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JimboWalker
3-Mar-2019, 17:23
I see Kodak info that says my Kodak 8.5in f6.3 Commercial Ektar can cover a 5x7 format. I cannot find the image circle specs to see if there is much movement beyond that format. I have only used on 4x5 and it is a wonderful lens, but I may be selling it to a guy shooting 5x7. Thanks!

Dan Fromm
3-Mar-2019, 17:28
Jimbo, the list contains a link to the best source of information on Ektar lenses in the known universe. Go there.

The best source ... quotes EKCo data sheets which give, IIRC, Commercial Ektars' recommended formats and angular coverage on those formats. They don't give image circles. When in doubt, use the f/6.3 Tessar rule of thumb. 60 degrees.

JimboWalker
3-Mar-2019, 17:54
Thanks Dan, but what list are you referring to?

Dan Fromm
3-Mar-2019, 18:47
Thanks Dan, but what list are you referring to?

There's a link to it in the first post in this discussion. It is a pdf with bookmarks that serve as an index. They don't work in on-line pdf readers, download it.

Pfsor
4-Mar-2019, 03:52
I see Kodak info that says my Kodak 8.5in f6.3 Commercial Ektar can cover a 5x7 format. I cannot find the image circle specs to see if there is much movement beyond that format.

How difficult is it to try the lens for yourself to see how much movement there is??

Sanford
4-Mar-2019, 07:05
How difficult is it to try the lens for yourself to see how much movement there is??
It could be very difficult if you don't have a 5x7 camera

Pfsor
4-Mar-2019, 07:11
It could be very difficult if you don't have a 5x7 camera

Really? What about having a piece of white paper and focus an infinity scene at it? Very difficult?

Bernice Loui
4-Mar-2019, 08:39
8-1/2" Commercial Ektar has been one of the "normal" lenses in barrel on the 5x7 Sinar for decades. Image circle is more than good enough for 5x7 with more than good enough camera movements under the majority of image making conditions.

https://www.pacificrimcamera.com/rl/00346/00346.pdf

Excellent if the specific example is in GOOD optical condition, the Kodak-Ilex or Kodak-Acme shutter might need work. In barrel using a Sinar or similar shutter, not an issue. If the lens is to be tested, it should be done using film under a wide variety of image making conditions or tested using optical specific instrumentation.



Bernice

Bernice Loui
4-Mar-2019, 08:46
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



Really? What about having a piece of white paper and focus an infinity scene at it? Very difficult?

Andrew Plume
4-Mar-2019, 10:24
Check out page 63:-

http://www.cameraeccentric.com/html/info/kodak_4.html

Andrew

Dan Fromm
4-Mar-2019, 10:29
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
4-Mar-2019, 10:36
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
4-Mar-2019, 11:04
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
4-Mar-2019, 11:15
Thanks David

regards

Andrew

David Lindquist
4-Mar-2019, 11:32
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
4-Mar-2019, 12:57
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
4-Mar-2019, 14:05
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
4-Mar-2019, 15:17
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
4-Mar-2019, 16:32
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
5-Mar-2019, 09:23
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.info/forum/showthread.php?148427-Tripod-recommendations&p=1464173#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.

Pfsor
5-Mar-2019, 11:02
A piece of white paper used to see the covering circle of a lens is a good way to see what format the lens can be used for. Every one has right to measure a lens covering capability as it pleases one. Like it or not. Enough said.

Louis Pacilla
5-Mar-2019, 11:04
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.info/forum/showthread.php?148427-Tripod-recommendations&p=1464173#post1464173


Bernice



I know of no one on this forum that gives as concise & cogent answers to many questions posted here it's you Bernice. So I would suggest (ignore list) you don't let him bait you EVER. BTW I LOVE your work very much. I appreciate your images and your contributions to our forum. Thanks brother!

JimboWalker
5-Mar-2019, 18:42
JEEZ! A friend of mine found the image circle in some literature to be 270mm. More than enough for 5x7. Thanks for your discussion.

Pfsor
5-Mar-2019, 18:52
JEEZ! ...270mm. More than enough for 5x7.

If that is the case you would be able to see it on a piece of white paper too and easily. Bless you!

David Lindquist
6-Mar-2019, 08:55
JEEZ! A friend of mine found the image circle in some literature to be 270mm. More than enough for 5x7. Thanks for your discussion.

Well good, looks like my trigonometry was on track. 10.62 inches = 269.75 millimeters.

David

ManWithManyHobbies
7-Mar-2019, 21:57
I see Kodak info that says my Kodak 8.5in f6.3 Commercial Ektar can cover a 5x7 format. I cannot find the image circle specs to see if there is much movement beyond that format. I have only used on 4x5 and it is a wonderful lens, but I may be selling it to a guy shooting 5x7. Thanks!

https://www.pacificrimcamera.com/rl/00346/00346.pdf

Bernice Loui
7-Mar-2019, 22:34
Indeed, as previously posted. Been using an 8-1/2" Commercial Ektar on 5x7_13x18cm for decades. Covers GOOD with more than enough camera movement. Have yet experience a problem with image circle at any aperture (f6.3 to f22, typically f8 to f16 is used) with any camera movements applied.


Bernice



Well good, looks like my trigonometry was on track. 10.62 inches = 269.75 millimeters.

David