Canong G2 and Ikelite DS50 Strobe

Aloha Shooters,

I'm a researcher with the University of Hawaii currently working on an EPA project. Part of my task is to get a photorecord of 1m x 1m sections of reef all around the state of HI (don't you wish you had my job?)! Problem is that most of my experience is with Nikonos V. The project purchased a Canon G2 with Ikelite housing and DS50 strobe/slave sensor and the Sea & Sea wide angle lens. My images look like they're not capturing the DS50 light. I've redirected the cam flash to the slave sensor with foil in the housing instead of the provided widget. The DS50 is definitely firing and the illumintation should hit at least part of the 100 degree field of view, but images are darker than when I use only the cam's flash. Any thoughts about how I'm screwing up?

P.S. Love the Kona shots, I'm there in two weeks.

What exposure mode are you using? What aperature?

I recommend you use Av mode, and play with the aperature, and the flash exposure compensation adjustment, and see if you can get results that make sense.

Do you have "force flash" on?

I have the same Problem as wormguy. I tried Av Mode, but nearly all pictures are underexposed (way too dark). When shooting in Manual Mode it works fine, but you have to fiddle around with the aperture and exp. time a lot. As your Pictures look wonderful could you please post some specs on your settings (aperture, white balance etc)?

I think you've got a bad sensor. Return to Ikelite and they'll send you a new one.

This is a common problem that they have now fixed.

Karl

I agree that it is probably a bad sensor. Ikelite is great and will fix it no questions asked.

I use the same set up but with the DS-125 and I have had no problem since I had my sensor fixed.

You definitely should should on Av mode or Manual to get the best results.

G'Day,

I have the same problems as Mark (pictures

are underexposed, specially close-ups, but

the DS-50 is firing).

But I've got my DS50 & sensor last week!

Is there a way to test if the DS-50/sensor

is working properly?

Cheers,

Peter

If you shoot in Av mode, the ds50 must be in ttl mode. If it is not, it will dump a full dump, for the pre-flash, and be recycling, for the main flash.

Could this be your problem?

The aperatures are all over the place. Each picture, on my website, has the aperature listed, as well as the shutter speed, (which of course was calculated by the camera).

Don

My Sensor is in TTL Mode, and the DS-50 doesn't dump in full because the red light is still on after the shot. If I remember right then the red light indicates that there's still enough charge for another immediate flash. Is that correct?

I found your posting about your settings, will test them tonight. Is the positioning of the sensor a big issue? I just pointed it towards the reflector-gadget from ikelite. Anything special about that?

It is the switch on the strobe that determines the mode.

Not the sensitivity adjustment on the sensor.

Can you get decent pictures, using Av mode and the camera's built in flash, above water?

Pointing it is not critical at all.

Don

I did tests with all kinds of various settings (on land), but without success:

- if I use DS-50 in TTL, and G2 in Av mode, I always get underexposed images (specially close-ups), with various Av settings (from 2.0 to 8.0). The camera seems to set shutter speed to 1/60 in most cases.

- If I use strobe in manual, I get over-exposed images. Even with 1/250, 8.0

- in Tv mode, with shutter speed settings from 1/200 to 1/6, the images are always under-exposed, and aperture is up to 2.0

The DS-50 definitely fires, I also changed the positions, the Min/Max sensitivity of the sensor etc.

Nothing worked...

What next... ?

I'm off to the Great Barrier Reef in two weeks... would be great to have a working system by then :-)

Cheers,

Peter

Bummer! Sure sounds like a bad sensor or strobe.

If you contact ikelite immediately, they can probably find a way to work it out with you.

Or, if you just bought it, from some place that has stock, go ask them to let you try a different unit..??

Good luck.

Don

Yes, it must be the strobe or the sensor, because taking pictures with the internal flash is fine,

both in P or Av mode. See my UW pictures page (URL below).

I ordered the strobe from the official Australian Ikelite distributer, and they got it from Ikelite two weeks ago.

That's why I thought the sensor and strobe should be OK (I was aware that people had problems with the sensor earlier this year).

Cheers,

Peter

http://cs.anu.edu.au/~Peter.Christen/scuba/

pchristen,

How far from the subject is your strobe?

varies... between 15 cm in macro mode and up

to a meter in normal. As said earlier, I only made tests on land up to now. The pictures seem to be better when the subject is further away (I guess this is because more ambient light is available).

Cheers,

Peter

Wow, lots of great shots!

And done in Gimp, yet! Are you running it all on linux?

Have you compared Gimp with photoshop?

Really good results!

Don

pchristen,

Try this:

Use manual exp mode set 8.0/250

Adjust the strobe so that it is not closer than 45cm to the subject when the subject is say 15 cm from the lens. (The strobe will be angled back from the camera.)

With trial-and-error adjust the shutter speed so that the exp is correct. (or adjust the f-stop if you have to)

As you take shots with the subject further and further away adust the shutter speed (or f-stop) one step at a time.

Note: make sure the sensor is pointed in the direction of the cameras built-in flash

Shutter speed has NO effect on flash exposure.

Further, using manual mode on the G2, prevents using TTL, which is the whole point here.

Don

I noticed an improvement of picture quality when I turned up flash-exposure compensation to about + 1 and 2/3. I read that you (don erway) sometimes use negative flash exp. comp. How can this be with the exact same camera model and exact same strobe model?

Still trying to make my new DS-50/ Canon G2 system working...

I did lots of tests yesterday, and found a method which seems to

work (it mostly did for me):

Use DS-50 in TTL, sensor max or min (doesn't seem to matter), diffusor

on, G2 camera in Av, set to 8.0

Aim at your subject, press the * (exposure lock) button, then focus (normal

shutter half pressed), shoot, and the exposure is OK. This even works in

macro mode (subject distance around 10cm, lens on wide (34mm)).

When I used Av larger than 8.0 the image got over-exposed.

A press on the '*' is the same as a preflash...

The position (distance to subject) of the strobe seems to matter,

as does the diffusor.

I'm still not 100% convinced that this is the way to go..

Unfortunately I haven't been able to test the system under water yet.

Cheers,

Peter

Peter, it shouldn't be that touchy.

Since it seems to help, if you introduce this time delay, between the preflash, and the real flash, I still think you've got a faulty unit.

By the way, are you shooting ISO 50?

With my setup now, I only have to use F8, when closer then a foot or so. (Well say camera to subj 1 foot, and strobe up another foot or so...)

At about 2 feet, I can use f4.

This is all in air. You need that light much more, underwater.

And for me, it works in the normal, half-press to focus, recompose, and shoot, mode, no exp lock needed.

Of course, distance does matter. Because you may be hitting up against the "smallest light pulse" that the strobe/camera can put out. In that case, you do need to stop down, and exposure comp will not help.

Make sense?

Don