Originally posted by Lev hmm... very interesting. Don't have any lens with manual aperture to test it. In the first part it is obvious will get darker but in manual mode isn't it compensating with iso or shutter speed? which mode is set on camera in that case?
Well on my K-1
In Manual mode
If you set the Aperture ring to "A" and stop it down a bit --
With LV off the lens sits there wide open as you expect
With LV on it stops down to the designated fstop. When flicking the LV on/off you can see the lens open close.
The LCD screen responds to adjustments in aperture, shutter speed and Iso.
With the Aperture ring in the manual mode in LV the lens is wide open and there is no response to aperture, shutter and Iso adjustments.
For critical manual focusing this manual aperture setting has optimised the camera for best practise. Which to me is- wide open , LV focus peaking in association with the zoom function.
Using the "A" setting optimises the camera for depth of field preview. But for my approach it is less than ideal because I tend to leave my Iso at base 100 (utilising Iso invariance in PPing) So often my LCD is severely underexposed in "A".