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UltravioletPhotography

High Speed UV on a budget - Super Syncing Vintage Flashes?


Tsubo

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Hey there,

 

since I am planning my first steps in UVP and are highly interested in high speed photography I wonder whether it would be possible to utilize an older UV-modded flash like a Canon 199A or Vivitar 285HV to work with high speed shutter speeds below 1/250s (native X-sync limit may of course vary a bit with your camera).

 

First of all I want to clarify a few things...

 

Why High Speed Photography for UV?

Shutter speeds of up to 1/8000s allow you to freeze moving objects much more efficiently. It is not only suited for sports but also fast moving animals or creative use in studio.

 

Concerning UV, you could for instance capture liquids in superior sharpness.

As an example, I have found a blog with some astonishing results capturing fluorescent paint (sadly, with a fairly overpriced Helling flash):

http://www.nimmervol...s-mit-uv-blitz/

 

Why not using HSS flashes?

Since modern flashes (including those featuring HSS) often come with coated bulbs, the UV performance can be much worse than with older "vintage flashes".

In addition, the continuous bursts given by the HSS technology can further decrease the quantity of light. Thus you are gathering even less light and requiring higher ISOs.

 

What is Super Sync about?

Super Sync combines the advantages of both worlds by synchronizing the full power of a "manual" (non-HSS) flash with the advanced shutter speed of the camera. The goal is to time the single burst that precisely so that the moving curtain shutter will capture an evenly exposed image, without any black bars which are often seen below 1/250s with normal flashes.

You can learn more about that phenomenom from the following articles:

https://en.wikipedia..._X_and_HSS_sync

https://digital-phot...ur-photo-shoot/

 

For flashing super synced you basically have to exactly tell the manual flash when to fire its single burst. To achieve this you can for instance acquire a wireless transmitter that is capable of unlocking the HSS timing on the camera which is then used to trigger a linked flash just in time. Alternatively you could use a HSS-capable flash (directly mounted on the camera) to work as an optical master.

 

Unfortunately, the cheaper "vintage flashes" we are considering don't come with such fancy technologies (neither an advanced optical nor wireless receiver) and thus won't natively harmonize with the HSS feature.

As a workaround, I thought one could link the flash manually via cable or an attachable aftermarket optical trigger...

 

BUT, there may still be some bottlenecks such as:

  1. The technology itself might be too old and slow to align with the shutter speeds requested by the modern HSS standard.
  2. Even the third-party optical trigger could add too much delay.

 

In theory I could imagine that the older flashes are suited perfectly for matching with higher shutter speeds since modern flashes often try to achieve really fast flashing times. Consequently those modern manual flashes are sometimes not capable of filling the whole shutter speed with its moving curtains with enough light. Even with a perfect timing you can receive unevenly exposed images since the light intensity emitted by the bulb simply drops too quickly. Vintage flashes otherwise should provide a longer burn down time which could allow much more scope for properly aligning the firing curve to the shutter speed.

 

To finally hit the nail on the head:

What are your thoughts in relation to vintage flashes such as a Canon 199A or a Vivitar 285HV and high speed usage?

Would you assume there is any chance to match such an old system with a modern high speed trigger?

 

I look forward to reading your comments and ideas.

Maybe we can find a cost-effective solution for that use case :)

 

Best Regards,

Tsubo

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Hi Damon,

 

thank you for that information!

Does your camera have a X-sync speed limit? Are your images being exposed consistently, even at 1/8000s?

 

At least on my E-P5 the maximum shutter speed with guaranteed flash synchonization is 1/320s. Above that, the image will start getting black bars and finally fade to black. At least on this system, I have then to use external HSS devices to couple the manual flash to the camera and allow the synchronized speeds of up to 1/8000s ("Super Sync" technique).

 

Regards,

Tsubo

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I might have misunderstood what you are looking for, but here is my input.

 

It would be very unlikely that you would need such a short exposure time, causing flash sync problems, for UV to surpress ambient light.

The exposure times are long due to a very much lower sensitivity of the sensor in that wavelength-band, if you are using sensible ISO-settings.

At least this is true for macro where you get enough DOF by stopping down to at least f/8 or F/11.

 

The actual exposure time with a flash to freeze motion will be defined by the burn time of the flash. A very rough estimate for that time is 1/1000s.

To get as much UV energy as possible you will use the flash or several flashes at manual, full power and vary the ISO-setting to find a good exposure level.

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Even though such dramatic speeds as 1/8000 of a second might not be achievable in reflected UV photography unless one had illumination from two Suns and at least 25 UV-flashes, it is still a worthy goal to try to set up some kind of high speed sync for UV. So I'm eagerly awaiting any info about this.

 

I'm thinking it would be easy enough to try first in Visible light using a couple of inexpensive unmodified non-HSS Vivitar flashes? If it all works, then worry about modding the flashes to output more UV.

