A900 strange behaviour...

Started Oct 29, 2010 | Discussions thread
Tony Beach Forum Pro • Posts: 11,967
Re: A900 strange behaviour...

Jakub Kubica wrote:

How to reproduce:

Tools needed: Tripod, A900, fast lens (1.4 preferably)

Set camera to M mode, set proper speed, aperture set to maximum.

Make photo #1.

Next step, disconect lens (press lens release button and hold), make photo #2 using the same speed (aperture will be maximum because lens will be disconencted).

Compare photo #1 and #2.

I didn't have to actuate the shutter to see the issue on my A850. Metering changes and is 1/3 of a stop less when used wide open. This works on all my lenses except one, my Super Angulon 28/2.8 PC which is not chipped. You also get a clue about what is happening when you turn on the menu and look at the AF fine tune which disables when you press the lens release button -- that is, the lens ID is lost.

Interestingly, the metering anomalies are largely rectified if you stop the lens down a 1/3 of a stop, so that would confirm that there appears to be a 1/3 of a stop hedge in the metering. Also, switching between Matrix, Center-weighted, and Spot metering appears to change things, with Matrix metering being the least affected. I suspect that this hedge is there because lenses vignette more wide open and that changes metering, to compensate for that the meter does a look-up of the lens ID which is not possible when you push the lens release button.

Post (hide subjects) Posted by
Keyboard shortcuts:
FForum PPrevious NNext WNext unread UUpvote SSubscribe RReply QQuote BBookmark MMy threads
Color scheme? Blue / Yellow