1/125 Flash Sync Speed...

[pophoto]

Hi,

The newly announced Pentax 645Z has a FSS of 1/125, what does this mean to most DMF users who shoot flash in the studio?

While I understand the following:
1) Shutter speed controls Ambient light the sensor receives, and 1/125 may limit how dark the Ambient gets!
2) Strobe flash duration is more important than shutter speed in freezing subjects, when not using Leaf shutters but the focal plane shutter.

What does this mean to the Studio Lighting photographers out there, and the work flow you have been used to? I know it will be harder to judge for those used to Leaf shutter lenses, but please feel free to chime in!

Thanks
Po

 

[dougpeterson]

You're absolutely right that the majority of the benifit of a leaf shutter lens comes when shooting in purposefully-mixed light, like on-location, outdoors, or in a daylite studio. In a studio setting the issues that arise from a limited sync speed will more often be noticed by studio shooters shooting motion (e.g. dancers leaping) or shooting longer lenses hand held or shooting wide open than those who shoot only static subject matter or shorter lenses or only at f/11.

There is a very handy rule of thumb for determining how much the ambient light matters in a given situation. Turn off the strobes and take a picture.

If there is any meaningful illumination of the subject then the ambient light matters.

For instance if you're shooting with dim modeling lights in a dark studio at 1/125th at f/11 at ISO100 and you turn off the strobe and take a picture then you'll get a near-black frame. In such a situation there will be no meaningful difference of using 1/125th vs a faster shutter speed like 1/500th.

If on the other hand you're shooting in a daylite studio, or with bright modeling lights, or a light source is inside the frame, and you're using f/2.8 then you might well notice a meaningful exposure with the strobe off. This doesn't necessarily mean there is an issue, but it can create the following challenges:
- it's hard to produce consistent color when the ratio of light from the modeling/ambient light vs the strobe is changing. If producing a single editorial image this is probably not significant, but if shooting for a catalog or shooting several images meant to be presented together it can get tricky
- if the ambient-only exposure isn't sharp (e.g. you're using a 210mm lens hand held at 1/125th) then you'll have a mixture of sharp (from the strobe exposure) and unsharp (from the ambient). Again, not necessarily a deal breaker, and you may even like the look it produces. But if you don't like the look it can be a real annoyance.

Generally speaking solutions for issues arising from having a poor sync speed include:
- darkening your working environment (e.g. turning down your modeling lights, or blackening out window light)
- using a higher-number aperture (e.g. f/8 instead of f/2.8)
- adding an ND filter to the lens and then increasing the amount of strobe power to compensate

Each of those workarounds has some drawbacks, but can work in some/many situations.

Higher speed sync is most useful in my opinion because you don't have to think about it. You can change the shutter speed and aperture to (more or less) whatever combination you want and it will "just work" without need for workarounds and without large restrictions (obviously there are small restrictions like using strobes with sufficiently short enough flash duration that you're not clipping the strobe with your shutter speed, and you have to use either a sync cable or a wireless transmitter with a fast enough transmission speed to work at high speeds).

 

[pophoto]

Thank you Doug for your detailed explanation!

Please let me add another question to the mix: (Warning: it may be a tireless one already!)

The Pentax 645Z has 14-bit raw files vs say the Hasselblad H5D having 16-bit files, and the A7R having I believe 12-bit files. Some online articles in the past from tests have shown better shadow details (less so in highlights but depends on the manufacturer bias of the full spectrum) with higher bit files, say 14 vs 12. From experience is there enough of a difference?

 

[Shashin]

I have shot in a studio off and on for a long time. I have never found 1/125 with strobes to be a limit. I have also used a Pentax 645D in the studio. Really nice camera.

 

[Shashin]

Thank you Doug for your detailed explanation!

Please let me add another question to the mix: (Warning: it may be a tireless one already!)

The Pentax 645Z has 14-bit raw files vs say the Hasselblad H5D having 16-bit files, and the A7R having I believe 12-bit files. Some online articles in the past from tests have shown better shadow details (less so in highlights but depends on the manufacturer bias of the full spectrum) with higher bit files, say 14 vs 12. From experience is there enough of a difference?

