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Best Aperture for Sironar N 150mm...Also, Using Graflex Polaroid Back???



 
 
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  #1  
Old February 27th 04, 12:31 PM
Dr. Slick
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Default Best Aperture for Sironar N 150mm...Also, Using Graflex Polaroid Back???

Hello,

I went ahead and got a Rodenstock Sironar-N 150mm, which is
supposedly a good overall lens, but since it was still a tiny bit
sharper than the Tominon 127mm, i decided to get it. A very good deal
at $220.50 on Ebay!

Anyhow, with the sironar i rented at KS, the best aperture was at
f32, 11 seconds (yeah, i know i should get brighter lights!). So i
expect it to be the same for this lens...but i'm still going to try
f45...the water-jug hanging from the tripod sounds like a good idea at
this point!

Can anyone who has this lens give me some input?

Also, i'd like to use my now-obsolete Graflex polaroid back (500
model) if i could. Someone wrote:

"Polaroid says that the model 500 is obsolete and that anybody
that has the next model, the 545, needs to either have it rebuilt or
buy the new 545i.

While the 500 is obsolete, current sheet film (types 52,54,59,55, and
others) can work. BUT

The new model 545/545i has a catch in the mecanism that keeps the dark
envelope from pulling completely out. The 500 has no catch.

So the trick is to waste a sheet of film and get a reference point.
Without putting the holder in a camera, insert a sheet of film all the
way and then, pull the dark envelope until it just passes the image
area then look at the back and see that "When the letter P in Polaroid
passes the edge of the holder, its clear" or something similar."

Is it possible someone can tell me how to use this thing?


Slick
  #2  
Old February 27th 04, 12:48 PM
Reciprocity Failure
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Posts: n/a
Default Best Aperture for Sironar N 150mm...Also, Using Graflex Polaroid Back???

Anyhow, with the sironar i rented at KS, the best aperture was at
f32, 11 seconds (yeah, i know i should get brighter lights!). So i
expect it to be the same for this lens...but i'm still going to try
f45.I


I don't own this lens but the best aperture for any lens is the aperture
that provides the desired depth of field (so that areas intended to be
"sharp" are) and no more (so that unnecessary diffraction isn't introduced).

"Dr. Slick" wrote in message
om...
Hello,

I went ahead and got a Rodenstock Sironar-N 150mm, which is
supposedly a good overall lens, but since it was still a tiny bit
sharper than the Tominon 127mm, i decided to get it. A very good deal
at $220.50 on Ebay!

Anyhow, with the sironar i rented at KS, the best aperture was at
f32, 11 seconds (yeah, i know i should get brighter lights!). So i
expect it to be the same for this lens...but i'm still going to try
f45...the water-jug hanging from the tripod sounds like a good idea at
this point!

Can anyone who has this lens give me some input?

Also, i'd like to use my now-obsolete Graflex polaroid back (500
model) if i could. Someone wrote:

"Polaroid says that the model 500 is obsolete and that anybody
that has the next model, the 545, needs to either have it rebuilt or
buy the new 545i.

While the 500 is obsolete, current sheet film (types 52,54,59,55, and
others) can work. BUT

The new model 545/545i has a catch in the mecanism that keeps the dark
envelope from pulling completely out. The 500 has no catch.

So the trick is to waste a sheet of film and get a reference point.
Without putting the holder in a camera, insert a sheet of film all the
way and then, pull the dark envelope until it just passes the image
area then look at the back and see that "When the letter P in Polaroid
passes the edge of the holder, its clear" or something similar."

Is it possible someone can tell me how to use this thing?


Slick



  #3  
Old February 27th 04, 03:02 PM
Largformat
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Posts: n/a
Default Best Aperture for Sironar N 150mm...Also, Using Graflex Polaroid Back???

I don't own this lens but the best aperture for any lens is the aperture
that provides the desired depth of field (so that areas intended to be
"sharp" are) and no more (so that unnecessary diffraction isn't
introduced).

