Snoot aiming advice - Retra LSD

[TimG 62]

Snootistas!

 

I need some advice please.

 

I'm using a Retra LSD on an Inon Z240 sitting on an Inon tripod. I activate the Inon Z240 focus/aiming light and the critter is perfectly light by the LSD. Because I'm using the LSD on a tripod, I know me moving the camera has no impact on the aim of the Inon/LSD.

 

I fire the shutter, the Retra'd strobe fires - but the critter is in darkness. And I'm darned sure the flash fired but is not lighting where the aiming light is pointing.

 

Is there some sort of offset between the aiming light and the strobe output? I would have thought not given the construction of the Retra LSD but can't think of any other explanation.

 

If you use a Retra LSD off-housing (ie on a tripod) what is your experience of getting the aiming light and strobe output hitting the exact same place?

 

Thanks!

 

Slightly Frustrated in Bonaire

 

 

 

 

 

[Tom_Kline 143]

Make sure your main strobe is not using pre-flashes!! You might be seeing the slave responding to these. If the snooted strobe is not a slave you need a more complete description of your setup to figure this out.

Edited June 17, 2019 by Tom_Kline

[TimG 62]

Thanks Tom.

 

Yeah, I'd thought of the pre-flash issue. With the Z240 the selector should be pushed in and locked down, ie, what Inon describe as Position 1?

 

So I'm using a D500 with the flash set to /1/125FP and on Manual. So flash activation isn't impacted by the TTL board.

 

I've got a Z240 as the snoot strobe. It's set to manual and the pre-flash button is pushed in - so no pre-flash anticipated. It's being slaved using an Anglerfish sensor and a fibre optic cable.

 

The housing also has Z240 on it as the snoot-strobe initiator. Again, the pre-flash selector is pushed in. I'm using the strobe on manual and it's aimed at the Anglerfish sensor.

 

So, two strobes, both set to manual, both set to no pre-flash..... Camera on manual, no TTL flash.

 

 

 

The

[Tom_Kline 143]

Sounds like it should be working. First thing I would do is the mirror test. See my example. Remove the snoot first. You may have to do this with a spot next to you where you can place the slaved strobe. The idea is to make sure both strobes are going off and synch with the shutter. I took this last month in Hawaii.

[TimG 62]

Yep, good idea. Tom. I'll try that.

 

Thanks!

[ChrisRoss 150]

The aiming light is offset relative to the strobes so I would expect it would illuminate a different spot. I would try a few things on land first - connect the snooted strobe direct by fibre optic to see if the slave is the problem. Also shoot with wide angle to see where the snoot beam illuminates and confirm it's the same spot as the aiming light.

[TimG 62]

With both strobes set with the pre-flash button pushed in, the scooted strobe firing from the Anglerfish trigger, both strobes fired at the same time. So that seems ok.

 

But it still looks to me that the actual flash position isn't quite the same as the area of light that the modelling light illuminates. Weird. There's only one "tube" for the light to go down - so how could that be the case?

 

I'v emailed Retra and asked them the question!

[TimG 62]

Hey Chris

 

Thanks for this. Our posts crossed.

 

Yep, as I set out above, the strobes do seem to be firing at the same time and the camera is capturing the scooted flash correctly.

 

The issue does seem to be an offset. But curious, I'd have thought, given the Retra construction with both the modelling light and the flash coming down the same 1" (approx) tube. Shouldn't they hit the same spot? And if they don't how on earth do you work out where the "sweet spot" actually is when, sometimes, you are trying to light an area the size of a quarter?

 

What's the deal, Oskar?

[Tom_Kline 143]

Sounds like you passed the mirror test, part 1. Repeat with snoot. Repeat again after each adjustment.

 

I gather the LSDs have been problematic with Inons - there may be something on this somewhere on Wetpixel. There is a diffuser in the LSD that should help but having the aiming light in the center of the flash tube (may be the case with the 330) is better.

[Tom_Kline 143]

Alex M was able to make it work here: http://wetpixel.com/articles/field-review-retra-lsd-prime-snoot

 

Do you have an older Z240 with a bulb rather than an LED?

see this: http://wetpixel.com/forums/index.php?showtopic=51586

 

See what Oskar says in post 10: http://wetpixel.com/forums/index.php?showtopic=62595

 

An idea: swap your 2 Z240s so the one on the camera is now the slave. Maybe the other one lines up better????

Edited June 18, 2019 by Tom_Kline

[TimG 62]

Thanks, Tom. Two helpful articles.

 

I’ve got the Type 4 Z240 and the aiming light is quite powerful. No problem there. It’s just that what it illuminates doesn’t seem the same as what the strobe then illuminates. Although judging from the articles, that shouldn’t be an issue.

 

I’ll play around some more tomorrow......

[ChrisRoss 150]

The aiming light is off to the side and as I understand it there are optics in the LSD, it's only offset a little but the optics are right on top of light so quite a difference in angle of entry of light into the optic element. Should be a simple matter to aim the strobe and take a wide angle shot to see where the aiming light is relative to strobe beam.

[Oskar@RetraUWT 55]

Thank you Tom and Chris for quickly responding to Tim's issue and helping out. Since this topic was started at the same time as Tim sent us his email I said that I will reply here.

 

If you can see the pilot light clearly and more or less in the center of the beam this means the LSD is mounted correctly which is the most important thing.

Since Tim already has experience with the LSD on his Z-240 I will skip the basics but if someone is interested here is the topic where most of the beginner stuff was covered: http://wetpixel.com/forums/index.php?showtopic=62595

 

What I would like to add is that masks act as apertures. The smaller the hole the darker the light output and with our masks it goes down about 0.5-1 F-stop per step.

With smaller holes and the Z-240 it is normal to use full power. The new Z-330 is more suited for this because of higher power and the pilot light is slightly tilted making it more central in the LSD which helps with aiming. But still the ideal scenario for snooting is a pilot light and flash tube shining from the same spot or what is more common: a round flash tube with a pilot light in the center.

[TimG 62]

Thanks Oskar and Chris

 

Useful info and I'll play around some more!