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What does focus distance written on zoom Lumix lenses refer to?

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Prampaj

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I’ve noticed that on some lenses (like my 35-100), it is the closest distance on the most telephoto end (says 0.9m on my lens, focuses from 0.9m when I’m on 100mm, but I can get closer than that with shorter focal lengths). But that clearly doesn’t apply to all the lenses - the 12-32 pancake has 0.2m written on it, but according to Imaging Resource test, it is 0.2m at 12mm and 0.3m at 32mm.

Why does it differ? Did Panasonic change it at some point? Or does it depend on the lens type (long end for tele zooms, short for wide angle)?
 
Prampaj said:
I’ve noticed that on some lenses (like my 35-100), it is the closest distance on the most telephoto end (says 0.9m on my lens, focuses from 0.9m when I’m on 100mm, but I can get closer than that with shorter focal lengths). But that clearly doesn’t apply to all the lenses - the 12-32 pancake has 0.2m written on it, but according to Imaging Resource test, it is 0.2m at 12mm and 0.3m at 32mm.

Why does it differ? Did Panasonic change it at some point? Or does it depend on the lens type (long end for tele zooms, short for wide angle)?
Click to expand...
The shortest Focus distance is normally at the widest end of the zoom range. The elements of a zoom lens move as the focal length is changed, hence the closest focal length will change. Not sure it’s even theoretically possible to maintain the same closest focus distance, that’d be one too many constraints.
 
Prampaj said:
But that clearly doesn’t apply to all the lenses - the 12-32 pancake has 0.2m written on it, but according to Imaging Resource test, it is 0.2m at 12mm and 0.3m at 32mm.

Why does it differ? Did Panasonic change it at some point? Or does it depend on the lens type (long end for tele zooms, short for wide angle)?
Click to expand...
The closest focus distance isn't usually constant in a zoom lens. When you check the full specs for that 12-32mm lens on the Panasonic website (link), you'll see that it says:

Closest Focusing Distance: 0.20m/0.66ft (at focal lenghts 12-20mm) / 0.30m/0.98ft (at focal lenghts 21-32mm)

I think they only denote the smallest of those on the lens itself.

By the way, the closest focus distance is measured from the sensor plane, not from the front element of the lens. The latter is sometimes specified separately as 'closest working distance'.
 
Danielvr said:
The closest focus distance isn't usually constant in a zoom lens. When you check the full specs for that 12-32mm lens on the Panasonic website (link), you'll see that it says:

Closest Focusing Distance: 0.20m/0.66ft (at focal lenghts 12-20mm) / 0.30m/0.98ft (at focal lenghts 21-32mm)
Click to expand...
Thank you for that, it’s good to know I can also find this info straight from Panasonic. Sadly it seems like they don’t specify it like that with all of their zooms.
Danielvr said:
I think they only denote the smallest of those on the lens itself.
Click to expand...
That’s the confusing part - my 35-100 has 0.9m written on it, but that’s only for 100mm, it can focus from 0.6m on 35mm. I don’t know how they decide which value to put on their lenses
 
True, I’m only wondering how they decide which value to put on their lens bodies. Sometimes it’s the smallest value from the short end, sometimes it’s the longer focus distance from the tele end. It’s also not the focus distance that fives the highest magnification - I’m just not seeing a pattern in it.
 
Prampaj said:
I’ve noticed that on some lenses (like my 35-100), it is the closest distance on the most telephoto end (says 0.9m on my lens, focuses from 0.9m when I’m on 100mm, but I can get closer than that with shorter focal lengths). But that clearly doesn’t apply to all the lenses - the 12-32 pancake has 0.2m written on it, but according to Imaging Resource test, it is 0.2m at 12mm and 0.3m at 32mm.

Why does it differ? Did Panasonic change it at some point? Or does it depend on the lens type (long end for tele zooms, short for wide angle)?
Click to expand...
This is normally at the maximum magnification which for a zoom lens is at the telephoto end.

For the LUMIX GX VARIO 35-100mm / F2.8 II / POWER OIS at the Panasonic site:

5ec0dd9b29134eb3b9bd9aae33f97448.jpg.png

Note that the say explicitly from the image plane.
Not working distance which is from the front of the lens.

--
Bill ( Your trusted source for independent sensor data at PhotonsToPhotos )
 
Last edited:
bclaff said:
Prampaj said:
I’ve noticed that on some lenses (like my 35-100), it is the closest distance on the most telephoto end (says 0.9m on my lens, focuses from 0.9m when I’m on 100mm, but I can get closer than that with shorter focal lengths). But that clearly doesn’t apply to all the lenses - the 12-32 pancake has 0.2m written on it, but according to Imaging Resource test, it is 0.2m at 12mm and 0.3m at 32mm.

Why does it differ? Did Panasonic change it at some point? Or does it depend on the lens type (long end for tele zooms, short for wide angle)?
Click to expand...
This is normally at the maximum magnification which for a zoom lens is at the telephoto end.
Click to expand...
That’s what I thought at first, but it’s not the rule with all of their lenses - for example, this is about 25-50/1.7 (which has 0.28m value printed on the body):



388192d004eb4925be1a2f575227f3ab.jpg

Either I’m not seeing something, or they just choose the value to put on the lens randomly (and I’m looking to deep into this). It’s just a pity that it’s not unified.
 
Prampaj said:
bclaff said:
Prampaj said:
I’ve noticed that on some lenses (like my 35-100), it is the closest distance on the most telephoto end (says 0.9m on my lens, focuses from 0.9m when I’m on 100mm, but I can get closer than that with shorter focal lengths). But that clearly doesn’t apply to all the lenses - the 12-32 pancake has 0.2m written on it, but according to Imaging Resource test, it is 0.2m at 12mm and 0.3m at 32mm.

Why does it differ? Did Panasonic change it at some point? Or does it depend on the lens type (long end for tele zooms, short for wide angle)?
Click to expand...
This is normally at the maximum magnification which for a zoom lens is at the telephoto end.
Click to expand...
That’s what I thought at first, but it’s not the rule with all of their lenses - for example, this is about 25-50/1.7 (which has 0.28m value printed on the body):

388192d004eb4925be1a2f575227f3ab.jpg

Either I’m not seeing something, or they just choose the value to put on the lens randomly (and I’m looking to deep into this). It’s just a pity that it’s not unified.
Click to expand...
Hmmm. Mildly interesting. Most brands don't put this anywhere on the lens, it's just part of the spec. Does seem inconsistent.

--
Bill ( Your trusted source for independent sensor data at PhotonsToPhotos )
 
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