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Archive 2017 · Profoto B1 - HSS Colour consistency

  
 
leethecam
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p.1 #1 · p.1 #1 · Profoto B1 - HSS Colour consistency


I've just updated my firmware to allow a greater range of power with my B1's when using HSS.

A curious quirk has been noticed - it may have done this with the older firmware, but I don't use HSS much so not sure if this is a new thing or not.

With shutter speeds set at a leisurely 1/100 sec I take two images of the same area. (5D Mk3)

All shits are manual shutter / aperture / ISO / colour set manually to 5600K

With the TTL Remote set to TTL, colours are reasonably as expected.

With the TTL Remote set to HSS, colours are somewhat warmer - guessing about 500-600K

Now I might expect colours to shift when I start pushing the HSS system with shutter speeds in excess of 1/200 (we can't have everything in life), but at a slower 1/100 I would assume the B1's behave with a normal flash operation.

Happens equally on both of my B1's, with exactly the same E1 firmware update, (which all went through just fine) and the C3 firmware update verified fine on the remote.

(As a side note, TTL seems a little under-exposed with the Profoto ETTL system, maybe 1/2 stop?).

Thoughts anyone? (I've got Profoto digging, but their UK office is unsure at present).



Aug 23, 2017 at 04:33 AM
Eyvind Ness
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p.1 #2 · p.1 #2 · Profoto B1 - HSS Colour consistency


1/100s isn't much of a HSS scenario, and ambient light could leak into the exposure perhaps? Do you see the same thing with actual HSS speeds, i.e. 1/500 or faster?




Aug 23, 2017 at 07:03 AM
Konablue
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p.1 #3 · p.1 #3 · Profoto B1 - HSS Colour consistency


1/100 of a second is a long time for the B1's bulb to be rapidly pulsing on and off. I'm just speculating here but one possibility is that the capacitor is dropping it's full charge while trying to power a cycling bulb during a relatively long 1/100 shot. The strobe demands a high power range when operating in HSS Mode. As a result, The bulb may end up being a little short on power during that type of shot and therefore may produce a slightly warmer light.

The obvious solution is to use High Speed Sync for what was designed to do; Capture high-speed shots. TTL and manual are much better when used for X-sync or slower speed shots. HSS is a powerful feature to have when you need it but due to the nature of HSS, it isn't perfect and can be inconsistent at times even when used in conjunction with fast shutters. I recommend taking multiple shots when using HSS to ensure a keeper.

One more note: HSS will shorten your bulb life but you would have to do an awful lot of HSS shooting to really notice.(See B1 manual, page #16).




Aug 23, 2017 at 07:15 AM
leethecam
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p.1 #4 · p.1 #4 · Profoto B1 - HSS Colour consistency


Thanks for the input.

I tested at 1/100 after I initially noticed the colour shift because I wanted to find out if it was the strobe working extra hard to work at a fast shutter or whether it was simply the engagement of HSS mode.

I'll come back with findings after Profoto get back to me.



Aug 23, 2017 at 03:13 PM
Konablue
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p.1 #5 · p.1 #5 · Profoto B1 - HSS Colour consistency


Let us know when Profoto gets back with you. I'm interested to hear what they say about it.


Aug 23, 2017 at 03:19 PM
leethecam
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p.1 #6 · p.1 #6 · Profoto B1 - HSS Colour consistency


Feedback from Profoto is that HSS is engaged all the time when selected.

ie. It doesn't intelligently kick in after the sync speed of your camera when selected, but uses conventional flash at under sync speed. (We were hoping that the remote and camera would talk to each other and it would know what the camera sync speed might be).

They confirm that due to the method of achieving HSS, colour temp will be effected a little and because HSS is engaged throughout the whole shutter speed range when engaged, this colour shift is apparent even at low shutters with HSS set to on.

Fair enough. It just means I shouldn't have HSS on by default, like I do with my speedlights.



Aug 25, 2017 at 05:50 AM
NCAndy
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p.1 #7 · p.1 #7 · Profoto B1 - HSS Colour consistency


leethecam wrote:
Feedback from Profoto is that HSS is engaged all the time when selected.

ie. It doesn't intelligently kick in after the sync speed of your camera when selected, but uses conventional flash at under sync speed. (We were hoping that the remote and camera would talk to each other and it would know what the camera sync speed might be).

They confirm that due to the method of achieving HSS, colour temp will be effected a little and because HSS is engaged throughout the whole shutter speed range when engaged, this colour shift is apparent even at low shutters with HSS set
...Show more

Thanks for that info.



Aug 25, 2017 at 10:47 PM
story_teller
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p.1 #8 · p.1 #8 · Profoto B1 - HSS Colour consistency


Strange. I have the Nikon version of the TTL remote and it automatically goes into Hi-S when I select a shutter speed faster than normal sync and then it falls back into regular 1st. Sync when under the max sync speed. I can't force it into HSS while in normal sync. Must be a Canon-specific thing.



Sep 02, 2017 at 01:18 PM





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