Using Ilford Multigrade below lens

Can I cut down a set of Ilford Multigrade 3.5" filters for below-the-lens
use?

In other words, are below-the-lens filters different in any way optically?

Mike spake thus:

Can I cut down a set of Ilford Multigrade 3.5" filters for below-the-lens
use?

In other words, are below-the-lens filters different in any way optically?

Yes, worse, because they can degrade the image (more easily than above
the negative). However, if they're kept clean, you should still be able
to get decent prints.


--
.... asked to comment on Michigan governor George Romney's remark that
the army had "brainwashed" him in Vietnam—-a remark which knocked Romney
out of the running for the Republican nomination—-McCarthy quipped,
"I think in that case a light rinse would have been sufficient."

(Eugene McCarthy, onetime candidate for POTUS)

In article ,
Mike wrote:

Can I cut down a set of Ilford Multigrade 3.5" filters for below-the-lens
use?

In other words, are below-the-lens filters different in any way optically?

Yes they are- dust and scratches are more likely to be seen. Best place
to put them is above the negative if you don't have a in the lamp house
drawer.
--
LF Website @ http://members.verizon.net/~gregoryblank

"To announce that there must be no criticism of the President,
or that we are to stand by the President, right or wrong,
is not only unpatriotic and servile, but is morally treasonable
to the American public."--Theodore Roosevelt, May 7, 1918

Are there glass filters available for this purpose ?

"Gregory Blank" wrote in message
...
In article ,
Mike wrote:

Can I cut down a set of Ilford Multigrade 3.5" filters for below-the-lens
use?

In other words, are below-the-lens filters different in any way
optically?

Yes they are- dust and scratches are more likely to be seen. Best place
to put them is above the negative if you don't have a in the lamp house
drawer.
--
LF Website @ http://members.verizon.net/~gregoryblank

"To announce that there must be no criticism of the President,
or that we are to stand by the President, right or wrong,
is not only unpatriotic and servile, but is morally treasonable
to the American public."--Theodore Roosevelt, May 7, 1918

In article , "bill"
wrote:

Are there glass filters available for this purpose ?

The question your asking is does someone make a
ready made boxed set....my answer is not to my knowledge.
In the 25 years of my photo existence I haven't seen them
but that doesn't mean they don't exist.


You could use any screw in type on the lens if it has threads, but its
a PITA. You certain can buy glass or resin filters if money is
inconsequential .
--
LF Website @ http://members.verizon.net/~gregoryblank

"To announce that there must be no criticism of the President,
or that we are to stand by the President, right or wrong,
is not only unpatriotic and servile, but is morally treasonable
to the American public."--Theodore Roosevelt, May 7, 1918

"Mike" wrote in message
news
Can I cut down a set of Ilford Multigrade 3.5" filters for
below-the-lens
use?

In other words, are below-the-lens filters different in
any way optically?

Filters are more critical in the image path than in the
light path. If the filters are very clean, free of scratches
or blemishes, and are homogenious they will work fine in the
image path. The last is important. The filters should not
distort when you look through them. Also check by moving one
around in front of the lens, there should be no effect from
this.
In theory, flat block with parallel surfaces will have
no effect on light which is collimated. This is usually the
case when a filter is used on a camera. The light from the
objects is far enough away so theat the light rays are
nearly parallel. When used in a convergent or divergent beam
the block can introduce aberrations. The amount depends of
the thickness and the index of refraction of the material.
When its necessary to use a filter in an image forming path
where the light is vergent the best material is gelatin
since it is thin and the index is close to that of air. The
plastic filters used for some VC filters has a higher index
than gelatin but is still better than glass. So, the effect
of lamp house type VC filters used below the lens, should be
minimal, provided they are in excellent condition.
I've given a somewhat long answer so you will know what
the factors are here.


--
---
Richard Knoppow
Los Angeles, CA, USA

"Mike" wrote in message
news
Can I cut down a set of Ilford Multigrade 3.5" filters for
below-the-lens
use?

In other words, are below-the-lens filters different in
any way optically?

I left out a line, namely that the light rays from an
enlarging lens are vergent rather than plane. Again, the the
practical effect of this in enlarging as far as introducing
aberrations from a thin film filter are minimal.


--
---
Richard Knoppow
Los Angeles, CA, USA

Mike wrote:

Can I cut down a set of Ilford Multigrade 3.5" filters for below-the-lens
use?

In other words, are below-the-lens filters different in any way optically?


Why not buy the real thing? Ilford offers a set of Multigrade filters
that are specifically designed to be used below the lens.

http://www.pictureline.com/product.php?id=1645

If you want to see what they look like, there is a set for sale on
eBay UK.

http://cgi.ebay.com/ws/eBayISAPI.dll...tem=7562708722

Tony Polson wrote:

Mike wrote:


Can I cut down a set of Ilford Multigrade 3.5" filters for below-the-lens
use?

In other words, are below-the-lens filters different in any way optically?



Why not buy the real thing? Ilford offers a set of Multigrade filters
that are specifically designed to be used below the lens.

http://www.pictureline.com/product.php?id=1645

If you want to see what they look like, there is a set for sale on
eBay UK.

http://cgi.ebay.com/ws/eBayISAPI.dll...tem=7562708722


Text in French, but just scroll down to the bottom for pictures of how
it fixes to the lens.

http://www.nightlight.fr/Pagesprodui...utre_kodak.htm

FYI, the text below the pix talks about the filters in general and not
how the fixation works.

Mike wrote:

Can I cut down a set of Ilford Multigrade 3.5" filters for below-the-lens
use?

Should work fine. If they are as good at the 6"ers I have I don't
see any problem. But that means NO scratches, fingerprints, globs,
blobs and/or dust.

If they need cleaning then test the cleaning method on the 0.5"
strips you have cut off.

You wont get the filter frames, filter holder and storage box
the underlens set comes with.

To keep the set ebayable you might make a cardboard under-lens gizzy to
hold 3 1/2" filters. If you cut them they are yours for life; if you
decide to get a real set of UL filters then you can lessen their $$ by
selling the old 3 1/2's.

== On a related matter ==

I once cleaned an under-lens Polymax with water & stuff. I can't
vouch what the stuff was, probably Windex or distilled water
on the end of a Q-tip.

I wondered where the yellow went
When I examined the Q-tip it was evident

Don't apply anything waterish to below lens filters. Any one
want a perfectly clear filter labeled "2 1/2"?

--
Nicholas O. Lindan, Cleveland, Ohio
Consulting Engineer: Electronics; Informatics; Photonics.
To reply, remove spaces: n o lindan at ix . netcom . com
Fstop timer - http://www.nolindan.com/da/fstop/index.htm