Olympus 5050 with Nikonos 105 strobes

I need some help with set up with my OLYMPUS 5050 with its PT-015 and Nikonos SB105 strobe. I took it out for its virgin dive last Sunday and had mixed results. I used the strobe on full and the camera was set on manual, F8, 1/60 sec. I kept getting a one second preview that was all washed out. Since F8 is as stopped down as you can go, I lowered the power of the flash to 1/4 ,,, still a bit over exposed. So then I changed the flash to 1/16th power and got a little better results-- but I seemed to have lost my reds as they shots were a bit greenish.

It was recommended by a friend to tape the flash over the camera. Will that work? He thought that it might be a timing issue.

Also could someone tell me when you shoot zoom and Macro how you have to compensate in regards to exposure?

If anyone has any other helpful hints with my set up I am all ears as I am a newbie at this!!!

thanks, tarzana

Tarzana,

If you don't mind reading some theory as opposed to advise derived from actual experience with respects to your specific rig, read on:

You leave out a couple of important components of the exposure equation, sensitivity (ISO) and distance (strobe to subject). It would also help to know if your camera's flash was set to slave (no pre flash).

Without a diffuser, your SB 105 has a guide number rating of 11, ISO 100, measured in meters, underwater. Those specs would indicate that at f/8, ISO set to 100, your distance from strobe to subject should be no closer than 1.38 meters (4.5 feet) to avoid overexposure. I've determined this by relying upon the Guide Number Formula:

Distance = Guide Number divided by Aperture

D = GN/A

?=11/8

11/8 = 1.38 meters

If you lowered the output of the strobe to 1/4 power, your new guide number at ISO 100 would be 5.6 (11/1.4)/1.4

If the aperture remains at f/8, your new minimum distance from strobe to subject would become:

D = GN/A

? = 5.6/8

5.6/8 = .70 meters or 70 centimeters or slightly over two feet away

1/16th power has an equivalent guide number of 2.8 at ISO 100 (5.6/1.4)/1.4

At GN = 2.8 can you determine how close you can be, strobe to subject, without overexposing the target?

If you do decide to tape over the digicam flash to avoid backscatter,etc, you must still insure that your external strobe will be able to see the impulse of light emitted by the onboard flash ( master strobe) that will command your SB 105 (slave) precisely when to trigger. If you have trouble with triggering the optical slave, one option you may have is to utilize Matthias Heinrichs' Digital Adapter in conjunction with a sync cord attached to your SB 105. This combination should allow you to use your SB 105 slave strobe in manual mode. You would have to check directly with Matthias if his new DA2 would offer you the option of TTL with this set up.

Whether you're in zoom or macro, the Guide Number formula ( GN = A*D) for the foreground exposure does not change.

The background exposure of your composition is capturing the effects of ambient light. Ambient light is the natural light that is present at time of exposure. Ambient light is subject to time of day, clouds, etc. The control and capture of ambient light is achieved by choosing the appropriate aperture in conjunction with the proper shutter speed to obtain the desired effect. By increasing the shutter speed or stopping down the aperture, you allow less light to enter through the lens. The result will be a darker background. A very fast shutter speed may even render the background black in broad daylight. A slower shutter speed or larger aperture allows more light to enter the lens, resulting in lighter blue backgrounds.

Hi Bobf,

Thanks for your response...I am having a bit of trouble understanding all that you are saying in relation to the chart/guide number chart on my flash but I will add that I had the ISO set on 100 and shot most of my shots at 2-3 feet with the strobe at that distance and also set on Slave...

With the OLY 5050 there was no option to set the camera for less light than f8. Does this mean that I cannot shoot at f8 or a lower fstop? I had been accustomed to using my Nikonos V, shooting on auto flash, 64 film, shutter on A and varying the fstop and distance but -- I could go as far as f22 to close it down to get those close shots looking up towards the surface. I could get as close as 9 inches with my 20 mm lens. I hope I can learn to use this new rig so I can take similiar shots. It is a whole new ball game for me. If you have any more comments please let them ring...thanks chrisse

Hi Bobf,

Thanks for your response...I am having a bit of trouble understanding all that you are saying in relation to the chart/guide number chart on my flash. They seem like different recommendations. I will add that I had the ISO set on 100 and shot most of my shots at 2-3 feet with the strobe at that distance and also set on slave.

