TTL, Strobe to Subject distance, 1:1 Macro/Supermacro

I was doing a bunch of tests and learned how far behind the times underwater TTL is. After scouring through the manuals, these forums and other books, I realized that there were parameters that need to be followed for TTL to work effectively, even for macro work.

Here is my question..... my YS-110 manual indicates a MINIMUM working distance of 0.3m. That is with ISO under 400 and f22 minimum aperture. I have "confirmed" these parameters with topside tests. When I get closer than this, things tend to get overexposed and the strobe indicator does not light green for a few seconds to show TTL use. Does this mean that if I were to get closer to the subject (say shooting a static subject with 105mm macro lens and diopters- which reduce working distance), I MUST switch to manual settings? Some have suggested that I pull back the strobes. Will TTL work properly at all by moving strobes back or is this just a way to reduce the flash output?

I am happy with using manual. Switching to manual seems easy enough with the Sea & Sea TTL Converter III. However, I would like to know my options available. Especially if I don't have the time to fiddle with settings and take extra bracketed shots during a dive.

Will someone enlighten me?

Hi,

I think what that means is that the TTL system can not QUENCH the strobe fast enough at those settings. If you're shooting close macro at ISO400, the strobes won't have to put out very much light, and if you think of the light as water coming out of a faucet, you have to turn it on and off REALLY fast to get a correct exposure.

So switch to a lower ISO or try the strobes in manual at a lower power.

Cheesr

James

Thanks. I think I understand. Nothing beats getting out there and experimenting I suppose.... Unfortunately, thats not so easy for me.

Hey - it works just as good above water :-) Get out and try shooting some flowers in the afternoon or evening.

Cheers

James

hey esaki, its funny, I noticed the same thing last week with my S&S TTL converter III while doing some supermacro with my 105mm and diopter, I switched to manual also. sometimes the shots were over-exposed.

ok - I have a question for all of you, and especially James - (hope this isn't hijacking the thread)

- how is the S&S TTL working, is it

choice A - firing pre-flashes to measure the exposure, and then putting out a strobe pulse of a pre-defined time period

or

choice B - firing the strobe and "quenching" the pulse (turning it off) when the proper exposure is reached?

based on reading, it seems like choice B might be true for canon TTL, and choice A might be true for nikon cameras such as d80,d200, d300...

does anyone know for sure?

thanks alot

scott

No, all digital TTL is choice A.

thanks James, that's what I had originally thought, my friend and I were recently having a spirited debate about it.

I'm surprised the TTL converter would have trouble having the strobe fire at its lowest power setting, if a camera can do it you would think the TTL converter could do it also.

I think it's going to be full manual for me sgietler.....I had a go again trying things out topside..... manual focus, manual strobe....much better than frustration caused.

I love TTL when it works. Can't blame S&S for what's outside their table of condition's/parameters I suppose. I will simply stick to TTL for when I know it will work and do a quick switch when needed.

The fact remains that the strobes cannot quench the flash output fast enough when they are that close. 0.3m seems to be the limit. It's not that the converter can't do it's job...If I'm not wrong, it's the limitation of the strobe itself.....although I reckon at times it needs even more than 0.3m! Fiddling with strobe arms and especially when the working distance is already narrowed due to diopters makes adjustment seem more cumbersome to me. Much easier to turn the TTL converter dial to manual and adjust strobes to manual settings....

It's going to be a challenge though. I am using the 105VR in the Athena port and an Inon UCL165 wet dipoter screwed up front..... However, I think it's easier than chasing bees topside. I really hope so.

Thanks for the info James!

In these conditions I'd be surprised if manual works better than TTL. Lower power manual works by quenching the strobe before full output is reached. I thought that the shortest TTL burst was actually shorter than the lowest power manual.

What is important is strobe to subject distance not camera to subject distance. So moving the strobes back to .3 of a metre from the subject would work even if the subject is closer to the lens than this.

What is important is strobe to subject distance not camera to subject distance. So moving the strobes back to .3 of a metre from the subject would work even if the subject is closer to the lens than this.

That's right and light intensity decreases by approximately the square of the distance, so doubling the strobe distance reduces light on subject by about 4-fold. If that still isn't good enough you may be able to use neutral density filters or diffusers on your strobe. On Ikelite strobes the diffuser eats up about one stop of light. I know some people on this list have been using colored filters on their strobes, so if you can find salt-water-tolerant neutral density filters that should be an option as well.

Bart

I know some people on this list have been using colored filters on their strobes, so if you can find salt-water-tolerant neutral density filters that should be an option as well.

Try shopping at the movie/theater lighting supplier, Rosco and Lee filter both make filter for the cinematographic industry that are both heat resistant and waterproof material, I routinely use green CC as wel as 80B filters on my strobes underwater for balanced flash. They have a variety of neutral density acetate in 30x30 or something like that, and cheap too, expect less than 10 bucks a sheet (they obviously don't realize it can go underwater otherwise they would sell it at 50.00 a sheet .

Cheers

Am shifting to a DSLR system soon and sorry to intrude in this section BUT insted of moving the strobe distance from the subject back and forth would it not be easier to just shift/move the strobe angle to a wider degree ? This way less light will hit the subject when there is an over exposure ?

Thanks for any input,

Diggy

Try shopping at the movie/theater lighting supplier, Rosco and Lee filter both make filter for the cinematographic industry that are both heat resistant and waterproof material, I routinely use green CC as wel as 80B filters on my strobes underwater for balanced flash. They have a variety of neutral density acetate in 30x30 or something like that, and cheap too, expect less than 10 bucks a sheet (they obviously don't realize it can go underwater otherwise they would sell it at 50.00 a sheet .

 

Cheers

In these conditions I'd be surprised if manual works better than TTL. Lower power manual works by quenching the strobe before full output is reached. I thought that the shortest TTL burst was actually shorter than the lowest power manual.

 

What is important is strobe to subject distance not camera to subject distance. So moving the strobes back to .3 of a metre from the subject would work even if the subject is closer to the lens than this.

That is truly weird.... I did a bunch of test shots whereby TTL consistantly overexposed and my strobes were a bit less than 0.3m away from the subject and the lens about 15cm away....dialing it to manual at 1/3 power exposed perfectly....I though I had it sorted....need more tests....damned thing is so heavy topside!

After introducing myself to TTL technology recently (my extra muscle after testing housing+lenses+flash over ground are proof), I will stick with the counsel of other members. Reduce ISO, Flash output that close should be enough to work even lower that ISO 100.

With my DS51 I had to reduce the flash output to -3 to avoid burned pictures at that short distance. I forgot to check the pre-flash calculation of the camera but... not many creatures of the deep will remain still after a short lightining

heavy topside!

If you're using the strobes in optical (wireless) mode I believe they are suppose to slightly overexpose the shot topside. At least that is what I'm told about my Inons.