Using Medium Format lenses on 35mm

Neare · Joined: 09 Sep 2009 Posts: 43 Location: New Zealand

Ok, got a question.

If I were to use a Hassy 80mm f2.8 on my Contax RX for example,

When shot wide open, would the resulting DOF be the same size as using it wide open on the hassy itself.

As of course, the 2.8 on MF is really equal to around f1.5 on 35mm.
So would that 80mm 2.8 produce DOF equal to that of a f1.5 lens (made for 35mm)?

Note: This question has nothing to do with focal length. I understand it will be like shooting a short tele, and the DOF will be increased to the eye through that, but this is generally speaking. From the image circles point of view.

sichko · Joined: 20 Jun 2008 Posts: 2475 Location: South West UK

Neare · Joined: 09 Sep 2009 Posts: 43 Location: New Zealand

Attila · Expire: 2025-11-18

Crop = means really crop nothing else, digital cameras crop an area from genuine images what you can take with Hasselblad nothing else change.

poilu · Expire: 2019-08-29

Scheimpflug · Expire: 2011-11-18

Very informative. Thanks for the description and the link, poilu. Cool

indianadinos · Expire: 2011-12-05

Hi,

Thanks for the explanations and the link, i was asking myself the same question ...

Cheers

vulko · Posted: Sat Jun 19, 2010 10:33 am Post subject:

sichko · Joined: 20 Jun 2008 Posts: 2475 Location: South West UK

Eugen Mezei · Joined: 17 May 2008 Posts: 265

Budget tip 1:
Don't hunt ePay for that f 1.2 K-bayonet or even more expensive M42 lens. (Branded by smart sellers as Tomioka made.) Better buy for the same money or even less a 6x6 camera with the standard 80 mm f2.8.

Budget tip 2:
Don't hunt that portrait focal of 80, 90, 100 or 105 mm (I'm sure you have plenty of 135 mm already), better buy an adapter and use the above lens you bought with your 6x6 camera.

Eugen

josedad · Joined: 10 Feb 2010 Posts: 15 Location: Indonesia

If you shot an object with 6x6 lens on 35mm with same composition as if you shot with 6x6 camera, you`ll loose its `blur` since the distance to the object become longer. The longer distance to the object, the wider DOF. Unless you shot smaller object.. CMIIW

CarbonR · Posted: Sun Aug 15, 2010 7:46 pm Post subject:

PaulC · Joined: 23 Dec 2008 Posts: 2318

If you shoot with an MF 80mm lens at f2.8 on a 35mm camera you will get exactly the same DoF as shooting with an 80mm f2.8 lens designed for 35mm.

All the confusion about DoF arises from a failure to understand that the charts assume that a 35mm shot will be magnified for viewing by a different amount than a medium format shot. If they are magnified by the same amount (i.e. if you crop a 35mm shape from the centre of a 6x6 neg and blow it up) and then compared they will be exactly the same.

You can't cheat the gods of maths and money by buying a medium format f2.8 lens and turning it into an f1.2 lens just by sticking it on a 35mm camera, more's the pity.

visualopsins · Expire: 2025-04-11

Magnification is a factor with print viewing distance. The printed image viewed far away has more dof than when viewed close. For example, my avatar image viewed at 8x12" from 18" away is out of focus, but when viewed at 1.3x2" from 18" away looks in-focus because of increased dof due to less magnification; same as result seeing 8x12" print from 18"x6=108" away.

I have a question about dof seen in viewfinder. For a given size print what viewing distance shows the same dof seen in the viewfinder? I think that can be calculated if the 'virtual' size of the viewfinder image seen by the eye is known. Anybody know? (http://forum.mflenses.com/viewfinder-distance-from-eye-to-focus-screen-t29737.html)

RioRico · Posted: Sat Dec 11, 2010 4:39 pm Post subject:

DOF is a complex function of photography, presentation, and perception. With ALL ELSE HELD THE SAME, moving a lens between cameras with different sized frames will NOT change the DOF. Cut a picture from a magazine. Draw upon it nested rectangles of 56x42mm, 36x24mm, 24x18mm - those are the sizes of 645, 135/FF, and APS frames. THE PICTURE REMAINS THE SAME! Smaller frames merely see less of it.

That is the photography. When you look at different crops from different distances, you've changed the presentation. When someone with different visual acuity sees the image(s), perception has changed. Presentation and perception affect DOF more than does moving a lens between cameras. But moving lenses between cameras probably incites the photographer to use different distances and angles and exposures, which changes DOF.

Thinking about crap.factor is confusing and misleading and induces all sorts of misconceptions about optical properties. But because format differences cause different behaviour by the photographer, there is a handy ROT (rule of thumb) when using a 135/FF lens on an APS camera: nudge the lens' DOF scale by at least 1 f-stop. When I put a Pentax M28/2.8 lens on my K20D and I set the aperture to f/11, I read the DOF scale at f/8, or maybe a bit under under. I do this mostly when hyperfocusing wide lenses for maximal DOF like if I want sharpness from 1m to infinity. This is what the Zeiss table means: you won't approach a scene the same way with different format cameras, so adjust the lens to your behaviour.