Issues with FX-1 - Manual Focus

[Alex Perkins]

Howdy folks. I am a newbie, and this is my first post.

To my experience, still digital cameras' auto-focus systems lock onto the closest subject 99% of the time. Not FX-1's auto-focus. Many times, it locks onto brighter or more contrasty background. This forces me to use the manual focus feature.

This question is for those who actually use the manual focusing ring:

On my FX-1, the focus ring is too sensitive. A movement of less than 1mm will shift the focus a long way. Here is the way it goes (in meters):
0.1 0.2 ... 1.9 ... 2.0
2.2 2.5 2.9 3.4 4.0
5.0 6.5 10
20 100 <infinity>

No matter how careful I move, I cannot achieve any other numbers in between. In 90% of the shootings, I really need a stable (not sensitive) manual focus ring to move between 2.2m to 5m (6ft - 15ft).

Even between 2.2 and 5.0 is a mere touch or bump on the ring.

Did Sony intentionally do this to "dumb down" the FX-1? Or this is a known issue and my camera is defective?

( EC lingo: I am sure, replacing a resistor or soldering a shunt resistor to the ring's output will make the ring less sensitive. Also, changing a number in the software might do the trick too. )

Thank you guys!

-Alex

[Boyd Ostroff]

Welcome to DVinfo Alex. I have a Z1 and I also see similar behavior, but I'm not sure that you understand exactly what's happening. Try zooming all the way in to the max. Now you should find that the focus distance increases and decreases much more smoothly. Now zoom out all the way to full wide and you will see the focus jumps in big increments as you describe.

This has to do with the relatively small sensors (1/3" nominal) on the Z1/FX1 and other prosumer cameras as well. At the wide end of the zoom the camera has tremendous depth of field and focus is much less critical.

So I think the numbers you list are accurately portraying your depth of field. For example, at full wide and a medium f-stop it's possible that everything between 20' and infinity will all be in sharp focus. This is also affected by the f-stop; larger f-numbers will result in greater depth of field for a given zoom setting.

I don't think there is anything wrong with your camera, that's just the way it is. Personally I like the focus ring on my Z1, it's much better than my PDX-10 or VX-2000. Try connecting your camera to a good HD monitor and observe what happens as you focus. With a little practice it works very well, so I don't think you should fixate on what those numbers are telling you.

[Alex Perkins]

You are right....focusing scale is dramatically different from wide to closeup.

I wonder, why they make the video chips so small? Is cost the only factor?

In full-frame DSLR and 35mm film, the imager has the size of 2 quarters.

In our 1/3" CCDs, the imager is a tiny puny bit, only big enough to fit the word "united" stamped on the quarter.

Broadcast grade CCDs are 2/3"...still a joke to 35mm film. Gosh, I thought 35mm film is small enough already!

( Yes...yes...I know about the weirdo 1/2" CCDs too. )

I guess...that's why all the soap operas seem darn sharp compared to film movies!!

Well, now I am clear that I can never get Fujinon kind of focus scale on my 1/3" handycam!

( I missed the focusing experience from Vivitar Series-1 28mm-70mm f/2.8 lens. It takes a good turning between 10' and 30'. Shot many basketball games with that. )

Cheers,
Alex

[Serena Steuart]

Welcome to video. And you haven't even mentioned the lack of TTL focusing!

[Vaughan Wood]

Nor the lack of light!