Eagle BIFs and URGENT AF-S question to birders/tele shooters/trouble shooters!

Started Jan 30, 2013 | Discussions thread
OP windsprite Senior Member • Posts: 2,614
Re: Relax, you do not have a problem!

FrankG wrote:

Marianne Oelund wrote:

You are creating a problem by shooting through an open door, from a heated indoor environment, through the high temperature gradient to the cold outdoor air. It's the turbulent air at the open door which is causing the AF jitteriness and inaccuracy.

If you go completely outside, close the door behind you, move away from the building and try your AF again in an entirely cold environment, I'll bet the problem goes away - especially if you let the camera and lens acclimate a bit to the outdoor temperature.

You could be right, although she did originally say:

"Then yesterday I took it out on our deck and tried shooting some objects around my house (I have a cough and fever right now and can't venture out into the wilderness to test this thing). I live right in the city, so my subjects were urban junk like TV antennae, electrical poles and insulators, crows, airplanes, etc. ..."

I'd assume "out on our deck" means outdoors (that's what it would mean in the UK!)? So I'm not sure how that is shooting through a high temperature gradient?

As I mentioned I have encountered what at least sounds superficially like a similar symptoms with my 300 AFS in use with my D7000. just as bad even with either a 1.4 or 1.7 TC fitted. I have put it down to an intermittent contacts problem between the lens and the D7000 as I can make the problem temporarily go away either by exerting a slight twisting force on the lens barrel or by tilting the camera significantly upwards (as if shooting birds in flight for example). By contrast the same lens works fine with my D800 - no sign of the problem at all.

Anyway let's hope you are right!


I did get out on the deck and shoot, as I wrote in my earlier post, but it seems I didn't get far enough away from the house.  The house is brick, and it was a little cold but sunny that day, so the brick had probably absorbed heat and was creating a little envelope of warm air around the house.  Once I go far enough outside the envelope, the focus stabilizes.

I got completely outdoors for a short time yesterday and was able to test the 300/4 and D300 on my dogs.  Everything seems to be working perfectly.  So I'm pretty well convinced my particular problem is solved.


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