I agree. Don't use a smaller f-stop then necessary

steve simmons
  #4  
Old February 27th 04, 03:39 PM
Bob Salomon
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Default Best Aperture for Sironar N 150mm...Also, Using Graflex Polaroid Back???

In article ,
(Dr. Slick) wrote:

I went ahead and got a Rodenstock Sironar-N 150mm,


Optimal aperture is f22. at smaller apertures you will be in diffraction.

--
To reply no_ HPMarketing Corp.
  #5  
Old February 27th 04, 11:18 PM
MikeWhy
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Default Best Aperture for Sironar N 150mm...Also, Using Graflex Polaroid Back???

"Bob Salomon" wrote in message
...
In article ,
(Dr. Slick) wrote:

I went ahead and got a Rodenstock Sironar-N 150mm,


Optimal aperture is f22. at smaller apertures you will be in diffraction.


What wavelengths of interest would suffer diffraction losses in a 5mm
aperture?


  #6  
Old February 27th 04, 11:45 PM
Bob Salomon
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Posts: n/a
Default Best Aperture for Sironar N 150mm...Also, Using Graflex Polaroid Back???

In article ,
"MikeWhy" wrote:

"Bob Salomon" wrote in message
...
In article ,
(Dr. Slick) wrote:

I went ahead and got a Rodenstock Sironar-N 150mm,


Optimal aperture is f22. at smaller apertures you will be in diffraction.


What wavelengths of interest would suffer diffraction losses in a 5mm
aperture?


I would be happy to mail you the data sheets. But past f22 you will be
in diffraction.

--
To reply no_ HPMarketing Corp.
  #7  
Old February 28th 04, 12:14 AM
MikeWhy
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Posts: n/a
Default Best Aperture for Sironar N 150mm...Also, Using Graflex Polaroid Back???

"Bob Salomon" wrote in message
...
I went ahead and got a Rodenstock Sironar-N 150mm,

Optimal aperture is f22. at smaller apertures you will be in

diffraction.

What wavelengths of interest would suffer diffraction losses in a 5mm
aperture?


I would be happy to mail you the data sheets. But past f22 you will be
in diffraction.


That is surprising, and yes, I would would like to see the data sheets. I'm
replying by email also, so you will have the real email address.

In general, is this a manufacturing and engineering issue, or one of general
physics and optics? What little I recall of undergrad optics talked in terms
of small multiples of wavelengths for diffraction effects.

  #8  
Old February 28th 04, 01:44 AM
Reciprocity Failure
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Posts: n/a
Default Best Aperture for Sironar N 150mm...Also, Using Graflex Polaroid Back???

What wavelengths of interest would suffer diffraction losses in a 5mm
aperture?


I would be happy to mail you the data sheets. But past f22 you will be
in diffraction.


That is surprising, and yes, I would would like to see the data sheets.

.. . Is this an engineering and manufacturing issue or one of general
physics and optics. .

Diffraction in photographic terms refers to the effect obtained when light
rays are bent as they pass sharp edges such as aperture blades. The higher
the proportion of "bent" (i.e. diffracted) light to total light, the more
noticeable the loss of "sharpness" due to the bent light becomes. The
smaller the aperture, the greater the proportion of "bent" light to total
light so that diffraction is an issue only at smaller apertures. However,
there is some amount of diffraction at all apertures, you won't just "be in
diffraction" at F22 with this or any other lens. In addition, as the
aperture size is reduced undesirable aberrations are also reduced so there
is a trade-off between the benefits (reduction of aberrations) and
detriments (diffraction) of small apertures. Finding the "optimal aperture"
depends in part on finding the point beyond which the benefits of smaller
apertures are more than offset by the detriments..

