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Are 35mm legacy lenses 'slower' on m4/3?

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Thanks for that, I was thinking the physics would make it impossible for the Depth of Focus to change given the same lense. Only the Field of View changes due to the smaller sensor size.

When people claim that both the FOV and the DOF change they are really being missleading, because they get to that different DOF by changing the distance parameter in order to get the same FOV. Which in turn contradicts the statement that both the FOV and the DOF changed.
 
Vaughan Williams said:
Pixnat2 said:
You can say that using a 50mm f/2 on 4/3 is like :
  • using a 100mm f/4 on FF for FOV and DOF
  • using a 50mm f/2 on FF for speed.
Click to expand...
To be more exact:
You can say that using a 50mm f/2 on 4/3 is like :
  • using a 100mm f/2 for FOV
Click to expand...
The f number doesn't have any influence on the field of view, right? So better to say it's like a 100mm for FOV.
Vaughan Williams said:
  • using a 100mm f/2 for shutter speed and aperture and ISO
Click to expand...
Correct! My mistake :-)
Vaughan Williams said:
  • using a 100mm f/4 for DOF
Click to expand...
--
Cheers,

Frederic
http://azurphoto.com/blog/
 
He dislikes the idea of equivalencies. Its been difficult for me coming from Canon--35mm FF for 4 years and APS-c for a good long while--where I still thought in equivalencies to the 35mm FF (1.6x crop) when choosing lenses, etc.

I am trying--and getting a lot better at it--to think how each lens (both FL and speed) works with the 4/3rds sensor. As I shoot more and more with the m4/3rds and less and less with my 5D I am moving away from thinking in equivalencies--it will drive you nutsy IMO LOL.

Diane
Vaughan Williams said:
Pixnat2 said:
You can say that using a 50mm f/2 on 4/3 is like :
  • using a 100mm f/4 on FF for FOV and DOF
  • using a 50mm f/2 on FF for speed.
Click to expand...
To be more exact:
You can say that using a 50mm f/2 on 4/3 is like :
  • using a 100mm f/2 for FOV
  • using a 100mm f/2 for shutter speed and aperture and ISO
  • using a 100mm f/4 for DOF
Click to expand...
--
Diane B
http://www.pbase.com/picnic
G1 gallery http://www.pbase.com/picnic/temp_g1
 
The lens itself is not slower, but you are only looking at the central section of the image. For the same framing, you must therefore be further away (a 50mm 35-mm lens has the FoV of a 100mm 35-mm lens). In terms of the depth of field, this means that for the same framing you have the effect of using a smaller aperture on a 35-mm system (a 50/1.4 would have the framing and depth of field of a 100/2.8 on a 35-mm system.

However, the lens is still the same lens. In terms of the light that reaches the sensor you're still getting the amount of light per unit area on the sensor that you would with a 35-mm system (if you start thinking of it as having half the aperture, you'll have to think of your ISO setting as halved as well to make the exposure equations work). At a given distance from your subject, you'll get the same depth of field - just with a smaller field of view.

Robert
 
Focal ratio remains the same when using the same lens on u4/3 as 135 film, at the same "f-stop" setting on the lens.

However, the problem when talking about DOF equivalencies is that there's ALWAYS an assumption of an enlargement factor at play; this enlargement factor was taken into account on legacy lens DOF scales when they were engineered: an enlargement from 135 frame size to an 8"x10" print, viewed at 14", given the human eye's angular resolution limit. And since you have to "enlarge" a u4/3 image at 2x the factor of 135 to achieve the same print final print size, then DOF scales are technically not equivalent between the two formats.

However, for practical use, I ignore such details and frequently use the DOF scales on my legacy lenses with the G1; I'm not enlarging my prints to 8"x10" anyway (usually no larger than 5"x7"), so it's not an issue.

Joe
 
f 2.0 is f 2.0. It doesn't change with film or sensor size. I think Kirk in this post says it all.

visualsciencelab.blogspot.com/2009/09/available-light-photos-of-zach-scott.html

Best wishes

Regard

João
 
Jogger said:
Bilgy_no1 said:
Taking a photo from the same distance (same lens, but with two cameras: FF camera and m4/3), you will record the exact same dof. Only difference is that the m4/3 camera captures a smaller portion of the subject.
Click to expand...
Sure. But, nobody takes photos like that. They compose/frame according to what they see in the viewfinder... in which case, thinking of it as 2x DOF makes more sense.
Click to expand...
nor does anybody use FF lenses on 4/3 bodies by doubling the distance to all their subjects. Yes, people will compose according to what they see in the VF. But, they will also use lenses differently as a result. E.G. a 50mm f/1.8 FF lens becomes a great portrait lens on 4/3. And I would not attempt to use it for the same purpose as on FF (general walk-around lens). For that purpose, the 25mm f/2.8 or 30mm f/1.4 Sigma would be a better solution.

Note that my point was to explain to the OP that changing the format does not change the physics of the lens.

Damien
--
http://www.flickr.com/photos/bilgy_no1
 
Lee Davis said:
Hi Trevor

Which adaptor are you using for your Pentax lenses?
Click to expand...
I boughyt the jinfinance adaptors via eBay - they work well.

I will probably get a novoflex as well, to give better control over aperture on "digital" Pentax lenses, the ones without an aperture ring. At the moment I use zip ties (cable ties) with just the "head and about 8mm of tail protruding, to hold the diaphragm open. A 4mm tie gives about f5.6.

--
Cheers

Trevor G

http://www.computerwyse.com/photo.html
 
Diane,

I think you may have the most sensible approach of all here: just see what the lens does on the camera you use. No one will use a 50mm f/1.8 lens on a 4/3 camera for the same purpose as on a FF camera. So figuring out how it works when you try to reproduce the same image is not a very useful exercise.

Damien
Diane B said:
He dislikes the idea of equivalencies. Its been difficult for me coming from Canon--35mm FF for 4 years and APS-c for a good long while--where I still thought in equivalencies to the 35mm FF (1.6x crop) when choosing lenses, etc.

I am trying--and getting a lot better at it--to think how each lens (both FL and speed) works with the 4/3rds sensor. As I shoot more and more with the m4/3rds and less and less with my 5D I am moving away from thinking in equivalencies--it will drive you nutsy IMO LOL.

Diane
Vaughan Williams said:
Pixnat2 said:
You can say that using a 50mm f/2 on 4/3 is like :
  • using a 100mm f/4 on FF for FOV and DOF
  • using a 50mm f/2 on FF for speed.
Click to expand...
To be more exact:
You can say that using a 50mm f/2 on 4/3 is like :
  • using a 100mm f/2 for FOV
  • using a 100mm f/2 for shutter speed and aperture and ISO
  • using a 100mm f/4 for DOF
Click to expand...
--
Diane B
http://www.pbase.com/picnic
G1 gallery http://www.pbase.com/picnic/temp_g1
Click to expand...
--
http://www.flickr.com/photos/bilgy_no1
 
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