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DDT uk

Focus gears and diopters

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I have been Alex Mustard's article in UwP on mid range zooms and it set me thinking. I have an 18-50mm Sigma lens (the f3.5-5.6) that fits within my dome port. The first question is: if Sea and Sea (who make my housing) do not sell a zoom gear for the lens, how do you go about controlling the zoom? Is it a case of knocking one up in a workshop?

 

The second question is: in many articles people appear to add diopters to the lens in varying strengths. How do you know which strength to use for the best results, or even whether to use one at all. Here I am talking about the zoom lens rather than on macro lenses. Is it a case of trial and error. Bearing in mind that most of my shooting in 2 dives a day off the south coast of England over a weekend rather than on week or two week liveaboards.

 

Thanks

Daniel

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HI Daniel

 

I would ask you local dealer to see if sea and sea makes the gear or not. If not, there are a few people who have DIY their own gears, can't find a thread at the moment but you might think of posting a question in the DIY section with that as the title, like "How to DIY focus/zoom gear" it might get more attention that way.

 

Here is a recent thread on diopters

http://wetpixel.com/forums/index.php?showtopic=18678

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Hi Daniel,

 

Many lenses are very similar in diameter - and although there isn't a gear made specifically for your lens there will often be one that fits. I have 5 zoom lenses that I use underwater and only one officially has a gear made for it. But all the others I have managed to get gears for off the shelf.

 

I was using my mid range 28-70mm Sigma this morning - worked very nicely on a whitetip resting on the seabed, amongst others.

 

Alex

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Thank you all for your help. I must say that I would never have considered looking for help on diopters in the Gear Lust catagory under the heading for a Canon lens!

 

It would appear that I am able to fit a thin sleeve into an existing gear to make the zoom work. Excellent.

 

Daniel

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