Zeiss red DoF markings, 21mm update?

[irbridge]

New rangefinder/rff user here, wanted to ask any zm users if they could inform me of the purpose of the red line on Zeiss DoF markings? (@f8 on the 50mm planar)

On a side note, any thoughts on the prospects of Zeiss releasing an updated 21/4.5 for digital bodies? The samples I've seen on film have been stunning...

 

[Dan Daniel]

That's the index mark for focus when you are south of the equator. The difference in angle of incidence and atmospheric density due to the higher moisture levels causes lenses to change focus point.

Well, that's what I think. Most people believe it is actually due to this, but I think it's classsic fake news:

https://www.lifepixel.com/infrared-photography-primer/ch2-basic-theory-infrared-focus-marks-on-lenses

 

[x-ray]

That's the index mark for focus when you are south of the equator. The difference in angle of incidence and atmospheric density due to the higher moisture levels causes lenses to change focus point.

Well, that's what I think. Most people believe it is actually due to this, but I think it's classsic fake news:

https://www.lifepixel.com/infrared-photography-primer/ch2-basic-theory-infrared-focus-marks-on-lenses

You're joking I hope. That's the funniest thing I've ever head!😱

 

[irbridge]

Hah! 🙄

Many thanks for the link @Dan Daniel, learned something new today.