360mm lens on Ebony RW45

[ChrisN]

I've acquired a Rodenstock Apo-Ronar 360mm f/9 lens in Compur #2 shutter, which I'd like to try on my Ebony RW45. A quick trial last night indicates that I have just enough bellows extension to be able to focus down to about 6 meters away (about 20 feet).

How much more extension would I need to focus down to two meters? I think I could make up an extended lens board (opposite of a recessed board) with too much trouble.

Thanks!

[Peter K]

Chris, with your 360mm lens and 2m subject distance the image reduction is 0.22 or an image scale of 1:4.5. This corresponds to an extension of 79.2mm, focal-lenght plus extension from infinity position, or a total bellows extention of 439mm.

I hope this helps

Peter

[Gudmundur Ingolfsson]

https://www.badgergraphic.com/store/..._detail&p=1146

[drew.saunders]

This: http://www.ebonycamera.com/articles/lenses.html
Says the APO-Ronar needs 351mm of "Flange Back" distance at infinity. Think of that as a built-in 9mm extension tube when doing this calculation:
1/focal length - 1/bellows extension = 1/subject distance.

This: http://www.ebonycamera.com/cam/main.RW45.html
Says you can squeeze 395mm out of the RW45 if you use front and rear base+axial tilt, which may be inconvenient for what you want to do, and 325mm if you don't. You can't focus that lens at 325mm, so you have to use some tilts.

With tilts, the calculation becomes 1/360 - 1/(395 + 9) = 1/3305 so you should be able to get within 3.3m, which still doesn't get you to 2m without the top hat.

If you say you're getting 6000mm of subject distance, then you can do the math as:
1/360 - 1/6000 = 1/383, so, in theory, you can get more from using the extremes of the front/rear tilt trick.

Drew

[Drew Wiley]

I often use a 360 Fujinon A on my Ebony RW45. It's a true 360 and not a telephoto.
No problem and the lens is steady. What you need to do is first use the base tilt on
both the front and rear to get close to maximum bellows extension, then adjust the
center tilt on each as needed. You will still have enough room left over in the focus
mechanism for most applications. Since the assumption is, that the whole point of a
360 on a 4x5 would be for "reach" into middle and far distances, you should have
no problem whatsoever with sufficient bellows length. The only concern I'd have is with a no.3 shutter at this kind of extension, and if it will produce excess vibration at certain speeds. Since my 360 A's are in a no.1 shutter, the shots are very crisp. Can't remember if I've ever tried my 14" Dagor on this camera, which would have similar wt and shutter to the Apo Ronar.

[Drew Wiley]

Should have added - I believe the lens will be more steady if you adjust the camera as
I described, rather than using a "tophat" extension board. Ebony has designed this
feature quite intelligently. Since I have never used a #2 shutter, I have no idea whether it is more apt to approximate a #1 or #3 in "kick". You'll probably be fine.

[Ken Lee]

Would a + Diopter filter, also allow for closer focusing ?

Might that be easier and cheaper than more extension - or would it introduce distortion of some kind ?

By the way, for those with the gift of higher mathematics, is there a formula we can use to determine how much closer we can get, depending on diopter correction ?

For example, my Sinar won't allow me to use a 600mm lens, without adding a bellows and a standard to hold it. A 450 is fine, but 600 is too long. If a simple +Diopter filter would do the trick, I'd consider a nice 600mm barrel-mounted APO Nikor for example.

[Drew Wiley]

Ken - can't imagine a diopter improving anything. But in his case, the necessary base
adjustments are really quite easy, and when something in the close foreground is involved, typcial tilts will allow them to come into focus. I've done it plenty of time.
As far as a Sinar is involved, by comparison, I put a 28" Horseman bellows on mine and
an extra extension, so it was a wonderful outfit for long lens use. Ironically, now I'm
taking some of those old Sinar components and making the system rigid with carbon
fiber material for a 4x5 fixed-focus camera for infinity grab shots, probably with a
180 lens. Shoulder bursitis spelled the end of my day for carrying a huge Sinar rig.
For some reason, even an 8x10 folder is more ergonomic for me to use.

[Ken Lee]

Ken - can't imagine a diopter improving anything.

http://www.cs.mtu.edu/~shene/DigiCam...Up-Lenses.html

http://www.eyecaretyler.com/hyperopia.htm

[Drew Wiley]

Ken - anything like an apo Ronar is a very critically mfg lens, and even adding a filter
will affect performance a bit. I guess for goof-off use someone could experiment with
an add-on closeup filter, like they sometimes do on 35mm lenses, but even in those
cases there's a substantial penalty in image quality unless the lens/add-on combination
is dedicated right from the start of engineering. In the world of soft-focus all kinds of
crazy things are being done, but in this particular query I don't understand why anyone
would choose a 360 for closeup work with a 4x5, when there are vastly more practical
alternatives. The logic of a 360 would be for "reach" and narrower perspective. The
Ebony RW45 does allow this, even if the foreground is right at your feet. No problem
with a 360; but a 450 would need a cumbersome tophat.