Process lens image circle nature

[erian]

I am planning to buy my first large process lens and I am wondering how does various process lenses image circle behave. Is it quick cut off or more gradual fade?

I am considering something around 750-800mm range and I plan to use it for portraiture (i.e. 1:1).

[Tin Can]

Depends on magnification and format

I have a 900mm Jena and it needs a lot of bellows for a head on 11x14

Tell us your plan

[Drew Wiley]

Officially published image circles for process lenses are geared to very high quality apochromatic standards and tight dot reproduction right out to the corners. Therefore these figures are far more conservative than those used for ordinary photography. They might be rated at infinity as well as for 1:1, but frequently at f/22. So you have a number of variables to contend with. But you must be dealing with an enormous piece of film if you're worried about image circles for process lenses that long. The 780 Apo Nikkor I have was used on a process camera, max 22 feet long and equipped pin-registered for 30x40 inch repro film. The way you are probably contemplating using a process lens, straight on, even a 305 would easily cover 8x10 film corner to corner without any falloff or sacrifice of precision, even by f/11. A 240 does it by f/16. Gradual fade isn't in process lens vocabulary; it would be unacceptable except in cheaper process lenses like those used in old Stat cameras and T-shirt silkscreening shops. But if you intend to use something around 700mm at 1:1, you must have an awfully long bellows yourself!

[Dan Fromm]

I am planning to buy my first large process lens and I am wondering how does various process lenses image circle behave. Is it quick cut off or more gradual fade?

I am considering something around 750-800mm range and I plan to use it for portraiture (i.e. 1:1).

I think you're asking about illumination, not about image quality. Long process lenses such as you mentioned all cover relatively narrow angles. For example, the 750/9 Apo-Nikkor (tessar type) covers 37 degrees (500 mm @ infinity, 1,000 mm @ 1:1) and the 760/11 Apo-Nikkor (dialyte type) covers 42 degrees (600 mm @ infinity, 1,200 mm @ 1:1). At 17.5 degrees off axis, cos^4 reduces illumination by no quite 1/4 stop. At 21 degrees off axis, less than 1/3 stop. Stop worrying.

To echo Mr. Wiley, if you must worry, worry about how you're going to get the extension needed to shoot at 1:1 with such lenses.

[erian]

Depends on magnification and format

I have a 900mm Jena and it needs a lot of bellows for a head on 11x14

Tell us your plan

I plan to build a camera obscura. The one where you can walk in. I plan to focus by moving the back inside the camera. I am thinking to use large photo paper and by large I mean really large like 1 meter by 60 cm or similar.

[erian]

To echo Mr. Wiley, if you must worry, worry about how you're going to get the extension needed to shoot at 1:1 with such lenses.

I am not worrying about the bellows because I do not plan to use them. The idea is to build a walk in camera obscura.

[Andrew Plume]

Good day to all of you

This has been discussed on here before (possibly on a slightly different basis):

https://www.largeformatphotography.info/forum/showthread.php?145140-Understanding-Allen-Rumme-s-Lens-Database

which may or may not help the OP

rgds

Andrew

[Dan Fromm]

I plan to build a camera obscura. The one where you can walk in. I plan to focus by moving the back inside the camera. I am thinking to use large photo paper and by large I mean really large like 1 meter by 60 cm or similar.

How will you keep the paper plane perpendicular to the lens' axis?

[Tin Can]

Many people have done this, which doesn't mean don't do it. It's huge fun! I did it a few years ago and plan to do it better next year.

Read this https://www.largeformatphotography.info/forum/showthread.php?89571-890mm-APO-NIKKOR-IMAGE-CIRCLE-1-1-amp-INFINITY&p=874269&viewfull=1#post874269

Then this, I have the 790mm http://re-inventedphotoequip.com/Formats.html

Some just sit inside and look. https://www.vice.com/en_us/article/xy4m9k/gowanus-bridge-camera-obscura-brooklyn

Other's make big wet plates https://www.ianruhter.com/

Largest print ever made https://en.wikipedia.org/wiki/The_Great_Picture

Soft or sharp edges I cannot say as I never worried about that.

[Pere Casals]

How will you keep the paper plane perpendicular to the lens' axis?

A solution would be placing a toy laser in the lens board (well perpendicular to the lens board!) and then placing a piece of mirror on the paper plane, or the counter, the laser on the paper and the mirror on a filter mount.

The laser refrigerator base I've it is perfectly perpendicular to the axis, I use that to align the enlarger, but it should work perfectly in that application...

