Bokeh! 35mm vs 6x7

colonel · Apr 19, 2013

I enjoy taking certain types of pictures with very thin DOF but also enjoy smooth out of focus areas. At the moment I am having great fun playing around with a Canon EOS 3 and 50mm f1.8 lens. I don't like too narrow a FL which is why I keep to 50mm. I was thinking of buying a Canon 50mm f1.2 lens, but as this is around £1100 I started to browse MF forums out of curiosity. It seems the Mamiya 7 series is very popular and 120 film is still easy to get and process, but the lenses don't see to go more open then f4.5 (which is f2.2 on 35mm equiv.) So it seems that I will not gain much in DOF by going to MF, in fact loose some DOF. I would welcome any interesting comments on this point.

Mainecoonmaniac · Apr 19, 2013

The larger the format the longer the lens for the same given perspective. So if you have a longer lens for a larger 6x7 format, you have shallower DOF. A "normal" lens for a 35mm piece of film is 50mm while for 6x7 format piece of film requires a 90mm lens roughly. You will lose DOF with a 6x7, not gain.

artobest · Apr 19, 2013

You may find some medium format lenses give distinctive out-of-focus rendering that doesn't always conform to the current notions of 'perfect' bokeh.

colonel · Apr 19, 2013

Mainecoonmaniac said:
The larger the format the longer the lens for the same given perspective. So if you have a longer lens for a larger 6x7 format, you have shallower DOF. A "normal" lens for a 35mm piece of film is 50mm while for 6x7 format piece of film requires a 90mm lens roughly. You will lose DOF with a 6x7, not gain.

Thanks. so are you saying that a 6x7 lens of 100mm f4 would be equivalent to a 35mm lens of 50mm f2, but the 6x7 lens wold still provide less DOF ?

colonel · Apr 19, 2013

artobest said:
You may find some medium format lenses give distinctive out-of-focus rendering that doesn't always conform to the current notions of 'perfect' bokeh.

That has also peaked my interest

Mainecoonmaniac · Apr 19, 2013

I was looking for the "perfect" bokeh and bought a LensBaby. Didn't workout. I sold it. I'm still wanting a Petzval lens, but it's out of my budget. Sure makes a beautiful swirly blur.

Fixcinater · Apr 19, 2013

A Pentax 6x7/67/67II with a 105mm f/2.4 would be similar to a 50mm f/1.1 (roughly), I've recently just got my P67 kit together and love the size over smaller 35mm cameras. I have big hands so an EOS 3 + grip is more comfortable than just the body.

You might want to look at the FD 50mm f/1.2L or Asph with an F1/A1/AE1 if you stick with 35mm as the f/1.2 lenses are much cheaper in manual focus.

Mainecoonmaniac · Apr 19, 2013

DOF and perspective are two different things

colonel said:
Thanks. so are you saying that a 6x7 lens of 100mm f4 would be equivalent to a 35mm lens of 50mm f2, but the 6x7 lens wold still provide less DOF ?

I'm saying that the perspective of a 6x7 camera with a 90mm lens is about the same perspective as a 50mm lens on a 35mm camera. The only difference is that the 6x7 camera with a 90mm lens has less depth of field than a 50mm at the same focused distance. Feel free to correct me if I'm wrong.

msbarnes · Apr 19, 2013

I don't think any MF lens matches an 50mm f1.2 outside of maybe the contax 80mm f2 (645)or Hasselblad 110mm f2 (6x6), but both I think are incredibly expensive as well as the supporting cameras. For thinnest DOF for the money, then I think that you would want to go with the Pentax 67 105mm f2.4.

But personally, I don't think super thin DOF is necessary and MF bokeh is incredibly smooth. I have an 80mm f2.8 lens but I prefer a little more DOF so I shoot at f4-f5.6 if light permits.

Untitled by Michael_Sergio_Barnes, on Flickr

11 by Michael_Sergio_Barnes, on Flickr

msbarnes · Apr 19, 2013

Oh and I'm no bokeh expert but Mamiya's reputation is not the best.

E. von Hoegh · Apr 19, 2013

Mainecoonmaniac said:
I'm saying that the perspective of a 6x7 camera with a 90mm lens is about the same perspective as a 50mm lens on a 35mm camera. The only difference is that the 6x7 camera with a 90mm lens has less depth of field than a 50mm at the same focused distance. Feel free to correct me if I'm wrong.

You mean field or angle of view, not perspective. Perspective depends solely upon one's point or position of view, regardless of format and focal length. Also, since the aspect ratio of 35mm is 3:2 and the aspect ratio of 6x7 is 7:6, focal length/field of view comparisons don't really work.

I'm not really sure what the OP is asking.

spijker · Apr 19, 2013

Using a DOF calculator (Barnack) set at CoC= 0.02mm
35mm format: 50mm f/1.2 lens focused at 2m gives 7cm DOF
6x7 format: 100mm f/4.5 lens focused at 2m gives 14cm DOF
Both lenses have a view angle over the diagonal of the frame of approx. 45 degrees

colonel · Apr 19, 2013

msbarnes said:
I don't think any MF lens matches an 50mm f1.2 outside of maybe the contax 80mm f2 (645)or Hasselblad 110mm f2 (6x6), but both I think are incredibly expensive as well as the supporting cameras. For thinnest DOF for the money, then I think that you would want to go with the Pentax 67 105mm f2.4.

But personally, I don't think super thin DOF is necessary and MF bokeh is incredibly smooth. I have an 80mm f2.8 lens but I prefer a little more DOF so I shoot at f4-f5.6 if light permits.

