Ike DS-50 Slave Sensors, PT-015/5050: Man or TTL?

Folks,

Having recently upgraded my Olympus C4040Z / PT010 to the Olympus C5050Z / PT015 (finally buckled after much deliberation) I now find myself in a quandry. I enjoy the compactness and portability of my setup in combination with the Ikelite DS-50 substrobe. I have not found an overriding reason to move to an Ikelite DS-125, the Inon or Sea&Sea counterparts, nor for that matter to move to higher cost housings. As far as strobes go, the DS-50 has worked well for me with my previous setup.

The issue I face has to do with which of the two currently available forms of the Ikelite wireless slave sensor would work best with my combination of DS-50 strobe and Olympus PT-015 housing; with particular consideration being given to the super macro mode, newly introduced in the Oly 5050. Ikelite offer their original wireless TTL (auto) sensor #4100.5 and a newer manual controller for DS series strobes, #4100.6. The question is which one is best for the 5050 / PT-015 / DS-50 Camera/Housing/Strobe combination?

In super macro mode the internal flash is disabled on standard flash settings; however, setting the camera to slave mode will fire the internal flash at 10 different user configurable intensity settings, potentially allowing the wireless slave sensor to function. I note that Ikelite now provide a table for the DS-50 strobe with TTL (auto) Sensor (see www.ikelite.com/web_pages/oly5050flash.html ). The table only provides camera Slave Flash Settings 10 through 6 possibly implying that lower number settings (5 through 1) are of no use.

In my web travels to date, there seems to be conflicting opinion as to whether the DS-50 substrobe's TTY (automatic) slave will function adequately and that the newer manual controller for DS series strobes, #4100.6 would be required. Since I already have the wireless TTL (auto) sensor #4100.5 I have a vested interest in using this sensor. I would like to hear your views if you have experienced and hopefully resolved this issue.

In anticipation,

Colin

I just finished testing a bunch of strobes, and evaluated the DS-50 with both controllers. The positive side of the DS (TTL) Sensor is that it delivers very accurate exposures in those situations where TTL works well (frame is filled, little blue water, subjects mostly at similar distance to the camera). The downside is that the SuperMacro mode is virtually useless, since the camera must be in normal flash mode to work with the DS Sensor, and SuperMacro cancels the internal flash.

The EV (manual) Controller can be set up to work with the camera's "Slave" mode, which significantly shortens the shutter lag and allows you to use a flash with SuperMacro.

If you're not in a rush, I have it directly from the top that there will be a combined controller (both manual and TTL) sometime after the first of the year. Whether you will be able to switch between "normal" and "Slave" function without surfacing is something yet to be explored.

Jeff

Firstly, let me commend you on an excellent article. I found it very informative and it caused me to consider the issue. Further investigation however has left me wondering whether Ikelite in providing the table for the DS-50 strobe with TTL (auto) Sensor (see www.ikelite.com/web_pages/oly5050flash.html ) consider this to be a workable solution.

As mentioned in my original post, their table, as below, only provides camera Slave Flash Settings 10 through 6 possibly implying that lower number settings (5 through 1) are of no use.

[5050 SlaveFlash Setting] : [DS-50 power with TTL Sensor]

[10] : [1/6 th]

[ 9] : [1/8 th]

[ 8] : [1/10 th]

[ 7] : [1/11 th]

[ 6] : [1/16 th]

Note that they specifically say 'TTL Sensor', not 'Manual'. Reducing the slave flash setting on the camera apparently reduces the DS-50 strobe power.

In your evaluation using the TTL (auto) sensor with the DS-50, did you try using 5050 slave flash settings 10 through 6 and did this make any difference to your results?

Many thanks,

Colin

Following URL is the complete table of flash durations, showing how little light is provided in lower setting numbers:

http://www.ikelite.com/web_pages/oly5050slave.html

Ike

Thanks for your response. I'm getting more pieces of the puzzle together now. Would you be able to confirm my hypothesis that the Ikelite wireless TTL (auto) sensor #4100.5 will trigger satisfactorily in super macro mode with the 5050 (PT-015 Olympus housing) when the camera flash is set to slave mode with sufficient intensity, ie. somewhere between 6 and 10.

