Schneider Xenon FF-Prime 35mm: A Review

Introduction

The Schneider Kreuznach line of Xenon full frame cinema primes are truly a very interesting set of lenses.  Essentially, they're marketed as entry-level cinema lenses, primarily competing with Canon's CN-E Cine Primes and Zeiss CP.2 lenses.  While Canon and Zeiss's offerings are rehoused versions of their respective L and ZE/ZF still lens lines, Schneider touts their Xenon primes as being built from the ground up for cinema.  Coming in at roughly 70-80% of the price of CN-E's or CP.2's, it is easy to see why I say these are very interesting lenses.  Do they, however, live up to what looks like a slam-dunk on paper?  I'll examine the 35mm member of the Xenon FF-Prime lineup.

Specs

Like most of the lenses in this line, the 35mm Xenon features a maximum aperture of only T/2.1 (roughly ƒ/2.0), a full stop slower than most other competing cine lenses and essentially all premium still lenses.  The Xenon line boasts a fairly complete set of lenses with the 25mm, 35mm, 50mm, 75mm, and 100mm currently available and 18mm (this one is T/2.4) and 135mm coming soon.  All the lenses in the set are color matched and the same physical size (unlike some of the competition).  The Xenons also support a 95mm screw-on front filter, thus enabling the use of ND filters without a matte box.    

Build Quality

Upon unboxing the 35mm Xenon FF-Prime, one sees that this is a "real deal" cinema lens.  It is sizable, but not much longer than a high-end still lens, such as the Sigma Art 50mm, and fairly heavy.    This lens is built like a tank: all metal and very solid feeling.  It has a clickless aperture ring, with decent spacing between stops and a focus ring with 300° rotation.  Focusing is very smooth, although I find the Zeiss ZF lenses to be every-so-slightly more smooth and "buttery."  The long focus throw on the Xenon really aids in precise focusing.  The lens cap is a simple plastic cover that slides over the front of the lens, but is actually quick and functional.  

Image Quality

In my evaluation of the Xenon 35mm FF-Prime, I mainly pitted it against the other lenses I currently have on hand, the Sigma Art 50mm ƒ/1.4 and the Zeiss ZF 50mm ƒ/1.4.  My tests were conducted on a Panasonic GH4.  While I believe such a crop factor does embellish some of the imperfections of lenses designed for larger sensors, it also serves lens comparisons well to help point out weaknesses.  Hopefully Blackmagic will ship the Ursa Mini 4.6K on time so I can test it on a S35 sensor.

Sharpness

From my tests, I'd say the Schneider is just a bit sharper than the Zeiss, which is a bit alarming since the ZF 50 ƒ/1.4 is by far the worst performer of any Zeiss ZF and is simply destroyed by any Sigma Art or Zeiss Otus offering (take a look at the table below).  Although the Sigma was more difficult to nail focus with, due to it's very short focus throw, it is much sharper than the Xenon, even wide open at ƒ/1.4 versus T/2.1 on the Xenon.  The Sigma simply wipes the floor with the other two lenses when examining the amount of detail resolved.

Lens	DxO Sharpness
Zeiss ZF 15	23
Zeiss ZF 25	29
Zeiss ZF 35	23
Zeiss ZF 50	17
Zeiss ZF 50 Makro	23
Zeiss ZF 85	22
Zeiss Otus 55	33
Zeiss Otus 85	35
Sigma Art 35	30
Sigma Art 50*	33
Sigma Art 24*	27
Sigma Art  18-35**	32

Table 1: Various lenses and their DxOMark sharpness score (higher is better) when mounted on a Nikon D800E.
*These lenses were not tested on the D800E. Extrapolated from comparisons with other lens on a Canon 5D Mark III and adjusted.  
**This lens does not cover a full frame sensor. Extrapolated from comparisons with other lens on a Canon 7D Mark II and adjusted.  

Bokeh

One of the things you'll hear about the Schneider Xenon's is their excellent, creamy bokeh.  I do find the bokeh to be the most pleasing out of these three lenses (likely due in part to the 14 aperture blades versus 9 blades on the Zeiss and Sigma), but only by a very slim margin and only in some shots.  The out of focus highlights are almost perfectly round with the Schneider, but can get just a bit pointy when stopped down on the other 2 lenses.  In many instances, bokeh is very similar among the three and in the next sections I'll discuss some of the factors that almost ruin this excellent bokeh on the Xenon.

Maximum Aperture

This is where things start to get a bit problematic for the Xenon; it's a full stop slower than the Sigma or Zeiss.  Other longer lenses in the set are even one and a third stops slower than what's available from Canon.  At first, I thought that this wouldn't be a problem.  On many other lenses ƒ/1.4 doesn't produce a very usable image anyway.  If this lens performed wide-open like a $4000 lens should, losing the one stop of low-light performance would be a sacrifice, but potentially worth it.  This turned out to unexpected be a very big "if."

