Advice wanted

[aquakiwi]

I've been using my Sigma 50mm macro in an Ikelite housing. Up to now I have'nt used any focusing ring etc, just used it on auto. Some of the results have been disapointing as it hunts around for focus. I'm know about to try it with a focusing ring in manual. Anyone had any experience with this lens? I think Cussy uses one?

[Cussy]

It works fine on manual, bit slow (obviously), so anything fast moving is out. What I've now tended to do is try to learn how to shoot auto, using a focus torch as much as possible when it's needed. I've now got the 105, which without modification isn't compatible with manual focus. Downside of the Sigma is no clutch, so once you are on manual that's it for the whole dive.
Rob

[DDT uk]

I don't use the Sigma 50mm but all of my macro lenses do tend to hunt around if you are not careful (though sometimes it is unavoidable). What I do is to use a focus light to help the AF and to sure make that the area focus selector is on a point of contrast (such as an edge). You can also engage the lenses focus limiter to restrict the range through which it will hunt.

I hope that this helps

Daniel

[KenByrne]

I have teh Sigma 50mm and use it on AF all the time. Yes sometimes it hunts but it's still more accurate than I am. I use a torch fastened to each of my strobes to aid focusing and get the focus point on an area with a bit of contrast if it starts to hunt.

I've never used the limit switch which would help the range it hunts through. Downside would probably be missing out on the occasional larger animal which might swim by, I know the 50mm isn't ideal for this type of subject but if the opportunity arises and that's what you've got on it can get a shot.

[ChristianG]

Have a look at my avatar. Immediately below each of my strobes is a black blob that happens to be (twin) quite powerful torches. Have I said this before?

I took to one of them (at my left shoulder in my case, doesn't really matter other than that most people's left strobes are their primaries) with a scouring pad which gave it a nice, pretty even, glow which allowed it to act to serve my AF and duly got overpowered by the strobes. I left the other one severely alone as a general "sweeping, penetrative" torch.

Worked pretty well, beware forgetting to shut off or turn away the "sweeper", gives you a hot spot every time.

This has the added benefit of giving you a pretty good idea of where you're strobe/s are pointing provided the torches are in parallel to them.

[Mike W]

I use a Sigma 105mm with my 350D Canon. The Canon is widely regarded as being slow to focus and prone to hunting, despite which I get good results. Manual focus isn't an option with this lens, unless you accidentally catch the auto/manual switch and do the whole dive only able to photograph subjects two feet six and a half inches from the front of the port...not that I've ever done that you understand

My strobes are an old Ikelite Ai and a 100A, both of which have modelling lights built-in. They're fine as the primary light for night dives - I tend to leave one on for the outward bit of the dive, and the other for the homeward leg, though in reality either one holds more than enough charge for an hour plus as many full power flashes as I need. They're also good enough to act as focus lights, even for 1:1 shots where the world goes dim.

[aquakiwi]

Thanks for the replies, perhaps I'll perservere with it on auto. With my aging eyesite it makes sense. One of my problems last weekend was having the camera shutter on burst causing me to take multiple images whilst trying to focus, I did get some keepers tho.

[TimIngmire]

This is not directly relevant to your lens but I have found that once I moved to Manual focus with my 105, I was getting much much better results.

I don't yet have the gears to run manual focus on my 60mm and as a result, I just haven't used that lens in a while. More times than I care to remember I have a lost a shot as the noise of the lens hunting back and forth has spooked a subject - and that's even in bright clear conditions in blue water, let alone at 25m meters in typical UK conditions.

Just MHO.

Tim

[DDT uk]

Tim,

Do you use a standard eye piece?

I do have a gear for my 60mm but I was unsure at how accurately I would be able to focus looking through my mask and my standard viewfinder. It is often hard enough to just see the composition. I take it that you do not have any problems?

[Cussy]

Does the Nikon 105 have a luxury of a clutch? Downside with Sigma is that once on manual you are stuck for the entire dive and sometimes that can be a pain.

Looking at the first photo the far background is razor sharp. It might just be my eyes, but the vegetation in front of the fish is not as blurred as the fish. Are you sure this isn't a case of not high enough a shutter speed? Depending on distance, I always try for 1/200th (fastest my D80 will sync) and as high an f number as I can get away with (based on how far light will travel from the strobe). That was a tip I got from Digigreen that seems to really work.

I always try to get the focus on the eye. If the eye is sharp you can blag that the blurred body was what you were trying to do artistically . The eye almost always has high contrast so the focus works better.

As you have all the kit to try manual, just try it top side. See what you think. Go from close focus to far distance and see if the pain of changing focus a lot is what you can live with. I would agree with Tim that manual gives better shots, but if your buoyancy isn't spot on and you don't hold perfectly steady it can be just as frustrating as the auto shunting. If you are at a site that has a sandy bottom to sit on then go manual, if it a wall then think about whether you can be perfectly still.
HTH,
Rob