Kodak 8.5 in f6.3 Commercial Ektar?

[Dan Fromm]

I must not have been clear in post #2 above. The EKCo data sheets don't give coverage, they give the lenses' recommended formats. When the give angles, it is the angle that, given the lens' focal length, covers the recommended format's diagonal. Neither is what we usually mean by coverage.

[Pfsor]

Image circle observed as projected in a sheet of white paper will not behave in the same way as that same image circle projected on film. Film does not respond to light in the same way as the human eye.


Bernice

Notice that you don't want to and don't expect a piece of white paper to emulate a sheet of film or behave like one. You're just checking on a coverage circle of a lens. For that a piece of white paper is more than enough. BTW with your logic you could also dismiss a gg as not sufficient to check on a lens covering capability. With your logic the OP would be stranded with his question even if he had a 5x7 camera. Nobody surely waists sheets of film to see a lens coverage! Do you?

[David Lindquist]

Page 62 of the reference Andrew posted has this statement regarding the Commercial Ektars: "The four f/6.3 lenses described here cover at full aperture an angle of 53º and at small stops an angle of 64º."

David

[Andrew Plume]

Thanks David

regards

Andrew

[David Lindquist]

And if my trig is correct (please check my work) the corresponding image circle diameter for an 8 1/2" Commercial Ektar focussed at infinity and at a "small stop" would be 10.62 inches.

David

As I say, check my work.

[Bernice Loui]

That how it was done back in the day. Put the lens in question on a 8x10 camera, make two exposures on color transparency film (one film holder) focused at infinity, take the film holder to the E6 lab, wait two hours, pick up the film, evaluate the results. Then use the lens to be added in real world image making to see if the lens is a keeper. If not, the lens goes back to the dealer. This was how it was done back in the 1990's.

Again, lens image projected on to paper or ground glass (ye, this is a dismissal of observing the image on GG, been there done this wast of film, resources and effort) then observed with the human eye is not the same as what will be recorded on film.

Could be expectations, demands on lenses and needs are different here. IMO, lens-camera-camera support and all related image making devices MUST operate as they should due to image making demands. I'm at the point where experimenting is not needed or have any interest. All of that experimenting and tinkering around was done decades ago and it is much about making images, not experimenting or tinkering. What was share in the reply is based on using a 8-1/2" Kodak Commercial Ektar in 5x7 / 13x18cm for about three decades now and many, many, many sheets of film under a very wide variety of image making conditions.


Bernice

Notice that you don't want to and don't expect a piece of white paper to emulate a sheet of film or behave like one. You're just checking on a coverage circle of a lens. For that a piece of white paper is more than enough. BTW with your logic you could also dismiss a gg as not sufficient to check on a lens covering capability. With your logic the OP would be stranded with his question even if he had a 5x7 camera. Nobody surely waists sheets of film to see a lens coverage! Do you?

[Pfsor]

Again, lens image projected on to paper or ground glass (ye, this is a dismissal of observing the image on GG, been there done this wast of film, resources and effort) then observed with the human eye is not the same as what will be recorded on film.
Bernice

Again (and the last time) - your human eye does not need to see an image on the ground glass in the same way as film will see it if you want to judge the image circle of a lens sufficient for 4x5 or 5x7 photography. If the image circle you see is smaller than 5x7 film format you will see it.
Some of us would like to go and get an 8x10 camera, take a picture and see then if the small image circle will somehow get bigger with a bigger camera but most of the common people will not have that hope. YMMV.

[Bernice Loui]

You're trolling for verbiage I'm not interested in.

Done.
Bernice

Again (and the last time) - your human eye does not need to see an image on the ground glass in the same way as film will see it if you want to judge the image circle of a lens sufficient for 4x5 or 5x7 photography. If the image circle you see is smaller than 5x7 film format you will see it.
Some of us would like to go and get an 8x10 camera, take a picture and see then if the small image circle will somehow get bigger with a bigger camera but most of the common people will not have that hope. YMMV.

[Pfsor]

Just don't be so thin skinned, there ARE better ways to check a 5x7 lens coverage than buying a 8x10 camera and taking a pic on an 8x10 transparency sheet film, like it or not.

[Bernice Loui]

Why should ANY one accept verbal abuse under the guise of being thin skinned?

YOU realize what was written is verbal abuse and dis-respectful of facts, knowledge and wisdom gained over decades of this LF stuff.

Written text are telling of the individuals who write them.
https://www.largeformatphotography.i...73#post1464173


Bernice

Just don't be so thin skinned, there ARE better ways to check a 5x7 lens coverage than buying a 8x10 camera and taking a pic on an 8x10 transparency sheet film, like it or not.