Extension Tubes

i thought 105mm would be long enough for water droplets and insects, anyway i agree with arclight extension tubes are inexpensive and can get you close to the subject. the kenko ones are highly recommended because there good quality and they autofocus.
 
Don't forget supplementary close-up lenses, they work very well, try a +1 and +4 to see the different magnifications possible.
 
The sigma 105mm f2.8 or tamron 90mm f2.8 are the usual weapons of choice for macro work.

It really does depend on the quality of glass for macro work, especially if using extension tubes, but these tend to be used with non macro lenses to improve magnification.

The Kenko ones are very good and give you abit more flexibility then the branded ones, but would have thought the sigma wouldn't need extension tubes? as the lens minimum focal distances already gives you 1:1 ratio.

sigma 105mm f2.8 (Minimum focus distance = 32cm)

The Extension Tube is used to allow a lens to focus closer than it does natively. This is accomplished by moving the lens 12 or 20 or 36mm farther away from the camera body's film plane or digital sensor by fitting between the camera body and the lens.

The end result of focusing closer is a larger magnification. A rough rule of thumb to use for the increased magnification is ...

Additional Magnification = (Extension Tube Length)/(Lens Focal Length)

Based on this rough rule, the 20mm Extension Tube put between the camera body and say a 50mm Lens will result in a .4 magnification gain (20mm divided by 50mm).
 
A set of tubes will be a worth while investment with a macro lens, if you get a set of auto tubes you will retain aperture control from the body which makes everything so much easier, tubes will have no effect on IQ but you will get a little light loss. A full set of tubes used with the 105mm will give approx 2:1 magnification.
 
mastertrinity said:
sorry if i thread hijacking but would it be better for me to get some extension tubes for my 50mm than buy a sony 30mm f2.8 macro lens?
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Depends what you spec is for the 50mm, and what you want to photograph. A 30mm macro lens would take some serious fiddling to takes images and is probably abit short for macro work. Perhaps the Tamron 90mm f2.8 or the extension tubes on your 50mm would be better.
 
mastertrinity said:
well i only want to shoot products and flowers, along with some smoke and water droplet photography, pretty much anything thats not insects.

my lens is a minolta 50mm f1.7.
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Personally, I would buy the extension tubes from Kenko and use them with your Minolta 50mm f1.7 would make a very good combo. Minimum focus distance for that lens is 45cm.
 
Don't forget supplementary close-up lenses, they work very well, try a +1 and +4 to see the different magnifications possible.
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Personally, I think that you should not spoil the quality and sharpness of the Sigma 105mm Macro with some extra glass, with the close-up filters. I think that macro filters are great for cheaper lenses with poor macro, but the Siggy is already great and good quality as it is! I think that extension tubes are the way to do it, but in my opinion, the Sigma 105mm gets close enough as it is, for the work that you would like to do. It is a 1:1 ratio lens as it is.

All the best
 
Cheap close up lenses can give very good results, but the lens used really decides what maximum close up lens you can use.

A small focal length like the 18-55mm kit lens can successfully use up to +10 diopters but a longer length like the 70-300mm IS USM lens used here at +1 dioptres at 300mm:

http://www.flickr.com/photos/20926615@N05/3553836928/sizes/o/in/set-72157613651261240/

is not much good at +10 dioptres but is OK at +1 dioptres.

Also the wider the front lens the more likely you are to get distortions when using close up lenses.

On the other hand on my 70-300mm IS USM lens with a +1 dioptre means I can get good close ups without having to get too close and maybe have the insect etc fly away.

Extension tubes work very well on something like the "Nifty Fifty" 50mm F1.8

This was taken using the "nifty Fifty" and Kenko extension tubes:

http://www.flickr.com/photos/20926615@N05/4032796615/sizes/o/in/set-72157613651261240/

Also the small size of the lens meant I could use the inbuilt flash.
 
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