Canon 550D aperture without a lens

[mag10]

Hello,

When I take off the lens to attach my Canon 550D body onto my C-8, I can't get an f-stop reading. The display says f/00, and I can't change this in any way.

I understand the aperture values are linked to the lens that is used, but in practical terms, what does f/00 mean? I suppose it means my aperture is wide open, but could someone confirm this?

Thanks.

[Cornelius Varley]

Hello,

When I take off the lens to attach my Canon 550D body onto my C-8, I can't get an f-stop reading. The display says f/00, and I can't change this in any way.

I understand the aperture values are linked to the lens that is used, but in practical terms, what does f/00 mean? I suppose it means my aperture is wide open, but could someone confirm this?

Thanks.

If there is no lens attached to the camera the camera will display f/00. The electronics in the camera would normally show what aperture has been set on the lens but without a lens attached F/00 is displayed. The same applies if you attach the camera to a telescope.

Peter

[jgs001]

The aperture value displayed, is the focal ratio (focal length/aperture) of the lens. When you connect something with no electrical contacts to the camera, the camera cannot determine the setting in use, so displays f/0.0. In the case of your scope (I don't know the exact details,but I suspect) it's f/10. This is not adjustable from the scope (the focal ratio is fixed by the design, a camera lens has an adjustable opening), but you can add barlows and reducers to change the focal length, changing the focal ratio.

[Merlin66]

Without the lens you can't use the camera readouts of aperture....

This now comes from the optical set-up of the telescope.

The camera should be set to M manual.....exposure time to suit the object.

A remote control helps reduce possible vibrations.

[mag10]

Thank you very much.

(Of course. The C-8 is f/10) I keep forgetting important bits like that.

Thanks again!