Chromatic Aberration 

Without pixel peeping or examining 1:1 crops, chromatic aberration has never really been a huge issue for me.  Generally stopping the lens down just a bit solves any really issues with this.  As can be seen in Table 2, the Zeiss ZF 50mm ƒ/1.4 is pretty bad when it comes to CA, but I've never had many problems. By ƒ/2.0, it's generally a non-issue.

Before getting the Xenon, I had read that CA could be an issue, but for a $4K cinema lens, I thought this was probably just internet forum dwellers whining because it wasn't as good a $20K Zeiss Master Prime.  CA is where the Xenon really falls apart.  At T/2.1 the Xenon exhibits far worse CA than the Zeiss at ƒ/1.4.  In fact, the Xenon is still worse at T/2.8 and at T/4.0 only marginally better than the Zeiss still at ƒ/1.4.  The Sigma shows just a bit of CA wide open, but is imperceivable at ƒ/2.0.  CA is not completely absent from the Xenon until T/5.6.

From my testing it seems if you really want to eliminate chromatic aberration and still shoot as open as possible, you'd need to shoot at two and a half stops slower than the Zeiss (pretty bad if you consider that this lens is a poor performer with respect to CA) and three to three and a half stops slower than the Sigma.

To make matters worse, the Xenon generally presents purple AND green fringing in most of my tests whereas the Zeiss only produced the green fringing in addition to purple in a few instances and the Sigma never showed green fringing in any of my tests.  In my opinion, trying to correct two different color fringes in post is even more of a hassle, and green can be more difficult to to correct especially in outdoor shots.

Worse still, the fringing can ruin the Xenon's wonderful bokeh.  Any contrasty bokeh is riddled with purple and green.  Often, circular out of focus highlights appear with purple and green rings around them.  Any reflective surfaces that give off an overexposed reflection have than highlight trimmed in purple.  At T/2.1, the Xenon is by no means a super low light lens and these CA issues tend to crop up even more when trying to shoot in low light at apertures wider than T/4.0 or T/5.6.

On the Xenon 35mm CA forces you to stop the lens down, which also makes it more difficult to attain the creamy bokeh you may be looking for.

Lens	DxO CA
Zeiss ZF 15	9
Zeiss ZF 25	5
Zeiss ZF 35	9
Zeiss ZF 50	14
Zeiss ZF 50 Makro	7
Zeiss ZF 85	11
Zeiss Otus 55	6
Zeiss Otus 85	3
Sigma Art 35	6
Sigma Art 50	6
Sigma Art 24	6
Sigma Art 18-35*	8

Table 2: Various lenses and their DxOMark chromatic aberration score (in µm; lower is better) when mounted on DSLR with full frame sensor (either a Nikon D800E or Canon 5D Mark III).
*This lens does not cover full frame.  This score is extrapolated from testing on a Canon 7D Mark II and adjusted.
Note: If I had to estimate from my testing I would say the Schneider Xenon FF-Prime 35 would have a score of at least 18, if not even into the twenties.

Color Rendition/Contrast

Overall, all three lenses exhibit similar color rendition, with the Zeiss perhaps being just a bit cooler than the other two and also just a bit more contrasty.  There results are consistent with the general consensus of Zeiss lenses producing a cool and contrasty image.  The Schneider and Sigma are more neutral and have good contrast, just not as much as the Zeiss.  

Conslusion

I would not make a blanket statement advising against the purchase of the Xenon 35mm, but for the price it a fairly weak performer.  Physical design and build quality are definitely the main strengths of this lens.  If you need 300° focus rotation, clickless aperture, and consistent physical size across the lineup above all other features, then for roughly 25-30% less than the price of CN-E's or CP.2's, the Xenons may be a good fit.  If you correct for some of the big weaknesses of this lens, it can produce a very pleasing, cinematic image.

For me though, this lens simply does not pack enough punch to warrant its price tag.  The build quality does not make up for the fact that this lens costs over three times as much as a Zeiss ZF 35mm ƒ/1.4 and five times as much as the Sigma Art 35mm.  If the optics of this lens were in a Canon L housing, I would NEVER consider buying this lens.  Right off the top you lose one stop versus the competition and even then it is still not as sharp as some other lenses.  Even without its main weaknesses, I don't think the Xenon has good enough image quality to justify its price tag.

It is really the horrible, horrible chromatic aberration, fringing, and ugly purple and green bokeh circles that really plague this lens and destroy some of its best attributes.  If you really want to ensure that these abnormalities don't ruin your shot then this really becomes a T/4.0 lens at best.  

Verdict: Unless physical attributes of the lens trump all else for you, there are better, faster alternatives that produce better overall images at a much lower price point.

Don't miss my upcoming post with my Ulitmate 2015 Cinematic Lens Kit Recommendations, where I put my years of research to good use and suggest the best bang for the buck set of lenses for a complete S35 kit!  Coming very soon!