RETRA Strobe Thread

I apologise for the slightly off topic question, but if beam angle isn't that important for double strobe setups, wouldn't it be preferable in most situations to not use diffusers that widen beam angle at the cost of power (especially on weaker strobes like YS-01 or S2000)? So far I've always defaulted to using diffusers. Maybe that was wrong?

First of all thank you for your extensive opinion, we appreciate the extra input.

Lab test in air on a wall with a single light do not really represent real life usage of products because with a single light beam angle is not important

Just to clarify, we use studio testing on land because it is consistent and can be repeated relatively quickly without major deviations. But this data is not the sole measure of the quality or the power of light the flashgun produces. We rely on field testing to confirm that something really works as intended and sometimes it doesn't.

I apologise for the slightly off topic question, but if beam angle isn't that important for double strobe setups, wouldn't it be preferable in most situations to not use diffusers that widen beam angle at the cost of power (especially on weaker strobes like YS-01 or S2000)? So far I've always defaulted to using diffusers. Maybe that was wrong?

That is not what I said beam angle is important but clearly past the 110 degrees is very hard to get anything really meaningful looking at those tests and this is a combination of physics of light and physics of the strobe bulb

Diffusers are useful for non circular bulbs like your sea and sea and the inon. Less interesting for circular bulbs

Without a diffuser the beam will be a rectangle or a cross not a circle. Clearly when you are so close that even that rectangle completely covers the subject it does not matter that much but how do you know.

There is one question though that I have for Retra. Now I am known for fact checking everything so I go and turn every stone this does not mean I do not appreciate the product I have actually seen the prototype at Alex Mustard home few weeks ago and seems very well built

However one concern I have is about the battery choice. Using NiMh is obviously a requirement as the low internal resistance means shorter recharge time and also this is the only battery that can delivery the required high current

However the retra have normal NiMh AA size assuming Eneloop Pro this means around 12 Wh when full best case. The lamp used in the Pro version has a declared energy of 150 Ws and typically when you suck 2-3 A the real charge is around 70% so only 7.2W x 3600 c 30000 Js / 150 = 200 this is a best case scenario

So what we are saying is that the Retra Pro is likely to handle 200 flash and the new Retra around 300

Most manufacturers employing 150Ws tubes use a bespoke battery pack typically 3050 mAh which pushes the number of flashes to 250 minimum

First of all thank you for your extensive opinion, we appreciate the extra input.

 

 

Just to clarify, we use studio testing on land because it is consistent and can be repeated relatively quickly without major deviations. But this data is not the sole measure of the quality or the power of light the flashgun produces. We rely on field testing to confirm that something really works as intended and sometimes it doesn't.

Thank you Oskar

How many full strobe flashes can you do with a fully charged set of Eneloop Pro on the Retra Pro version?

We haven’t tested this yet on the new Retra Flash but Adam tested more than 400 flashes on the original Retra Flash which has 100Ws: http://wetpixel.com/articles/strobe-tests-inon-z330-retra-flash-and-symbiosis-ss2/P3

This is quite ideal test situation with new batteries, almost constant room temperature and consecutive firings. In real life there are things that can reduce the number of flash, mainly the temperature and battery age/condition. But we can expect something roughly around 200-300.

Anyway we are working on a proprietary battery pack design which will improve the new flashgun performance (not compatible with original Retra Flash). The new battery pack design will require more intensive work and we aim to confirm it’s design after the new Retra Flash Prime/PRO are already shipping. Specifications will be announced in due course. News on this here: https://www.retra-uwt.com/blogs/news/new-retra-flash-update

We haven’t tested this yet on the new Retra Flash but Adam tested more than 400 flashes on the original Retra Flash which has 100Ws: http://wetpixel.com/articles/strobe-tests-inon-z330-retra-flash-and-symbiosis-ss2/P3

This is quite ideal test situation with new batteries, almost constant room temperature and consecutive firings. In real life there are things that can reduce the number of flash, mainly the temperature and battery age/condition. But we can expect something roughly around 200-300.

 

Anyway we are working on a proprietary battery pack design which will improve the new flashgun performance (not compatible with original Retra Flash). The new battery pack design will require more intensive work and we aim to confirm it’s design after the new Retra Flash Prime/PRO are already shipping. Specifications will be announced in due course. News on this here: https://www.retra-uwt.com/blogs/news/new-retra-flash-update

Thank you Oskar I think you need 3000 mAh to feed 150 J lamps

Now let me ask you a question if you knew that the Retra 100W version had GN 16 and you had to shoot half power which is GN 11 in air in water f/8 at ISO 100 would you buy it?

