# Thread: Carl Zeiss Jena Apo Germinar 600mm f9 Image Circle?

1. ## Carl Zeiss Jena Apo Germinar 600mm f9 Image Circle?

Hello,

I'm looking for a lens that will work with the 24x24 wet plate camera I'm building. I'm going to be using this camera for portraits, so the lens only needs to cover that size at around 1:1.

I've come across a Carl Zeiss Jena Apo Germinar 600mm f9. I've heard it's specs are usually measured at an aperture that's stopped down a bit (where it's intended to be used for reproduction) — but I'm wondering if the image circle will cover that size wide open (since it's wet plate) at f9?

Thanks,

Ross

2. ## Re: Carl Zeiss Jena Apo Germinar 600mm f9 Image Circle?

Hello from France

I hope that someone on this forum will be able to give you 1st-hand information about the apo-germinar 600 lens and its coverage.

To start with, you'll find some useful information in Arne Cröll's article here:
http://www.arnecroell.com/czj.pdf
The 600 mm Apo Germinar is similar to the Apo Ronar, it is a (4/4) symmetrical design and is listed for 46° of coverage, see table 5a page 14 and 5b page 16.
Hence it will cover about 500 mm of image circle in infinity-focus and about 1000 mm at 1:1.

Since you want to cover the diagonal of a 24" square, i.e. 34" = 860 mm, your 600 mm Apo Germinar will certainly not cover the format in infinity-focus setting, but if your magnification ratio M is above 0.1, you have a chance to cover, if we extrapolate the covered diameter at infinity by a factor 1+M.
For example if M = 0.5, your subject's size is 48"x48" and you 'll probably cover an image diameter of 500 x 1.5 = 750 mm: you are almost done.

Regarding using an Apo Germinar or Apo Ronar at full aperture, I doubt that you'll gain in image circle, my guess is that you'll loose in sharpness in the corners but you'll probably not loose much in terms of actually illuminated image circle.

3. ## Re: Carl Zeiss Jena Apo Germinar 600mm f9 Image Circle?

Thank you for your reply Emmanuel!

Looks like maybe it will work, but maybe not. I'm not too worried about softness in the corners since this will be used for portraits. A little softness would be fine. Also not worried about infinity (even though that would be nice), more looking just for 1:1.

I'll keep investigating. I may need to go for a slightly larger lens to make sure I'm covered. Maybe the 750mm f9—it's just so much more expensive ��

Cheers,

Ross

4. ## Re: Carl Zeiss Jena Apo Germinar 600mm f9 Image Circle?

Must you have a 600 Apo-Germinar?

I ask because there are other 600 mm process lenses. Nikon claims that the 610/9 Apo Nikkor covers > 1,000 mm @ 1:1. Rodenstock makes a similar claim for the 600/9 Apo Ronar. Arne Croell estimates ~ 945 mm for the 600/9 Apo Tessar. Goerz claims "24x28 + 15%" for the 24"/11 Apo Artar.

If you're shooting 24 x 24 without movements, you'll need a lens that covers about 34" = 862 mm. You have many choices.

5. ## Re: Carl Zeiss Jena Apo Germinar 600mm f9 Image Circle?

Nope, just looking for a lens that will cover 24x24 at 1:1 for portraits. Anything extra is just bonus points. Think they are all fairly similar in that range no? The Germinar is just what I've come across online. If someone else has another lens they are willing to part with, then please let me know

Originally Posted by Dan Fromm
Must you have a 600 Apo-Germinar?

I ask because there are other 600 mm process lenses. Nikon claims that the 610/9 Apo Nikkor covers > 1,000 mm @ 1:1. Rodenstock makes a similar claim for the 600/9 Apo Ronar. Arne Croell estimates ~ 945 mm for the 600/9 Apo Tessar. Goerz claims "24x28 + 15%" for the 24"/11 Apo Artar.

If you're shooting 24 x 24 without movements, you'll need a lens that covers about 34" = 862 mm. You have many choices.

6. ## Re: Carl Zeiss Jena Apo Germinar 600mm f9 Image Circle?

If you want a lens right now, go to eBay. If you want a lens at a price somewhat below market, go to eBay and wait.

7. ## Re: Carl Zeiss Jena Apo Germinar 600mm f9 Image Circle?

Another thing to keep in mind is the FL versus the format - wide lenses (anything a lot shorter than 862mm) will not be as flattering for portraits as slightly long (1,000mm) but having said that you need to decide at 1:1 if you are shooting full body, head and shoulders, or just head which will also dictate your FL. Also, the longer lenses tend to be slower f12.5 / 14 and heavier - so that may present a problem with exposure time, front standard strength and bellows draw (remember it's x2 for 1:1). The 35" and 42" Artars are the ones to go for IMHO - they are generally cheaper, smaller and lighter than the newer competition if you can find them in aluminum rather than brass.

24" by 24" is a pretty massive wet plate - you could slim it down a bit and more comfortably use a shorter and faster lens. You could build to a format that has some ULF film options or that you can easily get plates made to - or just custom scale it down to 20x20 for example. Artificial lighting can also reduce your exposure time and allow for a slower lens.

8. ## Re: Carl Zeiss Jena Apo Germinar 600mm f9 Image Circle?

more looking just for 1:1.

Hi again!

So if your setting is 1:1, the "1+M" rule of thumb predicts about one meter (40 inches) of image circle for a 600 mm apo-repro lens like the Apo Germinar or the Apo Ronar. So at 1:1 your are all set for a 24"x24" image size (diagonal = 34").

To the best of my knowledge, the focal length or the magnification ratio have no direct effect on perspective and projection, only the distance between the subject and the lens matters.
So with a 600 mm lens, at 1.1 your distance between the subject and the lens is only 1.2m (4 feet) and perspective rendition might not be optimal, at least for a classical portrait requiring a longer distance.
But for illustrating a vinyl record of a British rock 'n roll music group of the last century, on the contrary, 4 feet is too far away, the musician's faces will not be distorted enough at a distance of 4 feet

As far as depth of field (DoF) is concerned, it needs to be studied more carefully, DoF for ULF lenses and related images is something really non-trivial, but at 1:1 ratio, in any situation, DoF does not depend at all on the focal length in use!

Regarding the 750 mm Apo Germinar lens, I know a German gentleman named Jörg Krusche who owns one, so you can contact him regarding this lens (Jörg is an expert on East-German and West-German lenses of all kinds).
Jörg Krusche at our 2006 French Large Format conference with his 750 Apo Germinar "aus Saalfeld" mounted in front of a COMPUR 5FS shutter, attached to a 8"x10" Plaubel monorail camera.

9. ## Re: Carl Zeiss Jena Apo Germinar 600mm f9 Image Circle?

I believe that the exposure is x4 for 1:1 ratio subject size to image size (inverse square law).

Best wishes --- Allen

10. ## Re: Carl Zeiss Jena Apo Germinar 600mm f9 Image Circle?

I have three lenses in that range; The 790mm F11 Apo Ronar, the 600mm F9 Apo Ronar, and the 590mm Zeiss Apo Planar.

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