[Maddy]

I have read through the other posts regarding filters, but haven't found an answer to what I'm looking for.
I'm sorry, this may be a stupid question, but I don't understand this and just can't find any information about it.
Ok, here it is: when I bought the camera from the store, I wanted a UV filter also, and the guy give me a 58 mm filter for my 18-55 mm lense. At first I thought...well, that's odd...but quickly forgot about it as I was more interested in the camera itself.

But now I want to buy a 100 mm lense and I have no idea what filter works for that, or if I can buy an adapter ring instead. And if I buy an adapter ring....what kind?

Please, if someone can explain to me how these things work, I would really appreciate it.

Thanks,
Maddy

[danpen]

Generally it's a good idea to have a UV filter permanently mounted on each lens, it protects the glass from fingers and scratches etc. If you're buying a new lens just get a UV filter to go with it.

58mm is the diameter of the lens filter ring, quite a few lenses have 58mm filter rings. If you started to use other filters such as polarisers it's good if your lenses all take the same size. Alternatively you can use adapters to mount different sized filters or invest in a slot in filter system (like Cokin).

cheers

Dan

[Maddy]

Thanks for your answer Dan.

[Steve]

First of all there are no stupid questions, only questions to which you may not know the answer

While dan's answer is almost correct it may not be totally correct for you due to us not knowing which 100mm lens you are considering.

The size of the filter you need for your new lens will need to be exactly right and generally saying that 58mm is a common size will not cut it if your 100mm lens needs a 77mm filter

You have not filled in your camera gear list nor written which make/model of 100mm lens you are looking at, without that information the replies that you will receive will be at best a guess and more than likely could be completely wrong. If you wish to supply that information we can much more accurately answer your query Otherwise if you have not bought the lens yet, all you need to do is buy the filter at the same time and make sure that the supplier knows that you want the filter for the new lens

HTH

[danpen]

I must not have made it clear, I was suggesting that Maddy get a UV filter to go on each lens when she buys the lens, this will obviously not necessarily be 58mm as these are generally permanently mounted.

I went on to explain what the 58mm meant and that there's a few things to consider if she decides to start using other filters too.

Sorry if that wasn't clear I wouldn't want to mislead anyone.

cheers

Dan

[Maddy]

Thanks Steve, I'm sorry I haven't given you more information.

I have a Canon 350D and the lens that I want to buy is Canon EF 100mm f/2 USM.

[Steve]

No problem

A quick google search brings back the following information...

This lens is an EF 100mm 2.0 USM.

Features

* Focal length and maximum aperture: 100 mm 1:2
* Lens construction: 8 elements in 6 groups
* Diagonal angle of view: 24°
* Focus adjustment: Rear focusing system with USM
* Closest focusing distance: 0.9m / 3ft
* Filter size: 58mm

So the filter size in this case is 58mm as dan first suggested

[Maddy]

Thank you very much Steve.

I was looking at this lense's review at this site, and there is no information about the filter size in the description, but I see now that someone did mentioned it...I don't know how I missed that.

Anyway, thank you for clearing this up for me, I thought that there is a logic way to find out what size every lens needs.

Regards,
Maddy

[Rob Barron]

Not actually about filters as nothing mnore to add other than to endorse the comment that you should stick a UV filter on every lens you own and leave it there.

Just wanted to check Maddy whether you are going for the right lens. You may well be for what you want and that is fine. Just that the 100mm f2.8 macro lens is one of the most popular lenses in Canon's range and I wouldn't want you to end up with the wrong one. The macro one is about £75 more but gives you one of the best macro lenses around, allowing you to get up nice and close for superb shots that are pin sharp.

The Non-macro version does have a slightly wider aperture at f2, just under one stop extra, but you'll get plenty of excellent blurring at f2.8 and the extra benefit of macro. The lens is slightly longer than the f2 version but that version only has a closest focusing distance of 3 feet whereas the macro version is one foot. When you consider that distance is from subject to sensor, it basically means you can get as close as about 5 inches from your subject. It is true macro, ie it gives genuine 1:1 lifesize reproduction, meaning the size of the object you are photographing takes up the same amount of size on the sensor. You can entirely fill the frame with a normal postage stamp!

Anyway, it may well be that you know all this and I am just blathering on and boring you to pieces so i'll shut up now. At least you know about both and can choose the one you want for your needs. Sorry if I was teaching you to suck eggs.

Cheers,
Rob

[Maddy]

Thanks for the info Rob, I really appreciate it.
To be honest, I haven't looked at the the 100mm f2.8 macro lens because the less I spend on this the better I don't necessarily want a macro lens, I want a good lens that can do a bit of everything, but you've definatelly got me thinking about this, I'll have to reconsider things.