The original Retra flash is rated at 100 Ws, and multiple reviews have praised its brightness. Is 100 Ws for a circular bulb somehow different from 100 Ws for a linear bulb?

 

The original Retra flash is rated at 100 Ws, and multiple reviews have praised its brightness. Is 100 Ws for a circular bulb somehow different from 100 Ws for a linear bulb?

The original retra flash has a linear tube while the new one has a circular bulb

Obviously the total amount of light emitted is the same however when you bend the tube part of the light hits each other this gives you a wider beam with less overall intensity at the centre.

Whilst this is a desirable feature you need to make sure you have enough steam or is just too dim to be useful

Typically a 150 J circular bulb has guide number at centre of 20 in air dropping at 14 in water this is OK. With 100 J this drops typically to GN 10 in water which means if you needed to shoot at f/11 iso 100 at 1 meter you don’t have enough power so you need to increase gain

The original retra strobe construction is very similar to a sea and sea YS D2 however the reflector is different so it keeps a wider beam

Does it make sense?

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So basically a circular bulb acts like an always-on diffuser, right? With the advantage of not suffering from the diffuser's own light absorption, and disadvantage of not being able to take the diffuser off for a more focused beam.

So basically a circular bulb acts like an always-on diffuser, right? With the advantage of not suffering from the diffuser's own light absorption, and disadvantage of not being able to take the diffuser off for a more focused beam.

Circular strobes have a different shape

If you look at this chart from backscatter

https://www.backscatter.com/reviews/post/Best-Underwater-Strobe-Flash

The Ikelite DS161 has a circular bulb you can see that the shape with or without diffuser is quite similar and the slope is more gentle compared to linear bulbs

Strobes with linear bulbs need diffusers more otherwise the shape of the bulb shows some manufacturers of strobes with circular tubes do not even sell diffusers

In terms of 'focussing a beam' not sure what you mean but in both cases to achieve narrow beams you need a snoot. Anyway this is the retra strobe thread so you should open another thread otherwise we go off topic

I apologise for the slightly off topic question, but if beam angle isn't that important for double strobe setups, wouldn't it be preferable in most situations to not use diffusers that widen beam angle at the cost of power (especially on weaker strobes like YS-01 or S2000)? So far I've always defaulted to using diffusers. Maybe that was wrong?

I shoot without diffusers on my Inon strobes when cave diving to get the extra power. I know others that do this too.

 

I shoot without diffusers on my Inon strobes when cave diving to get the extra power. I know others that do this too.

I think the new Retra can be shot without diffusers in all circumstances looking at their own tests you can see the diffuser does very little in terms of diffusing maybe does something to the light colour am not sure

Typically strobes with 150 J circular lamps have GN 20 in air and GN 14 in water with a very wide beam. Linear strobes such as the YS-D2 or the Inon Z330 will have a higher guide number but stronger fall off centre so they need diffusers more. If you shoot the Z330 or the Z240 without a diffuser you get a stronger beam but you are left with a cross shape with strong light within the 60 degree beam and harsh drop outside. If that works for you this is not something that a circular bulb will ever give you and in terms of sheer power at centre it will be weaker

Having started my underwater photography on Z-240's and recently upgraded to Z-330's I can testify to their reliability and power in the field. But on a recent dive trip I was "lucky" that my dive buddy got sick on the last few days and I could borrow his rig with Seacam 150's for 6 dives using them for wide angle and macro. Short story, I was sold!

On paper the Z-330's have a higher GN but in reality the Seacam's are a completely different league, here's why:

• Because they produce a wider beam it's much easier to position them for wide angle and I could get better results with fewer adjustments. Even with diffusers on the Z-330 I could immediately notice the difference when switching to the Seacam.
• For macro photography I appreciated their slightly narrower design so I could position them more freely around the port. Also for macro it's not so important to have a high GN because everything is more or less at 1-2 feet and every strobe can handle f22@iso100 from that distance.

If Retra can deliver what they show in their test it can be an interesting choice in the future.

We haven’t tested this yet on the new Retra Flash but Adam tested more than 400 flashes on the original Retra Flash which has 100Ws: http://wetpixel.com/articles/strobe-tests-inon-z330-retra-flash-and-symbiosis-ss2/P3

This is quite ideal test situation with new batteries, almost constant room temperature and consecutive firings. In real life there are things that can reduce the number of flash, mainly the temperature and battery age/condition. But we can expect something roughly around 200-300.

