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150mm G-Claron the WRONG lens for Over 25" Paintings?



 
 
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  #1  
Old February 15th 04, 11:46 PM
Dr. Slick
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Default 150mm G-Claron the WRONG lens for Over 25" Paintings?

Hi,

I got a hold of a brochure for the G-Claron:

"The normally used range of linear magnification is between
5:1 and 1:5. ...the G-Claron may also be used for distances up to
infinity by stopping down to f/22 or less."


Ok, so if i understand this correctly, the reduction is 1:5, so if
you take the largest side of 4x5, this would be a maximum of 5x5=25"
on the largest side of the painting.
So i was taking about 35" images @f16, so perhaps this was out of
the range of the lens? Or perhaps i really needed f22, even at this
size, and not just for infinity?

One fellow at KS said that the G-Claron is mainly for really up
close marco work, like product pics of wallets and purses and stuff
like that. And that some people use it for landscape work when
stopped down more than f/22, because it's a very light shutter and
lens.

Then he recommended a 150mm Rodenstock Apo-Sironar-N, and didn;t
charge me for the rental because the pics i took with the G-Claron
didn't turn out (nice, eh?).

Said this would be good for 8.5"x11" up to 3'x4', as well as
infinity.

The brochure says the optimum aperture for 4x5 is f16-22.

I'll try f16, f22, and f32 tonight!


Slick
  #2  
Old February 16th 04, 01:09 AM
Reciprocity Failure
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Posts: n/a
Default 150mm G-Claron the WRONG lens for Over 25" Paintings?


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

I got a hold of a brochure for the G-Claron:

"The normally used range of linear magnification is between
5:1 and 1:5. ...the G-Claron may also be used for distances up to
infinity by stopping down to f/22 or less."


Ok, so if i understand this correctly, the reduction is 1:5, so if
you take the largest side of 4x5, this would be a maximum of 5x5=25"
on the largest side of the painting.
So i was taking about 35" images @f16, so perhaps this was out of
the range of the lens? Or perhaps i really needed f22, even at this
size, and not just for infinity?

One fellow at KS said that the G-Claron is mainly for really up
close marco work, like product pics of wallets and purses and stuff
like that. And that some people use it for landscape work when
stopped down more than f/22, because it's a very light shutter and
lens.

Then he recommended a 150mm Rodenstock Apo-Sironar-N, and didn;t
charge me for the rental because the pics i took with the G-Claron
didn't turn out (nice, eh?).

Said this would be good for 8.5"x11" up to 3'x4', as well as
infinity.

The brochure says the optimum aperture for 4x5 is f16-22.

I'll try f16, f22, and f32 tonight!


Slick



  #3  
Old February 17th 04, 04:20 AM
Richard Knoppow
external usenet poster
 
Posts: n/a
Default 150mm G-Claron the WRONG lens for Over 25" Paintings?


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

I got a hold of a brochure for the G-Claron:

"The normally used range of linear magnification

is between
5:1 and 1:5. ...the G-Claron may also be used for

distances up to
infinity by stopping down to f/22 or less."


Ok, so if i understand this correctly, the reduction

is 1:5, so if
you take the largest side of 4x5, this would be a maximum

of 5x5=25"
on the largest side of the painting.
So i was taking about 35" images @f16, so perhaps this

was out of
the range of the lens? Or perhaps i really needed f22,

even at this
size, and not just for infinity?

One fellow at KS said that the G-Claron is mainly for

really up
close marco work, like product pics of wallets and purses

and stuff
like that. And that some people use it for landscape work

when
stopped down more than f/22, because it's a very light

shutter and
lens.

Then he recommended a 150mm Rodenstock Apo-Sironar-N,

and didn;t
charge me for the rental because the pics i took with the

G-Claron
didn't turn out (nice, eh?).

Said this would be good for 8.5"x11" up to 3'x4', as

well as
infinity.

The brochure says the optimum aperture for 4x5 is

f16-22.

I'll try f16, f22, and f32 tonight!


Slick


It should work fine for the paintings. They are not much
out of the optimum correction range. The main aberation
picked up when outside of the optimum object to lens
distance is coma. Coma is proportional to the f/stop so
stopping down gets rid of it. You should be able to work at
f/16 without any loss of quality at the corners.
The APO Sironar-N may or may not be a better lens but its
optimised essentially for infinity (actually for around 20
feet) so the G-Claron is actually more nearly in its optimum
range.
To find the widest f/stop you can use look at the corners
of the image. Check using a small bright highlight, even a
pen light at the corner. When wide open the image may have a
slightly tear-drop shaped smear. As you stop down it will
shrink and finally disappear. That's the largest stop you
should work with. Symmetrical and semi-symmetrical lenses
are automatically corrected for coma when the entire system
is symmetrical but have very substantial cancellation of
coma even at infinity focus. Field flatness and other
aberrations should not be a problem.


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




 




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