Helping E-TTL II Outdoors with Optic Cable?

[neil_v.]

Any thoughts on

running fiber optic

cable between EX

strobes and ST-E2

outdoors?

 

I have a few

low-budget/non-profit editorial

shoots outdoors this

summer, to be shot

with ST-E2 and

multiple EX strobes

using high-speed

sync for 1/500.

 

I'm concerned that

occasionally I'll be

at a shoot and won't

be able to work

around the ambient

IR to get E-TTL II

to work wirelessly.

I'd like to have a

backup plan other

than moving to a

single on-camera

strobe.

 

A RadioPopper P1 kit

would do the trick,

though that's

pricier than I'd

like ($180 per

receiver or

transmitter).

 

Which leads me to

the idea of keeping

a couple coils of

optic cable and with

some kind of pickup

on the end, that I

can gaffer-tape to

the fronts of

strobes and ST-E2 in

an emergency.

 

Another option is to

mod the EX strobes

with sync jacks, but

then my max sync is

1/250, which won't

always be

sufficient.

 

Thoughts?

[cabbiinc]

I know this gets brought up so much when someone talks about off camera strobes that it's turned into a cliche' but here it is again

 

How much would the optical cable cost? Would you really be able to lay that cable where it wont get broken? (you wont be able to splice it back together without some specific gear) What ambient IR do you think you will run into?

[cabbiinc]

http://www.flickr.com/groups/strobist/discuss/72157594546073354 Something like this may actually be easier and more reliable. There are limitations of course, but you could get your ST-E2 up high enough to be over whatever is your interference. Or you could get more creative than that.

 

Dan

[mark u]

I assume you have worked out whether high speed sync flash will be adequate for you. At ISO 100, the guide number is halved at 1/250th. You gain nothing by using a higher ISO or a wider aperture, because it is effectively a continuous light with a limited maximum brightness that has to compete with ambient light. You may wish to consider a 1D which will sync at 1/500th albeit at the expense of just 4 MP, or possibly one of the Nikons that will sync at even higher shutter speeds.

[cabbiinc]

According to this site http://www.night-ray.com/PhotoCheatSheet.pdf you would lose on stop by exceeding your x-sync, then you would lose another stop for every stop past the x-sync that you go. You can still use it, but you need to be aware of the limitations. Multiple strobes, as you say you have, would be in order.

 

Dan

[mark u]

...except that usually you are exposing for the ambient light, using flash as fill. In that case, if you use a faster shutter speed you will use a wider aperture that will offset it. Likewise, if you use a higher ISO, you will use a narrower aperture or faster shutter speed to offset the ISO gain, or if you use an ND filter you will use a wider aperture or slower shutter speed (which may bring you within range of X sync). Essentially, the maximum range of HSS flash depends on the brightness of the ambient light, and NOTHING else. Conceptually it's just the same as using a desk lamp or other continuous light to add to an outdoor scene.

[neil_v.]

Thanks for the ideas.

 

Hacking an OCSC looks like a win. I'll get at least one off-camera strobe firing that way.

 

Also, by putting a 580EX on the end of the cable in ETTL II master mode, the fixed position of that will be more likely than ST-E2 on moving camera to maintain a wireless link with slaves.

 

I did use 580EX 1/500 high-speed sync at an outdoor test shoot this afternoon under lightly cloudy skies, and outside of the shade it was good for fill at least at several meters.

 

As a backup-backup plan for the outdoor shoots, I should bring extra reflectors and $20 bills for recruited bystander assistants.