First trip, issues, photos

I did my first dive trip with a Digital Rebel XT in an Ikelite housing, a 60mm macro lens, a 10-22mm wide angle lens, and two DS-51 strobes. The main thing that bugged me is that I found TTL flash useless. Not, I think, because there is anything wrong with Ikelite's TTL conversion circuitry, but because the camera simply seemed wildlly wrong in measuring the light. Usually I was greatly underexposed if I allowed the camera to choose the aperture, but sometimes I was hugely overexposed as well.

By day 3, I was using manual exposure and manual flash all the time, and adjusting it up or down based on trail and error. Typically I'd start at ISO 200, 1/200th, f/11, and the flashes at -1 stop (half strength), and I'd change the aperture or flash strength based on the appearance of the previous exposure.

I'm not sure if that's common, or if there's something I was doing wrong.

I shot RAW + JPG, but didn't find that I could do much with underexposed images even from the RAW. Mainly because a lot of them were as much as 4 stops underexposed. f/11 was a good place to start for macro shots, but wasn't good for fish that were 3-4 feet away and skittish.

I've posted a handful of my better results in a thread here.

- Gus

I did my first dive trip with a Digital Rebel XT in an Ikelite housing, a 60mm macro lens, a 10-22mm wide angle lens, and two DS-51 strobes. The main thing that bugged me is that I found TTL flash useless. Not, I think, because there is anything wrong with Ikelite's TTL conversion circuitry, but because the camera simply seemed wildlly wrong in measuring the light. Usually I was greatly underexposed if I allowed the camera to choose the aperture, but sometimes I was hugely overexposed as well.

 

By day 3, I was using manual exposure and manual flash all the time, and adjusting it up or down based on trail and error. Typically I'd start at ISO 200, 1/200th, f/11, and the flashes at -1 stop (half strength), and I'd change the aperture or flash strength based on the appearance of the previous exposure.

 

I'm not sure if that's common, or if there's something I was doing wrong.

 

I shot RAW + JPG, but didn't find that I could do much with underexposed images even from the RAW. Mainly because a lot of them were as much as 4 stops underexposed. f/11 was a good place to start for macro shots, but wasn't good for fish that were 3-4 feet away and skittish.

 

I've posted a handful of my better results in a thread here.

 

 

 

- Gus

Hi Gus,

I looked at your pics you posted, and have a few comments. I should point out that I do not have Ikelite, and I only use manual presently, so I cannot give you any specifics on your set-up.

In general, I think TTL is of value for macro and fish portrait type shots where most of the image is lit by the strobes. Once you have large backgrounds like open water, larger reefs etc, you have to first consider your ambient light exposure and then use the strobe for fill of your foreground subject. I have not been able to make ttl work for this, maybe others have. In general for blue water etc, I start with metering the ambient light and underexposing a half to one stop, then adjusting strobe power to give the correct foreground exposure. Usually this means a higher shutter speed 1/125 - 1/250, and larger aperture. Remember you have your histogram to give you a lot of info, and you can do test shots ahead of time to get your exposure.

With regard to some of the pics you posted, some of the lighting seems to be uneven, and with some shadows cast which you should be able to avoid with 2 strobes. A good technique to practice was advocated by Alex Mustard on this forum recently. The idea is to practice in a pool with various size targets, and adjusting the placement and angulation of your strobes to get more even lighting.

Hope this helps.

I'm not familiar with the Ike TTL, but I've seen good results from the the Ike TTL + DS-125's and that same camera.

I'm far from an expert on this (just play one online ) but if you're talking about TTL problems when using the 10-22 lens, I think you'll find the TTL somewhat unpredictable especially with blue water shots, unless you're doing close up w/a shots. Or at least that is what I had noticed with a 350D/400D+10-22, S&S TTL Converter, & Inon strobes.

If it is anything like the S&S TTL Converter, I recall the TTL was pretty spot on except at very wide apertures (f/2.8-f/4) or over f/22. With a very wide open aperture, I found the TTL converter couldn't squelch the strobe fast enough resulting in overexposures.

Can you post a sample of a bad TTL shot unadjusted including exif info?