The Phase cameras have 16-bit AD converters, but the sensors are still 14-bit. The same for Hasselblad. That is just a marketing gimmick. I also shoot with a p25+, which I believe Phase states is a 16-bit camera. There is not difference between my 645D and p25+ in regards to dynamic range, except the 645D has more.

I also shoot with an RX-1 which does similar things as the a7r to the RAW files. If there is a loss of data from 14-bit in my files, I have yet to see it.

 

[dougpeterson]

I would not get caught up on tech-specs like bit-depth. Instead I would get your hands on both systems and shoot in some challenging situations which fit within your likely use, and then put them through a post-processing and output workflow relevant to your needs/style and see how the end results (and workflow) compare.

I would (from my very biased perspective) say that P1 has historically shown it can get the best results from a given sensor when multiple companies used a particular sensor, especially when using Capture One to process the files. The sensor is just part of the long and complex image quality chain.

Some links in the image quality chain:
Lens hood (or other method of reducing flare) > Lens coating > Lens elements > Aperture blade design > internal body coating > Anti aliasing filter (or lack thereof) > IR filter spectral cutoff location and sharpness of cutoff > microlens > sensor type > sensor read-out speed and method > heatsinking > A/D converter* > Black Calibration > debayering/detail/color algorithms > noise reduction (based on black calibration file) > color profiling > noise reduction (based on image data) > sharpening

*may be incorporated into the sensor itself in some designs

 

[dougpeterson]

The Phase cameras have 16-bit AD converters, but the sensors are still 14-bit. The same for Hasselblad. That is just a marketing gimmick. I also shoot with a p25+, which I believe Phase states is a 16-bit camera. There is not difference between my 645D and p25+ in regards to dynamic range, except the 645D has more.

Of relevance: the 22mp sensor in the P25+ was released in 2003, making it 11 years old. In my opinion if you compare an H25 or P25+ (which used the same sensor) to a 5DIII (at low iso, for short exposures) it will more than hold it's own.

 

[kapil Syal]

perhaps it's irrelevant in the "digital age"
but leaf shutters are not very consistent .. and actually give differing exposures with different Apertures ..

(more 'swings and round-a-bouts)

 

[Shashin]

Of relevance: the 22mp sensor in the P25+ was released in 2003, making it 11 years old. In my opinion if you compare an H25 or P25+ (which used the same sensor) to a 5DIII (at low iso, for short exposures) it will more than hold it's own.

The p25+ is a great back. I have nothing but good things to say about it. I love the images that come off it. But it is not a 16-bit back.

 

[fotografz]

Doug has given a pretty good explanation of sync speeds.

The best insight he mentioned is that "with higher sync speeds you do not have to think about it, it just works".

For the most part, 1/125 sync works in a studio that is dark and you are stopping down a fair amount. My studio is not dark in the day-time even when I black out the windows, so in some cases it can be an issue at 1/125 sync speed. When I shot chrome wheels for a car company, and was using a Contax 645, I usually had to work at night.

For me, high sync speeds are a "must have" and have been for quite some time now. I previously used mostly Hasselblad H in studio, which were somewhat limiting for other work where I may have wanted to shoot a wider aperture in very bright ambient conditions, but only had a top shutter speed of 1/800.

With the dual shutter cameras like P1 and Leica S, that restriction has gone away. High leaf-shutter sync speeds when needed … flip a switch … and high focal plane shutter speeds to 1/4000 when they are needed.

It is outdoors where leaf-shutter sync speeds really come into play. The ability to knock down bright backgrounds while balancing the light on the subject is invaluable.

I use Profoto lighting with AIR radio … the with the AIR Transceiver set to transmit, you can set it in "Speed Mode" by pressing the mode button for 7 seconds … then the 1/1000 of the Leica S, or 1/1600 of P1 is possible.

In a darkened studio, stopped down, I wouldn't worry to much about 1/125 sync.

- Marc

 

[Steve Hendrix]

The Phase cameras have 16-bit AD converters, but the sensors are still 14-bit. The same for Hasselblad. That is just a marketing gimmick. I also shoot with a p25+, which I believe Phase states is a 16-bit camera. There is not difference between my 645D and p25+ in regards to dynamic range, except the 645D has more.

