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  #1  
Old 21st February 2015, 11:54 AM
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Default Focal length for 9x12 camera?

I got some time ago a Goerz Tenax 9x12 camera with a Goerz Tenastigmat 130mm. The lens is really sharp but also very boring with no personality, especially compared with the Rodenstock Eurynar on my other camera. I thought I could replace it but I wonder if there is any flexibility with the focal length. I now a shorter focal length might not cover the 9x12 film, but what about a slightly longer one? Is there gonna be issues with focus? Would a 135mm have problems with focus too?

Also, where to get one of this tools to remove the lens, the one resembling a two-pronged fork? I've seen something like that somewhere, how is it called?

What about thread sizes, where they standardized or there are a lot different ones?

Any advise will be greatly appreciated. Thanks!

Ivan

Last edited by ivanbpalli; 21st February 2015 at 12:06 PM.
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Old 21st February 2015, 03:39 PM
paulc paulc is offline
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The tool you want is called a "lens spanner" or wrench - Quite a few listed on ebay from around a tenner and up.

As for the lens, anything with an image circle of 150mm or larger should work. If you go longer (or shorter), you will need to make a new focusing scale. With another 130mm lens, you may need to move the scale or pointer slightly as not all lenses have the same lens to film distance.
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Old 21st February 2015, 04:26 PM
Lostlabours Lostlabours is online now
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If it's aTaro Tenax it was available with the 130 or 135mm f6.8 Tenasigmat or a 150mm f4.5 Dagor.

Most of the similar cameras from other manufacturers were offered with 135mm or 150mm options of differing standards, Triplets in cheap Shutters (Varia), Tessars and equivalents in Compur or Ibsor (pre-Prontor) and higher end lenses like Dagors, Celors, Eurynars etc.

130mm lenses weren't common. The 135mm & 150mm f4.5 Eurynars are quite large lenses and may not fit all 9x12 cameras, I have 135mm f6.8 Doppel-Anastigmat Goerz-Ihagee that's a Dialyte similar to the Eurynar & Celor, it's a small lens.

I have a Rodenstock 9x12 camerawith a 150mm Eurynar - it's a nice lens, I like Dialytes and use a 203mm f7.7 Ektar with my Super Graphic and as well as the Goerz-Ihagee have a Kodak 170mm f6.3 Dialyte.

Ian
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Old 22nd February 2015, 04:43 PM
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Hi Ivan,
I've just had a look at some of my small shuttered lenses and I can confirm that there is no one standard size for the flange thread or lens cells.
However I would estimate at a handful as some of the shutters and cells are compatible. The shutters are Prontor-press, Vario, Compur, and Kodak.

Which shutter is your lens in?
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Old 22nd February 2015, 05:43 PM
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Thank you for your replies. I was also considering the possibility of getting a shorter focal length as I might crop the sheet film to 6x9 so I can enlarge the negatives. Am I correct thinking that with a shorter focal length the lens will be closer to the film to be in focus? Therefore, getting a longer than 130mm lens could be tricky as to achieve focus the lens might need to be extended beyond the bellows capability which could be problematic given they don't allow double extension. Is that correct?

Marty, the shutter is a Compur, the older one on a round dial.

Thanks again.

Ivan
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Old 22nd February 2015, 06:22 PM
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The bellows are capable of taking a 150mm lens, it would just need a different focus scale. Often the bigger dealers fitted the lens/shutter asked for by the customer to the body or ordered the combination from the importers.

Are you sure it's a 9x12 model, the importers only listed Quarter plate and 10x15cm Taro Tenax cameras in 1924. It's a dial-set Compur, Goerz had been absorbed into Zeiss Ikon before the rim-set Compur's were released. It'll be the smallest Compur as it has a slow lens.

Ian
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Old 22nd February 2015, 06:33 PM
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Your correct in your thinking Ivan. Longer focal length lenses need more bellows extension and vice versa for shorter focal lengths. Also that increased bellows extension is required the closer you focus.

Any idea what your max. bellows length is?
And what is the closest focusing distance of your current lens?

Depending on your subject matter, you could perhaps get away with a slightly longer focal length.
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Old 22nd February 2015, 07:22 PM
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The Quarter plate (& 9x12) Taro Tenax cameras claim to give double extension this would be with the 130mm & 135mm lenses this means you should be able to focus 1:1. They also state that all 4 lenses they offered can also be used with one lens cell to provide a longer Focal length lens. The body and extension/bellows are the same regardless whether it has a 130, 135 or 159mm lens,

Some of my 9x12 cameras have 135mm lenses others 150 all have pretty much the same bellows extension, 27-29cm.

In real terms with a 135mm lens and 27cm extension the minimum focus is 27cm with a 150mm lens minimum focus at the same maximum extension will be 33.8cm, still very close working.

Ian
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Old 22nd February 2015, 11:02 PM
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Mmm... This is all very interesting. Marty, the bellows on my model don't go beyond 13cm, and the minimum distance on the scale is 1 meter. Ian, the negative size is a tad shorter than 9x12. It looks like this one:

http://collectiblend.com/Cameras/Goe...aro-Tenax.html

The focus is done by a lever which won't allow further extension beyond the 1 meter mark. The bellows look quite stretched by then so I don't think it could go any further. I haven't tried using one lens cell only, I've done that with my Eurynar, though as I recall I needed to extent the bellows further, so not sure I could do that with this one.

I'm guessing it would be better to stick to 130, 135 or shorter with this one given the limitations on bellows extension?

Need to get a lens spanner to check the thread size before getting a new lens, though.

Cheers,

Ivan
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Old 23rd February 2015, 12:03 AM
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The plot thickens Ivan.
I would have thought that in order for a 130mm lens to focus down to 1m it would need quite a bit more than 13cms of bellows draw?

So what's the overall distance from the lens to film plane?

I can't imagine you can focus the lens with a single cell as this will effectively make it a 260mm lens needing 26cms of extension just to focus on infinity never mind anything closer!
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