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Archive 2010 · 4/3s format/lens question

RGS65
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p.1 #1 · p.1 #1 · 4/3s format/lens question

When Oly and Panny advertise a "20mm" lens or a "14mm" lens is that a reference to what we now consider "full frame" film field of view?

In other words - does 4/3 have a "crop factor"? Are these lenses designed to give the equivalent of 20mm - what us old guys are used to from the good old days or are they actually wider than that but the 4/3 "crop factor" nets you this field of view?

Or doesn't this question make sense in 4/3 format.

Bottom line is if I buy one of these suckers is my 20mm gonna be 20mm?

And if I use some older glass with a converter is my 45 gonna be 45mm?

I've been shooting Canon 1.6 croppers so I know and understand the answer there.

Thanks,
Rob

Sep 13, 2010 at 03:18 PM

jotdeh
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p.1 #2 · p.1 #2 · 4/3s format/lens question

43s are 2x crop. The lenses specifically for the platform state the actual physical focal length. So a 20mm lens on 43 will give you 40mm 135 equivalent FOV.

Sep 13, 2010 at 03:22 PM

melanopsin
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p.1 #3 · p.1 #3 · 4/3s format/lens question

The crop factor of m4/3 compared to 35mm film/full frame is 2.

A 20mm lens on m4/3 camera gives the same angle of view as a 20mmx2=40mm lens on a 35mm film or full-frame digital camera.

Notice that to get the same depth of field on both cameras, the 40mm lens will need to be stopped down; stopping down the lens, for same shutter speed as m4/3, the camera with 40mm lens needs ISO increased the same number of stops. Thus FF gains the depth of field range from f/# to stopped-down value, and, the m4/3 gains in shutter speed/iso at apertures where both cameras give identical depth of field.

Sep 13, 2010 at 03:28 PM

RGS65
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p.1 #4 · p.1 #4 · 4/3s format/lens question

That sucks - so Pannys 20/1.7 is a 40mm lens equivalent field of view?

Sep 13, 2010 at 04:06 PM

jotdeh
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p.1 #5 · p.1 #5 · 4/3s format/lens question

Yes- did you expect Panasonic's 7-14 to be a 7mm 135 equivalent FOV rectilinear lens at its widest??

Sep 13, 2010 at 04:12 PM

RGS65
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p.1 #6 · p.1 #6 · 4/3s format/lens question

I was hoping the 20mm would be. Its a nice price and a nice system - if it was actually 20mm. I had not considered the 7-14 when I asked the question.

Why the hell do they advertise it as 20mm when on their camera it's not? At least Canon sells full frame cameras so it makes sense for them. But if a 4/3 lens is NEVER 20mm why say its 20mm?

Sep 13, 2010 at 04:18 PM

RGS65
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p.1 #7 · p.1 #7 · 4/3s format/lens question

BTW - thank you both for the responses!

Sep 13, 2010 at 04:19 PM

ptys
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p.1 #8 · p.1 #8 · 4/3s format/lens question

But it is a 20mm lens. They state the focal length and so do other manufacturers. Canon 17-55mm is meant for their crop cameras, and yet they state true focal length on it, not the 35mm equivalent.

3/4 lenses sometimes have a sticker with their 35mm focal length equivalent value (70-300 had 140-600, etc.)

RGS65 wrote:
I was hoping the 20mm would be. Its a nice price and a nice system - if it was actually 20mm. I had not considered the 7-14 when I asked the question.

Why the hell do they advertise it as 20mm when on their camera it's not? At least Canon sells full frame cameras so it makes sense for them. But if a 4/3 lens is NEVER 20mm why say its 20mm?

Sep 13, 2010 at 04:27 PM

Paratima
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p.1 #9 · p.1 #9 · 4/3s format/lens question

RGS65 wrote:
That sucks...

You said it!

Sep 13, 2010 at 04:35 PM

Jman13
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p.1 #10 · p.1 #10 · 4/3s format/lens question

As ptys says, 20mm is 20mm. 35mm film/full frame sensor is not some 'magical standard format' where focal lengths are true. A 20mm lens on 4/3 has a similar AOV to a 40mm lens on full frame, which has a similar AOV to a 66mm lens on 645 medium format, which has a similar AOV to a 142mm lens on 4x5 large format, which has a similar AOV to a 284mm lens on 8x10 large format.

Which one of these is 'true'? The answer is, they're all true focal lengths, even though all of these lenses have the same angle of view on their respective formats. The crop factor does not actually change the focal length, it's simply a tool used to compare angle of view between two different formats. The crop factor of m4/3 vs APS-C is 1.25x. The Crop factor of 35mm film vs. medium format is 1.6x The crop factor of 35mm film vs 8x10 large format is 7.2x.

See the point? BTW, the Panny 20/1.7 is an outstanding lens.

Sep 13, 2010 at 04:52 PM

CKrueger
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p.1 #11 · p.1 #11 · 4/3s format/lens question

They couldn't rightly call a 20mm lens "40mm", could they?

I understand where you're coming from; all the different crop factors (1, 1.5, 1.6, 1.7, 2) get confusing, but at least 2x is simple to do the math on.

