loneranger
Well-known
Does anyone know what is the coversion factor when you put an olympus pen lens on a panny G1. Is it 1.5x or 2x?
Trius
Waiting on Maitani
It's 2x for all lenses on 4/3 and m4/3 bodies.
Hamster
Established
Isn't the Pen a half frame already, shouldn't it be 1x?
Trius
Waiting on Maitani
Focal length is focal length.
Dunk
Established
Yes ... so there are some interesting Olympus half frame lenses which might adapt including a 250/5, 400/6.3 mirror and 800/6.3 mirror.
Cheers
dunk
filmfan
Well-known
So, is this a yes or no? I am wondering because I am also interested.
JoeV
Thin Air, Bright Sun
Focal length is focal length: it's a physical property of the lens.
"Equivalent angle of view" -- the angle of view of a lens used on the G1 that's equivalent to what you would see on a full-frame 35mm camera -- is equivalent to a 2x focal length lens on full-frame 35mm.
Thus, a 15mm lens on the G1 has an "equivalent angle of view" of a 30mm lens on a full-frame 35mm camera. But the actual focal length is still 15mm, so the depth of field effects are different than an actual 30mm lens.
If you're comparing angle of view between half-frame lenses and the G1, the difference in image size (diagonal) between the formats is about 1.4, so use a factor of x1.4 to compare equivalent angles of view between half-frame and u4/3 format.
The u4/3 format is a tad larger than "1/4 frame" at 13.5x18mm; it's not nearly the same as half-frame, which is about 18x24mm. The attached diagram shows the format sizes, the blue square is u4/3, the yellow is half-frame, and the entire rectangle is full-frame 35mm.
~Joe
"Equivalent angle of view" -- the angle of view of a lens used on the G1 that's equivalent to what you would see on a full-frame 35mm camera -- is equivalent to a 2x focal length lens on full-frame 35mm.
Thus, a 15mm lens on the G1 has an "equivalent angle of view" of a 30mm lens on a full-frame 35mm camera. But the actual focal length is still 15mm, so the depth of field effects are different than an actual 30mm lens.
If you're comparing angle of view between half-frame lenses and the G1, the difference in image size (diagonal) between the formats is about 1.4, so use a factor of x1.4 to compare equivalent angles of view between half-frame and u4/3 format.
The u4/3 format is a tad larger than "1/4 frame" at 13.5x18mm; it's not nearly the same as half-frame, which is about 18x24mm. The attached diagram shows the format sizes, the blue square is u4/3, the yellow is half-frame, and the entire rectangle is full-frame 35mm.
~Joe
Attachments
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The Pen lenses are a perfect match for the G1, I have several I use, from 20 to 250mm.
Good luck on the 400 and 800mm lenses, those are extremely rare.
Good luck on the 400 and 800mm lenses, those are extremely rare.
jke
Well-known
You are thinking too hard here.
A Pen 25mm lens is not a half-frame lens. There is no such thing. It is just a 25mm lens. The only part that makes the Olympus Pen camera half-frame is the body which only allows half a frame of 35mm film be exposed when the shutter opens. If you put a Pen 25mm lens on an Olympus OM-1, you'd get a full frame exposure because the OM-1 allows a full-frame of 35mm film to be exposed. The 25mm Pen lens might not have full-coverage (i.e. it might vignette) on a full-frame of 35mm film, but you wouldn't end up with a half-frame image.
A Pen 25mm lens is not a half-frame lens. There is no such thing. It is just a 25mm lens. The only part that makes the Olympus Pen camera half-frame is the body which only allows half a frame of 35mm film be exposed when the shutter opens. If you put a Pen 25mm lens on an Olympus OM-1, you'd get a full frame exposure because the OM-1 allows a full-frame of 35mm film to be exposed. The 25mm Pen lens might not have full-coverage (i.e. it might vignette) on a full-frame of 35mm film, but you wouldn't end up with a half-frame image.