I'm guessing with f/11 & 1/200th shutter settings, the DS-50's aren't strong enough to light something 3-4 ft away. Looking at the exp. guide for the DS-51 (pg 7), which I'm not sure would be 100% accurate for digital cameras, you'd have to up the ISO significantly to light something 3-5ft away with a f/11 aperture setting.

I'll let the experts take over from here

Hi and welcome to Wetpixel.

I think your experience is pretty normal. Letting the camera choose the aperture and SS underwater just doesn't work. The camera doesn't know it's underwater and tries to make teh water look like a blue sky which looks yuck!

The TTL should work very well for macro though, with maybe one overall correction required at the start of the dive to get a + or - setting that works. You should really only have to set that once.

James

On my initial dive, I was having a hard time convincing the camera to fire the strobes, and I was ending with underexposed images anyway. I started full auto: Program mode + TTL. Then I shifted to shutter priority + TTL, then manual + TTL, and then finally manual + manual flash.

For example, there's this one. Shutter priority, ISO 400, 1/200th, f/32, TTL, 60mm lens.

I did have some good overexposed examples using manual exposure + TTL flash, but I deleted them as too obviously unusuable. I had some vague hope of salvaging the underexposed images, which is why I hung on to them.

Almost all of my exposures were with the 60mm macro lens, not the wide angle, but I do have a lot of obvious goofs from the first manta dive with the 10-22. Here's an example: Program mode, ISO 400, 1/200th, f/29. There's enough of an image that I'm sure the flash fired normally, but the camera decided there was so much light it needed to stop down to f/29.

- Gus

Yep, i would stick with manual exposure as much as you can and TTL. Program will just be a lesson in frustration for you.

Pakman's link to the exposure guide is extremely valuable for you, take it and write it down on some duct tape and tape it to the back of your camera. That really helps when trying to choose your fstop. It is called strobe to subject distance and gives you the proper strobe exposure based on distance from your subject. I think you will find f11 is far too small of an fstop for objects 3-4 ft or further away.

I didn't look but it should be something like this:

less than 1 ft -f16-f22

1 ft away f11-f16

2ft away f8-f11

3ft away f5.6 -f8

4ft + away f4-f5.6

Hope that helps

The distance / f-stop limits are good to know, but I still don't trust TTL. As I said, after several dives doing full manual, I tried some macro shots with manual / TTL, and I was very unhappy with the results. The camera was calling for about 4 stops more flash than the subject actually needed at 8". And as I showed with my above example, on an early dive I was usual shutter priority or manual exposure + TTL and getting nothing from the strobes.

This is very weird for me because I absolutely rely on TTL for land photos, and I would never have dreamed I'd be saying I didn't trust it.

- Gus

I shoot with a Nikon D80 and Ikelite iTTL housing with 2 X DS125.

Few things I would share & I hope it helps

- Must use manual, tired apeture or shutter priority, it just doesnt work under water.

- For Macro (60mm), start with 1/125 to 1/200 (or whatever your camera can sync to) and from f11 all the way to the max depends on how blur you want the back of the subject. The bigger the f number the more depth of field, more clear of the tail.

- When I leave at iTTL setting, I often found myself dial down to almost min for close up macro work.

such as this f11/ 1/160

or this f32 1/125

- and since I dial down the ittl setting for macro, that's not a lot of different then switching the dial to the bottom half and use manul and set them at minimum, just about the same !

- For wide angle which I am new to and have not have too much success yet but here is a shot with a 17-50mm set at 50mm (which is not wide) but had the strobe aim at the kelp below and let the camera absorb the light from the above. I was able to get some ray and not too dark and not to over expose. (Credit to Dr. Steve who gave me some tips on flickr) f8 1/100.

The point is I think having ittl and manual on the Ilkelite housing are very very nice but I begin to use more of the lower half of the dial (manual) now and when I use ittl, the upper half dial, I found myself setting at minimum for macro and max for subject 2+ ft away. Most of the time stobes are aim parallel or away from direct shine to the subject (which solves some of the uneven lighting or certain hot spot in my opinon).

Hope it helps.

