Wetpixel Live: Retra Pro X Flash review

During the recent Wetpixel Red Sea Photographic Odyssey, @adamhanlon was able to use and test the Retra Pro X flash guns. Retra kindly loaned both the strobes and a set of accessories for them and they were used by Adam continuously over the two-week trip. In this episode Adam provides some insights into what he liked about the flashes and lists some improvements and  ideas for getting the best from them in the field. 

Reposting here...

Enjoyed the review, and using the pair of Retro Pro-X strobes with superchargers, first on the Wetpixel Cenotes workshop, and then last week in Bonaire at the Digital Shootout. For the most part I really liked the strobes. I especially liked the reduction with the macro & super macro reduction accessories. They were my first experience snooting and that was quite successful.

Where I had difficulty with them was using them to light a subject in front of a sunball (see attached photo, as it came right out of the camera). At f14, 1/400th, ISO 100, the strobes at full power weren't able to correctly light my subject even as the sun at ~15' depth was a bit blown out (thankfully the Sony A1 was able to recover the detail in the shadows in post). Yes, maybe part of the problem was using WWL-1b with 28mm Sony lens instead of the 15mm fisheye which would have allowed me to get closer, but given I was only at f14 and should have been at f22 to properly expose the sunball, I don't know if that would have been enough. 

Hi, thank you for sharing your experience.

The wide angle shot at f14, iso100, 1/400 does not look like anywhere near full power from the flashguns. Can you please explain the power settings on the flashgun and the mode you were in?

What was the issue when using the LSD? In general what we see is that photographers get too close to the subject and this has the opposite effect than expected, it produces less light. The focus distance of the LSD is 175mm, in water. Moving further gets softer light, moving closer can result in dark spots in the middle of the beam.

Hi Oscar.  Alas EXIF data about flashgun strength isn't captured by the camera.  My recollection is they were at full strength/power, shot in Manual. Attached is a third sunball+subject photo with Retra Pro-X + superchargers at what I'm pretty sure was full strength/power, again in Manual.  It came a few days after the first sunball I shared, and I was paying particular attention to settings.  1/400th at f20, ISO 100, Sony 28-60mm lens at 28mm behind WWL-1b again.  Photo right from camera (other than Lightroom shrinking dimensions and saving to JPEG).

With the LSD, I just found manipulating it more challenging.  I had better luck manipulating the Backscatter snoot with their light source.  Alas, I'm not finding any shots that I'm certain were taken with the LSD to post/share.

I am not sure about the sync speed of the Sony A1 but normally it’s about 1/200. Above this you need to use HSS. Can you check with a dry test? Use any lens and set the camera as you have here f14,iso100,1/400. Make an exposure at full power in M and then in HSS on the flashgun. Is there any difference in lighting?

Compare 1/200 and 1/400 as well. The difference should be about 1 f-stop. If it looks like more it could indicate some sync issue.

I think there is either a sync or a power setting issue here (on both images). I can barely see any effect of the strobes and at the distance the subject seems to be, I would expect to...

As a comparison, this was shot at 1/250, f/11 ISO 160 with the Retras at 3/4 power:

Not my finest work, but you can see the effect of the strobes on the reef, which is much further away than your model in the first picture.

The a1 offers mechanical flash sync at 1/400, and electrical at 1/200. This does need specific setting via the camera's menu: MENU →  (Exposure/Color) → [Flash] → [Flash Sync Spd. Prty.] → desired setting.

How were you setting up the LSD? Has anyone talked you through how to do it? Snooting is typically frustrating, but there are specific techniques that can make it feasible. 
 

Adam I gather you did not use the new style cable adapters. (???) It looks like an FO in the cover shot for the vid. Since I already have two sets of Retra strobes - the original and Pro models - I have been reluctant to buy a third set!! For me the main advantage of the X models is the new style cable adapter (call it model 3) which I am compelled to use since I have Seacam housings which do not have dedicated FO ports (the brand's main weakness). I am thus curious about their use.

While the improved version of the non-attachable cable adapter (model 2) works, there is a lot of lose cabling as well as dealing with the lose heavyish adapter. The supplied velcro strap is highly unsatisfactory IMHO (I could use more colorful language!). The only advantage is the ability to swap out FO cables and even not attach them until settled in under water. I have been attaching them just before deploying a pole-rig for recent night work (until spring started).

3 hours ago, korn said:

My other disappointment with the Retra Pro-X was how difficult it was to use the LSD. I wasn't ever successful with it - felt like it was really best suited for super-macro only. Whereas the "super-macro" ring worked well for me - see an example photo of that, again right out of the camera. 

Hey korn

I'm sorry you had problems using it - but I have to say that I find the lSD brilliant. It did take me a while to get the hang of it and especially increasing the power when using smaller mass openings. But in general, for me. it has produced some images I'm really happy with and I never leave home without it when shooting macro.

