From: "Robert Rolf"
> It is not your FPS that is the problem. It is your shutter speed
> and/or lack of sensitivity of the sensor (CMOS is about 1/4 that of CCD).

Yes, I stated the problem in a wrong way.

> Cheap web cams use cheap lenses with high 'f' numbers to get good
> depth of field, since they don't have autofocus. This means that the chip 
> has to have a lower shutter speed, so lower effective FPS.

I'm thinking about getting a fixed iris lens for this exact same reason, to 
leave it fixed at some f-stop that provides enough depth of field. Do you 
think the auto-iris would be a better choice or it would only bring 
complexity as I leave it to the camera to decide which f-stop to set?

> USB web cams are limited by the USB 1.x data rate (12Mbps),
> so I would recommend a firewire camera if you want a serious
> amount of FPS (we're doing 120 FPS for a gait analysis project).
> Or a good video digitier (presumably High speed USB or Cardbus),
> and GOOD composite video cameras (but you pay a price in lost resolution).

I don't need a very high fps, 30-60 fps is more than enough, it's really the 
shutter speed that I need. May I ask which camera do you use? Right now we 
are looking at three models that fit our budget and weight requirement: the 
Cohu 3600, the Hitachi KP-D20B and the Kowa PX-70K. The first two are 1/2" 
CCD sensors, and the Kowa has a 1/3" sensor. While Cohu and Hitachi are 
known brands, I'm not sure about the Kowa. It has a very attractive price 
point ($325) against around $800 for the others. They have similar specs 
(except the sensor size), I wonder if the price difference implies in much 
lower quality.

>
>> certainly create an active gimbal ala Red Team, we don't have the 
>> resources to do that. Instead, a higher fps should be enough to freeze 
>> movement under certain vibration scenarios.
>
> Not really. It just increases your bandwidth and processing requirements.
> Presumably your vehicle is moving fairly slowly relative to processing
> speed.
> Why do you not want to tackle the problem correctly, by shock mounting
> the camera or using a shorter exposure time (the FPS can be the same)?

The camera will be shock mounted, but I won't spend time on an active shock 
mounting device. That's what I meant... and the fps, yeah, you know, my 
mistake.

Cheers

Padu 

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