So if I am understanding what you say, then a chart would read like this:

GN power Distance to subject

11 full 4.5 feet

5.6 1/4 2 feet

2.8 1/16 1 foot

correct?

Could you please define exactly what you mean by the minimum distance to the camera? It is physical distance from the strobe to the subject, correct? The display of light also covers a certain distance...I used to have a chart of that.

With the OLY 5050 there was no option to set the camera for a smaller aperture/less light than f8. Does this mean that I cannot shoot at f11 or 16 with this camera? Or do I have to set up my camera differently?

I had been accustomed to using my Nikonos V, shooting TTL , 64 film, shutter on A and varying the fstop and distance but -- I could go as far as f22 to close it down to get those close shots looking up towards the surface. I could get as close as 9 inches with my 20 mm lens. I hope I can learn to use this new rig so I can take similiar shots. It is a whole new ball game working with completely manual.

I will check out the DA2 if I do not have better results with practice...thanks again for your tutoring and any other comments are welcome...chrisse

Chrisse,

First, it appears that you are comfortable with measuring in feet, me too.

Guide Numbers on land (light traveling through air) are determined initially by placing an object ten feet away from a strobe that is set to full dump. A series of exposures are then taken. Whichever f/stop captured the best exposure is then multiplied by 10 ( the distance from strobe to subject). The result of the test is then considered the Guide Number. The sensitivity is usually set to ISO 100.

Let's say that an aperture of f/6.4 captured the best exposure in the previous example. 6.4x10=64. Therefore the Guide Number of that particular strobe would be 64 at a sensitivity setting of ISO 100.

To simplify, the formula that was just created would look like this:

A times D = GN

We took the aperture and multiplied it by the distance, resulting in a Guide Number.

Water is much denser than air and therefore filters light much differently. It would be impossible underwater to place an object 10 feet from a strobe and have light emitted from that strobe reach the object and be reflected back to be captured by the camera. But we can still use the same Guide Number Formula for predicting how the light will work.

The SB 105 is listed by Nikon as having a Guide Number Rating underwater of 33 at ISO 100. What that means is that if you were to choose an aperture of f/8 ( the smallest available with a c5050), and set the SB 105 to a full dump (GN 33, ISO 100, air), the recommended distance from Strobe to Subject ( not lens to subject) is a little over four feet.

Nikon research already indicated to us that the Guide Number was 33, ISO 100, underwater.

http://www.nikonusa.com/template.php?cat=1...productNr=11202

We also knew that you chose an aperture of f/8. By using the same formula, we are able to determine the missing factor.

A times D = Guide Number

f/8 times ? = 33

What number multiplied by 8 equals 33? The answer would be the distance we would set our strobe to properly illuminate our subject.

I'm not suggesting that we all take calculators underwater with us to determine these measurements. But when someone in attempting to understand why something is happening, it is often best to explain why and how something works. That was what I was attempting in my first response. That said, here's what I think you're looking for ( numbers are rounded off):

SB 105, ISO 100, measured in feet

power level= GN

full= 33

1/2 (full +diffuser)= 24

1/4= 17

1/8 (1/4 + diffuser)= 12

1/16= 9

--------------------

you asked:

GN power Distance to subject  

11 full 4.5 feet  

5.6 1/4 2 feet  

2.8 1/16 1 foot  

 

correct?

Yes, if the aperture chosen was f/8 and the sensitivity was set to ISO 100. As a reminder, the guide numbers in that example were all listed in meters (IOW, GN 11 measured in meters is approximately equivalent to GN 33 measured in feet). To approximate meters to feet, multiply by 3 ( actually 3.28, but 3's close enough)

------------

"With the OLY 5050 there was no option to set the camera for less light than f8. Does this mean that I cannot shoot at f8 or a lower f/stop?"