Benjamin Marks
Veteran
Hmmm, not so fast
Hmmm, not so fast
Well, it isn't that simple. This strays from the OP, a bit Buuut: Focal length is focal length, but each lens design has a maximum format it can be used for to completely cover the frame. I think of like a flashlight which casts a circular cone of light from its aperture (think of it like a flashlight casting a circle of light on the wall). Some lenses are designed to cover a certain format (e.g. the largest rectangle that can be carved out of the circle projected at the film plane, without unacceptable image fall-off). It sounds from one of the posters above that the Pen-F lenses work fine on a G1-sized chip, but that is not always necessarily the case. Try using a 90mm angulon on 8x10 film - you get a circular image. Try using Nikon's new 35mm lens on a FF camera and you'll get severe image drop-off in the corners.
The question that the OP should have asked was: does a lens from a Pen-F adequately cover a G1 chip? Once that question is answered "yes" then the "focal length" is "focal length" answer is perfectly correct and the answer is straightforward.
BTW "crop factor" is just industry jargon for translating the specs of digital cameras companies could afford to make into the most readily available frame of reference: 35 mm film equipment. Everyone gets this, right?
Ben Marks
Hmmm, not so fast
Well, it isn't that simple. This strays from the OP, a bit Buuut: Focal length is focal length, but each lens design has a maximum format it can be used for to completely cover the frame. I think of like a flashlight which casts a circular cone of light from its aperture (think of it like a flashlight casting a circle of light on the wall). Some lenses are designed to cover a certain format (e.g. the largest rectangle that can be carved out of the circle projected at the film plane, without unacceptable image fall-off). It sounds from one of the posters above that the Pen-F lenses work fine on a G1-sized chip, but that is not always necessarily the case. Try using a 90mm angulon on 8x10 film - you get a circular image. Try using Nikon's new 35mm lens on a FF camera and you'll get severe image drop-off in the corners.
The question that the OP should have asked was: does a lens from a Pen-F adequately cover a G1 chip? Once that question is answered "yes" then the "focal length" is "focal length" answer is perfectly correct and the answer is straightforward.
BTW "crop factor" is just industry jargon for translating the specs of digital cameras companies could afford to make into the most readily available frame of reference: 35 mm film equipment. Everyone gets this, right?
Ben Marks
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To make it simple:
25mm lens on a full frame camera = 25mm effective field of view, as compared to 35mm film
25mm lens on a Pen F = 35mm effective FOV (1.4x)
25mm lens on a G1 = 50mm effective FOV (2x)
As Ben says, this doesn't mean said 25mm lens covers the frame.
Sonnar2
Well-known
The usage of a lens on a camera is optically limited by the following physical facts, each of them independent:
1 - focal length
2 - back focus (or with the more precise German term "hintere Schnittweite")
3 - circle of image
ad 1: this cannot be altered (except through focussing, it varies very little)
ad 2: this can be altered with adaption rings, when the lens has a longer back focus than the camera. If the lens is too short for the camera it can be used as a Macro lens only. This is why a Leica M lens cannot be used on an SLR camera at infinity.
ad 3: this cannot be altered. This fact is mostly understand and discussed for individual lenses in the Large format (LF) scene. A Leica M lens is calculated to cover 24x36, it also covers 24x18. A Olympus Pen F lens covers 24x18, it also covers 18x13. A "Robot" Xenon 40/2 covers 24x24, it don't cover 24x36.
1 - focal length
2 - back focus (or with the more precise German term "hintere Schnittweite")
3 - circle of image
ad 1: this cannot be altered (except through focussing, it varies very little)
ad 2: this can be altered with adaption rings, when the lens has a longer back focus than the camera. If the lens is too short for the camera it can be used as a Macro lens only. This is why a Leica M lens cannot be used on an SLR camera at infinity.
ad 3: this cannot be altered. This fact is mostly understand and discussed for individual lenses in the Large format (LF) scene. A Leica M lens is calculated to cover 24x36, it also covers 24x18. A Olympus Pen F lens covers 24x18, it also covers 18x13. A "Robot" Xenon 40/2 covers 24x24, it don't cover 24x36.
Trius
Waiting on Maitani
Yes ... Since 4/3 is a smaller format than half-frame, the original question needed no modification ... Which is why I gave the answer I did.