Untitled by Michael_Sergio_Barnes, on Flickr

11 by Michael_Sergio_Barnes, on Flickr

thanks. unique quality of the background is good. possibly more important then wafer thin, you are right.

colonel · Apr 19, 2013

msbarnes said:
Oh and I'm no bokeh expert but Mamiya's reputation is not the best.

what are the issues with Mamiya ? and what camera(s) are good in your opinion ?

Klainmeister · Apr 19, 2013

colonel said:
what are the issues with Mamiya ? and what camera(s) are good in your opinion ?

I've heard this repeated over and over, yet everytime I see a pic from a M645 or a M7, I think it's fine. But I'm no expert in this field.

Have you looked into the Mamiya 645 series? The 80mm 1.9 and the 55 2.8 are both fine lenses that could give great effect.

Thomas Bertilsson · Apr 19, 2013

Depth of field is a result of the size of the aperture.

For example:
A 35mm lens at f/1.4 has a 25mm aperture.
A 100mm lens at f/4 has a 25mm aperture.
A 400mm lens at f/16 has a 25mm aperture.
They will all have the same depth of field at those f/stops.

That is the math behind it. Once you know the size aperture (depth of field) you like to shoot at you can start comparing lenses.

msbarnes · Apr 19, 2013

colonel said:
what are the issues with Mamiya ? and what camera(s) are good in your opinion ?

My favorite type of photography is available light portraits so I can't help but pay attention to bokeh.

I am qualified to answer this question because I only use Rolleiflex cameras for reasons that are independent to the bokeh properties.

This is only from what I've read but...

Most MF lenses (Pentax, Mamiya TLR/SLR, Hasselblad, Bronica, etc.) seem to be suitable/good but the Mamiya RF lenses seem to be knocked down the most and also Fuji RF lenses. From what I've read, the Mamiya Rangefinder lenses were designed to be very high contrast and so the bokeh is very busy. Similar with the Fuji RF's (The GF670 is an exception though). Most people believe that the bokeh on these RF lenses are either bad or "suiteable" but nobody really raves about them.

The most hyped MF bokeh for a normal lens typically belongs to:
Rolleiflex 80mm f2.8,
Nikkor 80mm f2.8 (Plaubel Makina), and
Hasselblad 110mm f2.0 (really expensive though and you need a 200/2000 series Hasselblad).

But these are all very different cameras.

I've had 5 Rollei's from MX-EVS (Tessar) to 2.8E (Planar), and they've all been excellent:

Even the Tessar:

Untitled by Michael_Sergio_Barnes, on Flickr

TheFlyingCamera · Apr 19, 2013

I have no complaints about the bokeh from my Mamiya 180mm f4.5 for my RB67. But that's a different animal than the Mamiya 7 or a Fuji rangefinder. But I do agree overall with msbarnes - the bokeh king in hand-held medium format is the Rollei f2.8 lens.

Both taken with a Rollei 2.8E with the Planar lens.

Klainmeister · Apr 19, 2013

Well, here's one shot on the M7II 80mm @ 5.6

Alan Gales · Apr 19, 2013

colonel said:
Thanks. so are you saying that a 6x7 lens of 100mm f4 would be equivalent to a 35mm lens of 50mm f2, but the 6x7 lens wold still provide less DOF ?

Normally they tell you to double the focal length of a lens that you use with a 35mm camera to get what you want with a 6x7 camera. Of course this is an approximation. Also a 6x7 camera's viewfinder and negative are more square than a 35mm camera's so it will still look a bit different. I used a 180mm for tight portraiture on my Mamiya RZ67. It had the same depth of field as my 180mm lens on my Contax 35mm camera. Of couse it had less depth of field than the 100mm that I used for tight portraiture with my Contax.

I'm no lens expert but from my understanding, Bokeh is determined by the lens aperture. The more aperture blades a lens has, the more circular the aperture. Lenses with great Bokeh have a very circular aperture.

Fixcinater · Apr 19, 2013

Alan Gales said:
Normally they tell you to double the focal length of a lens that you use with a 35mm camera to get what you want with a 6x7 camera. Of course this is an approximation.
<snip>
I'm no lens expert but from my understanding, Bokeh is determined by the lens aperture. The more aperture blades a lens has, the more circular the aperture. Lenses with great Bokeh have a very circular aperture.

Alan, agreed on the first point. 55mm f/1.8 on 35mm film looks a lot like 105mm f/2.4 on 6x7.

Agreed somewhat on second point, the aperture blades only factor in when you're using them. Some lenses don't have smooth/nice bokeh even when wide open.

Slixtiesix · Apr 19, 2013

Some lenses don't have smooth/nice bokeh even when wide open.

Yes that´s true. The aperture geometry is just responsible for the highlight discs but it has nothing to do with the overall quality of the bokeh.
And even if you have a lens with pentagonal or hexagonal aperture shape you can easily avoid showing it by choosing an uniform background without any backlight sources, e.g. the sky or a distant wall. But if you shoot against a tree with the sun gleaming trough all its branches, you will have dozens of them in the bokeh.

Alan Gales · Apr 19, 2013

From my understanding, the definition of Bokeh is the bright out of focus areas of the background which would be controlled by lens aperture.

Polder · Apr 19, 2013

Hi, You could always mount a pre war lens from a Folder camera on a bellows with an adaptor on your Canon. The lenses are pretty cheap and you could do a lot of experimenting with bokeh and dof. Good Luck, Henk.

Alan Gales · Apr 19, 2013

Fixcinater said:
Agreed somewhat on second point, the aperture blades only factor in when you're using them. Some lenses don't have smooth/nice bokeh even when wide open.

Yeah, you are right about the aperture blades not affecting bokeh when shooting wide open.

Bokeh! 35mm vs 6x7

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