 

I am completely UN-knowledgeable about working with flashes myself beyond using my SB-140 UV-mod by flashing it 3 times during a 15" second exposure. Not exactly going to freeze any motion with that method, am I ?? :D :D :D

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Light intensity is a problem with shortening shutter times, of course. But coming from 1/320s as a limit I think there is still some room for improvement :)

Would be nice to achieve at least something in the 1/1000s to 1/2000s range. That said, it looks like I need a HSS device as an initial flash or trigger to unlock those limits on my camera. That's what the "X-sync speed" is all about. Since the camera can't guarantee a synchronization above 1/320 with manual non-HSS-rated flashes, it simply locks the range.

 

My question at this point would be whether those older "vintage flashes" can actually provide such a fast synchronization from a technical perspective. Like mentioned in my first post, there might be limitations due to the triggering system...

 

The more I think about it, I can indeed imagine that simply firing the flash multiple times could be a reasonable workaround. Since there is still enough contrast in light intensity between the atmospheric UV radiation on the one hand and the full power of a tweaked flash on the other hand, there might be enough time to manually determine the exposure by flashing several times with full power.

I guess the contrast ratio (atmospehric light vs electronic flash) is actually the key for this technique.

 

However, those observations do of course only count for stills!

When shooting moving subjects, you are once again forced to shorten the shutter speed. Thats why I thought about a super synced configuration to allow a better synchronization of the burn time and thus utilize the full potential of the flash(es).

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I do not understand the reason for high speed synchronisation of a flash for UV.

Please explain how you are thinking it can be needed.

 

In visual photography high speed synchronisation is used when there is a lot of light.

in that case you use this function to get shutter times short enough to balance and decease the ambient light in the exposure compared to the light from the flash.

 

In normal UV-photography it is quite unlikely that you will need that kind of sync time ever.

Only if you can get enough light as Andrea suggested above by" illumination from two Suns and at least 25 UV-flashes," that will happen.

However if you accept a lot of noise and turn up the ISO setting to maximum there might be needing a fast flash sync.

 

The reasons are that the sensor has much less sensitivity for UV and the ambient light from the sun contain a lot less UV-A than visual light.

these two factors combined give a long exposure time.

 

For UV, the flash is only strong enough to be reasonably useful at short distances in macro range.

In macro range you will like to stop down the lens to get some DOF.

 

I looked at several exposures from mid July, sunny days, of flowers taken with a Baader U filter on a lens stepped down to f/11.

The camera at ISO320. The exposure times ranged from 1s to 20s.

The reference pictures in visual of the exact same scene had exposure times ca 1000 times shorter.

 

Do you have an interesting application with UV where quick flash synch really could be needed?

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Wasn't my initial listing clear enough?

I'm running out of words gradually :D

 

Imo being able to shorten the shutter speed while preserving a fair amount of light is generally a good thing because you are decreasing the effect of vibration and movements from the camera as much as from the subject which can lead to a blurry image. Even if the ambient UV light isn't intense enough to affect the scene so you can shoot a flash multiple times with longer shutter times: a flower for example is likely to move over time (if not shooting in an perfectly controled environment) so you will probably end up with a blurry subject.

 

Of course this technique won't allow you to break the laws of physics. But it can help dissolving the X-Sync barrier (which is present on my camera at least) and increase the overall luminous efficiency. Since the burn time is usually not optimally synchronized with non-HSS flashes, there can be a loss of light in general as well as black bars with increasing shutter speed. The "Super Sync" technique mostly solves that problems because it restores the proper timing for triggering the flashes.

 

With ordinary flashes you still have to consider the effective range and light output limitations, of course. The shorter the range and the more flashes you use the better.

However, with some fine tuning you might be able to shorten the shutter time and thus improve overall sharpness. For how much, has still to be found out. That's why I wanted to share my thoughts on this technique and ask, whether someone has maybe already made experiences with synchronizing flashes vor UV photography.

 

I could imagine an advantage for macro photography. Especially in studio where you probably have more room for light sources and reflectors that maximize the light intensity. You can then decide to alter either the ISO or shutter speed. If shooting liquids for example, you might decide for the shutter speed.

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Sorry but you are still not clear enough to make me fully understand. I hope that you have some more words to let me see your point. :-)

 

The advantage of using a flash to avoid blurring is quite clear and need no further explanation, but the need to "dissolve the X-Sync barrier" is a mystery to me when applied to UV photography.

I really have problems to imagine any situation when you need short exposure times even close to any X-sync time during UV-photography.

 

The main problem for UV photography in macro, assuming that you have camera lenses and filters working for this, is the very long exposure times.

They never ever get close to any X-Sync time, not even with special lamps and reflectors.

 

The only way to get short exposure times is with an UV-emitting flash, but then without any need to use short exposure times.

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My native x-sync speed is 1/500. As I raised the shutter speed, up to I think 1/1250, the images were still exposed but it was getting darker. However, it did work and would be enough to freeze a hummingbirds wings if somehow you got close enough. :)
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I'm sorry. Maybe I'm a bit confused, as well, being still in the planning phase of my UV rig :wacko:

 

Following the UV flash affair, you can still work with the usual (longer) shutter speeds but only fire the flash once. Then you will mostly only have the duration of the flash time that dominates the exposure.

