image out of focus

[rrrobb]

I recently noticed that when i shoot something thats really bright (eventho i'm turning down the iris or adding nd filters) the image goes out of focus and there's no way i can pull the focus back. it's like all the whites are blurring the image.

Is there something wrong with the camera or do i need some sun shades on the camera to prevent the extra unwanted light from coming in ?

here's an example:
http://www.vimeo.com/1145253

[Evolve]

HI,
Liked the piece of work. Nice shots. Very pretty girl. I also liked the musical selection, given that I'm sure you had very few good score choices.
However, to me over half the shots looked soft. So I'm not sure if it's the camera or the user, as there were some real discrepancies there in terms of sharpness across both interior/exterior shots.....

[rainermann]

I experienced when the iris is down to f8 or more the image gets very soft on the EX. Seems to be the case here... it a thing of the optics, not the camera itself...

[matthew77]

It's diffraction softening. It's a property of light when it passes though small apertures. And on the wide focal lengths used by a 1/2" camera, the apertures can get very small.

Actually it happens at all apertures, but because the percentage of diffracted light vs. non-diffracted is greater at smaller apertures, that's when you see it.

Only stop down to f/8 when necessary and never go beyond that and you'll be fine. I try to keep it at 5.6 or wider.

[thxdave]

I'd love to see this tested just so we ALL would know what the optimum f-stop is for the Fujinon lens. If I can get the time to do the test, what is the best way to pull a full-res .jpg image out of the stream that won't degrade (or falsely improve) the frame grab?

[gabrielflorit]

I think the ideal f-stop is between 2.4 and 4. Doug Jensen of Vortex Media says so on his training DVD.

[rrrobb]

thanks guys, you've all been a great resource. Yes the indoor shots are sharp, Matthew77 you're probably right on the optics thing, I did have it over f8 I think. Too bad that information isn't stored in the mp4 as I don't have the original bpav folder anymore to check on the cam.