Re: Cosina Voigtländer APO-Lanthar 90/4 VM officially announced for August release
Fred Miranda wrote: Steve Spencer wrote: Fred Miranda wrote: Michael Gordon wrote: dan98 wrote: Steve Spencer wrote: dan98 wrote:
Those MTF curves resemble the performance of my Voigtlander SL 90/3.5 APO-Lanthar, specifically in terms of the pronounced mid-zone dip. I am not suggesting that the new 90/4 has the same optical design--it clearly does not--but based on the MTF curves it would seem to have the same primary flaw. If this proves to be true then it would be a disappointment. The 90/3.5 is by far the weakest of the SL APO-Lanthars and is quite an old design, so I would have expected the latest Voigtlander offering to avoid this issue.
The 90/3.5 is also the weakest of the series in terms of control of various aberrations (especially LoCA and purple fringing), and at least here I am confident that the new lens will offer improvements. I believe that the old 90/3.5 is the least APO of all of their APO-designated lenses. Based on the few sample images I have seen, the new 90 produces very little fringing.
Dan, I had the old 90 f/3.5 APO Lanthar and I totally agree with your assessment of it. It is one of the few Voigtlander lenses I have owned in which I was pretty disappointed. I noticed with my copy the same things you mentioned and I do believe it had a pretty substantial mid-zone dip.
That said, the MTF's of this 90 f/4 APO Lanthar do not show a mid zone dip. A mid zone dip is indicated by worse performance (i.e. lower percentage contrast) from 12-18mm from the center than you see in the center *and* than you see in the outer part of the frame (i.e. 18-22mm from the center). When there is a mid zone dip as the name implies performance doesn't just go down in the midfield it comes back up toward the corners.
A gradual decrease in performance from the center to the corners in not a mid-zone dip and that is what we see in the MTF curve for this new 90 f/4 APO Lanthar. ...
....
While there is just a gradual decrease from the center to the corners at 10 lp/mm (which is not a mid-zone dip), there is a pronounced dip at 30 lp/mm and 40 lp/mm in the sagittal direction. This is most pronounced at 30 lp/mm and f/5.6, where the value hits a trough at about 12-13mm, and then rises steadily as we move out to 18%, but only for the sagital. This is exactly the same pattern as the MTF curve for the 90/3.5 at f/3.5. In the sagital direction a trough occurs at 12-13%, with the value rising steadily as we move out to 18mm. With both lenses the dip in the MTF curve only occurs in the sagital direction. Regarding the magnitude of the dip, it is is slightly more pronounced with the new lens, although they are really quite similar. It is this similarity that has me concerned, but I agree that the real-world results are what matters.
Curiously the max magnification of the CV 90 3.5 is 0.29 or about 1:3.5. That is almost identical to the new 90 f4 despite the design difference. I like my copy in OM mount and it behaves well on extension. The size is nice. One should expect excellent performance though for a mid tele with modest max aperture.
I don't think Cosina ever released an official max magnification figure for the CV 90mm f/3.5 APO-Lanthar M-mount, but based on its 1m MFD, I calculate it to be roughly 0.10x. The new 90mm f/4 APO has a stated max magnification of 0.28x, roughly 3x greater.
If I recall correctly, however (and I might not be), the 90 f/3.5 APO Lanthar came with a diopter that let you get a lot more magnification. I think it was about 1 to 3 with the diopter.
That's likely referring to the SL / SL II versions. We should compare apples to apples though - M-mount to M-mount.
I don't really think there will be much of a comparison or at least I hope not. The 90 f/3.5 APO was not a very well corrected lens and is easily my least favorite Voigtlander lens. I expect and hope that the new 90 f/4 APO Lanthar is a much better lens and there is no comparison. The new lens ought to be a lot better.
Jul 27, 2026 at 05:52 PM
Previous versions of Steve Spencer's message #17079460 « Cosina Voigtländer APO-Lanthar 90/4 VM officially announced for August release »
