release shutter without lens" but not the 70D.

[Waddizzle · Accepted solution]

You need to contact the manufacturer of your microscope about adding a T-mount adapter, or another type of camera adapter.

The message is normal.  There is not aperture control available. I recommend using Live View mode with ExpSim enabled.

[ebiggs1]

Try setting the camera to manual mode. It will not take an exposure with the lens removed except when in full manual ("M" on the mode dial).

[DocksideDave]

Thanks for the reply--I should have mentioned that I tried it in Manual. I can focus using the microscope controls and I can set the ISO and exposure time. The Aperture value, however, displays in the viewfinder as zero dot zero; and even though the shutter is set for 1/250, it stays open for about 20 seconds. I'm thinking that theoretically the aperture is f/1?

With this camera, am I going to need an adapter ring with electrical contacts in it to provide the needed inputs?

[Waddizzle]

If you have a T-mount adapter for the EF mount, then you should be good to go.

On most Canon bodies, the aperture displays as "F00", not as "zero dot zero" as you have described.  Can you take a screen shot of the camera display with a cell phone or something that shows that display?  Do you see it when you press [Q}?

Are you certain that there is a memory card in the camera?  There is a setting that prevents the camera from shooting without a memory card installed.

What shooting mode are you using for the camera to override the SS set for 1/250?  Use Manual mode, M.

[DocksideDave]

I should have typed "zero (dot) zero" as there is not actually a decimal point, just some extra space [photo].

I can choose the shutter speed in Manual mode by using the scroll wheel near the shutter release to move the exposure "needle" to the center of the scale.

Looking at the Quick menu, there's a screen for setting aperture manually, but no action is possible.

There's definitely a memory card in there and I can review what's on it.

I could use the iPhone but it's kinda kludgy and I thought I could do better with the Canon, plus the field would be quite a bit bigger shooting straight into the tube (no eyepiece).

[Waddizzle · Accepted solution]

You need to contact the manufacturer of your microscope about adding a T-mount adapter, or another type of camera adapter.

The message is normal.  There is not aperture control available. I recommend using Live View mode with ExpSim enabled.

[DocksideDave · Accepted solution]

Didn't find ExpSim in the .pdf, but LiveView shooting works--not with the Video/Still knob, but by touching the Start/Stop button in the center of the knob, the mirror is raised. In Manual mode it allows the shutter release and uses the focus and exposure time I selected. Touching the Start/Stop button a second time returns the mirror down. Thanks for sending me back to study that.