Why do 120RF's have slow lenses?

astrosecret

astrosecret

Recovering rollei snob
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Sorry if this has been asked before. maybe i should've asked: why doesn't the 7 system have faster lenses? TLRS and waist level cameras have relatively fast lenses in comparison. There are also cameras, like the Plaubel Makina, which also has a faster lens.
 
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Size and weight, I guess. Though my Graflex XL does have an 80/2.8 (which is why I bought it). With a fixed-lens camera like the Plaubel Makina the shutter and focusing mechanism is effectively 'distributed' through the camera.

Cheers,

R.
 
And also because wider apertures (wider than f/2.8) become more difficult to use with the very shallow depth-of-field achieved on the larger negative.
 
Also don't forget that it's harder to make a wide aperture lens with a leaf shutter than a lens for a focal plane shutter.
 
Roger Hicks said:
Size and weight, I guess. Though my Graflex XL does have an 80/2.8 (which is why I bought it). With a fixed-lens camera like the Plaubel Makina the shutter and focusing mechanism is effectively 'distributed' through the camera.

Cheers,

R.
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tlitody said:
and cost. They would be very expensive with all that extra glass to grind.
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Yes, consider the Mamiya Press lenses in 250mm; f/8 with a filter size of 58mm, and the f/5 with a filter size of 105mm. f/5 versus 5/8 if only about 1 2/3 stops. Wonderful lens that it it, the 250 f/5 needs a cart and team of horses to carry.
 
Its because none of the manufacturers put long base rangefinders in the cameras. Fast lenses cannot be accurately focused with short base RFs. Making an 80mm f2.8 isn't hard or expensive, Mamiya makes such a lens for the e645 system and its dirt cheap. They used to make that same lens in a leaf shutter version for the 645 cameras too, so fitting a shutter isn't the problem.
 
Chriscrawfordphoto said:
Its because none of the manufacturers put long base rangefinders in the cameras. Fast lenses cannot be accurately focused with short base RFs. Making an 80mm f2.8 isn't hard or expensive, Mamiya makes such a lens for the e645 system and its dirt cheap. They used to make that same lens in a leaf shutter version for the 645 cameras too, so fitting a shutter isn't the problem.
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Yeah, but 6x4.5 is a smaller image area to cover than 6x7. The Mamiya 6 has the same base length as the 7 but its fastest lens is f3.5.
Also, you'll notice that, apart from 80mm lenses, none of the major mf SLR makers make any f2.8 lenses with leaf shutters. Look at the Hasselblad 500 vs the 200 line. The omission of a leaf shutter makes considerably faster lenses possible.
 
God.. God made them that way.

Luckily, we can use faster film, but then results begin to look more like 35mm. Trying out the new Portra over the holidays.

So, digital is rapidly becoming the clear choice in low light. That said, the lens limitations of medium format are becoming less bothersome.
 
Jamie123 said:
Yeah, but 6x4.5 is a smaller image area to cover than 6x7. The Mamiya 6 has the same base length as the 7 but its fastest lens is f3.5.
Also, you'll notice that, apart from 80mm lenses, none of the major mf SLR makers make any f2.8 lenses with leaf shutters. Look at the Hasselblad 500 vs the 200 line. The omission of a leaf shutter makes considerably faster lenses possible.
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Mamiya made a 55mm f2.8 leaf shutter lens for the 645 line as well.
 
Chriscrawfordphoto said:
So is Bronica's RF645 which has slow lenses.
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Sure, but it's size also wouldn't allow for a longer baselength. Look, I'm sure cost of production is one aspect of camera and lens designs but it's probably not the only one. In the end size and weight are probably the main reason why most 120 RFs have slow(ish) lenses and short baselenghts.
FWIW I used to have a Bessa III which has an 80mm f3.5 lens and a very short baselength. I'd concede that on the Bessa III the sole reason for the short BL was probably cost of production. There would've been more than enough room to incorporate a longer BL but they probably thought it was easier to just put in the regular Bessa RF.
 
bwcolor said:
...

Luckily, we can use faster film, but then results begin to look more like 35mm. Trying out the new Portra over the holidays.

So, digital is rapidly becoming the clear choice in low light. That said, the lens limitations of medium format are becoming less bothersome.
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Not exactly sure what you are trying to say here. MF, especially 6x7 and 6x9, will need very fast (pushed) film to start looking like 35mm as far as grain is concerned.

When digital can beat MF in any light, I will consider getting one. I'm not trying to start a digital vs film debate again, it's just that digital isn't there yet. No doubt some day it will be. But as far as I know, it still can't beat 35mm in resolution (close perhaps), certainly not dynamic range of negative film. Therefore it can't beat MF either.

