Flashy tips?

dunc

New member
I've had a digital camera for quite some time and took loads of pics underground, but as expected results can be a bit naff with a camera mounted flash. So, just the other week I made the leap and acquired a firefly and a cheap flashgun and made the first steps into using them down Mistral the other week.

As of yet I haven't made an attempt to protect the slave unit or flash in any way - I've seen various different suggestions for protecting them and wondered what everyone elses opinion was of what works well/what doesn't, any must do's etc..??

Cheers! :D
 
L

Lincolnshire poacher

Guest
I use a Canon 300D with 2 metz flash guns (C43's I think) Never used the firefly thingy at all. I use the Jessop slave flash units. They are £9.99, and seem to be very robust. My only complaint about them is the plug sometimes doesn't make contact properly and the flash doesn't go off.

My best results have been using the flash guns to 'paint' the picture ie set up camera on tripod, open shutter, walk away from camera flashing the flash etc, close shutter. Or set the camera/tripod, put one flash up passage a bit, set shutter to 30 secs, open shutter and keep flashing the flash gun in your hand. This will set off the other flash (if your slave unit is working correctly). After 30secs you have a prety good photo. I did a couple like this down Box the other week....but seem to have deleted them off the camera without downloading them :oops:
 

SamT

Moderator
A suberb trick that my friend uses - is to get a bit of the spare film you get at the end of your negatives, and tape it over your inbuilt flash, this filters out all the 'light' but lets the ifra red light though, The ifra red will trigger your fire flies but you wont get any 'fogging' from the inbuilt flash.

seems to work a treat.
 
K

Kelvin

Guest
Opening the shutter and painting with flash guns is great for 'film' cameras, unfortunately with digital ones (or at least the ones I can afford :( ) you can't hold the shutter open.

I've been experimenting with multiple flash guns, either on tripods or mobile bipods (they tend to make strange grumbling noises after an hour or two!), then using the self-timer of the camera to avoid any shake when pressing the button - this also give you chance to run into shot for a self-portrait or to give it scale (my excuse :D ).

Depending on the size of the chamber/cavern etc.. I either use a cheap £2 flash and slave from Dixons closing down sale or a larger flash fitted with a firefly or both, triggered from the camera flash. Cheap 2nd hand flashguns are ideal as you can buy loads of them! Also try sealing them in a Tesco "Pour and Store" bag - water tight and see-thru'.
 

Brendan

Active member
I use a digital - Canon A75 - and that gives a manual exposure up to 15 seconds. It has worked quite well with multiple flashes - you just need a quick recharge time on the flash gun.
Its not too pricey either, one of my friends just bought one for just over £100.
 

mudmonkey

New member
Speaking of flashing, Brendan - I was talking to an old housemate of mine yesterday. Says he saw you at the freshers fair but didn't recognise you with your clothes on.....

(I can say authoritatively that although it's difficult to persuade him to keep them on, Mr October does in fact normally cave fully dressed - he just has exhibitionist tendencies when there's a camera around.....)
 
F

Fiona

Guest
:D Hi all just spotted this post . I have just got myself a flash gun a Centron F G 30 off ebay for £11 quid not sure whether got a good or bad deal as not very little about flash guns .I have just started doing cave photography with my canon A 80 dig but the buit in flash is causing problems with steem so was told to get a flash gun and slave unit so can move flash away from camera .
Can anyone tell me will this flash gun go with any slave unit ? and will I any cables to connect it ?
any tips advice would be good
Thanks Fiona.
 
M

Mole

Guest
Your Centon (Jessops) flash should work with one of their hot-shoe slave cell units.
There's a threaded socket in the bottom of the slave cell,I use one of those mini-bendy tripods on my slaves,they keep the flash off the floor,and you can wrap the legs around things to put the flash in other places.

The only way to stop the "steem" is not to get wet in the first place (difficult),or wait for it to dissipate,and don't move around in the subject area.
 
