DX-2G + YS-01: how to use TTL?

[Matt S.]

I just put something over in the manufacturer's forum and then noticed this one, which looks a little more lively. Anyway, I have a new setup, and while I am not new to UW photography in general I have quite a bit to learn about THIS setup. If anyone can give me some leads I would appreciate it.

1. W/ the YS-01 in TTL mode, what mode should I put the camera in? Is there a magic aperture setting I need to stick with, or anything like that? The manual is pretty good but doesn't talk much about using the camera and strobe together.

2. With the YS-01 in TTL mode, how can I dial in exposure compensation? My test shots (aperture mode) are in the ballpark but I definitely need some finer control over the exposure... and exp. comp. doesn't do anything when the strobe is in TTL. Changing the aperture doesn't do anything predictable... The power dial on the strobe is also ignored. I haven't tried flash exp. compensation since the camera's flash is just triggering the YS-01.

If someone could post their technique I would be most appreciative.

 

[Compressed]

Hey Matt,

I generally do not post on SB, but rather give it a quick "lurk" each morning for news, etc. That being said, I wanted to respond to your query.....

First, Congrats on the '2G, this thing produces awsome images!

Second, I would recommend the following settings:

ISO get out of Auto and set at 100
WB (White Balance) also get out of Auto and set at either "Cloudy" or "Daylight"

MANUAL Set function to "Manual" and set your "Shutter Speed" around 1/100.

With all this, you can now control light with "F-Stop". Play with your exposures by bracketing your shots (changing F-Stop settings) and then review your images for the best exposure.

I would strongly encourage you to set up your kit and play with this in the backyard prior to diving to get a feel for where everything is. Also.....GREASE THOSE O-RINGS!

Have fun with this and Safe Diving!

 

[Matt S.]

Thanks for the reply. In my experimenting last night I arrived at a similar spot, though I had fixed exposure and shutter and was varying exposure with the flash power dial. I suspect that manual is the way to go, though I do want to understand the TTL feature since I paid for it.

 

[marzum01]

Hi Matt,

I can't 100% vouch on this but it might be worth a shot. I look at the YS-01 specs online. My guess is that if you put it into the DS-TTL mode (instead of just normal slave) then it would replicate the flash as well as the PRE-FLASH emitted by your DX-2G built-in flash. And if it's a true TTL flash then it should exactly duplicate the DURATION of each flash/pre-flash emitted.

Which means when the DX-2G fires pre-flash using its built in strobe, the YS-01 will fire at proportional output. The DX-2G then sees this additional light when evaluating the exposure through the lens (wow that's bright!) and then adjust the power level accordingly, then fire the main flash. Again the YS-01 will respond by also replicating this - giving you the final illumination.

Long story short, the FLASH EV compensation on your DX-2G should be your ticket to giving a fine tune on the TTL exposure.

I can't prove this theory however but that's what I plan to try out as soon as my (on order) DX-2G arrives. I have a couple of old sea&Sea YS-50 and TS-60 TTL/s strobes for film which I connect to a HenrichsWeikamp digital TTL adapter, and should achieve the same effect as the YS-01 or YS-110a on "DS-TTL" mode. But I own neither of these newer strobes.

Hope this helps.

Mario

 

[deeper thoughts]

This is good

 

[Matt S.]

Mario,

You were right... The internal flash compensation does function as overall EV when in DS-TTL. I should have tried that before, but I was so sure it wouldn't work either.

I'm curious if there is another way to accomplish this though. The internal flash is not contributing to the exposure, being blocked by the fiberoptic adapter. It's wasteful of the camera's battery power to use a full flash output just to tell the strobe that it needs to do the same. It may not matter in real world usage though.

Anyway, I see a couple of ways to use the rig now.

