From: Alan Friedman <alan@greatarrow.com>

Date: September 8, 2010 2:09:05 PM MDT

To: Astro_IIDC@yahoogroups.com

Subject: Re: [Astro_IIDC] Re: Flea2 cameras on the 'bay

There is also the light issue to consider. At focal lengths of 7 meters+ I do not have enough light to set the shutter faster than 33ms - and at this shutter I have the gain almost all the way up. 

The only subject I can shoot with my little 8 bit DMK set to 60fps is the sun...

best,

Alan

On Sep 8, 2010, at 3:28 PM, Milton Aupperle wrote:

Hi Jim;

On 8-Sep-10, at 12:23 PM, Jim Chung wrote:

> Hi Milton,
>
>
> So I got the eBay Flea2 and it works so the ad was legit, don't know
> why eBay pulled it.

I have one here too for testing (FL2-08S2C model) with FW 800 cables.
>
> I haveit plugged into my 4 year old Mac Book Pro FW400 port and I can
> do 60 fps at full resolution (1032x768) but in only 8 bit. My
> original Flea could only do 30 fps at 8 bit (same resolution).

Actually that's in Format 7 and your not getting 60 fps. Your likely
getting 31.33 fps in 8 bit and maximum 32.95 in 16 bit with a FW 800
cable (just tried it).

If you check the Capture log in Astro IIDC 4.06, it indicates what the
theoretical maximum frame rate is for Format 7 camera modes.

For 8 bit it shows:

IIDC Format:7 Mode: 0 ClrCode: 9 MaxFps: 31.33 MaxPacketSize: 3136

and for 16 bit it shows:

IIDC Format:7 Mode: 0 ClrCode: 10 MaxFps: 32.95 MaxPacketSize: 6596

Format 7 cameras can have all sorts of weird frame rates as they are
camera specific. We pigeon hole them within the range of the fixed
rate Format 0, 1 and 2 modes a camera can run in, otherwise the
interface gets really strange to work with. However the maximum rate
is a compromise. If the camera is in a Format 7 and it's frame rate is
faster than one of the other ones, then we enable the next highest
frame rate.

So if the maximum frame rate is 31.33 frames per second, then it's
faster than 30, but slower than 60, so then we enable the 60 fps so
you can run the FMT 7 cameras as fast as possible.

>
> Do my question is, if I run a 10 m cable from I5 IMac in my 2nd floor
> office down to my front lawn so that I can take advantage of full
> FW800 speed, will I actually get more than 60 fps?

I'm not sure if a 10 meter FW cable will work reliably. It certainly
violates specification when running at FW 800 speeds for distance, as
the maximum is 4.5 meters without a repeater.

If you run the cameras at lower data rates, then you can use longer
distance with FW 800. So at FW 400 speeds, you might be able to run a
10 meter cable. I've heard of people running FW 100 cameras speeds at
100 meters distant over FW 800 cables.

> Like Mark, I have
> to order a FW800 cable to try the Flea2 on the IMac.
>
>
> Jim

HTH..

Milton Aupperle