Synthesizer Patel

Hi - I recently bought a sigma 105mm macro (EX DG). I have not had a chance to take it underwater yet - but have been taking a few shots on land to get a feel for it and what it can do.

While overall it's a very satisfactory piece of kit - particularly considering the price point between it and the Canon alternative, it does have a few limitations and drawbacks.

I was hoping to get some tips from other people who use this lens so that I can get the most from it - particularly Canon/Ikelite users like me.

1. The autofocus is very slow and a bit clunky - it seems to spend a lot of time hunting - sometimes without any success - particularly as you head closer towards 1:1 - on land, manual focus is the way forward here, however my Ikelite housing does not allow manual focus control of this lens as the focusing ring is too far forward for the zoom/focus gear to reach.
- can anyone give me any tips as to how to minimise AF hunting?

2. Image sharpness/aperture - overall my pics have been sharp as a knife however I have noticed that Images stopped up beyond F22 start to get a bit squishy - making what I thought was a very nice feature on paper (stopping down to F44) almost irrelevant
- has anyone experienced the same? any tips on improving sharpness in the smaller aperture range?

3. Camera shake/shutter speed - on land I normally shoot at around 1/30 - 1/60 or sometines even slower due to the small apertures involved - however when I'm shooting at or close to maximum magnification, images seem to suffer from some camera shake - my guess is that this would be relatively easy to combat underwater as the increased light from my strobes would enable me to use a faster shutter speed, plus with the added stability that the larger size of the housing would give me, shake would be reduced -
any thoughts or advice on this?

I'm hoping to spend a month diving in Koh Tao Thailand this summer, and I'm after a good macro lens.

I've decided on the sigma 105mm macro.

I can buy an imported one off ebay for around £220 including postage (equiv US$430 approx) - which is a great deal compared to Uk retail or UK internet prices, and I'm more than prepared to take a risk on international warranty issues for the money I'll save.

However I'm wondering whether prices are similar in thailand - it would make my life a lot easier if I could simply pick one up retail when I arrive in Bangkok - The price doesnt neccessarily have to be better or matched, happy to pay a bit more for the convenience - say 10-20% more.

can anyone advise me on what I'm likely to pay for this lens at retail in bangkok? reccommend a good camera retailer there? Perhaps a decent Ikelite retailer as well as I may pick up a port or two.

thanks in advance

PS - mods - not sure if this is the right place to post this so feel free to move this post to a more appropriate location if neccessary

Finally gone digital after years of shooting on film - and I have to admit, I'm pretty clueless of how to set up my camera for shooting without the security blanket of TTL - particularly for macro shots.

I'm fairly used to shooting manually for wide angle, so that's less of an issue - but any tips for a good starting point for macro shots would be handy - I have to admit I've never flown anything other than autopilot for macro in my life :-)

I have 2 100a ike strobes and one ss50 - I'd assume that a 100a + ss50 would be best combo  for starters - perhaps with a home-made diffuser on the 100a and increase the subject to strobe distance relative to the ss50 ??

reccommended F-stop? - shutter speed?

what about other digi specific settings like white balance - I'll admit that I don't even know what this is or means

tha nks in advance guys

I'm guessing that there's not much chance getting hold of a used one as these seem to be the most useful of the macro ports for canon shooters like me and people tend to hang on to them - but if someone out there wants to help out a financially challenged student I'd appreciate it.

Anyone used this lens successfully in an ikelite housing?

judging by the focusing distance and physical dimensions of the lens it sounds like it should work behind a 5503 standard dome port.

Its closer focusing than the 15mm, slightly lower magnification, but a fair bit cheaper - so perhaps a worthy compromise.

any comments / advice ?

anyone tried it out?