Autofocus on the Sony Alpha SLT A-77

[Cleto-Nevio]

Greetings All,

I recently took delivery of my much-awaited A-77 (with 16-50mm lens) and loving every minute playing with it. It's one mean camera and I'm looking forward to a lot of fun with it.

I however seem to have what appears to me to be a 'lazy' autofocus function. By that I mean that occasionally when pressing half-way down on the shutter button, nothing happens. If I then put my ear close to the lens I can hear it feintly humming, but no green focus squares in the viewfinder/on the LCD screen or any indicator beeps. If while holding my finger on the shutter button, I give the focus ring a nudge, it then activates and focuses - and the next 10 or so shots work fine before it then stops autofocusing for a shot or 2.

Could this be due to the lens being brand new, i.e. the moving parts still a little tight? Although I've never heard that camera-lenses need to be 'run-in' to facilitate smooth functioning.

Any ideas or tips would be most welcome.

Many thanks,

Cleto

PS:- I have done the latest firmware update.

[Mick2011]

Hi Cleto, welcome to the Sony Forums

There should be no delay of this kind. The a77 is pretty quick to autofocus and I suspect there is either dirt or misalignment causing the problem.

You could try removing the lens, visually confirming there is no physical issue (dirt etc) with the gold contacts on both camera and lens. Avoid touching them; let me know if you see anything and I'll let you know how to go about cleaning. Make sure the lens mount is fully engaged when you replace it – there may be a small amount of 'play' but the lens should be turned fully anti-clockwise.

If the problem persists (or if you'd prefer not to do any checks yourself) contact the guys at Sony Customer Support who will advise you further, including whether a warranty-based repair is required. This 'sticky' post explains the procedure:

https://www.sony.co.uk/discussions/message/651957#651957

Cheers

Mick

[Cleto-Nevio]

Hi Mick,

Sincerely appreciate your kind reply - thanks a lot.

I have taken a careful look at the contact points and other likely areas for dirt - no traces that I can see. I've also tried an 18-55mm lens and all works normally.

So I think the problem is the 16-50mm lens itself. I took approx. 100 pics today, around 50% of which were with the AF working fine. The other half needed me to toggle the focus ring before the AF would engage. As mentioned yesterday, if I put my ear to the lens body when pushing halfway down on the shutter button, I hear the motor inside working (obviously trying to focus), but not managing to activate the green light and shutter. This is why my thinking is that the issue could be due to tightness of the moving parts in the lens. Or possibly the camera settings? But I don't think so.

Lastly, when looking into the lens, I notice that the aperture is not a unifrom pentagon (please see attached, an image illustrating the aperture-shape). I know this lens is a fixed (2.8), but is this shape normal?

Again, I appreciate your feedback.

Kind regards,

Cleto

[Mick2011 · Accepted solution]

Hello again

This is all pointing at a defective lens, I'm afraid.

Personally, as it's brand new, I'd be looking to get a replacement at the shop/dealer you bought it from. Failing that, a repair as suggested above.

Good luck

Mick

[Cleto-Nevio]

Thanks Mick,

Much obliged for your advice - I will continute with the dealer. Fortunately, he has been quite professional and accomodating on the items I've purchased thus far so I'm confident he'll assist.

Best regards,

Cleto