40D pop-up flash use with manual lenses

Hi there. I'm using some vintage fully manual lenses (like M42 or OM , etc.. with adapters). I set the camera on "M", choose my aperture on the lens and adjust my ISO and shutter speed manually (no auto ISO). The strange thing is when I use fill in with the build in flash, the exposure remains the same, no matter what changes I do to any other setting ! Really ! Doesn't make much sense to me... given 1/125, 400ISO and F2 looks just the same than 125, 400 ISO F8 ! (of course aperture works, I checked) Can someone please explain ? Turning the big wheel (as for +/- ) doesn't make a difference either. Looks almost like the flash output compensate automatically for exp differences... Thanks for reading.

I don't know what what's going on but I read that the 40D has a 'flash exposure lock' button. See this link. From what I read, it seems that using the button - even in manual mode - instructs the 40D to automatically determine the exposure settings based on flash illumination. If the button's stuck on "on" (physically or electronically), then you'd probably get the result you describe. You may be able to check in in the Exif Metadata the whether flash exposure lock has been set or not.

 

Hope this helps,

 

Mike

 

UOTE="Philipp500, post: 5803843, member: 1524048"]Hi there. I'm using some vintage fully manual lenses (like M42 or OM , etc.. with adapters). I set the camera on "M", choose my aperture on the lens and adjust my ISO and shutter speed manually (no auto ISO). The strange thing is when I use fill in with the build in flash, the exposure remains the same, no matter what changes I do to any other setting ! Really ! Doesn't make much sense to me... given 1/125, 400ISO and F2 looks just the same than 125, 400 ISO F8 ! (of course aperture works, I checked) Can someone please explain ? Turning the big wheel (as for +/- ) doesn't make a difference either. Looks almost like the flash output compensate automatically for exp differences... Thanks for reading.

I don't have my 40D in front of me, but when you access flash control in the camera menu, what are the "built-in flash settings"? If it's set to E-TTL, it will change the power to expose properly.

Let us know!

Adrian

Thanks a lot guys. All sorted.

How?