Simple strobe question (I hope!) from a simple person..

[stiebs]

Thanks Jerome. I'm flaberdergasted.
I wasn't asking or expecting anyone to go into nearly that much detail, but I'm extremely grateful that you have.

And all of it even makes sense to me! It is a little disappointing that the P5 doesn't budge much when the flash on, but I guess its primary purpose isn't for professional underwater photography.

Well, I figure that with a strobe I can't do any worse than the photos that I'm producing at the moment. And as you say, if I properly select a strobe that is going to outlast my camera, it'll be hard to go too far wrong.

Once again, thanks for all your help.

 

[Cecil]

Thanks Jerome, also. Good stuff and thanks for the work and sharing. I have the P5 also. No external flash (not convinced of the need). What I did get from your analysis is to up the ASA setting before going underwater. I had always assumed the camera would in low light (well we all know about assume). I have been having considerable problems with motion blur, now I know the stupid camera was using 100 ASA. Not anymore, it's to bad the water's gotten to cold to dive. Next year.

 

[cmdasia]

I actually own (and use) both the DS125 and the YSDX90 - I also own the Ikelite slave sensor which I have NEVER been able to get to work properly in TTL (Oly 4040) - for every correctly exposed shot I took I had 10 junks shots, the 11th was good because I had always gone back to manual at that point out of frustration- the slave sensor is not TTL (as we consider it with a film camera), its a pain. It does work OK for triggering the strobe in manual though.

Which is the better strobe? Neither - the Ike's inbuilt aiming light, recharge battery pack, sheer power/ 1 sec recharge, power meter are its pros - cost is a negative.

The seansea's simple well made enclosure, adjustable power settings, ability to use AA's, lightness (though be careful with off arm shots - its buoyant in salt water!) and above all price make it a great strobe.

Which is the better choice for shooting manual using a PS digital housed camera - the seansea - no doubt the 12 power settings make manual shooting easier because you simply adjust the strobe setting after each shot rather than messing around with the camera controls(f stop or shutter speed). its also lighter to carry and the o ring gives me more confidence than the Ike O ring which is glued in place (I no like - I like to take them out and clean them). Which do I use most - the Ike (complicated he!) because I just love the aiming light and the 1 sec recycle (sometimes the 4 sec of the CnC is a little too long but not in 90% of cases).

Which do I think you should buy as a starter- probably the CnC, fibr optic cord, with a pelican aiming light, 8 NiCAD 1800 rechargables and a 1 hour battery charger.

Hope this helps

 

[JeromeYep]

Hi cmdasia (sorry, don't know how to address you)

I'm sorry to hear that you've never been able to get the DS125 and C4040 in TTL mode. From what I gather they make an excellent combo, especially in TTL.

What mode are you shooting in on the C4040? i.e. program, AP, SP, manual.

And what flash mode are you using?

Also, (dumb question ) but you are using the Ike 4100.5 (Digital) TTL slave senor?

 

[JeromeYep]

Cecil, be a little conservative when using higher ISO settings.

Whilst it's true that using a higher ISO setting in forced flash mode will up the shutter speed it will also introduce more noise in your picture (similar to film grain). Now while film grain can sometimes add aesthetical value to the picture digital noise is just plain....er...undesirable.

Also is it motion blur (slow shutter) or the camera being unable to focus correctly or the poor depth of field (DOP) because the P5 does an 'open sesame' - all due to less light being available at depth. Or possible a combination of all? All solved by a little bit of help by - you guessed it - taking a bit of sun with you - especially in poor vis or greater depths.

Just try a good dive torch (about 20w or more) - like an Alpha or the newer Treble Light - hire it from your LDS. You might need a diffuser - just attach a semi transparent piece of plastic from your local hardware store - to prevent hot spots and to soften the light for a more pleasing effect. Ok the color temperature is not quite right, you'll want about 4500 - 5500K, conventional halogen is warmer (redder), the new HID lamps about 4500K but are expensive and can be used for video and still (treble.com.de). But you'll see a significant change in the quality of you pictures. You'll also find it hell of a lot easier colour correcting a warmer shot in post than a greenish-blue pic.

 

[JeromeYep]

Ok. TTL is good for certain situations and has problems with others. The TTL sensor on your camera is not very smart. All it sees is how much light is falling on your film plane - in the case of digital - the CCD. It doesn't know if it's strobe light coming off the subject or ambient light coming from the background. The sensor will average all the light it sees and when it thinks the correct exposure has been reached it will quench the internal flash. So if your background is very bright from ambient light it will quench the strobe too early and underexpose your subject. On the other hand, if the background is very dark, the sensor may let the strobe run too long, and then you'll get a overly bright subject on a dark background.

Throw all this extra stuff about slave strobes, slave sensors, underwater etc out of the - no pun intended - picture and just think about the basic principal of auto exposure photography of a subject standing in front of a bright or dark background. Any book, even the camera's idiotic manual, will tell you - your camera is going to get fooled. It's going to average out everything, and when it thinks it's got an exposure that will render an eighteen percent grey correctly, it'll tell the camera to stop.

A general rule of thumb: if the foreground you're trying to light fills more than fifty percent of the frame chances are that TTL will work. Less than that and it will probably fail. Shooting wide angle? It'll probably fail. Shooting macro? TTL is probably going to be a winner, unless your macro subject is surrounded by a wide expanse of water.

All this tech. stuff aside - just go out there and shoot a lot - if it's digital it's free (i.e. when your credit card recovers from the initial shock) - have some fun. Just that you'll have more fun if you take a little sun down with you.

 

[Cecil]

Good advice, Jerome. I'm fairly sure it motion blur vs. focus. Easy to tell the difference, if I had some examples with me I would show you. Seems like I have tried the higher ASA's in the past don't really remember how the pictures come out. Next time I'll switch underwater and compare when I get home. Generally I can not tell the pictures are blurred on the LCD and don't know till I get them on a bigger screen.

I take pictures under the worse possible conditions, pea green water with lousy visibility, cold and lots of surge. The last is my biggest bane and has killed more pictures than 4' visibility. Surge combined with shutter lag (hard to do the half shutter depress with 7mm gloves) makes framing fun. Last dive I was steading myself on a rock to get a shot, after the shot I looked at the rock and there 6"'s from my finger was a Sea Raven (Scorpian Fish). Why he didn't bite me I still don't understand.

 

[JeromeYep]

LOL

Where on earth do you dive? I thought diving around Sydney was tough - we have some beautiful spots 15 min from the City Centre - but conditions can be tough - surge, difficult entry and exit, waves, rocks, 16C water in winter and sometimes shocking vis. Sounds like a cakewalk when you describe your spot!