M

Mine Explorer

Guest
Fiona said:
...I have just got myself a flash gun a Centron F G 30...
...I have just started doing cave photography with my canon A 80 dig but the buit in flash is causing problems with steem...
Can anyone tell me will this flash gun go with any slave unit ? and will I any cables to connect it ?
any tips advice would be good
Thanks Fiona.

A couple of people in our club use the 'jessops' flash slave, but they do have the disadvantage that they need a pretty clear line-of-sight to the flash that's triggering them. I much prefer David Gibson's flash slave, not really suitable if you're not into soldering together gadgets, so the next best would be the Firefly slave.

The largest cause of mist is your own breath being illuminated by the flash positioned right next to the lens. The best way to avoid it is to move the source of light (ie. flash) away from the lens.... not possible with a flash on the camera! The two options available are to hold your breath for two or three seconds before pressing the shutter, this will let the mist clear a bit. (Digital gives a clue whether it's misted up or not at the time - but can look clear on the camera but still misty when you look later on a PC... so I've been told)

The alternative is to hold the camera in one hand and a flash slave in the other, to stop the light from the camera you cover it with a piece of unexposed (but developed) slide film, this is black and will block visible light, but allows infra-red light through to trigger (a D. Gibson/Firefly) slave flash. Most people these days have access to negative film rather than transparency/slide film, this seems to work as well - only in this case you want to use a frame that's overexposed (might find a bit right at the beginning/end of the film where it hung out of the canister).

A combination of techniques can produce some good photos, ie. hold a flash slave in one hand but don't cover the camera flash - you still have to hold your breath before taking the picture (else risk mist) but if the slave is more powerful than the camera's flash (not usually difficult to achieve) then the subject gets some modelling from the light to one side, but you don't get inky black shadows because the less powerful flash on the camera acts as a fill.

If you've got a spare slave then it can really lift a photograph to use a bit of 'backlighting'. Position the flash behind your subject looking back at the camera - make sure the flash is hidden behind your subject or around a corner though (ie. no direct line of sight between flash and camera lens). This technique will put highlights on the edges of rocks/water etc. and gives the feeling of depth in a photograph, it can prevent the illumination just fading into muddy darkness. For the sake of a couple of slaves it's a trick worth trying.

If all of the above seems double-dutch, then just go underground and keep taking photos and experimenting. Change how you do things and make a note (mental or paper) on what works and what doesn't. Most important of all, have fun!


Mine X.


PS: Yes, the flash slaves usually connect to the flash gun using the 'hot-shoe', the slide in connector usually found on cameras. If you build a David Gibson one you have to make your own connections - or purchase a suitable hot-shoe adapter and cut the other plug off.
 

Fred

Member
Fiona,

One point worth noting with Digital Cameras is that a lot of them emit a very short pre-flash prior to the main flash. This (I think) is to help with the auto-focus but obviously will play havoc with any IR sensistive slave units i.e. your flashes are triggered by this pre-flash rather than the main one.

Whether this issue affects your camera I don't know but worth checking the manual (may be able to turn this feature off). An alternative is to use a long exposure e.g. 4 secs and manually trigger the flashes during this time.

Dave Gibson has just produced a modification to his original slave design which is designed to cater for this. He may be producing pre-assembled units as well for those of us not handy enough with a soldering iron.
 

dunc

New member
Most people these days have access to negative film rather than transparency/slide film, this seems to work as well - only in this case you want to use a frame that's overexposed (might find a bit right at the beginning/end of the film where it hung out of the canister).
When I bought my firefly it came with a piece of film to use for the purpose of blocking visible light. (saved me scratting around trying to find a piece!)

(Digital gives a clue whether it's misted up or not at the time - but can look clear on the camera but still misty when you look later on a PC... so I've been told)
Can't say I had noticed that when I was using just the camera flash without any slaves. Maybe it depends on camera model or something?
I reckon digitals are great for learning where to place the flashes, useful to see the results there and then and adjust flashes as necessary.

