Filter and adapter ring sizes

[ThelVlenace]

Currently looking to purchase some filters to get longer exposures for landscape in the day. I know you get what you pay for in terms of quality - just wondering how you know what size threads you need? I think I would rather go for the Cokin style filters (square) but how do you know what size adapter ring you need? I'm currently using a 50mm - (apologies if this has been covered a million times)

 

[mortimerhill]

if you look up the full specs of your lens(es) on the manufacturer's website, it will list the filter size.

Failing that, measure it with ruler!

Also, it might be on the lens cap!

for SLR lenses, the sequence of filter sizes is 49mm, 52mm, 55mm, 58mm, 62mm, 67mm, 72mm, 77mmm, 82mm

 

[markmullen]

On the outside edge of the lens there will by a symbol like a "o" with a line through it and a size in mm.

 

[stu.artd]

It often tells you on the lens itself, but when I can't be bothered physically checking one I tend to visit wex.co.uk and see if the lens is shown on their website. Click into the specifications and it's in there.
I've found that works better for me than digging through canon's website.

 

[graphilly]

I've used this in the past

http://photography-on-the.net/forum/showthread.php?t=257659

 

[rjbell]

Inside of the lens cap will tell you the thread size.

 

[ThelVlenace]

Yeah thanks for the replies! It's in the lens cap (doh)! It's a stupid question, but now I know - i won't have to ask it again! Thanks