Step up or step down?

[Galaxy66]

I have just acquired a 77 mm infra red filter which fits my lens ok, however my son wants to borrow it for his lens which is 67mm filter size.
Question is does he need a stepping up ring form 67mm to 77mm or does he need a stepping down ring from 77mm to 67mm or are they both the same:shrug:
Am I asking a stupid question

 

[antihero]

you would need a STEP UP ring mate, as you want to step the thread size up from 67 on the lens to 77 to hold the filter. A step down ring would be needed if you wanted to put a 67mm filter on a 77mm lens. Hope that makes sense

67-77mm step up rings are a bit hard to come across, but there is ONE on ebay at the minute...$0.99 from china otherwise you might have to combine a 67-72 with a 72-77.

 

[donut]

be a bit of a gap if you put a 67 filter on a 77 lens

 

[antihero]

he wants to put a 77 filter on a 67 lens now its getting confusing

 

[Galaxy66]

he wants to put a 77 filter on a 67 lens now its getting confusing

Not as confused as I was ......Its because I have bought it for myself to fit my 77mm lens but son wants to borrow it and he has a 67mm lens

But you got to admit, to the not so learned in photography the question of stepping up from the67mm lens to the 77mm filter or stepping down from the 77mm filter to the 67mm lens is confusing

Anyway, thanks for pointing me in the right direction, I have found one here and will order tomorrow.
http://www.ukcamera.com/denton/kood.htm