Sep 13, 2010 at 05:25 PM

photosmart42
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p.1 #12 · p.1 #12 · 4/3s format/lens question

RGS65 wrote:
Why the hell do they advertise it as 20mm when on their camera it's not? At least Canon sells full frame cameras so it makes sense for them. But if a 4/3 lens is NEVER 20mm why say its 20mm?

They actually do say in their literature that it's equivalent to a 40mm on a 35mm camera, just like they say their kit zoom 14-45 is a 28-90mm equivalent. As others said, focal length is focal length regardless of what camera you put it on. Sensor size determines the crop.

Sep 13, 2010 at 05:37 PM

RGS65
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p.1 #13 · p.1 #13 · 4/3s format/lens question

I totally understand the math and conversion...but

No I don't get the marketing point, and I think its a bit deceptive, because the 20mm lens is made for Pannys 4/3 format - that is its native application and its not 20mm in that use - right? So why say that?

I understand it's a great lens - but it's not 20mm equivalent and that is what I want.

35mm reference is "magical" because some of us have used it for 40+ years. We need some reference point otherwise these labels mean nothing - at least to me.

Jman13 wrote:
As ptys says, 20mm is 20mm. 35mm film/full frame sensor is not some 'magical standard format' where focal lengths are true. A 20mm lens on 4/3 has a similar AOV to a 40mm lens on full frame, which has a similar AOV to a 66mm lens on 645 medium format, which has a similar AOV to a 142mm lens on 4x5 large format, which has a similar AOV to a 284mm lens on 8x10 large format.

Which one of these is 'true'? The answer is, they're all true focal lengths, even though all of these lenses have the same angle...Show more →

Sep 13, 2010 at 06:15 PM

RGS65
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p.1 #14 · p.1 #14 · 4/3s format/lens question

That's well put - ok I get that. (Still don't like it!) Especially when the systems it's made for alters the focal length by default.

photosmart42 wrote:
They actually do say in their literature that it's equivalent to a 40mm on a 35mm camera, just like they say their kit zoom 14-45 is a 28-90mm equivalent. As others said, focal length is focal length regardless of what camera you put it on. Sensor size determines the crop.

Sep 13, 2010 at 06:18 PM

RGS65
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p.1 #15 · p.1 #15 · 4/3s format/lens question

I suppose they can't call a 20 a 40....ok, ok...Uncle. I still don't like it, but there it is.

CKrueger wrote:
They couldn't rightly call a 20mm lens "40mm", could they?

I understand where you're coming from; all the different crop factors (1, 1.5, 1.6, 1.7, 2) get confusing, but at least 2x is simple to do the math on.

Sep 13, 2010 at 06:19 PM

RGS65
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p.1 #16 · p.1 #16 · 4/3s format/lens question

Thanks BTW - of course this is dead on. I'm more bummed by the fact that to get the 20mm equiv I want I need to buy a $1,000 lens instead of a $350 lens...but that figures I guess eh?

I just find it hard to consider the 4/3 system if the lenses are going to cost what the Canon Ls I already own cost...so...back to the LX3 I guess.

Jman13 wrote:
As ptys says, 20mm is 20mm. 35mm film/full frame sensor is not some 'magical standard format' where focal lengths are true. A 20mm lens on 4/3 has a similar AOV to a 40mm lens on full frame, which has a similar AOV to a 66mm lens on 645 medium format, which has a similar AOV to a 142mm lens on 4x5 large format, which has a similar AOV to a 284mm lens on 8x10 large format.

Which one of these is 'true'? The answer is, they're all true focal lengths, even though all of these lenses have the same angle...Show more →

Sep 13, 2010 at 06:22 PM

Jman13
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p.1 #17 · p.1 #17 · 4/3s format/lens question

The Olympus 9-18 is supposed to be a pretty good lens, and it's $590. Gives the equivalent FOV of an 18-36mm lens, and it's VERY compact.

Sep 14, 2010 at 04:58 AM

RGS65
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p.1 #18 · p.1 #18 · 4/3s format/lens question

Did you guys see the new leaked 14mm/f2.5 today from Panasonic? Its on 43rumors.com

Sep 14, 2010 at 06:07 PM

CKrueger
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p.1 #19 · p.1 #19 · 4/3s format/lens question

I really like my Micro 9-18. It may be a slow zoom, but it's quite the versatile lens! 18/4.0 and 36/5.6 in a lens smaller than my old Canon 50/1.8? It's great!

The 14/2.5 looks pretty interesting, and I might be tempted, but I'm curious to see what Olympus' planned wide prime is like. Looks like it might be a 12mm (24mm-e) lens? That sounds like a great pair to my 20/1.7! (Well, to be honest I might still just carry the 9-18, but I'd sure want a 12mm prime!)

http://www.43rumors.com/new-olympus-lens-roadmap/

Sep 14, 2010 at 11:06 PM

mh2000
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p.1 #20 · p.1 #20 · 4/3s format/lens question

Panasonic anounced a 14mm lens... maybe that will be better for you?

Olympus is rumoured to have a 12mm prime coming out soon.

Sep 15, 2010 at 10:22 PM


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