However, the "optimal aperture" of a lens is IMHO mostly a matter of
theoretical interest with 4x5 and larger negatives where the magnification
factor of the typical print is small compared to prints from 35mm negatives.
The loss of apparent "sharpness" due to inadequate depth of field will
almost always be more noticeable than the slight loss of sharpness caused by
diffraction, regardless of what aperture is used. Therefore, I think it's
more important to select the minimum aperture needed to produce the desired
depth of field, whatever that aperture might be in any given situation, than
it is to worry about the effects of diffraction if something smaller than
the "optimal aperture" is used.

"MikeWhy" wrote in message
m...
"Bob Salomon" wrote in message
...
I went ahead and got a Rodenstock Sironar-N 150mm,

Optimal aperture is f22. at smaller apertures you will be in

diffraction.

What wavelengths of interest would suffer diffraction losses in a 5mm
aperture?


I would be happy to mail you the data sheets. But past f22 you will be
in diffraction.


That is surprising, and yes, I would would like to see the data sheets.

I'm
replying by email also, so you will have the real email address.

In general, is this a manufacturing and engineering issue, or one of

general
physics and optics? What little I recall of undergrad optics talked in

terms
of small multiples of wavelengths for diffraction effects.



  #9  
Old February 28th 04, 04:12 PM
Nicholas O. Lindan
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Posts: n/a
Default Best Aperture for Sironar N 150mm...Also, Using Graflex Polaroid Back???

Anyhow, with the sironar i rented at KS, the best aperture was at
f32, 11 seconds (yeah, i know i should get brighter lights!). So i
expect it to be the same for this lens...but i'm still going to try
f45.


I will lay odds something is seriously wrong with this man's camera or
his setup: things aren't parallel.

That or the definition of 'fuzzy' has changed to "less than 100 lp/mm
in the corners."

Would it be the case that, wide open, everything is sharp in the
middle and fuzzy at the edges, though if one looks closely
there are two sharp spots along the edge, one each side of the lens.

A Sironar-N is _very_ sharp, even wide open:

http://www.butzi.net/rodenstock/rodenstock.htm

http://www.hevanet.com/cperez/results.html

--
Nicholas O. Lindan, Cleveland, Ohio
Consulting Engineer: Electronics; Informatics; Photonics.

  #10  
Old February 29th 04, 04:28 AM
Dr. Slick
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Posts: n/a
Default Best Aperture for Sironar N 150mm...Also, Using Graflex Polaroid Back???

"Nicholas O. Lindan" wrote in message thlink.net...
Anyhow, with the sironar i rented at KS, the best aperture was at
f32, 11 seconds (yeah, i know i should get brighter lights!). So i
expect it to be the same for this lens...but i'm still going to try
f45.


I will lay odds something is seriously wrong with this man's camera or
his setup: things aren't parallel.

That or the definition of 'fuzzy' has changed to "less than 100 lp/mm
in the corners."


I don't believe this is the case, as the center of the trannies
using the Schneider Xenar was very sharp, really the sharpest so far,
and i will keep the Xenar for 6x6 work.

Someone mentioned the possibility of not using an adjustable
loupe, for focusing on the far side of the fresnel lens, but i'm using
a hand-held loupe (no fixed focal distance), so this is not the
reason.

It is possible that i'm being a bit too picky, or being somewhat
overly selfconscious when comparing to a semi-professional's work,
which seems to be very sharp everywhere. I tried to ask him what he
was using, but never got an answer back. Perhaps some sort of
enlarging lens?



Would it be the case that, wide open, everything is sharp in the
middle and fuzzy at the edges, though if one looks closely
there are two sharp spots along the edge, one each side of the lens.

A Sironar-N is _very_ sharp, even wide open:

http://www.butzi.net/rodenstock/rodenstock.htm

http://www.hevanet.com/cperez/results.html



So you are saying that if everything is ok with my camera, that
if i shoot one at say, f5.6, that the center should still be very
sharp, while the "coma" distortion should make the edges a bit fuzzy?

By the way, what are the approximate widths of the depths of
field for a lens like this? I mean at f22, f5.6, and f32, how wide
will the depth be, where you will not notice a difference in
sharpness?


Slick
 




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