How close is 1:2?

I'm looking for a macro JUST to do wedding ring photos. I don't want to spend the bucks for a lens that'll take a series of maybe 10 shots per wedding then go back in the bag. I'm considering the EF 50 f/2.5 because it's under $275 here in the States.

Will this lens do it without the 1:1 converter? I'd be using it on a 1D II.

If you don't need high magnification or very fast autofocus, I would say the EF 50mm f/2.5 is perfectly adequate for the task you describe. If you do need more magnification, you might consider the Sigma 50mm f/2.8 macro, as that lens can go to 1:1. Both lenses should be more than sharp enough, though you may have to get a bit closer to the subject as opposed to using a longer lens.

The 50 2.5 is a nice sharp little lens. It should be able to handle ring shots without the 1:1converter.

Thanks for the input fellas. I'm not too worried about sharpness or how close I would have to get physically. I'm just wondering if 1:2 can fill the frame with the ring(s). I already get 1:3.5 out of my 24-70L. Would 1:2 really be that much better?

EDIT: I forgot all about the Sigma 50. I might just go that route instead.

On a 1DII, the sensor size is 28.7mm across. That means that with a 1:1 lens, a subject that is that width across should exactly fill the frame from edge to edge. I would estimate that most wedding bands don't exceed 20cm across, so if you are shooting at maximum magnification with the EF 50mm f/2.5, 1:2, your frame will cover about 57.4 across; the complete ring would therefore occupy about 1/3 of the entire frame. Using a 1:1 lens like the Sigma, you will find that one ring will likely occupy about 2/3 of the entire frame.

Note that you may decide to shoot at a lower magnification to photograph more than 1 ring, add other props, improve the composition, etc.; I rarely find myself shooting at maximum magnification unless I'm trying to overrule the compositional quality of the photo with some real in-your-face blowup of a small object.

I would go for the sigma 50mm macro over the canon - from what I hear whilst its also a more budget line macro lens its a good worker and since it gives you proper 1:1 macro without the addon (which would take your budget over the price of a good macro lens like a sigma 70mm). For a ring you will I think need to have the abilty to reach closer than 1:2 magnification, but I would not expect you to really need to go beyond 1:1 and I suspect you will be working in between those two points (depending on the composition that you are setting up.)

Thanks for your input again, fellas. I held a 20mm screw mount extention tube between my 24-70 and camera and it gave me what I want so I decided to just get a cheap set in EF mount instead of a dedicated lens. Adorama has a set of plastic (but with electronics) for $49.95 so I went for it. They won't be used heavily so I anticipate no problems. Even if they break after a month, I still got my money's worth.

I really don't want to pack another lens anyway.