Reversal rings question, 82mm-52mm

[DarrenT]

I have just invested in a set of kenko extension tubes but was also wondering about the possibility of reversing my nikon 50mm 1.8 onto the front of my sigma 24-70mm 2.8. i wouldnt want to do it the other way round mainly because of the weight of the sigma.

i could just get step rings to take the 82mm down to 52mm and then attach that with a reversal ring to the 52mm on my nikon but would it impede too much light do you think? i suppose the one advantage is that its cheap enough to find out!

EDIT: i mean macro coupler not reversal ring. doh

[daft_biker]

Am not sure it's worth buying something to try it out on....I've done some messing about to try stuff out using masking tape to hold lenses to extension tubes or each other

The reason I'm thinking it's not worthwhile is I think the maximum magnification you'll get from reversing the 50mm onto the 70mm end of the zoom is about 1.4:1 when you can probably get 1.5:1 with a full set of Kenko tubes (68mm?) and the 50mm on them the right way round.

However, reversing the 24mm end of the zoom onto the 50mm should give something about 2:1 magnification but I'd be surprised if that gave you better quality than cropping from the 50mm with tubes. Also, try the zoom on the extension tubes....the wider the lens the greater the effect the tubes have but you might find working distance is a bit short at the wide end (something about 35mm might work quite well ).

Here's a link you might find useful :http://www.srb-griturn.com/about-cou...ings-386-c.asp