I use the XT with 2 DS-125's. I went through the same problems as you, and after taking an UWP course found that the easiest method to use is to set the camera to manual, but use TTL for the strobes. For macro, I typically start at F18, 1/100s and ISO 200. This allows the strobes a fairly wide range to correct for. If I find that the TTL is slightly off based on the histogram, I will adjust the strobes with exposure compensation on the housing.

For WA, I typically shoot at F8, 1/100s and ISO 100. However, TTL is fooled a lot more often with WA, so it takes quite a bit more fooling around. I hope this helps.

Gus (and others),

If I rant on in this post forgive me............Just sharing an explanation of TTL and modern digital SLR cameras for the umpteenth time.....

In any of the popular digital SLR cameras shooting in "M" manual mode where you set a shutter speed (mainly for background lightness or darkness) and then f-stop for strobe to subject distance STILL works with Ikelite's housing circuitry and strobe heads set to TTL. F-stop, ISO chosen plus strobe to subject distance are the key parameters.

Gus, an Ikelite DS125, DS200 or DS50/51 will not be able to put out enough flash even dumping full power to illuminate your subject at f29. A guide sticker that comes with every strobe shows at what ISO, at what f-stop automatic TTL flash will work. You just have to stay within the range for a set f-stop and the strobe(s) and camera talk to one another.

People who say TTL doesn't work with wide angle have never shot an Ikelite housed Nikon or Canon dSLR with Ikelite strobes. It works, even with blue water in part of the frame exactly the same as TTL on the surface shooting a dedicated flash and having sky in the upper 1/3 of a photo.

Most shooters simply don't get close enough so the flash can reflect off the part they want TTL flash to light, and thus the strobe dumps full power because it can't stop this if 2/3 of your frame is water! Thus no reflected light coming back to the camera to tell it to "quench" or stop the flash so as not to overexpose the image.

Doug Perrine, Dave Fleetham and others I know use TTL on wide angle and medium to close up shooting all the time. I do, too. Below is a photo I lit via TTL with ONE DS51 !!!! Shooting a Tokina 10-17mm FISHEYE lens at 10mm. Again, TTL works when you know how to use it.

Again, apologies for the rant, and I know not all UW shooters have TTL in their systems. But you do, Gus, and simply need to use it as hopefully I've described. It'll save you a lot of headaches and produce better photos........

Rant over

dhaas

www.haasimages.com

P.S. - I also don't understand why people up their ISO so much in tropical conditions. I rarely shoot above ISO200 and then more very early or late in the day. Plus the age old obsession of shooting such high f-stops to what, maximize depth of field? It's an AF (auto-focus) camera for crying out loud! So you hopefully know what main point of focus your camera locked in on before pulling the trigger

Also, unless you are shooting super tele-macro shots the difference between F11 and F22 is so slight as to not be noticed. Again, same old, techniques from the days of film.

Gus, an Ikelite DS125, DS200 or DS50/51 will not be able to put out enough flash even dumping full power to illuminate your subject at f29.

I'm aware of that. I was shooting in Program mode at the time, since I was still a little fuzzy on what the proper exposures would be, and the camera chose f/29. I'd never have cranked the aperture that small myself.

People who say TTL doesn't work with wide angle have never shot an Ikelite housed Nikon or Canon dSLR with Ikelite strobes. It works, even with blue water in part of the frame exactly the same as TTL on the surface shooting a dedicated flash and having sky in the upper 1/3 of a photo.

I was shooting with an Ikelite housed Canon Rebel XT using TTL-capable Ikelite strobes. Two DS-51's. And I simply could not get acceptable results with TTL for most subjects, wide angle or macro. Which I found surprsing and frustrating, but the fact is most of my exposures were coming back grossly underexposed, and it wasn't a limitation of flash power, because I got good results when I shot manual flash.

Most shooters simply don't get close enough so the flash can reflect off the part they want TTL flash to light, and thus the strobe dumps full power because it can't stop this if 2/3 of your frame is water!

Again, this was not the problem. The problem was that in TTL mode, the camera was either selecting a far too small aperture or simply not giving the strobes enough power. OTOH, in some very close macro shots, I got massive overexposure with TTL.

