This is my weakest point. I mostly have manual lenses and I got used to manual focus very much. Prefer it in most situations over autofocus.

But the problem starts for me when using manual lenses indoors where light is more dim.
My 5D is usually set at AV. After mounting the flash (580 FX) I make sure, that it is set on ETTL mode. I am also bumping the ISO up to 400. Now with this setting (aperture set around 4 to 8) the flash fires, but obviously to weak. The shutter speed is just below hand held. I am getting blurry images.

I am using an af-confirm adapter with my zuiko lenses. The chip has a is factory setting of f/1.8 50mm.

What is wrong ? Any advice I would appriciate.

Hi,

I use flash in manual mode strobist style. It is not hard to learn and it works great with manual focus lenses--no need for ETTL, which I also thought worked poorly anyway. As long as the light isn't changing quickly manual flash works great. I put a Nikon SB 28 on a flash bracket or off camera on a stand either way it only takes a minute or two to get the right amount of flash. I hope this helps.

No other way?

By using different settings on the flash ?

Likely the AF confirm chip is confusing the flash system by reporting an aperture of 1.8. Flash exposure is about aperture, ISO and subject distance. Reporting an incorrect aperture to the flash system will seriously mess with the exposure.

I'd recommend using a non-AF confirm adapter with your lenses for flash work or going to manual or auto flash rather than E-TTL.

I would like to test, if it will work by taping the contacts.
Of course I will lose the af-confirm feature and the camera and flash will get no information at all.

I am here in vacation now (Philippines).

I have a programmable adapter chip with my Contax VS f/3.6 35-70mm.

Would like to test it also by setting an appropriate aperture first, before using the flash.

Just now I gave it another try (5D + zuiko f/1.2 50mm + 580ex)

camera set on 200 ISO and AV (shot at f/5.6 and f/8)
flash set at ETTL

No problem !

I don't know this. Weird ! Sometimes like this, sometimes like that.

I use M mode with flash and MF lenses. I set a shutter speed of 1/60th or so, maybe ISO 400-800 (to pick up a good dose of ambient light), choose my aperture, then use FEC to tune the exposure. Once set, it works even over changing lighting very consistently.