Voigtlander 125mm F/2.5 APO-Lanthar Macro Anyone?

"David Kilpatrick" wrote in message
...


Robert Meyers wrote:


In general, I am wondering about quality, flare, contrast, build and
usability. I am also wondering if Lanthar lenses age well? Some rare
earth elements don't (see yellow glass Olympus lenses).



It's an incredible lens - I have not used it but I have published
results from it.

As for lanthanum glass ageing badly, I am not entirely sure whether the
Apo-Lanthar actually uses it - the name is simply a derivation from
Voigtlander's old name for a rare earth glass Tessar derivative (Skopar
was their triplet derivative and Heliar seemed to get used for anything
from large format oldies to modern Gauss fast lenses). I suspect Cosina
just used the name, because any real Apo-Lanthar would have been a
process camera lens in the past.

But plenty of rare earth glasses survive for decades without turning
yellow - are you wanting the lens to outlive you?

David


The yellowing is usually where Thorium is involved, due to yellow coloured
products of its radioactive decay (which in turn can largely be bleached out
with UV). Lanthanum isn't radioactive, so this particular issue doesn't
apply. In fact, the original reasons for using Lanthanum oxide in glasses
were not only to produce a high refractive index, but also because the glass
was regarded as 'non-corroding' relative to the alternatives available.

All that said, I agree with David that as 'Lanthar' is an old Voigtlander
name for a lens design, there's no real reason to assume there's any
Lanthanum in this particular lens.


Peter

Bill Tuthill wrote:

Can you buy this lens in the USA?

http://www.cameraquest.com/

Christoph Breitkopf writes:
It is long compared to some (most?) other macro lenses, but
likely somewhat shorter than non-macro lenses.

I'll check this at home, and report exact numbers here.

It's a good thing I measured this, because you are right,
and I'm wrong. I overlooked that the Voigtlander focuses
down to 1:1, and the MF Micro-Nikkors just to 1:2. That makes
up for the extra full focusing turn of the Voigtlander.

To get a value that is independant from the
focal length, it is better to measure the
angle between infinity and some fixed multiple
of the focal length. 20x is a good value, for which
angles between 50° and 170° are ok, and between
70° and 120° best for most people.
Here are the angles between infinity and 20x focal
length for some lenses:

150° Pentax Super-Takumar 3.5/135
146° Leica Elmarit-R 2.8/180
120° Nikkor AI 2/85
104° Zeiss Sonnar T* 2.8/180
95° Nikkor K 1.8/85
90° Nikkor AI 3.5/135
80° Nikkor AI 1.2/50
72° Nikkor AI 2.8/180 (non-ED, ED is just slightly different)
72° Nikkor AI 2.5/105 (the AI-S has a shorter focusing throw)
60° Nikon Series E 2.8/135
40° Nikkor AI-S 2.8/28
40° Vivitar 2.8/100 Macro
34° Micro-Nikkor-P 3.5/55
32° Micro-Nikkor 4/105
27° Voigtländer 2.5/125 Macro

So the Apo-Lanthar has the shortes focus throw of the lenses
I measured. I'm sure there are thill shorter throws in some
zoom and especially AF lenses, though.

Regards,
Chris

--
Bokeh test images: http://www.bokeh.de/en/bokeh_images.html

David Kilpatrick wrote:


As for lanthanum glass ageing badly, I am not entirely sure whether the
Apo-Lanthar actually uses it - the name is simply a derivation from
Voigtlander's old name for a rare earth glass Tessar derivative (Skopar
was their triplet derivative and Heliar seemed to get used for anything
from large format oldies to modern Gauss fast lenses). I suspect Cosina
just used the name, because any real Apo-Lanthar would have been a
process camera lens in the past.

Picking a few nits he
The old Lanthar is a three element design and the Skopar four (and a
well-deserved reputation as the best of the Tessars)...

Chris

Chris Loffredo wrote:

David Kilpatrick wrote:


As for lanthanum glass ageing badly, I am not entirely sure whether
the Apo-Lanthar actually uses it - the name is simply a derivation
from Voigtlander's old name for a rare earth glass Tessar derivative
(Skopar was their triplet derivative and Heliar seemed to get used for
anything from large format oldies to modern Gauss fast lenses). I
suspect Cosina just used the name, because any real Apo-Lanthar would
have been a process camera lens in the past.


Picking a few nits he
The old Lanthar is a three element design and the Skopar four (and a
well-deserved reputation as the best of the Tessars)...

Chris


A triplet isn't the same as a three-element - two of the elements in the
Skopar are cemented, it's still a triplet.

The original Lanthar is a large format lens of very old vintage.

David