I also shoot with an RX-1 which does similar things as the a7r to the RAW files. If there is a loss of data from 14-bit in my files, I have yet to see it.

The employment of 16 bit AD converters is valid and legitimate. The marketing of the digital back as "16 bit" without any real details would be where the vagaries and the "gimmick" might present themselves.


Steve Hendrix
Capture Integration

 

[pophoto]

Any guessing if the 645Z can use High speed Sync successfully and upto what shutter speeds?

 

[Ken_R]

Hi,

The newly announced Pentax 645Z has a FSS of 1/125, what does this mean to most DMF users who shoot flash in the studio?

While I understand the following:
1) Shutter speed controls Ambient light the sensor receives, and 1/125 may limit how dark the Ambient gets!
2) Strobe flash duration is more important than shutter speed in freezing subjects, when not using Leaf shutters but the focal plane shutter.

What does this mean to the Studio Lighting photographers out there, and the work flow you have been used to? I know it will be harder to judge for those used to Leaf shutter lenses, but please feel free to chime in!

Thanks
Po

The Pentax 6x7's have a flash Sync Speed of 1/30 sec. which is terrible but they were successfully used in the studio for years by a lot of accomplished photographers.

Yes, there were 90mm and a 165mm leaf shutter lenses available but they were somewhat clunky to use.

Of course the Pentax was really unsuitable for mixed light work (available light and flash) and even in the studio one had to be careful with modeling lights when using faster film (even iso 160! film) and larger (numerically lower) apertures. Yes, even f8 could be a problem.

Of course 1/125 sec is not that bad in the studio and for available light work outside without flash it is a non issue obviously.

But It really limits your options when mixing flash and daylight like it was explained in the previous posts. I for one really like having the option of using a wide aperture outdoors with flash. In fact a lot of times I am at f2.8 and have to use 1/500 sec even with iso 50.

 

[SergeiR]

While i am applauding and supporting whole leaf shutter discussion - there is nothing that stops you from shooting f2.8 in bright sun with flash - just use ND and real flash

1/125 in studio is fine, i am shooting that all the time with AFD bodies

 

[gazwas]

While i am applauding and supporting whole leaf shutter discussion - there is nothing that stops you from shooting f2.8 in bright sun with flash - just use ND and real flash

Yes, exactly what ND's are for. The price of one LS lens will buy you some very nice battery flash power that will open up much wider opportunities and creative techniques.

 

[dougpeterson]

While i am applauding and supporting whole leaf shutter discussion - there is nothing that stops you from shooting f2.8 in bright sun with flash - just use ND and real flash

That's exactly right. I noted the use of ND filters as one of the (several) workarounds to not having leaf shutter lenses.

But it comes with the obvious drawback that if you wish to shoot using the viewfinder your view is now dimmer. This is especially problematic on dSLRs which already have (compared to medium format) dim/small viewfinders. To get the effect of 1/250th sync from a 1/125th-limited body only requires 1 stop ND filter, but to achieve the same look at native 1/1600th sync would require 3.5 stops of filtration, which is quite strong. A strong ND filter can also wreak havoc on some autofocus systems.

If you're comfortable shooting in live view (and your camera supports shooting from live view in an elegant way) then using strong ND filters may not significantly effect your workflow, and may be a great option for you. If you prefer to look through an optical viewfinder then the cost of a strong ND filter may be far too high.

Clearly this option is with little downside if you're only needing to shift the effective sync speed by a stop, or maybe two, but drops off in utility depending on how far you want to go.

In fact the technique can be used even WITH leaf shutter lenses. A 2 stop ND filter in front of a Phase One kit would yield an effective sync speed of 1/6400th with standard strobe units, allowing you to shoot near night-level light even wide open at noon, without having to bring a huge quantity of strobes (maybe two B1 would suffice).

Another option is to use the flash systems which change from flash to effectively-continuous sources of light, which allows some crazy fast sync speeds. But the cost in that case is the drastic drop in effective power output of the flash, often requiring several flashes to be combined just to get a normal amount of effective output back.