A combination of techniques can produce some good photos, ie. hold a flash slave in one hand but don't cover the camera flash - you still have to hold your breath before taking the picture
I found breath wasn't my biggest problem, more that spotty problem (is there a technical term for it, can't think at the moment?) caused by moisture/dust in the air - streamways and wet pitches were always the biggest problem areas.
I've now got two slaves and flashes and don't use the camera flash (apart from lacking in power it causes more trouble than its worth) - two external flashes seem to produce good enough results.

Can anyone tell me will this flash gun go with any slave unit ? and will I any cables to connect it ?
any tips advice would be good
Look at the flash contact - does it have one contact point or multiple contact points??
I obtained a very cheap flash off ebay but didn't realise it was a 'dedicated' flash - it had more than one contact point on the bottom - this didn't work with the firefly. Best bet is to make sure it's 'non-dedicated' which usually just have a single contact point on them.
 
M

Mine Explorer

Guest
Best bet is to make sure it's 'non-dedicated' which usually just have a single contact point on them.

FYI.
Centon FG30

Available from Jessops £25-£30 = non-dedicated (details)
 
M

Mole

Guest
On the Jessops hot-shoe slave cells there's a stop where the cell fits onto the foot of the flashgun.
I used a sharp knife to remove it,this allows me to mount the cell back to front,i.e the slave flashguns face the subject,and the windows on the slave cells face the camera,and have direct line of sight to the flash mounted near the camera or the slave flashes behind them for long tunnel/passage shots.
Sometimes,relying on light being reflected off walls etc doesn't always work very well,especially in coal or metal mines

I'd like to use Firefly slaves,but can't afford to buy 10 of them to replace the Jessops ones I already have.

I never use the cameras built-in flash,that a sure way to get "Orbs",those round blobs that ruin shots.

(don't go on a u/g photo trip with Lincolnshire Poacher,you'll set all your flashes up and he'll take a shot,sneakily using all of your slaves :LOL: :LOL: :LOL: )
 

SamT

Moderator
any one got any tips on waterproofing your flash's - I've heard you can get quite a belt of em. Dont know if its true like.
 
L

Lincolnshire poacher

Guest
Never got a shock off a wet flash, but check out http://www.botzilla.com/photo/strobeVolts.html for info on what trigger voltages various flash produce. My £9.99 cheapy flash puts out, according to my test meter 240v!!. My Canon Eos D doesn't like anything above 5v. The only electric shock I've ever got underground wasn't from a flash!!. If you see bare wires hanging from a wall, never ever touch the ends to see if they are live. Because 9 times out of 10 they will be live and you will do a funny dance across the passageway!!.


Mole said:
(don't go on a u/g photo trip with Lincolnshire Poacher,you'll set all your flashes up and he'll take a shot,sneakily using all of your slaves)

I've only ever done that once or twice, least I didn't take 30 mins to focus a shot!!.
 
M

Mole

Guest
The tubes in flashguns use a voltage in the range 250--1000 volts DC,it depends on the spec of the tube.
The flashgun uses an inverter/converter to step the battery voltage up to the tubes operating voltage,this high voltage energy is stored in a capacitor.
The more powerful the flashgun,the more energy is stored,one old flash I had had a tube which worked at 750 Volts and the gun was rated at 100 Joules (100 Watt/Seconds).At a flash duration of 1/1000 sec,it was the equivalent of switching on a 10,000 Watt bulb.

The trigger voltage is stepped up to a few Kilovolts to cause the tube to conduct.

Basically,you're dealing with a high voltage/very low impedance source,and it needs to be treated with a great deal of respect and care,I've melted/blown-up a few screwdrivers over the years,repairing flashguns.
If one of mine got a real soaking or was dropped in water while it was switched on,I'd be inclined to leave it where it was,the combination of high voltage and the amount of stored energy means they can be lethal if something goes wrong.

(When the Lincolnshire Poacher touched that cable,he didn't just dance,he used some very rude words indeed :LOL: :LOL: :LOL: )
 
C

caveman

Guest
Mole said:
(When the Lincolnshire Poacher touched that cable,he didn't just dance,he used some very rude words indeed :LOL: :LOL: :LOL: )

It was the last place i would have exspected to find a live cable i must admit :shock:
 
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