This lens: R&J Beck No.3 Biplanat 6 inch focus f5.8 in Unicum shutter.
Can anyone tell me what type of construction it is?
I assume that since it is around 150mm it'll cover 4x5 anyway.

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On 2006-12-23 09:56, primus96 wrote: This lens: R&J Beck No.3 Biplanat 6 inch focus f5.8 in Unicum shutter. Can anyone tell me what type of construction it is? I assume that since it is around 150mm it'll cover 4x5 anyway.

The Vade Mecum thinks is is a Rapid Rectilinear. If so, it is probably a little short to cover 4x5. Suggest you count reflections and try it out. About counting reflections, each cell of an RR should have two bright and one dim.

Does anyone have any call on angle of coverage for a Rapid Rectilinear?
From what I have seen a RR.R. lens is two symmetrical cemented doublets, 4 ele 2 grps.
They came before the likes of the anastigmats like Dagor and Tessars, yes?
A R.R. lens has astigmatism and has anyone used such a lens to see what that means practically speaking?

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On 2006-12-23 15:23, primus96 wrote: Does anyone have any call on angle of coverage for a Rapid Rectilinear? From what I have seen a RR.R. lens is two symmetrical cemented doublets, 4 ele 2 grps. They came before the likes of the anastigmats like Dagor and Tessars, yes? A R.R. lens has astigmatism and has anyone used such a lens to see what that means practically speaking?

Yes, RRs antedate anastigmats. But reports on them are to the effect that late RRs were every bit as good as anastigmats and were displaced because they cost more to make. And even early ones are supposed to be very good centrally.

So control your impatience and after the lens has arrived ask it what it can do for you.

What sorts of other defects might one find in such a early lens design?
I have found that astigmatism may be shown in a image of a bike wheel. If the spokes were sharp then the rim & hub would not be sharp.
If you use a normal lens at around f22 for optimum definition how far down might one need to go with this lens?
It'd give me a starting point for experiments.

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On 2006-12-24 15:23, primus96 wrote: What sorts of other defects might one find in such a early lens design? I have found that astigmatism may be shown in a image of a bike wheel. If the spokes were sharp then the rim & hub would not be sharp. If you use a normal lens at around f22 for optimum definition how far down might one need to go with this lens? It'd give me a starting point for experiments.

So far I've had one lens with severe astigmatism, a 1000/11 Celestron C-90. With it, if vertical lines were in focus horizontal lines were out, and vice versa. I don't see how a lens with severe astigmatism could render all of a wheel's spokes sharp and not the rim.

I have no idea what you want to use your new gem for. When I get a new lens, I run it through a fairly simple acceptance test. I have a couple of targets, one near, the other far, that have fine detail at a range of scales. Camera on tripod, shoot each target at each of the apertures I'm likely to use the lens at. Then examine the results closely and compare with previous ones from other lenses.

I think you're making too much of your Biplanat's possible defects. The old lens nuts who use Aplanats have said many times that used within their intended coverage they're very, very sharp. But then, I ignore the old lens bokeh nuts who practice lens abuse.

Good luck, have fun,

Dan

The Biplanat will possibly be right at the limit of it's coverage, but i'm prepared to be surprised.
This creature is in a Unicum shutter. I don't know how it works.
The shutter design looks familiar, i'm sure I have seen something lke it on a Rochester made 4x5 plate camera.

I was looking for an effect whereby the edges & corners would be very soft indeed, but with a sharp enough centre for portraiture at wider apertures.
Softness would be a positive asset in a portrait.

The Unicum shutter was a POS, no exaggeration. I went to the expense of having SKG re-mount the Beck cells into a Copal #1.
Wide open, at f5.8 I get a very sharp centre & the edges are appropriately much fuzzier. Beck touted the Biplanat as a suitable lens for portraiture and landscapes, and I agree with them after examining my first negatives.
I expose on normal subjects at f16-22, no complaints with the results.
Of course I now have the luxury of flash contact, albeit 'x' sync only.
Not sure about using this lens with bulb flash. I will post on the approprate esction if I want advice on that.