P.S. - I also don't understand why people up their ISO so much in tropical conditions. I rarely shoot above ISO200 and then more very early or late in the day.

After learning the ropes and getting a feel for proper exposures, I was shooting 100 or 200 ISO most of the time. I was only shooting 800 when I had no idea what the problem was, and was grasping at straws trying to get an image. If I'd been calmer and my mask hadn't been flooding constantly, I'd probably have figured it out.

Plus the age old obsession of shooting such high f-stops to what, maximize depth of field?

I typically don't shoot really small apertures unless it's a macro shot. As I said, f/29 isn't something I would have chosen myself for those images.

- Gus

Hey Gus,

I realize in "P" mode the camera may have picked such a small aperture the strobes could never have put out enough flash to light your subject.

In "M" mode as I described it does work. Don't take my word, hook your camera and strobes up just to the back and play with it in air. The power output of the DS51 at only 79 degrees is within 1 f-stop power output of the DS125 unit!

As you surmise, manually setting a shutter speed and an f-stop, then staying within the RANGE of TTL for a particular f-stop.

If you look at the chart, you will see even at f16 or so the TTL has a MINIMUM distance to keep the strobe back or it CAN'T quench the strobe fast enough. When shooting macro that's the most common problem I've seen......

Just trying to help!

dhaas

P.S. - I found out something else interesting today for Canon devotees......If somehow the TTL flash was switched to manual (holding down both buttons on the back of the Ikelite housing to go from TTL to manual flash control) or switching one or both strobe heads off the TTL setting CANON CAMERAS IN "P" MODE WILL AUTOMATICALLY STOP DOWN TO F29!!!

This MIGHT have been why your Rebel XT kept choosing this setting.

Without me diving beside you I can't be sure what happened, but shooting in any of the "more AUTO" modes almost always results in wildly variable settings being chosen by the camera. But TTL DOES work even when the CAMERA is in "M" mode and strobe heads and housing back are set to TTL......

Food for thought

First off - if you set your camera to shutter priority and set the speed at 1/200th - THEN your camera chooses F32 or F29 then it needs to go to the repair shop because it's light meter is "whacked." Even at ISO400 that just doesn't make sense to me. It sounds like the light meter is 2 or even 3 stops off...

If you're a newbie, you should set your macro settings to M on camera, strobes TTL. Set SS to 1/180th and Aperture to F16 and bang away.

For Wide Angle a good starting point is to shoot in Aperture Priority mode, set your aperture to F8 for moderately bright conditions and F11 or F13 for really bright conditions. Then strobes to TTL and just bang away.

Give that a try on your camera table and if it doesn't work then you may have an electronics problem in your housing. Otherwise, it's probably a broken camera.

Cheers

James

If you look at the chart, you will see even at f16 or so the TTL has a MINIMUM distance to keep the strobe back or it CAN'T quench the strobe fast enough. When shooting macro that's the most common problem I've seen......

That's probably it. I wish I'd hung on to the photos that were overexposed, but it seems probable that they were the images where I ended with with 1/200th and f/20 for the proper exposure. These were extreme macro shots where I was nearly at the 1:1 limit, so the distance was very, very short.

For example (not cropped):

I found out something else interesting today for Canon devotees......If somehow the TTL flash was switched to manual (holding down both buttons on the back of the Ikelite housing to go from TTL to manual flash control) or switching one or both strobe heads off the TTL setting CANON CAMERAS IN "P" MODE WILL AUTOMATICALLY STOP DOWN TO F29!!!

 

This MIGHT have been why your Rebel XT kept choosing this setting.

That seems quite possible. I wouldn't be surprised if I clicked the strobes over to full power at some point after getting dark frames. It seems unlikely that f/29 is a coincidence.

I've never had problems with the camera's metering in air, or with a 430 EX Speedlite, so I'll never really be certain what's going on until I go diving again with the camera. I'll certainly give TLL another try, though clearly M mode is the way to go for the camera itself.

- Gus

I have the XTi and Ike TTL. I have had no problems at all. However, I have heard that some XTi's need to be calibrated as they tend to underexpose otherwise. You might check into that.

If those shots were in RAW format, they can be adjusted.