 

Anyway we are working on a proprietary battery pack design which will improve the new flashgun performance (not compatible with original Retra Flash). The new battery pack design will require more intensive work and we aim to confirm it’s design after the new Retra Flash Prime/PRO are already shipping. Specifications will be announced in due course. News on this here: https://www.retra-uwt.com/blogs/news/new-retra-flash-update

 

Hi Oskar, does this mean that the new Retra Pro will be compatible with the typical Eneloops, but you will also offer the proprietary battery pack? Will this proprietary pack offer half the recycle time and double the number of flashes (like the battery pack extension did with the original Retras)?

Hi Oskar, does this mean that the new Retra Pro will be compatible with the typical Eneloops, but you will also offer the proprietary battery pack? Will this proprietary pack offer half the recycle time and double the number of flashes (like the battery pack extension did with the original Retras)?

Having started my underwater photography on Z-240's and recently upgraded to Z-330's I can testify to their reliability and power in the field. But on a recent dive trip I was "lucky" that my dive buddy got sick on the last few days and I could borrow his rig with Seacam 150's for 6 dives using them for wide angle and macro. Short story, I was sold!

On paper the Z-330's have a higher GN but in reality the Seacam's are a completely different league, here's why:

• Because they produce a wider beam it's much easier to position them for wide angle and I could get better results with fewer adjustments. Even with diffusers on the Z-330 I could immediately notice the difference when switching to the Seacam.
• For macro photography I appreciated their slightly narrower design so I could position them more freely around the port. Also for macro it's not so important to have a high GN because everything is more or less at 1-2 feet and every strobe can handle f22@iso100 from that distance.

If Retra can deliver what they show in their test it can be an interesting choice in the future.

There is nothing like actually using a product! Even with the round flash tube of Seacam strobes I find that a diffuser is useful when shooting a fisheye lens. The Seacam 250D however did not have a diffuser so I improvised. I used a white almost transparent grocery bag tucked under the neoprene cover. It is in use in the attached pic.

The main disadvantage of Seacam strobes, except for the latest model, IMHO is that they use proprietary batteries. These batteries might be described as anti-Eneloop because of their short shelf life and rapid self-discharge, basically most unlike Eneloops.

Hi Oskar, does this mean that the new Retra Pro will be compatible with the typical Eneloops, but you will also offer the proprietary battery pack? Will this proprietary pack offer half the recycle time and double the number of flashes (like the battery pack extension did with the original Retras)?

Yes, with Prime and PRO. The battery pack will improve recycle time and number of flash, exact figures will be announced when the battery pack is ready for pre-order.

Idle curiosity - might it be possible to use the HSS mode (40 kHz flicker, I presume) to sync with a housed cellphone? As I understand it, the slow electronic readout of phones precludes syncing with a regular Xenon flash pulse, and the LED flashes on phones use a longer pulse to compensate, so could the HSS flicker be stretched long enough to cover a phone's exposure?

Many of the proprietary battery packs are in fact just stacked with multiple NiMH AA cells, they are soldered together however so they behave like a single battery. Examples include the battery for the old Canon 1D MkII cameras, this was a 12v pack that had 10 Ni MH AA cell batteries inside. Unfortunately manufacturers tend to put standard NiMH cells in these packs and they start to suffer from memory issues and high self discharge rates. As standard in our strobes we now have 2500 mA-hr at 4.8V. Doubling this to 9.6V would have a good impact, I suspect having the cells in series would be more efficient as you are stepping up the voltage anyway and the capacity would still increase as you are after watts (Volts x Amps).

Given the choice I would much prefer to have a battery pack that you removed the cells from to charge or at least had the capability to replace. That way if a cell goes bad while traveling you have some chance to replace it and you could use eneloop pros in it if desired. I would not want a pack with standard NiMH cells in it.

The non standard battery packs typically with C type batteries inside warrant higher capacity not higher current. This is because with a 150 Ws bulb you won’t manage more than 200 shots with 2500 mAh. Typically those packs are rated 3000 mAh so 20% more. Putting more batteries in series would charge the strobe faster assuming the batteries can deliver the current but this is not really necessary

Instead a pack of batteries in 4S2P would increase the capacity of the battery and deliver more shots

There is a risk in putting batteries in parallel when you generate AC though

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yes but if you put 8 batteries in series (or more) you still get the 2500 mAhr but at 9.6V instead of 4.8V. You still get the extra capacity, it takes less amps at the higher voltage (9.6V) to fully charge the capacitor as you are going through a transformer to boost the voltage at the capacitor.