My impressions reviewing the images on this thread (and the other similar thread here) is that it's an extraordinary lens at a reasonable cost given what you get. The comparisons to the Samyang 45mm show me that the Lanthar has less CA, and the difference in clarity/sharpness of the type on the jar/container is very significant to me. Overall, I've been impressed by the look of the lens, including the lack of CA, from the samples.
I was going to hold off for awhile, but instead I ordered one yesterday.
Steve Spencer wrote:
I think you may misunderstand the definition of APO. A regular lens focusses at just one specific wavelength exactly on the plane of focus. An achromatic lens focusses on just two specific wavelength exactly on the plane of focus. An apochromatic lens (i.e., APO) focusses on three specific wavelengths exactly on the plane of focus. Almost every lens that claims to be APO does not present evidence that it meets this strict definition. I suspect many if not most lenses that claim to be APO do not meet this strict definition. I would not be surprised if the Voigtlander 50 f/2 APO does not meet that definition either. Still we don't really know. It is perfectly possible for a lens to meet even the strict definition of APO and still show some axial CA. Imagine a lens that focusses exactly on the focus plane at a red wavelength that is almost infrared, at a middle wavelength, and at a violet wavelength that is almost ultraviolet. Now if you plot the focus of each wavelength relative to the exact focus plane you would have a graph with a hump below the line on one side of the middle and a hump above the line on the other side of the middle. Those humps, if they are big enough, could still give you magenta and green fringing typical of axial CA even in an APO lens.
The point is that an APO lens limits the magnitude that some wavelengths deviate from the exact focal plane it does not make all wavelengths focus at the exact focal plane and in fact only three wavelength focus exactly on the focus plane. In practice an APO lens will have very little axial CA, but it could have some, and the presence of axial CA does not necessarily mean a lens is not APO. So, although I suspect the Voigtlander 50 f/2 APO does not fully meet the definition of APO I can't know that from looking at pictures. It could be APO and still show the same axial CA we can see in some of the examples.
So, it is fine to be a bit disappointed that the lens shows more axial CA than one would like--it is the only thing I am slightly disappointed in with this lens--but don't be disappointed the lens isn't fully APO. We can't really know that without some very careful testing with probably pretty specialized equipment. It doesn't really in the end matter whether it meets the strict definition of APO. What matters is what the pictures look like, and in most instances the axial CA is very minor, but in some difficult situations it will definitely be recongnizeable especially when you blow up a 61 MP file to the pixel level of magnifications (i.e., view it at 100%)....Show more →
Maybe you are right, it could just be the high-res sensor that blows up the imperfection. Maybe I just expected to much.
Reminds me of similar discussion a few decades ago when Sigma started making APO lenses. I still have some of those. They are just as good as the modern day Voigtlander lenses for correction. The 50 seems to be the weakest for correction, of the 50/65/110.
The level of APO correction is variable lens to lens, just like sharpness, tilt, or centration. The 65 APO I has was very good for correction but I saw samples online that were noticeably less effective. Shoot a water fountain wide open in the sun, like phillipreeve.net does, and the differences become more apparent.
I wasn't REALLY trying to compare the CV 50 to the CO, more that to me the price of the CV is not unreasonable for what you get. No lens is perfect, but I think CV balanced speed, size, rendering....and APO'ishness very well IMHO. I'm really looking forward to using it more.
-Tim
realVivek wrote:
Although I am confused about the first para, I can tell you that the APO Lanthar is without focus shift all the way to Infrared.
Unlike, the CO lens, the APO Lanthar does not show a hotspot at close focus distance even with extension tubes attached.
tsdevine wrote:
I wasn't REALLY trying to compare the CV 50 to the CO, more that to me the price of the CV is not unreasonable for what you get. No lens is perfect, but I think CV balanced speed, size, rendering....and APO'ishness very well IMHO. I'm really looking forward to using it more.
With a Marumi close-up filter +5 almost 1:2 magnification...
How about DOF? Will the combination be usable handheld?
What will be the magnification with a +3 Marumi?
realVivek wrote:
That is easy to understand if you consider the 4 aspheric surfaces superimposed on each other and the resulting interference pattern.
Well I'm also disappointed with the shape of the bokeh discs at the non-round apertures. I really wanted it to do something cool like the Cooke S4 or Industar 61. But no luck, it's just something not very well defined....
vdo1 wrote:
Well I'm also disappointed with the shape of the bokeh discs at the non-round apertures. I really wanted it to do something cool like the Cooke S4 or Industar 61. But no luck, it's just something not very well defined....