[Pere Casals]

I am planning to buy my first large process lens and I am wondering how does various process lenses image circle behave. Is it quick cut off or more gradual fade?

I am considering something around 750-800mm range and I plan to use it for portraiture (i.e. 1:1).

My LOMO O-2 600mm, a dyalite type, covers 41º in the specs but it illuminates around 90º, with increasing softness when going beyond the specified coverage circle.

Illumination circle of APO-Nikkors are also reportedly very big: https://www.largeformatphotography.info/forum/showthread.php?8263-image-circle-of-Nikkor-Apo-455mm-f9-process-lens&p=56941&viewfull=1#post56941

So for your application they may work, as you may have the corners in the out of focus, still you will have fall-off in the outer illumination boundary.

[Vaughn]

I plan to build a camera obscura. The one where you can walk in. I plan to focus by moving the back inside the camera. I am thinking to use large photo paper and by large I mean really large like 1 meter by 60 cm or similar.

Cool! Vacuum frame? That would also be cool, but a bit of extra work. Have fun!

[erian]

My LOMO O-2 600mm, a dyalite type, covers 41º in the specs but it illuminates around 90º, with increasing softness when going beyond the specified coverage circle.

Illumination circle of APO-Nikkors are also reportedly very big: https://www.largeformatphotography.info/forum/showthread.php?8263-image-circle-of-Nikkor-Apo-455mm-f9-process-lens&p=56941&viewfull=1#post56941

So for your application they may work, as you may have the corners in the out of focus, still you will have fall-off in the outer illumination boundary.

Nice, this is exactly what I was looking for.

Does anybody know this about Ronars and Artars?

[erian]

Cool! Vacuum frame? That would also be cool, but a bit of extra work. Have fun!

I thought about this on my way home today. How to keep vertical junk of paper flat. Yes, vacuum would do put I thought that it definitely will not fit into thigh time frame. I have about a week to build and use this (in addition to other Christmas activities).

[Tin Can]

One week!
,
Use what you got, no vacuum, tape it up, use longest LF lens you have, use a hat for a shutter as paper is very low ISO, like 2 to 5 ASA which is the same almost as ISO.

If it's a family pic, do it after they all fall asleep and are not moving. The exposure may be very long.

No lens, use a pinhole and even longer exposure, Go here, https://www.mrpinhole.com/

Post the results here no matter what it looks like.

Repeat yearly.

Merry Christmas!

Out


I thought about this on my way home today. How to keep vertical junk of paper flat. Yes, vacuum would do put I thought that it definitely will not fit into thigh time frame. I have about a week to build and use this (in addition to other Christmas activities).

[blue4130]

I thought about this on my way home today. How to keep vertical junk of paper flat. Yes, vacuum would do put I thought that it definitely will not fit into thigh time frame. I have about a week to build and use this (in addition to other Christmas activities).

For a temporary camera, I'd just use low stick spray adhesive on the back of the paper.

[Pere Casals]

this about Ronars and Artars?

Ronars and Artars are also dyalites, with similar behaviour.

[Bob Salomon]

Ronars and Artars are also dyalites, with similar behaviour.

How about Apo Gerogons?

[Dan Fromm]

How about Apo Gerogons?

If you'd read this discussion from the beginning you'd know that the longest Apo-Gerogon is too short for the OP's project.

[Dan Fromm]

Ronars and Artars are also dyalites, with similar behaviour.

There are dialyte type Apo-Nikkors, too.

[Drew Wiley]

Yeah, Gerogons and their private-label reincarnations, were cheap lenses for compact stat cameras.

[Bernice Loui]

Maybe a single element achromat lens instead of a highly corrected process lens would do good. Many of these long focal length process lenses have been taken up by ULF folks paying !$! for them. Single element achromat could be found at modest cost at various optics surplus or hobby astronomy want-ads.


Bernice



I plan to build a camera obscura. The one where you can walk in. I plan to focus by moving the back inside the camera. I am thinking to use large photo paper and by large I mean really large like 1 meter by 60 cm or similar.

[Pere Casals]

There are dialyte type Apo-Nikkors, too.

Yes, I learned that time ago in your article http://www.galerie-photo.com/apo-process-nikkors-en.html

[MAubrey]

Nice, this is exactly what I was looking for.

Does anybody know this about Ronars and Artars?

My APO Ronar 480mm f/9 MC projects a circle of illumination of ~800mm across.

[erian]

I ordered Goerz 30 inch F12.5 Apochromat Artar for my project. The main influence was weight and tiny bit shorter focal length. With both combined I could even hope to use this lens on my 11x14 for landscape photography (camera extends about 77 cm).