Understanding what I have

Okay, I have a Canon T3i with a 18-55 kit lens, 55-250 and a 75-300. I have just recently purchased from a friend one of those macro lens that screws on to your existing lens. From what I've read, I need to use the 18-55 lens. I think it is a 45mm macro. When in use, what exactly do I have here? 18-55mm + 45mm Macro =?

I'm lost.

Something that screws on to your existing lens?

Is it perhaps this?
http://en.wikipedia.or​g/wiki/Extension_tube

Or this?
http://en.wikipedia.or​g/wiki/Close-up_filter

I am guessing that you purchased some extension tubes based on the fact that you gave us a number with mm units.

No, it's this. http://www.amazon.com …TF8&qid=1335765​299&sr=8-2

I think a close up filter would be better, Nikon and Canon make fine quality ones with more than one element.

JCox wrote in post #14406419
Okay, I have a Canon T3i with a 18-55 kit lens, 55-250 and a 75-300. I have just recently purchased from a friend one of those macro lens that screws on to your existing lens. From what I've read, I need to use the 18-55 lens. I think it is a 45mm macro. When in use, what exactly do I have here? 18-55mm + 45mm Macro =?

I'm lost.

Sorry you wasted your money. What you have is a piece of junk that's advertised to be a wide angle adapter. It's supposed to make a normal lens into a wide angle lens, but all it really does it degrade the image and ruin the photo. Virtually any screw on lens adapter is the same. You already have a wide angle to normal zoom, so adding that thing is simply redundant. It's definitely NOT a macro anything.

You can get screw on closeup lenses too, but they are equally useless if you want any sort of image quality at all. The best low cost option for macro is a set of extension tubes. The cheaper ones will work but don't have any electrical contacts, so you lose auto focus and maybe aperture settings too. The better ones have full aperture connectivity and are really the only way you probably want to go. Many brands are not compatible with EF-S lenses, and those that are typically won't autofocus with EF-S lenses. This link will take you to one set that does allow you to use EF-S lenses but only with manual focus: Tubes

Keep in mind that when using extension tubes (they are just hollow tubes which mount between the lens and the camera body), while you get better close focusing that the lens normally allows, you will lose the ability to focus at the long end on distant objects.

Thanks everyone for your help. Rick, it actually cost me nothing. I have a Rebel XS that I let a friend's daughter borrow and she knew I was wanting a macro and just let me have this setup. I know it won't do what a more expensive macro will do but at this point, I'm just playing around.

Screw-on adapters aren't automatically garbage. It does what it does: you can be the judge of how well it does it because you have it. If it gives a wider field of view than the lens had without it, than it serves that function and if the image quality is still OK, it's useful for that. These sorts of things generally don't have great optical quality, but that doesn't make them useless.

I think you would be much happier with the results of reversing the 18-55 than buying extension tubes

And don't I need just a ring to reverse it?

Preeb wrote in post #14408011
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You can get screw on closeup lenses too, but they are equally useless if you want any sort of image quality at all. The best low cost option for macro is a set of extension tubes.

...

No doubt the tubes are the best for simple, good quality shots. But not all screw-on adapters are junk; Raynox makes a couple of very well-thought-of screw-on adapters. I have posted several shots that use them here, and so have others.