Strobe Recommendation for SWC

[ChrisRoss 150]

Guide numbers tend to be works of fiction produced by marketing departments - nice in theory.  Most are produced indoors where you get additional light reflecting in from walls and ceiling.  Underwater light gets absorbed quickly so guide No. quickly drops.

Watt-seconds is the light power produced perhaps in theory you could convert to a guide number but it will vary with beam angle among other things. 

Far better to do test shots and adjust.  You can use a digital to work out exposures as an f stop is an f stop.  digital ISO is not always matching film ISO but you can work this out on land - how does a well exposed pic in the digital compare to film exposure?  Just use your chosen strobes on your digital system to work out correct exposure - set it up how you are going setup the Hasselblad and you'll get a starting point to work from.

[Tom_Kline 143]

You can determine the guide number empirically if you want to go that way. Probably easier to have standard settings - best not "overthink" the issue. I used 150 w-s strobes back in the day and recall using f/11 with Ektachrome 200 (which was available in 70mm) at the half to one meter range.

The bigger issue will be synchronizing the Retra Pro as the strobe needs fiber optics.

[The_Darkness 6]

On 12/14/2020 at 4:17 PM, Tom_Kline said:

You can determine the guide number empirically if you want to go that way. Probably easier to have standard settings - best not "overthink" the issue. I used 150 w-s strobes back in the day and recall using f/11 with Ektachrome 200 (which was available in 70mm) at the half to one meter range.

The bigger issue will be synchronizing the Retra Pro as the strobe needs fiber optics.

Thanks Tom. Retra makes a sync cord to FO converter with your choice of sync plug. Until I pony up the money for the digital back, I'm just going to shoot 70mm B&W with the SWC and channel my inner Ernie Brooks.  I ordered the Ilford HP5+ in 70mm x 50' from B&H. 

[Tom_Kline 143]

On 1/4/2021 at 8:26 AM, The_Darkness said:

Thanks Tom. Retra makes a sync cord to FO converter with your choice of sync plug. Until I pony up the money for the digital back, I'm just going to shoot 70mm B&W with the SWC and channel my inner Ernie Brooks.  I ordered the Ilford HP5+ in 70mm x 50' from B&H. 

Does Retra make the adapter for the Hasselblad bulkhead? If so it is news to me. I presently have two copies of the adapter for S6 bulkheads. I have found them to be rather unreliable due to the design of the connection between the adapter and the fiber optic cable (discussed in another thread). I have had to carry an allen wrench with me to my shoots and have had to re-terminate the connection several times using the wrench to loosen and then tighten the repaired FO. Not practical IMHO for scuba diving.

[Oskar@RetraUWT 58]

7 hours ago, Tom_Kline said:

Does Retra make the adapter for the Hasselblad bulkhead? If so it is news to me. I presently have two copies of the adapter for S6 bulkheads. I have found them to be rather unreliable due to the design of the connection between the adapter and the fiber optic cable (discussed in another thread). I have had to carry an allen wrench with me to my shoots and have had to re-terminate the connection several times using the wrench to loosen and then tighten the repaired FO. Not practical IMHO for scuba diving.

Hi Tom, we have updated the design of the E-Opto converter and it now features a rotating insert that fits the standard fiber optic plug. This new feature removes all stress from the cable and in case you need to exchange the cable it is done easily without any tools.

The new design fits all existing E-Opto converters, please send me an email when you can. 

Thank you

[The_Darkness 6]

So I haven't picked up any strobes yet as I'm content with shooting B&W for now. Here are some images from a recent trip to Catalina Island. Shot with the SWC, Zeiss corrector lenses, 70mm HP5+, home developed. This was the first time shooting the Hassy u/w.