Help: Lens size Filter size

Just bought a Canon AE-1 Program, the SLR I really _wanted_ to own back
when I was an 8th grader infatuated with photography in 1982. (Back
then I had to settle for a Canonet 28, but that's another story.)

I'm looking to get a UV filter for the lens, and am a little puzzled
about what size filter(s) to get. The lens is a Canon 50mm. But a couple
filters that came with the set-up are 52mm -- and they fit fine.

I've noticed that I can't seem to buy 50mm filters.

Is 52mm the correct/preferred size for a 50mm lens?

To complicate matters, the set-up also came with a Canon 28mm and a
Vivitar 75-205mm zoom. (Though the Vivitar also has "55mm" printed on
it.)

What's the best scheme for buying filters/adapter rings? Should I stick
to one filter size, and buy adapters for the other two lenses? What
filter size should I get?

Also: What filter size does the Vivitar take? 55mm?

Thanks in advance for any help.

--
CRAIG BAILEY
Winooski, Vt. USA
www.floydianslip.com

Lens focal length (55mm, 28mm, etc.) and filter size are 2 totally separate
measurements. Focal length is just that, the focal length of the lens. The
focal length of a lens is defined as the distance in mm from the optical
center of the lens to the focal point, which is located on the sensor or
film if the subject (at infinity) is "in focus".

Filters, on the other hand are measured according to the diameter of the
front element of the lens. Wider lenses equal wider filters.

This is, of course, assuming you are using screw-in filters. Larger lenses
(300, 400, 500, 600 mm and larger) use drop-in filters toward the back of
the lens body There are also other systems (Cokin, for example) which use a
mount on the front of the lens into which different square filters (and/or
vignettes) are dropped.

Hope this info helps!!

Craig Bailey wrote:

Just bought a Canon AE-1 Program, the SLR I really _wanted_ to own back
when I was an 8th grader infatuated with photography in 1982. (Back
then I had to settle for a Canonet 28, but that's another story.)

I'm looking to get a UV filter for the lens, and am a little puzzled
about what size filter(s) to get. The lens is a Canon 50mm. But a couple
filters that came with the set-up are 52mm -- and they fit fine.

I've noticed that I can't seem to buy 50mm filters.

Is 52mm the correct/preferred size for a 50mm lens?


You're confusing two different dimensions. The "50mm lens" refers to the
focal length.

52mm is the diameter of the front thread. I've seen 50mm lenses with
49mm front threads, 52mm front thread, and 55mm front thread.

You get the filter size that fits the front thread.



To complicate matters, the set-up also came with a Canon 28mm and a
Vivitar 75-205mm zoom. (Though the Vivitar also has "55mm" printed on
it.)

What's the best scheme for buying filters/adapter rings? Should I stick
to one filter size, and buy adapters for the other two lenses? What
filter size should I get?

Also: What filter size does the Vivitar take? 55mm?

Thanks in advance for any help.


If it says 55mm on the front bezel, it takes a 55mm filter.

Craig Bailey wrote:

What's the best scheme for buying filters/adapter rings? Should I
stick to one filter size, and buy adapters for the other two lenses?

That's the cheapest way...buy filters large enough to fit your largest
diameter lens and step up rings for the smaller diameter lenses to fit the
larger filters.

--

dadiOH
____________________________

dadiOH's dandies v3.06...
....a help file of info about MP3s, recording from
LP/cassette and tips & tricks on this and that.
Get it at http://mysite.verizon.net/xico

Joe Friday wrote:

Lens focal length (55mm, 28mm, etc.) and filter size are 2 totally
separate
measurements. Focal length is just that, the focal length of the lens.
The focal length of a lens is defined as the distance in mm from the
optical center of the lens to the focal point, which is located on the
sensor or film if the subject (at infinity) is "in focus".

Filters, on the other hand are measured according to the diameter of the
front element of the lens. Wider lenses equal wider filters.

Nitpicking here but they're measured according to the filter mounting
ring--while large diameter front elements will necessarily have large
diameter mounting rings the converse is not necessarily true.

This is, of course, assuming you are using screw-in filters. Larger
lenses (300, 400, 500, 600 mm and larger) use drop-in filters toward the
back of
the lens body There are also other systems (Cokin, for example) which use
a mount on the front of the lens into which different square filters
(and/or vignettes) are dropped.

Hope this info helps!!

--
--John
to email, dial "usenet" and validate
(was jclarke at eye bee em dot net)

Craig Bailey wrote:
Is 52mm the correct/preferred size for a 50mm lens?


It should say the thread size on the inside of the lens where the
threads are or on the outside

To complicate matters, the set-up also came with a Canon 28mm and a
Vivitar 75-205mm zoom. (Though the Vivitar also has "55mm" printed on
it.)


What's the best scheme for buying filters/adapter rings? Should I stick
to one filter size, and buy adapters for the other two lenses? What
filter size should I get?

If $ is an issue buy the filter for the largest lens then get to
adapter rings - best to have dedicated filters though.