Why Medium Format lenses are not as fast as 35mm?

[amellice]

Why there's no f/1.8 or f/1.4 medium format lens? The fastest medium format lens that I know of is f/2.8

 

[Prest_400]

Actually the fastest is the Mamiya 80mm 1.9 for the 645 series. There are a few f2's: Contax 645, Norita 66 and the P67 is almost there... IIRC for larger than 6x6 that is the fastest one.
I'm no optician but I understand that given a longer focal length, faster lenses require more optical width and heavier mechanics with more glass. Thus an f2 6x7 lens will be much heavier and costly to produce than a 645 coverage f2 lens.

 

[darkosaric]

If you don't look at f number, but at diameter (how "fat" is the lens) - then they are more less the same (f1.4 for 35mm vs f2.8 for 6x6).

 

[amellice]

If you don't look at f number, but at diameter (how "fat" is the lens) - then they are more less the same (f1.4 for 35mm vs f2.8 for 6x6).

I don't think that they are the same, f1.4 in 35mm will be f1.4 in medium format, it's the same amount of light that the lens will allow to reach the film

 

[Slixtiesix]

I assume it is because of the greater coverage. An 85/1,4 lens with coverage for 6x6 is more difficult to design and would be a lot heavier and more expensive than the same lens covering only 35mm. Apart from that, Dof would be ridiculously thin. E.g. a 180/4 lens for 6x6 has about the same Dof (and field of view) as a 100/2 lens in 35mm.

 

[ic-racer]

Why there's no f/1.8 or f/1.4 medium format lens? The fastest medium format lens that I know of is f/2.8

The same reason 35mm lenses are not as fast as 8mm format lenses and 8x10" format lenses are not as fast as 4x5" format lenses.

 

[Sirius Glass]

For the same f/stop the MF lens will have a larger diameter and heavier weight. Additionally larger lenses are harder to design and fabricate.

 

[darkosaric]

I don't think that they are the same, f1.4 in 35mm will be f1.4 in medium format, it's the same amount of light that the lens will allow to reach the film

Yes, but what I wanted to say that f1.4 in 35mm and f2.8 in 6x6 are more less the same diameter - physically they are in the same production complexity/weight/whatever, that is why you have many of those.

 

[cowanw]

Some hasselblads come as a f2. The size of the shutter plays a role.

 

[MattKing]

Because the medium format lenses have to cover a much greater area at the focal plane.

If you used a simple, single element meniscus lens it would be true that an 85mm f/1.4 lens would be the same size for both formats, but the distortions and other problems are tremendous. As soon as you start correcting the results, the correcting elements and design for a larger format are likely to be much larger then for a smaller format.

 

[NJH]

All very interesting but isn't it as simple as balancing depth of field with the ability to do available light photography? In other words the answer to that question was/is Leica M and Summilux lens, right tools for the job and all that.

 

[DREW WILEY]

In proportion as the lenses get longer to provide the same angle of perspective, you also proportionately decrease depth of field. In other words, a
100 mm lens for a 6x7 at f/4 will have as shallow a depth of field as a 50mm on a 35mm camera at f/2. So someone who needs a shallow depth of
field for portraiture, for example, doesn't need to cope with the inevitable extra weight and bulk of making a significantly faster lens for a bigger film
format. This is an oversimplified explanation, of course, but is an actual factor. Now let's make a quantum leap. Let's see what a f/2 lens for that same angle of view on 8x10 film would be like. A 12" f/2. Probably around forty pounds!

 

[Sirius Glass]

All very interesting but isn't it as simple as balancing depth of field with the ability to do available light photography? In other words the answer to that question was/is Leica M and Summilux lens, right tools for the job and all that.

I choose the focal length for the composition and then deal with the DoF. The Hasselblad lenses are so sharp wide open that DoF is never a problem.

 

[DREW WILEY]

As long as you can put up with a square universe...

 

[Sirius Glass]

Either square or 4"x5" is close enough to square. Beats a squooshed long wimpy rectangle that does not fit on 8"x10" nor 11"x14" paper well.

​

 

[amellice]

I totally agree that having fast lens for medium format will be heavy and bulky, but simply there are people who don't care about that and they would still buy it. this can't be the whole reason

 

[Alan Gales]

I totally agree that having fast lens for medium format will be heavy and bulky, but simply there are people who don't care about that and they would still buy it. this can't be the whole reason

They would cost you out the wazoo too! Yeah, I know. Some people don't care about price.

I think that there would have been too small a market for such lenses.

 

[Luis-F-S]

Why there's no f/1.8 or f/1.4 medium format lens? The fastest medium format lens that I know of is f/2.8

Cost, physics and gravity. L

 

[Jeff Bradford]

The extremely thin DoF at f/1.4 on a 75mm lens for 6x6 would not be useful very often.

 

[Chan Tran]

The extremely thin DoF at f/1.4 on a 75mm lens for 6x6 would not be useful very often.

I fully agree but that would make those paper thin DOF chasers very happy.

 

[chuck94022]

I totally agree that having fast lens for medium format will be heavy and bulky, but simply there are people who don't care about that and they would still buy it. this can't be the whole reason

Anyone buying a lens just because of the f/stop probably deserves what they get. And I bet they'd rarely if ever shoot it wide open, because they probably don't even know what the number means anyway. But they could buy a really nice big camera bag to go with it!

If the desire is extremely thin DoF, you're probably already shooting macro and have it. For "normal" photography, shooting wide open with our available lenses (e.g., 80mm f/2.8) is plenty narrow DoF, in my opinion (I don't shoot a lot of portraits, I'm more a landscape and street guy, so I don't need those big bulky lenses.)

If the desire is a fast lens in low light, given modern film's lattitude, I don't think missing that extra stop or two is a limitation. Portra is lovely even if off by 4 stops, and I can dig a good image out of pretty much any under-exposed B&W I shoot.


-chuck

 

[Sirius Glass]

I totally agree that having fast lens for medium format will be heavy and bulky, but simply there are people who don't care about that and they would still buy it. this can't be the whole reason

Hasselblad's approach was to have the CF and later lenses for the most part use the B60 filters. There are advantages to having one set of filters for all the lenses, especially because with so many high quality ISO 400 films to choose from, one does not need the really fast lenses that dominated during the 1960's and 1970's.

 

[RobC]

cost, weight, time it takes to grind and polish larger surface lenses (which is part of cost but also excessive prodution time), is it needed (probably not), useability/portability. Theres quite a few reasons against doing it compared to doing it.

 

[MattKing]

I would hazard a guess that most medium format cameras and lenses were designed to either be portable enough to use hand held, or to be used on a tripod.

In either case, very large, high speed lenses wouldn't have been ideal.

 

[David Brown]

I totally agree that having fast lens for medium format will be heavy and bulky, but simply there are people who don't care about that and they would still buy it. this can't be the whole reason

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