Step-down rings for filters?

I've got some 49mm filters that I want to use with a lens that takes 72mm
filters. I know I'm going to be shooting stopped down all the way to f/22
or smaller.

With a 72-49 step-down ring, this should work fine, right? As long as I
stay stopped down to a point where the effective aperture is below 49mm,
right? Or is it not that simple?

Probably not. Is this lens a Zoom?? You will probably get a barrel effect
on the edges if its too much for the lens. You didn't mention what kind of
filters you will be using?? If its any special kind of color, polarizer or
what not then I can see forcing it. If its just a UV Filter then dont
bother loosing part of the view because of that. If the filter set is an
expensive one I can see otherwise if the lens is of good quality and very
sharp I can't see it being worth it.

Not4wood


"Roy Smith" wrote in message
...
I've got some 49mm filters that I want to use with a lens that takes 72mm
filters. I know I'm going to be shooting stopped down all the way to f/22
or smaller.

With a 72-49 step-down ring, this should work fine, right? As long as I
stay stopped down to a point where the effective aperture is below 49mm,
right? Or is it not that simple?

"Not4wood" wrote:

Probably not. Is this lens a Zoom??

Yes. Specifically, the Nikon 18-200mm.

You didn't mention what kind of filters you will be using??

Neutral density. I want to play with very long exposure times. Sunny/16
says ISO 100 (the slowest the D200 will go, unless there's some magic I
missed in the manual), f/32, gets you 1/50th sec. I'm thinking more like 1
second, or about 6 stops slower. I've got some 49mm ND filters already. I
figure a step-down ring is cheap. Getting a new set of 72mm ND filters is
a fair chunk of change just to play around with some special effects.

I was at the Metropolitan Museum here in New York this afternoon, looking
at their exhibit of early photographs (paper negatives, that sort of
stuff). Got me thinking it might be fun to try some very long exposures.

On Dec 23, 11:22 am, Roy Smith wrote:
I've got some 49mm filters that I want to use with a lens that takes 72mm
filters. I know I'm going to be shooting stopped down all the way to f/22
or smaller.

With a 72-49 step-down ring, this should work fine, right? As long as I
stay stopped down to a point where the effective aperture is below 49mm,
right? Or is it not that simple?

Nope. Your logic would be correct if the filter was located where the
aperture is. But it isn't. It's in front of the front element, while
the aperture is within the lens..

72 down to 49 is an awful lot, and I would lay a sizable bet that you
will certainly get vignetting, unless maybe shooting a zoom at it's
longest focal length.

Why don't you just try it with a cardboard cutout?

Roy Smith wrote:
"Not4wood" wrote:

Probably not. Is this lens a Zoom??

Yes. Specifically, the Nikon 18-200mm.

From 72mm to 49mm is a huge step down. More than likely
even with the aperture stopped all the way down there
will be vignetting at 18mm focal length, but probably
not at 200mm.

Another problem is that you might not be able to find a
72-49mm, and it might require two step-down rings, which
makes it worse because the combination extends a bit
farther out in from of the lense.

You didn't mention what kind of filters you will be using??

Neutral density. I want to play with very long exposure times. Sunny/16
says ISO 100 (the slowest the D200 will go, unless there's some magic I
missed in the manual), f/32, gets you 1/50th sec. I'm thinking more like 1
second, or about 6 stops slower. I've got some 49mm ND filters already. I
figure a step-down ring is cheap. Getting a new set of 72mm ND filters is
a fair chunk of change just to play around with some special effects.

I was at the Metropolitan Museum here in New York this afternoon, looking
at their exhibit of early photographs (paper negatives, that sort of
stuff). Got me thinking it might be fun to try some very long exposures.

For the price of one or two step-down rings... go for
it! What's to be concerned. Eat beans for two meals
and it's paid for.

Of course, if you are really really intense, get a piece
of cardboard or whatever, cut a 49mm circle out, and
hold that up in front of your lense. You'll find out
what the minimum possible effect is. The real step-down
ring plus filter will extend several mm out from that,
and be worse. If you are really crafty you can even
simulate that too before buying a step-down ring.

I'd just go get the step-down ring and if it doesn't
work you can toss the ring into a junk box and chalk up
$20 to fun and experience.

--
Floyd L. Davidson http://www.apaflo.com/floyd_davidson
Ukpeagvik (Barrow, Alaska)

On 2007-12-22 17:22:30 -0800, Roy Smith said:

I've got some 49mm filters that I want to use with a lens that takes 72mm
filters. I know I'm going to be shooting stopped down all the way to f/22
or smaller.

With a 72-49 step-down ring, this should work fine, right? As long as I
stay stopped down to a point where the effective aperture is below 49mm,
right? Or is it not that simple?

Seems to me that it would be a lot simpler to just use a 72 mm filter.
You know, you can get vignetting at 18mm with that lens with just your
lens hood slightly askew. I had a problem with that when doing some 3
minute exposures using the 18-200 in Wyoming. It was stopped down all
the way, but the lens hood just being a little crooked caused
vignetting.
--
Waddling Eagle
World Famous Flight Instructor

"Roy Smith" wrote in message
...
I've got some 49mm filters that I want to use with a lens that takes 72mm
filters. I know I'm going to be shooting stopped down all the way to f/22
or smaller.

With a 72-49 step-down ring, this should work fine, right? As long as I
stay stopped down to a point where the effective aperture is below 49mm,
right? Or is it not that simple?

Not that simple. It would be that simple if the filter was placed at the
iris, but beyond the front element you will get vignetting, which will have
a harder edge at smaller apertures but will be very visible in any case. If
you want to see it for yourself, just cut a 49mm hole in a 72mm piece of
carboard and put it in front of your lens...

Toby

"Roy Smith" wrote in message
...
I've got some 49mm filters that I want to use with a lens that takes
72mm
filters. I know I'm going to be shooting stopped down all the way
to f/22
or smaller.

With a 72-49 step-down ring, this should work fine, right? As long
as I
stay stopped down to a point where the effective aperture is below
49mm,
right? Or is it not that simple?

It's simple but you will probably need 2 step down rings- cheap on
Ebay.
Most likely 72-62 then a 62-49.

"Roy Smith" wrote in message
...
I've got some 49mm filters that I want to use with a lens that takes
72mm
filters. I know I'm going to be shooting stopped down all the way
to f/22
or smaller.

With a 72-49 step-down ring, this should work fine, right? As long
as I
stay stopped down to a point where the effective aperture is below
49mm,
right? Or is it not that simple?

Whoops! I checked Ebay for inexpensive step down rings.
You may need two or three.
72-62,62-52,52-49 or 72-58,58-49

"Frank Arthur" wrote in message
.. .

"Roy Smith" wrote in message
...
I've got some 49mm filters that I want to use with a lens that takes 72mm
filters. I know I'm going to be shooting stopped down all the way to
f/22
or smaller.

With a 72-49 step-down ring, this should work fine, right? As long as I
stay stopped down to a point where the effective aperture is below 49mm,
right? Or is it not that simple?

Whoops! I checked Ebay for inexpensive step down rings.
You may need two or three.
72-62,62-52,52-49 or 72-58,58-49


Then check the eBay price for ND filters in 72mm - cheap as chips, even
branded Hoya.