But I'm still not sure how long this burn time actually is on the vintage models compared to a modern speedlight. On my Yongnuo 560 IV its probably about 1/200 at 1/1 of power. That would allow me to freeze a motion (lets say a falling water drop) within the burning down 1/200s. I would suppose that those older flashes (which I plan to convert for better UV efficiency compared with the Yongnuo) burn down much slower. That might or might not break the deal here with freezing things like particles or liquids because the actual exposure time given by the flash gets longer and longer. That would maybe give me no other choice than regulating the exposure by the shutter speed again. And then I am once more struggling with the synchronization because the old flashes might react too slow and this fire too late due to the trigger chain...

 

I know, I know,... a lot of IFs and WHENs :lol:

 

My native x-sync speed is 1/500. As I raised the shutter speed, up to I think 1/1250, the images were still exposed but it was getting darker. However, it did work and would be enough to freeze a hummingbirds wings if somehow you got close enough. :)

 

That's some great news, thank you for sharing you observation!

 

Did you fire with those three Vivitars at full power, triggered via optical slave mode?

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There are no obvious reason that an older electronic flash would burn slower. It might actually be the opposite.

I just measured the optical output from one of my Canon 199A flashes:

 

post-150-0-54517500-1512897802.jpg

 

As you can see the light output decay has reached 1/4 of the peak level after 1.5ms.

The remaining area below the discharge-curve after 1.5ms is also roughly 1/4 compared to the area before 1.5ms

These levels can be reasonable to define the practical flash duration.

 

This was an interesting measurement experiment. :)

I hope the results might be of some interest.

 

(I used a small Power LED array terminated with 50Ω as an ad hoc detector, running it as a fast current generator and avoiding any false delay results due to capacitance.

The peak voltage was 12.5V then diving 250mA through the terminator.)

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Hey Ulf,

 

thats some wonderful piece of information, thank you very much for your efforts! :)

The results look very promising!

 

Have you tried comparing that to the performance of a modern average speedlight like a Yongnuo at full power?

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No, I don't own anything like that.

The most modern flash I have is one Canon Speedlite 580, first generation.

I don't know if it still is working after several years unused.

 

Another experiment like the one above that could be interesting is to meassure if the UV-light intensity variation is the same as full spectrum variation.

When I find time I might redo the test and also measure through a Baader U filter.

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Thanks for your efforts, I would much appreciate further tests :)

I hope I can put things to the tests myself as soon as possible. A Canon 199A is already on the way.

 

Edit:

received my 199A today. With my E-P5 the shutter speed can be turned down to 1/400s without black bars. At 1/500s there is already some shading at the top.

 

On the occasion of testing and comparing the flash with my Yongnuo system I noticed a thing with the shutter speed limit by the way. Namely the limit of 1/320s does only apply for the built-in flash. As soon as I attach an external device such as a flash or wireless transmitter the full range will be unlocked and I can crank it up to 1/8000s. With both the Canon 199A as much as the Yongnuo YN560 IV / YN560-TX the exposure of the image appears to be fine as long as I stay above 1/500s. At 1/500s and below the black bars are getting stronger and stronger, moving from the top to the bottom of the image.

 

If im not totally wrong here, the sensor is reading its pixels from top to bottom during the shuttering operation. The faster the shutter speed, the narrower the slot that is driving down the area. Considering that the image at the sensor is optically reversed, we can now conclude that the black bars (expanding from the top of the captured image in its digital state) relate to the end of the shuttering process. Thus the power of the flash does not last long enough, it can't fill the whole image until the end of the capturing process. The faster the shutter, the more narrow the moving slot, the less light can hit a certain row of pixels on the sensor area, the stronger the black bars.

 

At this point - if I'm not totally wrong with my observations - I can conclude the following basic conditions for UV photography with flashes:

 

You can simply rely on the flash speed measured above and fire with a shutter speed that is slower than your X-sync speed. As long as you aren't shooting in environments with intense UV ambient light (which is normally the case), the blur should be minimal.

 

If you set your shutter speed faster than your X-sync speed, the slot moving down will be narrower than the height of the sensor area. Thus you can increasingly run into problems with black bars since the power of the flash is dropping too quickly and not able to provide enough light intensity over the whole shuttering process.

A perfect match for high speed UV would be either a flash with a very long burn down curve or a HSS flash (which is strobing constantly to ensure that the whole image is evenly exposed). However, the given power of those won't be strong enough to properly expose the restricted area that is produced when increasing the shutter speed (-> narrowing the moving slot between the moving curtains). For high speed UV there simply might be too less light.

 

 

Having that said, I am curious of how the attachable optical trigger for off-camera shooting is going to perform with the 199A + E-P5. I hope it won't add too much delay so I can keep the shutter speed as fast as possible.

To be continued... :)

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What about a UV-LED type flash? It would not have a burn down curve, would it?

Although you would be restricted to one UV wavelength peak (typically 365nm) with such a flash.

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I don't know specific UV models. But in theorey they should be powered via constant voltage or extremely high pitched PWM which won't allow any flickering or gradual burn down.

However, high powered LED for photography with decent quality do already cost a fortune. So I wouldn't assume that there will be any affordable UV-LED flashes for us being worth to consider. But if it did, please let me know :lol:

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