21.5" iMac (mid-2010) on location losing Multi-Shot capability

[Chris Gahran]

I'm shooting a CF-22MS back in 4-shot mode on location with a 555ELD. After a period of idle time, while the next subject is prepared, Phocus 2.6.6 will only recognize the camera as a single shot CF-22. I need to unplug the firewire cable, plug in the FW800 cable again and then Phocus will recognize that the back is a Multi-Shot model. I found out today, Tuesday, I can quit and restart Phocus to have Multi-Shot capability once again recognized. I can then proceed to make my 4-shot images without problems. I use a Tether Tools FW800 4.6 meter cable into a Lindy 5 meter FW800 Active Extension Cable. These cables work flawlessly with my MacPro towers.

I may have finally learned why I have this problem with my iMacs. Apparently, iMacs only supply 7 watts to the FW800 port. I believe I have read that ideally Firewire should supply 10 watts of power to keep Hasselblads happy. Could the lack of power to the FW port be causing Phocus to not recognize the Multi-Shot ability of my back? I've trashed the camera device profile and it did not help. Do I need a powered FW800 hub and who sells those hubs?

Thanks...

[Alex]

Hi Chris,

Although I'm not running on an iMac, I did experience problems with powering my H3DIIMS from bus power via a 10m FireWire. Although I'm not able to suggest how to feed the additional power from the iMac>FW800>Camera (I was using a FW 800 express card with my laptop which has a socket to allow for additional power if required), I can say that the camera and sensor would run all day without any disconnections (with a single battery grip remaining at 100% charge), if were given a 12 volts supply @ 1850mah. Lindy do a really good universal one AC adaptor, however it's useless without a the employment of an express card socket. Maybe Usbfirewire.com may have a cable that allow of a power injection inline.
Is there a way that one change the amount of power supplied to a specific port within the OS I wonder?

Good luck

[Chris Gahran]

It appears I need to add a powered FW800 Repeater to my cabling. I found a document online in which Hasselblad recommends using a powered Repeater. I've contacted the maker of the Repeater and they recommend placing the device in the middle between two 4.5 meter cables.

I'd like to put the Repeater on the location computer table and attach it to my iMac with a .5 meter cable. That way I can have access to the Repeater's additional ports for portable FW800 hard drives. The Repeaters maker is not sure that will work, i.e. get enough power to my digital back which is a CF-22MS.

I can test the device but I have one concern. With a powered Repeater close to the iMac I'll be pushing 10-20 watts into the iMac's FW port which delivers only 7 watts to any FW peripheral. Can that damage the iMac?

A more prudent arrangement might be to buy two Repeaters. Place an unpowered one at the computer and a powered one between the two long cables. (At this time I have a Lindy Active Extension Cable plugged into the iMac and a lighter TetherTools 4.6m cable going to the digital back. Works well but after idle time it can forget it's plugged into a multi-shot back offering only single shot captures.)

Thanks

[jerome_m]

I can test the device but I have one concern. With a powered Repeater close to the iMac I'll be pushing 10-20 watts into the iMac's FW port which delivers only 7 watts to any FW peripheral. Can that damage the iMac?

No. FW is designed to work so that you can connect your Mac (or any powered device) to another powered device.

Please also note that the maximum cable length specified by the IEEE1394 standard is 4.5 meters. This is why your camera does not work on your extra long cable.

[Chris Gahran]

Jerome, Thank you for your reply.

My 5m Lindy Active Extension Cable plus my TetherTools 4.6m cable works without problems when attached to my MacPros.

On location using an iMac which has a FW port supplying only 7 watts (all iMacs I believe are limited to 7 watts just like the laptops) has Phocus losing the camera's multi-shot capability. I'm guessing I just need to boost the wattage on the FW cables to keep my CF-22MS happy.

[NickT]

Chris
Worth noting that mac FW specs are all over the place and vary from machine to machine which I think is what you are seeing.