@Oskar - I did as you suggested.  The three images below are screen grabs from Lightroom.  First has a single flash connected but turned off.  Second two it was turned on at full.  All three set to manual.  Clearly the flash is firing at both 1/200th and 1/400th.  As you suggested, the one taken at 1/200th is brighter than the one taken at 1/400th (by about 1 stop), which frankly doesn't make sense to me.  Is the difference due to a bit more ambient light coming in?  The flash should be way faster than 1/400th, so the flash impact on both the 2nd and 3rd images should be the same, no?

13 hours ago, Oskar@RetraUWT said:

I am not sure about the sync speed of the Sony A1 but normally it’s about 1/200. Above this you need to use HSS.

Sony A1 is a special case; it can sync at 1/400s normally, and 1/500s in APS-C crop mode.

1 hour ago, korn said:

Clearly the flash is firing at both 1/200th and 1/400th.  As you suggested, the one taken at 1/200th is brighter than the one taken at 1/400th (by about 1 stop), which frankly doesn't make sense to me.

I really wish someone with access to an oscilloscope would measure the discharge curves of Retra strobes flashes. Refer to this thread:

View archived post in: Flash duration?

Since the Retras use a circular flash tube, it's quite possible that at full power, they emit at full intensity, or near enough as to make no matter, for 5ms or even longer - perhaps Oskar could enlighten us? When you're shooting at 1/400s, your exposure time is 2.5ms, and at 1/200s it's 5ms, so if the flash is emitting continuously during that period, a 1 stop difference between 1/200s and 1/400s makes perfect sense. For what it's worth, I shoot sunballs with an A6300 and a pair of Retra Pros, and I either use f/22 + 1/160s (my highest available normal sync speed) or f/8-f/11 and HSS at around 1/1000s.

In manual mode everything looks normal. There is no ambient light on the images, the light on the 1/400 is less due to longer flash duration. The maximum power flash duration is about 4ms. This is more or less standard on any flashgun with a circular flash tube. With a linear flash tube we can usually get shorter times, about 1-2ms. It seems that with Sony A1 they allow the slightly higher sync speed only by using the later.

As Adam explained with a practical example there is plenty of light available from the Retra Flash Pro X to light up large reefs. I am not sure why you are not getting that much light in your image. Please write to us at: info@retra-uwt.com We will go through more testing and find out!

@korn

Peter- it is hard to tell from your tests, but I don't think there is anything like the amount of flash I would expect with a full dump of strobe. It depends where your strobes were positioned relative to the "subject", but at f/20, I would expect the screen to be whited out idf the flashes are firing at full power. Flash output should be independent of shutter speed, although this may be complicated by fast flash sync speeds. 

When you get chance, lay your strobes alongside the lens (as you would shooting macro), and let's see how much they put out. Please shoot at a variety of shutter speeds too.

This prompts me to think you have some kind of a flash sync/communication/camera settings issue. I don't know enough about the a1's settings, but is this some kind of pre-flash issue? Is the camera triggering a pre flash? Does the camera "think" it is in TTL?

1/400 sec shutter speed is 2.5 msec and the flash duration at full power reported to be 4 msec.  This means that 1/400 sec the maximum power available at 1/400 is 60% of full power .   You need to shoot at 1/250 to get the full pulse length and full power reducing the benefit of the 1/400 flash sync with this combination.

However this seems unlikely to be the cause.  Half power should be capable of lighting up the scenes we are talking about.   I think Adam's suggestion is worth checking out.  If  your camera combo is pre-flashing then that is robbing the main flash of power and it may not be able to recycle quickly enough to recover.   

how are you triggering the Retras?  and which flash mode are you using on the A1? You can check for pre-flash if you can put the  A1 into rear curtain sync and use a longer exposure to take an image.  You can do this in a dark room using an exposure in the 1/4 to 1 sec range.  You will see two flashes if you have a pre-flash.

Adam, Chris, Oskar - thank you for your assistance, and your patience.  As I'm shortly to embark on a Backscatter trip to Cuba, I finally set aside the time and sat down to do a more thorough debugging session.  As I was experimenting with things, I noticed what sounded like a double-flash, and confirmed the sound difference vs. manually triggering the flash in BATT/TEST mode.  Digging deeper, I found that the UW Technics #11075 TTL Converter I'm using in my Nauticam NA-A1 housing was set to position #2 (for a Sea&Sea YS-D1).  I then found the UW Technics guidance to use position #7 (https://wetpixel.com/articles/uw-technics-sony-firmware-supports-retra-pro-flash-ttl of course), and I'm now only hearing the sound of a single flash.  Hopefully I'll be more successful shooting sunballs in the Garden of the Queen next week!  In fairness to the folks who sold me all of this gear, UW Technics doesn't make it easy to discover the correct settings for Retra, as their manuals take some digging to find, and the first hits (https://www.fun-in.com.tw/share/documents/uwtechnics/11075-Sony-UWT.pdf) don't mention Retra flash guns.  Be nice if https://uwtechnics.com/index.php/online-store/ttl-converters/for-sony/11071-ttl-converter-for-sony-for-nauticam-housings-na-a7-detail had a link to an up to date manual...