Backscatter help needed

[zan]

Hiya,
I've been having some issues with backscatter in my photos, and was looking for some advice on strobe positioning. My kit is a Canon 400d in an Ikelite housing with a single DS-51 strobe (+ikelite arm). The lenses I use are a 60mm macro and tokina 10-17 fisheye. I've managed to get lucky with it a few time so far, but I'm a million miles from getting this consistently decent results...

Wide Angle:
This is a typical example of the kind of shot I was getting on a recent Scapa trip:



Is there a way of positioning the strobe better to avoid this directional scatter? This appeared to be worst when the lens was set to 10mm.

Macro:
Where to start? I'm having most issues with this one. After finally realising that all the batteries need to be charger fully before going in the water or it's just plain hopeless, I gave it a go with the strobe placed directly over the lens. The backscatter was (expectedly) awful, but at least I was starting to get photos that were properly exposed. Since then I've been trying to move the strobe off to the side to light it properly, but this only works (sometimes) for animals in the open. Can anyone give me some advice on how to shoot decent macro in typical british sea loch conditions (e.g. stuff in nooks and crannies with rubbish vis)? I can post some examples if anyone wants to see some truly awful pictures

Cheers!
Zan

[aquakiwi]

I've found it differcult to advoid the backscatter with one strobe, I'm using 400D in an
Ikelite housing with dual Inons. Using two strobes angled out seems to solve the problem. With a single strobe however, you need to angle inwards towards the subject or risk under exposure in the right hand side (thats presuming your strobe is on the left and by your shot it appears that way). On my little compact which I use with a single strobe I've had pleasing results by hand holding it from above. Also well to the left and pointing towards in front of my right hand so the edge of flash beam sort of washes across the subject seems to work. I've probably not explained this well but I think you'll know what I mean.

[zan]

yeah I think I understand! Thanks for the help, I'll keep playing about with it and see if I get any better results

[DDT uk]

I think that a single strobe for macro shouldn't be a problem. I would place of the strobe above the lens port looking straight forward and then adjust the distance between the port and the strobe depending on the distance between the subject and the lens. The idea being that the edge of the beam is hitting the subject and not the water inbetween.

Trying to light a wide angle shot without hitting the water column would seem to be difficult at best. I assume the best option may be to use as much natural light as possible and be selective in what is lit by the strobe, preferable sticking to foreground corners. If you can add colour back into the subject without using full power then that would help.

Nice shot though.

Daniel

[KenByrne]

From the sample shot the strobe appears to be too close to the lens. I get this all the time with the 10-17 at 10mm the field of view is so wide you have to be careful to keep the strobe well back and out to the side.

As for macro with 1 strobe I used to do much as you are and place the strobe above the lens and point towards the subject, or probably beyond the subject to light it with the edge of the beam.

[zan]

ok, nice one. I'll try repositioning the strobes to point more outwards and see how I get on... Might be out on Tues, but I'll be at the Farnes next weekend, so will try and post my results after that at least.

Cheers!
Zan

[TimIngmire]

I've found for W/A with my 10.5 Fisheye that pulling the strobe right in (I mean right in - leave enough room for your hands to grip the handles tho) turning them out and positioning them behind the port and even behind the housing - does the job.

Sometimes tho I'll use just one strobe in which case it points forward but positioned straight above the housing - this works well with the 12-24.

For macro - not much different really if using two strobes - when using one then I position it above the housing by one hands width and tiliting it up to help catch the edge of the beam. Longer macro lenses well have the strobe positioned further forward. I've yet to house the 200mm macro - not sure how that will be positioned - I don't want to use a port ring.

Anyway - lots of options give them a try in some methodical fashion and see what works.

Let us know how you get on.

Tim

[zan]

Cool, I will do. Some folk are diving tomorrow, so I might go shallow and just play with strobe positions for while I'll let you know how it goes

Zan