Strobes, trigger, Synchro and Fibre Optic

9 minutes ago, newdiver said:

I am wondering what the real world power difference is between the Retra prime and Pro, I understand that the Pro provides 50% more power, however how much of a difference does it really make?

I rarely run my Pros on full power except for snooting. With the LSD on, however, as good as its light transmission is in comparison with basic restricting snoots, full power is still the order of the day. However, my experience with them so far has been largely with macro - I've been living on Koh Tao, Thailand for the past two months, and the water here is silty (5-10m visibility) far more often that not, at least during this time of year, so I've been shooting macro on muck dives. What I have observed, however, is that outfitting them with reflectors (+1 stop according to Retra) has increased the beam intensity quite significantly - in clearer water, at higher power levels, I was able to shoot fish portraits with 90mm macro lens from a distance that surprised me. I would guess that the difference between reflector/no reflector is close to the difference between Retra Prime and Pro. In two weeks I'm going on a liveaboard in Andaman Sea - this will give me better opportunities to evaluate the Retra Pros in wide-angle scenarios.

Interesting Barmaglot, thanks. A fair question from newdiver.

I've got the Primes and use the LSD a lot - almost all the time - for macro. Macro dives here tend to be in the 15'-18' range and natural light is pretty good.  

I tend to have my camera set at ISO 125, f22 (for macro on the Nikkor 105mm), Manual exposure setting. I change my shutter speed and Retra output depending on the exposure I want to create. I often found that I need to go to +3 on the strobe if I'm using one of the smaller slide holes - which is quite often.

I too have wondered whether a Pro would make a significant difference with an LSD. But, so far at least, I can't say that a lack of power has prevented me generally lighting the image as I'd want. It's usually a mix of surge, distance, operator-error, tiny depth of field, Act of God that has resulted in a duff image. It'd be nice though to try out a Pro and see if it delivers a real difference. But I still have room to play with in terms of increasing ISO and lowering shutter speed.

7 hours ago, Barmaglot said:

 What I have observed, however, is that outfitting them with reflectors (+1 stop according to Retra) has increased the beam intensity quite significantly - in clearer water, at higher power levels, I was able to shoot fish portraits with 90mm macro lens from a distance that surprised me. I would guess that the difference between reflector/no reflector is close to the difference between Retra Prime and Pro. In two weeks I'm going on a liveaboard in Andaman Sea - this will give me better opportunities to evaluate the Retra Pros in wide-angle scenarios.

Interesting, is the impact purely flash range or is ability to keep the beam contained to avoid backscatter or both?

The issue with the light shaper on the Retras is that most of the wide beam does not fit down the aperture of the snoot.  It has a native 130°beam and the geometry is such that only a fraction of the beam goes through the aperture.  the fraction that goes through is set by the distance from the tube to the aperture and the size of the tube.

3 hours ago, ChrisRoss said:

Interesting, is the impact purely flash range or is ability to keep the beam contained to avoid backscatter or both?

It's probably a combination of both. For example, I took this rabbitfish shot at something like 2.5-3 meters, with the strobes spread most of the way out (two 20cm arms on each side) and angled in towards the subject. You can see that the water is not particularly clear, yet there's good detail and color on the fish itself.

3 hours ago, ChrisRoss said:

The issue with the light shaper on the Retras is that most of the wide beam does not fit down the aperture of the snoot.  It has a native 130°beam and the geometry is such that only a fraction of the beam goes through the aperture.  the fraction that goes through is set by the distance from the tube to the aperture and the size of the tube.

I wonder what will happen if I coat the insides of the LSD mounting module with something reflective, like aluminium foil.

2 hours ago, Barmaglot said:

It's probably a combination of both. For example, I took this rabbitfish shot at something like 2.5-3 meters, with the strobes spread most of the way out (two 20cm arms on each side) and angled in towards the subject. You can see that the water is not particularly clear, yet there's good detail and color on the fish itself.

I wonder what will happen if I coat the insides of the LSD mounting module with something reflective, like aluminium foil.

Quite reasonable result all things considered.

on the foil, it would need to reflect the light into the aperture, the interior itself is like a matte silver colour so is already a bit reflective and foil wouldn't change the amount reflected by a lot I don't think.  Something shaped like the reflector would be what you would want I think?

28 minutes ago, ChrisRoss said:

on the foil, it would need to reflect the light into the aperture, the interior itself is like a matte silver colour so is already a bit reflective and foil wouldn't change the amount reflected by a lot I don't think.  Something shaped like the reflector would be what you would want I think? 

I don't think there's enough room in there for a proper reflecting setup, but maybe some bright white plastic sheeting to bounce the light around? The strobe itself already has a matte white backing to the lamp, so if the entire chamber is white rather than grey, the amount of light reaching the aperture should increase.

By the way, another benefit of the Retra Pro that is related directly to snooting is the more powerful modeling light - easier to see (and aim) in brighter ambient lighting conditions (shallow depth, bright sun, etc).

On 2/25/2021 at 3:50 PM, Barmaglot said:

I don't think there's enough room in there for a proper reflecting setup, but maybe some bright white plastic sheeting to bounce the light around? The strobe itself already has a matte white backing to the lamp, so if the entire chamber is white rather than grey, the amount of light reaching the aperture should increase.

By the way, another benefit of the Retra Pro that is related directly to snooting is the more powerful modeling light - easier to see (and aim) in brighter ambient lighting conditions (shallow depth, bright sun, etc).

Yes, I think the modelling light is in its favour. Retra has gone out of stock for the flashes