Nevertheless, whatever digital gives you that you prefer it, good for you. That is all that is important.
 
It's a great shame no one resurrected the Ermanox.

Ernemann-Ermanox-4.5x6.jpg


A 85mm f/1.8 or 100mm f/2 on 6x4.5 or 6x6 would rock if it got a rangefinder and a roll film back.

http://www.taunusreiter.de/Cameras/Biotar_en.html

Erich_Salomon_mit_Ermanox.jpg
 
I would also like to see a 120 RF with a fast lens (f2.0 or even up to 1.4) for low light photography with a iso 3200 b&w film because the huge film area of 6x6 to 6x9 cm will allow a film with much more grain than a 24x36 mm before is gets a problem due to the lower magnification factor.

Buliding a f2.0 75 or 80 mm lens for 120 film shouldn´t be much more complicated tha building a f1.4 50 mm lens for 35 mm film.

And since 35 mm RF can handle a f1.4 or even a f1.0 lens, I think it would be possible to build a 120 film rangefinder with a f2.0 lens.


But since this is not available, I will take d f1.4 lens at 35 mm film with a not so fast, but lower grain film...
 
Thomas78 said:
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Buliding a f2.0 75 or 80 mm lens for 120 film shouldn´t be much more complicated tha building a f1.4 50 mm lens for 35 mm film.

And since 35 mm RF can handle a f1.4 or even a f1.0 lens, I think it would be possible to build a 120 film rangefinder with a f2.0 lens.

...
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Certainly possible. But, if I remember everything correctly, the f/stop must let in the same amount of light at the same f/stop number. f/stop numbers are a fraction of the lens length. f/16 is a maximum diameter of 1/16 the focal length. Same with f/2, which is 1/2 the focal length. So for a 50mm lens, f/2 is 1/2, or a diameter or 25mm (about 1 inch). The maximum aperture size at f/2 is 25mm.

MF lenses must be longer for the same effect. Normal for a 6x7 is about 100mm. Therefore, the diameter at f/2 is 50mm. so the lens will have to be bigger. Usually as I recall, the front element should be at least the size of the actual diameter of the maximun f/stop, if not more. Some help can be gained in lens design to reduce the front element size, but the bigger the f/stop, the bigger the front element will have to be.

Of course in MF, even the wide angle lenses are longer. My Super Press 50mm lens is the equivalent of a 25mm on a 35mm camera. f/2 on the 50mm lens requires an aperture diameter of 25mm, or about 1 inch, not the half inch for the 25mm lens.

So the maximum f/stop on MF is a product of how big the lens will have to be for a given maximum f/stop. For a 100mm lens in MF, at f/1, the lens would have to have a maximum f/stop diameter of 4 inches, and the barrel would have to be bigger to accomodate that aperture size. Possible I am sure, but it sure would be a big and unwieldy lens.

If I am wrong, correct me.
 
oftheherd said:
Certainly possible. But, if I remember everything correctly, the f/stop must let in the same amount of light at the same f/stop number. f/stop numbers are a fraction of the lens length. f/16 is a maximum diameter of 1/16 the focal length. Same with f/2, which is 1/2 the focal length. So for a 50mm lens, f/2 is 1/2, or a diameter or 25mm (about 1 inch). The maximum aperture size at f/2 is 25mm.

MF lenses must be longer for the same effect. Normal for a 6x7 is about 100mm. Therefore, the diameter at f/2 is 50mm. so the lens will have to be bigger. Usually as I recall, the front element should be at least the size of the actual diameter of the maximun f/stop, if not more. Some help can be gained in lens design to reduce the front element size, but the bigger the f/stop, the bigger the front element will have to be.

Of course in MF, even the wide angle lenses are longer. My Super Press 50mm lens is the equivalent of a 25mm on a 35mm camera. f/2 on the 50mm lens requires an aperture diameter of 25mm, or about 1 inch, not the half inch for the 25mm lens.

So the maximum f/stop on MF is a product of how big the lens will have to be for a given maximum f/stop. For a 100mm lens in MF, at f/1, the lens would have to have a maximum f/stop diameter of 4 inches, and the barrel would have to be bigger to accomodate that aperture size. Possible I am sure, but it sure would be a big and unwieldy lens.

If I am wrong, correct me.
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Yes and the larger the lens' maximum aperture, the more difficult it is to incorporate a leaf shutter that works at reasonable speeds. Of course, nothing says a 120 RF must have a leaf shutter.
 
Jamie123 said:
Yes and the larger the lens' maximum aperture, the more difficult it is to incorporate a leaf shutter that works at reasonable speeds. Of course, nothing says a 120 RF must have a leaf shutter.
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I hadn't thought of that, but you are probably correct.
 
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