I need to do some macro photography which will require about x5 magnification. I have the 180mm Canon macro lens which goes to life size, or x1 magnification. What extension tubes will I need to get to x5?

Thanks.

No idea. You could just buy this ...

http://photo.net/equipment/canon/mp-e-65

With such a long focal legth, it would take a lot of extension to get to 5x. Perhaps mounting a reversed 50mm lens on the front of the 180 would be a better way to approach it.

Not sure what that would get you for magnification, though.

A lot. rough approximation: magnification gain = ex tube length / lens focal length.

So you want an additional 4x, which would be...720mm.

I'm sure this approximate calculation falls apart long before that kind of extension, but you get the idea.

Dave Chew

That's worth doing just for the entertainment factor.

Thanks Dave, yes I've looked it up and you're right, it's an unrealistic extension. Guess it's down to the x1-x5 macro 65mm; even though it's manual focus, the f2.8 aperture is calculated rather than real (so the image in the viewfinder is likely to be very dim), and I'll be too close to the subject for anything other than the ring flash!

I think at 5x you're screwed no matter what.

You could try the Canon 500D close up lens. I have one for a 70-200 zoom with a step down ring and it's sharp right across the zoom range, while a single element close up I tried was fine at 70mm and hopeless at above 120mm or so. I have a set of extension tubes and hardly use them as
1) putting them on without filling the camera body with dust seems impossible
2) by the time they are on the subject has died of old age
3) the close up lens works just as well for most of my needs.
You could probably borrow one from your camera store and try it out. I have no idea if it will do what you want. David

I thought the 500D focuses at 0.5m. How would one get a 5X magnification with this attached? I'm most curious since I have the same 500D.

No, you are not. On my camera (40D) with the 500D the minimum focus distance is 13" and the max is 20" across the range from 70-200mm. 48mm of extension tube was the most the lens would take before looking like a banana. At 200mm the min focus was 20" and the max was 31". David

Yeah, that's the thing with this kind of magnification. I wouldn't buy just the 65mm. You gotta get a ring light along with it, or some other set up that gets light in close.

I suppose there are execptions, like close-ups of big rocks that won't move much using the tripod from your 12" Schmidt-Cassegrain.

:-P

Dave Chew

Could you use a bellows extension to get the magnification you need? I know that Nikon makes a bellows unit but have never seen a Canon bellows. But I have seen third party units in the past so maybe if you look around you can find one.

Mark