I'm glad NDs work for you and how you shoot Christian.no problem jack but i do understand the relation between flash power, nd filters and shutters very well. the main question is what look do we want - an unnatural day for night style or a more balanced result with the flash as key light. if it is the first than yes you will need more flash power with an nd filter and the higher sync cameras has a clear advantage but if you are for the later it works very well in practice with just the use of an weak nd filter. i did use this technic in the past for a couple of people shootings most of the time at noon on sunny austrian glaciers with my elinchrom ranger and i did never run into not having enough flash power.
but when you look closer it gets more tricky anyway and another problem appears. high sync speed can come with the penalty that you loose some of the emitted power. a hensel porty needs 1/300 sec to deliver his 1200 J so depending on the flash head the power pack, the shutter speed and also how you tripgerr the flash, wirless or with a cord you end up with very different power results minimizing some of the advantages of higher sync speeds.
the last point i also think you made an error with you f stop calculations - my hasselblad h3dII for example syncs at 1/800 my sony a7r2 at 250 so the hasselblad has a speed advantage of 1 2/3 stops but in practice it is enough to compensate the flash power by 1 1/2 stop because of the better dynamic range of the sony.
christian
They do not work for me, and never have.
ND filters do not affect the lighting ratio when you trying to change that ratio. Shutter speed is what affects ambient while not affecting flash exposure … allowing you to alter the ratio.
In practice I never get the Day-For-Night effect in the conditions I'm shooting in where I need flexibility in changing conditions … which is easily accommodated by tweaking shutter speeds even 1/2 stop, and then adjusting flash output to achieve just the right balance.
While your Hensel Porty data is correct it is narrowly selective to support your POV. It assumes t1 @ 100% output using a ProMini 1200P head … I use the Speed Heads which are twice as fast @ t1, and t5 duration of 1,580 at 1200W/s is well above the max sync speed of my Leica S camera using the built in Profoto AIR radio in the Hensel Porty 1200L. I've yet to see any negative t5 effect @ 1/1000 sync with the Porty/Speed Head at full output.
BTW, it is a well documented issue that the 1/250 sync speed of the Sony A7R-II refers to use of Sony speed-lights. There is a deep discussion on DP Review with loads of experiences that place the sync speed at 1/160 for a clean image when using studio strobes. I've found the same thing with my A7R-II and Profoto, Hensel and EL Quadra systems, and so has my friend with Photogenics. Elinchrom is supposed to be working on a SkyPort transmitter for Sony to help achieve 1/250 … reported to be available in June.
- Marc