True.

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If you continue to find that the SB 105 is throwing out more light than you wish, you may also adjust the sensitivity level (ISO) of you camera. Instead of ISO 100, try ISO 64. An added benefit to this change may be less noise.

Hi Bobf,

Thanks for more explanations. The manual operation is becoming clearer.

Now what about the settings on the Oly 5050 as far as the strobe. There are several choices as far as how slow the flash is cynced with the camera and when. Please advise if you know.

chrisse

Hi Tarzana,

I use a 105 with the 5050. I have the flash set to operate as a slave and trigger it with a fibre optic cable attached at the flash diffuser on my PT-015 housing. I have taped over the diffuser with black duct tape and use the camera's slave flash mode, set at 1 to conserve battery power, to trigger the flash. By adjusting the flash output 1/16 - 1/4 - full combined with the distance of the flash from the subject I eventually get what looks like an acceptably exposed image on the camera screen. I save in RAW. This gives lots of latitude to adjust exposure in Photoshop CS raw convertor.

Hope some of this helps.

Regards,

Jim A

I envy how Jim can get his point across so concisely. Well done!

His use of the fiber optic cable addresses my concern that if the camera's flash were to be taped off, the strobe would have more difficulty in picking up the triggering signal (slave signal). Jim posted an image of his creativity on the net. Follow this link which also includes some supporting info:

http://www.digitaldiver.net/yabbse/index.p...g68848#msg68848

For information on how to set up the c5050 menu, visit Peter Schulz's web offerings:

http://www.splashdowndivers.com/photo_gall...up_settings.htm

Scroll down until you see the listings for the camera settings. I suggest his advise under the column heading "MY MODE 1" as a starting point.

Thanks both Jim A and Bobf... you both have given me some good suggestions. I went to both of the sites that you suggested, Bobf and will read the info that I printed up. I do not know if I have the know how to put that cable on though, and of course I do not have it now to even try. o I will have to take a plunge without it tomorrow- weather permitting.

I bought a 512 card so I hope that I can get more pics on it. Do you have to buy a larger card to shoot in RAW?

Tarzana

That all depends on how many pictures you want to be able to take per dive. When I shot the 5050 and used a 512 Mb card, I seem to remember it holding 73 shots. In those days I was still filling up a card per dive, and had to download between dives.

Lately, with a 2 gig card in the S2, it can hold 153 raw shots, and I rarely if ever fill it on a 4 dive day.

I think as your skills improve you take less shots.

MHO, and YMMV!!

Maybe this has been mentioned already, but the camera should be set up to fire in "slave mode." Otherwise it emits a preflash that will trigger your SB105 early - before the shot is taken.

With an SB105, my gut feeling is that you should get GREAT shots at f8 1/60th or 1/125th out to about 3 feet using full power. If you are shooting close, you will need to set it at a lower setting like Bob said.

Great tips so far gang, thanks for helping out.

Cheers

James

Tarzana,

I have a 1GB CF which holds 139 RAW images and a 512mb XD which holds 69 images. I have some of my 'My modes' set to use the CF and some to the XD. I have never been able to fill both my cards over a single days diving. If one card fills then I switch to the other with the bottom button.

Jim A

PS My new refinement for macro is at http://www.digitaldiver.net/yabbse/index.p...y;threadid=9197

Re "If one card fills then I switch to the other with the bottom button. "

Or, if you start to run low on space you can delete bad shots or switch to SHQ.

Thank you everyone for all of your suggestions. I have not only learned a lot but on my last dive I got a few great shots! I was so jaded at the end of my dive because I had so much fun photographing the sealife AND I was not cold for the first time here with my new titanium suit even after 72 minutes in the water. I was actually ready to resign from work and not go back to school to finish my grades that afternoon!! I totally have UFS- the Underwater Fotografers Syndrome! I am back in the water manana! Ciao!

Muchas Gracias!!

tarzana