DS-TTL:
- Strobe on TTL mode
- Camera set on always flash
- Camera on aperture priority, vary for DOF or to use the flash more efficiently in wide angle shots (however I have noticed that big aperture changes changes the DS-TTL exposure in unpredictable ways)
- Fix ISO at 64-100
- Use the camera's flash EV to fine tune exposure (time to set up a function button shortcut!)

Manual:
- Strobe set on 1 pre-flash
- Camera set to manual always-on flash, but cut down to 1/8 power (reliable flash triggering may be possible with less power, I haven't experimented)
- Camera set on manual, shutter speed around 100, balance aperture and flash output
- ISO fixed at 100
- Settle on some aperture and adjust overall EV with the power dial on the strobe (or vice versa)

I shoot raw, but I will probably keep the WB on auto for the jpegs.

I am very curious to see how smart this TTL feature is out in the field.

 

[marzum01]

Thanks Matt. I'm glad to hear that! This further confirms (whew!) that when my unit finally arrives, the whole setup should pretty much work as you've just proven.

The old Sea&Sea YS-50 and YS-60 TTL/S unfortunately do not allow for fine tuning of manual exposure. You can only go either full power, or half power. So I imagine I'd be using the TTL function quite a bit and having to get used to it.

Like you I'll be shooting in RAW and hence why I've been sitting out for the DX-2G (instead of snapping the DX-1G which by the way now are priced VERY aggressively).

Unfortunately with the YS-01 it looks like it can only be triggered optically - hence you cannot eliminate the requirement for using the camera's built-in flash. Yes it would chew battery power unnecessarily.

On the other hand, strobes like the YS-110a can be optically triggered, but it also has a port at the bottom which allows hard-wiring to underwater housings which have bulkheads. Not that the DX-2G have any, so it's not going to ever be an option with this particular camera setup. Underwater housings with bulkheads typically have wires and TTL converter circuitry at the end which mounts to the hotshoe of the camera inside the housing.

So it's the hotshoe which triggers the external strobes, not the built-in flash. I heard most DSLR housings operate this way (Ikelite especially).

 

[Matt S.]

When you get your setup, please do post when you figure out a good configuration!

From my experiments on dry land, it looks like the DX-2G picks shutter speeds around 1/30 when in aperture priority mode. I'd rather shoot at 1/60 or faster under water, but I can't find a way to do that yet--without going to manual mode.

 

[marzum01]

Well OK it's official. My DX-2G just arrived before the weekend. Conclusion, it works flawlessly with my dual strobe setup of Sea&Sea YS-50 TTL/S and YS-60 TTL/S using the Sea&Sea dual Y sync cord, and Heinrichs Weikamp digital TTL adapter. I mean really spot on - at aperture of f/4.1 to f/8 and close up distance I get PERFECT exposure histogram at +-0 flash EV compensation.

The flash EV compensation responds just as well - I need to dial by at least 1 stop to get any noticeable change in brightness and the DX-2G is happy to go +- 2 flash EV in any direction, while maintaining an automatic flash mode (just be sure you're not in the Red Eye mode, I suspect this would cause an erratic behaviour)

I am completely, overhwhelmingly surprised to obtain this level of performance using a pair of decade-old film strobes, a custom made optical adapter, and using on-board flash as trigger. I can't wait to see how well this works in the field - going for a test dive end of this month/early September and hopefully will post pictures (bbrrrr.. 15-16 celsius in a wetsuit)

One interesting to note is that the YS-90 TTL Duo (yes I also have one of this) doesn't play along with neither the YS-50 or YS-60 TTL/S, even when hard wired using the dual sync cable. It's completely FINE when there's only ONE strobe turned on at any one time, but not when both are on. They seem to have slightly different response times (even if by nanoseconds) and somehow fools the HW digital TTL adapter into firing longer strobe pulses than necessary for proper exposure

Oh well that throws away my idea for having a backup strobe. I'll have to stick with my YS-50/60 TTL/S dual combo, and if one fails I have to get another one of those, or hunt around for another YS-90 TTL Duo to make a matched pair

And til my next post...