Nearly all photographic problems can be solved any number of ways. Each way will have upsides and downsides (including cost). A great photographer can take a great photo in nearly any situation. But when one can eliminate an artificial technical limitation, it (IMO) naturally opens creative options. No one would choose to have their sync speed limited, so we are only arguing about the relative value of a higher sync speed vs the relative cost of achieving it by various methods (ND filters, working in darker environments, pseudo-continuos light sources, LS lenses etc).

 

[gazwas]

All very valid information Doug but not exactly a good enough reason for us to all go out and spend £35,000 GBP on a Phase One system over the Pentax. In the context of the original question, 1/125th second flash sync should prove quite adequate on the new Pentax, especially for studio work.

1/125th second sync also means the type of strobe equipment needs to be much less exotic and affordable. More Senso or Acute rather than Scoro or Pro8a levels of investment.

 

[fotografz]

All very valid information Doug but not exactly a good enough reason for us to all go out and spend £35,000 GBP on a Phase One system over the Pentax. In the context of the original question, 1/125th second flash sync should prove quite adequate on the new Pentax, especially for studio work.

1/125th second sync also means the type of strobe equipment needs to be much less exotic and affordable. More Senso or Acute rather than Scoro or Pro8a levels of investment.

I understand the first sentence, at least the part about 1/125 being okay for studio use (as long as the studio is relatively dark to avoid mixed color temps from ambient contamination at a slow shutter speed). Many focal plane 645s are limited to 1/125 sync. (Contax 645, Mamiya 645, Pentax 645) and have worked just fine in many, if not most studio situations since most studios ARE dark.

Not sure I agree that 1/125 is optimal for outdoor work even if using ND filters. Maximum 1/125 shutter is the constant, and depending on the ambient mix, longer MF lenses can introduce subject blur when working spontaneously mobile and handheld, or even on a mono-pod in the heat of shooting.

Also, if, like me, you work mobile outdoors with a strobe as key and a TTL speed-light in the hot shoe for fill, strong NDs diminish the effectiveness of the weaker speed-light to keep up with more powerful strobes (depending on distance to subject).

However, I DO understand that all the above is dependent on individual needs, situations, and expectations. We either pay-to-play, or do a work around and accept some limitations.

What I do not understand is the last sentence.

What does 1/125 sync verses 1/1000 sync have to do with the cost of the lighting? Just curious, because I do not have Scoro or Pro8B level lighting, and use higher sync speeds with less exotic Acute, Hensel, and Elinchrom gear … but freely admit I may be missing something

Enlighten me, please.

- Marc

 

[gazwas]

What I do not understand is the last sentence.

What does 1/125 sync verses 1/1000 sync have to do with the cost of the lighting? Just curious, because I do not have Scoro or Pro8B level lighting, and use higher sync speeds with less exotic Acute, Hensel, and Elinchrom gear … but freely admit I may be missing something

Enlighten me, please.

Less costly lighting as in the Senso and Acute do not have as good flash durations as the more expensive equipment, just compare the t.01 specs. If you shoot at 1/1600th second sync speed with the vast majority of strobe equipment the portion of flash intensity (flash burn) you are exposing the sensor to is massively reduced (2 or 3 stops). .

If you are talking over powering the sun etc where a fast flash sync is usually used for then you are dealing with 2 or 3 stops less power from your strobe equipment which could have an effect on the shoot (work around again). Meter up at 1/125th second and then decide you want 1/1600th sec for a night time feel and its not just a case of factoring the exposure. The more expensive packs have very fast t.01 times in comparison so shooting at these high sync speeds is not so much a concern.

As you said, we pay-to-play with MFD so just saying you can sync a Phase system at 1/1600th second is not quite as clear cut as it appears unless you're prepared to pay-to-play again with the strobes equipment also.

Non of this really matters though as the OP is asking about 1/125th sync sped in a studio which will work just fine.:thumbup:

 

[johnnygoesdigital]

According to specs. the Pentax 645z will shoot @1/4000th using strobes with HSS.The Paul Buff E640 strobe has one of the shortest durations of any light. This light is usually the choice for liquid photography where freezing action is key. You do not need leaf shutter lenses for high sync anymore.

Also, you can boost the cameras ISO for more control of ambient. Faster shutter speeds allow for better hand held photos.