To phrase my question directly: am I better off keeping my existing wireless TTL (auto) sensor #4100.5 or should I look at switching to the manual sensor, #4100.5, in order to effectively use super macro mode on the camera?

Many thanks,

Colin

Working the math backwards, Colin, at the maximum capacity of the Slave setting (10), you would have a flash level 2 and 2/3 stops below maximum -- requiring f3.2 instead of f8. That's a lot to lose. You'll have to shoot more wide open than you might want on subjects and at distances where you really want every bit of depth of field available. The technical answer to your question is, "Yes, it will work" The strobe will fire while the shutter is open, but the output of the flash will be minimal. I did not test this because it just didn't seem practical. I used a manual sensor when I wanted to use Slave mode.

Going back to my first response, unless you have big trip coming up before the end of the year, I would wait. If you're going someplace where muck diving is the name of the game before then, I would get the manual controller.

EDIT: Addition...

Colin, I believe that Ike's page on this issue only mentions the TTL controller (DS Sensor) because it is assumed that the manual controller will work. I used it in "Slave" 5. I didn't test it below that, but I imagine that the manual controller will trigger from even the very lowest settings.

Jeff

Thanks again for clarifying this. I think I'll wait for the release of the combined controller in the hope that it is mode switchable in-water (Ike please please take the in-water switching capability as a feature request!)

I do have a trip coming up soon (Niue) but since I have an Inon macro lens I would be no worse off from a magnification point of view using this lens with the standard flash and 'standard' macro setting than I was using my 4040 / PT010; and poss. less barrel distortion too. It will likely give me more time to come to grips with all the other new features available on the 5050.

If I get a chance to blow bubbles before then I'll experiment and add to this thread.

Colin

1. Oly 5050 in super macro

2. slave setting on oly set to 10,

3. DS 50 in TTL, yielding 1/6 power when mimicking strobe duration of oly set to 10

Gn= guide number at ISO 100 (ft)

DS 50 Gn:

full 28

1/2 20

1/4 14

1/8 10

assume therefore 1/6 power = gn around 12

Therefore if your subject in supermacro was 1' from DS 50 inTTL and Oly set to slave 10:

gn = distance*aperture

12 = 1 *12

f/stop in this scenario would require f/12

If your subject were any closer to the strobe, then 1/6 power is too strong. You would have to actually dial down the slave setting, move strobe further back, or set lower ISO.

hth

Having thought about this a little further I have come to realize that there are some practical considerations. I have performed some dry tests using the DS-50 with TTL Sensor which can be viewed at the following URL. Incidentally, the weather wasn't that great this weekend...

http://www.gans.co.nz/dive/5050_DS50_TTLTest/

The results of the dry tests tell me that Super Macro mode and the TTL remote sensor work reasonably well for close distances, on the dry at least. Testing was performed at 10cm (4") which is typically the distance I would be looking at using this feature and at this distance there appears to be more than sufficient light. As BobFpoints out, it is more a case of having to reduce light.

In my dry testing at a distance of 10cm from the subject the following settings appeared to work best: ISO64, Slave10, 1/2000sec, F8.0 this was followed by ISO64, Slave5, 1/2000sec, F8.0. The above two settings still allow for maximum depth of field.

While I would expect strobe light to be reduced underwater and more so with poor viz I would guess that the satisfactory results achieved on the dry with maximum shutter speed and aperture would give sufficient breadth to compensate for this. Maybe I'll get a chance to perform similar tests in the wet shortly.

Colin

Colin,

Very interesting tests. I found them very educational.

Please verify that the test you conducted was with the strobe diffuser in place and that the camera lens was 10 cm from subject, not the strobe. It appears from the test image that the strobe was 35-40 cm away ( @ 18"). Strobe distance (not lens) is the important element in the formula.

Yes, I can confirm the following:

i) the strobe diffuser was used;

ii) I autofocussed and then locked/switched to manual focus which reported the distance as 10cm (v. useful feature) and also measured this distance to verify (you can see the ruler in the left foreground of the 1st pic)

iii) BobF, you are correct in saying that the strobe distance was in fact further and while I did not measure at the time, your estimate of 30cm - 40cm would be correct.

Colin