[xanda]

hi, i am thinking of buying a macro lens, but i am confused as to what it will actually offer me.

i have an 18-200mm lens already, but if i were to buy a '200mm' macro lens what would the difference be over my 18-200mm lens? i suppose i'm asking what makes a macro lens a macro lens?

[don_bertone]

What makes a Macro lens a Macro lens is the focusing distance. Macro lens has a 1:1 magnification. Your 18-200mm is probably not a macro so it wouldnt focus near enough for 1:1 magnification.

[ChrisRabior]

The key is the minimum focusing distance. I have a 28-75 macro lens that gives me better closeups than my 75-300 non macro lens. The 75-300 needs to be like two or three feet from the subject in order to focus, while the 28-75 lets me get a few inches away.

Macro simply allows you to get 'closer' to your subject. A good way of describing what you can do would be to put the 18-200 on, and try to get closer and closer to your subject (at 200mm). The closer you walk up, the bigger it seems. Go closer and closer, until it starts to blur out of focus. Imagine if you could move closer without losing focus. Instead of losing the shot at 40 inches, you can go to 5 or 10 inches. The focal length of the lens is 200mm for both, but the macro lets you move the lens closer to the subject.

That's the difference.

[xanda]

ok, i'm pretty sure i get it, but my 18-200mm says it has a shortest focus distance of 50cm, but looking at this one Sigma - Lenses it has shortest focus of about 30cm which doesn't seem a dramatic impprovement. Perhaps you could give me a few links to the macro lens that you have Chris, or any other good lenses?

[don_bertone]

That is actually a pretty good lens. The Tamron 100mm macro is very nice too. But I think the Canon 100mm macro is really the best of the bunch(it has internal focusing).

[ChrisRabior]

Its actually a pretty big improvement when you think about it. To give yourself an idea of how much of a difference it is, just move 20cm closer and imagine what the image would look like if the lens could actually focus on it. You won't notice very much at 18mm, but you'll notice a lot more of a difference as you go up towards 200. The larger the zoom, the bigger the difference you get from a closer focus distance.

Btw, my only macro capable lens is the Tamron 28-75mm f/2.8.

I've played around a bit with extension tubes to get the macro capabilities. My dad machined the kenko set to fit EF-S lenses in addition to EF, so I can use those with any lens in my collection or in his. The 50mm f/1.8 works quite well with extension tubes, but I have to say I like the actual macro lens better for the closeup shots.

[Markulous]

It's also about sharpness - the prime lens will give much better results

Here's a comparison:

Sigma 70-300mm @ 300mm Macro




Sigma 105mm




Personally, rarely use my 70-300mm for macro work as it just doesn't cut it sharpness-wise

And, BTW, one of the Macro options tou have is the Sigma 105mm - better price albeit at the price of external focussing (Canon is internal)

[Hacker]

If you want to go down the macro/close up route without breaking the bank try using a something like a Canon 500D or Nikon 5T/6T diopter on the front of your 18-200mm lens, it gives good results for a reasonably small outlay (compared to a dedicated macro lens).

Have a read of the Beginners Guide to Macro, it might help.

[xanda]

ok, thanks for those pics, and i think i would prefer a dedicated macro lens.
i have had a look at the sigma 105mm and thought it looked pretty good apart from some reviews that said it had very poor auto focus.
The other option would be the Nikon equivalent with vr, but that is about £500 compared to the sigma which is around £260 or so. Anyone have any idea which one to go for? also any preferences over a 105mm compared to a 180mm or so?

thanks for your help

[Markulous]

I think you can get away with some view type shots being quite soft but never a macro! Focus isn't fantastic but I rarely use auto anyway, keeping to manual with much more control - occasional auto when trying to follow something moving when it does work OK

I looked at the 180mm and, IIRC, it was near double the price and knew it wasn't any better/sharper, just that you needn't be so close to the 'beastie' - and anyhow half the 'fun' is trying to get close!

[xanda]

thanks, so do you think that the sigma 105mm is a pretty good buy compared to the nikon equivalent?

[Markulous]

Originally Posted by xanda

thanks, so do you think that the sigma 105mm is a pretty good buy compared to the nikon equivalent?

Probably, but never having used the Nikon I can't say for sure!

But I did compare the Sigma 105mm with the Canon 100mm and the main differences were the internal focussing and slightly better build of Canon. Quality of image seemed to be the same (which is all I really care about!) tho' I should state that I can only use the Sigma!