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Huw Groucutt
Guest
would using a digital camera and slaves to other flashes work properly?
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mudman
Guest
Depends on the camera. Digital camera often fire two flashes, one to get focusing and exposure correct followed by another to actually light the shot. This means that the first flash fires all your slaves which are wasted.
I think the early cameras also fired two flashes to build up the picture in two passes, so the effect here would be only one half of the picture exposed.
I think the early cameras also fired two flashes to build up the picture in two passes, so the effect here would be only one half of the picture exposed.
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Huw Groucutt
Guest
yeah. A lot of modern ones have variable flash settings so presumably you can turn off the double flash thing....isn't the two flashes to stop red eye?
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mudman
Guest
Again, the ability to turn off the double flash thing would depend on the camera. You can add an external flash to the S602 so this would work ok.
Features such as red-eye reduction would be a separate process to the picture-exposing one. With red-eye reduction, you'll get one or more flashes to close down the iris followed by the flash to expose the picture. This again could be a single flash to determine exposure followed by the 'big' one.
Truth is though, I don't really know and I think that each camera would be different.
If you want to use a digital camera underground, then I would get one that provides external flash/hot shoe, manual focusing and a shutter speed setting.
If you already have one, then test it out first. We have a cheapy one and that has the two flash effect that results in a picture only lit by the on-camera flash and hence very underexposed. There are various flash settings on it, but all still have the same effect.
Features such as red-eye reduction would be a separate process to the picture-exposing one. With red-eye reduction, you'll get one or more flashes to close down the iris followed by the flash to expose the picture. This again could be a single flash to determine exposure followed by the 'big' one.
Truth is though, I don't really know and I think that each camera would be different.
If you want to use a digital camera underground, then I would get one that provides external flash/hot shoe, manual focusing and a shutter speed setting.
If you already have one, then test it out first. We have a cheapy one and that has the two flash effect that results in a picture only lit by the on-camera flash and hence very underexposed. There are various flash settings on it, but all still have the same effect.
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Huw Groucutt
Guest
but most affordable digital cameras don't have controllable shutter speeds. You could put infra red tape over the flash to set off slaves but not give off anay visible light.
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mudman
Guest
bubba, problem then is that you have a very long exposure time and you end up with increasing amounts of noise in the picture. IIRC Andy Sparrow reckoned about 2 seconds was the limit.
Huw, you can do that, but again you can run up against the double flash problem. This time though you get nothing because the camera is only getting infra red light.
I do recall though that Dave Gibson is/was working on a delayed slave unit that will fire on a second flash or something like that. That would make it possible to use the more affordable cameras.
Huw, you can do that, but again you can run up against the double flash problem. This time though you get nothing because the camera is only getting infra red light.
I do recall though that Dave Gibson is/was working on a delayed slave unit that will fire on a second flash or something like that. That would make it possible to use the more affordable cameras.
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Huw Groucutt
Guest
yeah i've seen a picture of that slave.
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Mole
Guest
I very rarely use the built-in flash on my digi,I connect a seperate flash to the hot-shoe and use that to fire the slaves.
For long exposures I hold a flash near the camera,open the shutter and fire the hand-held flash manually which sets of the slaves,then fire again when the flashes have charged up again,and repeat as necessary.
The reason for taking the flash off the camera and manually firing it is it stops the physical shock from the flashgun firing from being transmitted to the camera and causing shake.
For long exposures I hold a flash near the camera,open the shutter and fire the hand-held flash manually which sets of the slaves,then fire again when the flashes have charged up again,and repeat as necessary.
The reason for taking the flash off the camera and manually firing it is it stops the physical shock from the flashgun firing from being transmitted to the camera and causing shake.
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Huw Groucutt
Guest
Mole said:
er no the general reason for taking flashes of the camera is that you want to stop the picture being foggy and if you fire it from close to the lens light relfects straight back into it. But that may be a reason aswell i suppose.
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Mole
Guest
If I use the built-in flash,I occasionaly get "orbs" in the pic.
This doesn't happen when I use a flash in the hot-shoe.
But for multiple flash firings on a single exposure,I remove the main gun and handhold it.
This doesn't happen when I use a flash in the hot-shoe.
But for multiple flash firings on a single exposure,I remove the main gun and handhold it.
cap n chris
Well-known member
I suppose this depends on your definition of affordable; spending around £150 will get you a camera with customable features like manual aperture, shutter, flash power settings etc..
A Canon Powershot will set you back around £150; it has variable shutter speeds etc. and the flash is easily switched off and photographs underground CAN be taken without any flash at all - see the stuff I posted in the Forum.
Shutter speed on the A60 CAN be set as long as fifteen seconds but this will generate noise - on long shutter speeds you must use a tripod but if the passage size is small you can get nice effects without flash/slaves. You don't really need much more than half a second but check it out and see what works. I use my Nova to create (white) foreground lighting with a no-flash setting and long shutter speed.
The best bet, Huw, is to experiment and see what you come up with - there's great stuff possible but I sometimes feel people are too "cosseting" about their cameras - mine got totally flooded in the BDH down Llygad Lywchwr but I just took the batteries out (immediately) and dried it out slowly on the radiator and it was fine again - mind you, I wouldn't want to do this on purpose just to prove a point!
Andy Sparrow's multiple layering technique generated some good results; see his website and the picture of the Gorge in GB Cavern to see what you can do with 30+ slave shots overlayered.
And in answer to your first question about using slaves; the answer must be "No problem". This is because (on the Canon) you can set the flash in a variety of modes - red eye, auto, auto red-eye, on, off etc.. Just select "single", alter the aperture and shutter speed to take account of the additional light coming from the slaves, and experiment with your settings according to the results on screen.
Enjoy. Post your results so we can see what you get up to.
I recently bought a Canon A75 and using the long exposure with seperate manual flashes worked really rather well. If you use a tripod there is no reason why the picture won't be as good as a long exposure with multiple flashes on a conventional camera. The only problem is if there is a pre flash and you are trying to use the camera flash to trigger others. Haven't tried this yet as someone had borrowed my Firefly but will have a go next weekend and tell you what happens.
Cave_Troll
Active member
Yes but i've given it back to you know 
Johnny
Member
I try not to get involved in photography myself but the guys on the Cuetzalan Tiger exped. took all of the pictures with digital cameras and remote flashes and the results were excellent, all of the pictures posted on the exped thread were taken in this way.
It didnt look too faffy either.
Steve created these pictures using this technique.
http://www.ukcaving.com/board/viewtopic.php?t=396
It didnt look too faffy either.
Cap'n Chris said:
Steve created these pictures using this technique.
http://www.ukcaving.com/board/viewtopic.php?t=396
JJ
Member
Anyone used the Pentax Optio 33WR camera, meant to be a waterproof digital camera to about 1m. Apears to have all the right specks and gets rave reviews in the last Wanderlust mag.
£199 at Amazon but available cheaper elsewhere, any thoughts would be usefull.
http://www.amazon.co.uk/exec/obidos/tg/stores/detail/-/electronics/B0000C4E4R/system-requirements/ref=ed_tec_dp_2_1/026-5720624-1093226
JJ
£199 at Amazon but available cheaper elsewhere, any thoughts would be usefull.
http://www.amazon.co.uk/exec/obidos/tg/stores/detail/-/electronics/B0000C4E4R/system-requirements/ref=ed_tec_dp_2_1/026-5720624-1093226
JJ
DavidGibson
Member
mudman said:
This has been available for a while now. You can buy a kit from me for £30 ( http://caves.org.uk/flash/ ), or a ready-built unit from Firefly ( http://firefly-electronics.co.uk )for £60. I do not really recommend the kit as it is very very fiddly to build.
However, you are probably better off buying a better camera. It is a false economy to "use the more affordable cameras". Would you take a really cheap point-and-shoot film camera underground, or your trusty SLR? The cheaper digital cameras are the equivalent of point-and-shoots - their main feature is that they have crap lenses and crap optics. It always amazes me when people rave on about the number of mega-pixels you can get for your money, without any thought as to the quality of the optics. There is no point in having 5Mpx if the optics are poor!
Sorry to rant on - but you really are better off putting your money into a decent camera that has all the features you need for good cave photography (manual shutter and aperture control, manual focus, external flash) and then you'll find you dont need several of these expensive digital slave units
DavidGibson
Member
Sorry, bad URL there: try http://www.fireflyelectronics.co.uk/DavidGibson said:
Getwet
New member
JJ
I have a pentax optimo. If you only want a simple point and shoot its great. Its small. robust, waterproof, gives very good results. It allows pictures in very wet condtions without worry
However to operate a slave flash to reduce misting, give extra light etc you will need something like the Firefly digi slave at around 60 pounds.
if you want to do serious cave photography you would be better with something that gives more control over exposure.
Check out other posts as there has been more witten on this subject
I have a pentax optimo. If you only want a simple point and shoot its great. Its small. robust, waterproof, gives very good results. It allows pictures in very wet condtions without worry
However to operate a slave flash to reduce misting, give extra light etc you will need something like the Firefly digi slave at around 60 pounds.
if you want to do serious cave photography you would be better with something that gives more control over exposure.
Check out other posts as there has been more witten on this subject
