Loxia vs. ZM ?

[ShooterSteve]

I'm looking for a few wide angle lenses for my Sony A7R and R2. I have been watching a few ZM lenses on ebay and wondering if there is any difference at all in the optical formulas between them and the new Loxia lenses? I'm looking at the 35 f2 and 21 f2 at the moment. Has anyone had both or done any research to see if the Loxia are just re-housed ZM versions or not? Prices and specs seem to be very similar.

I'd also be curious how the Batis lenses compare optically with the others.

Steve

 

[Annna T]

I'm looking for a few wide angle lenses for my Sony A7R and R2. I have been watching a few ZM lenses on ebay and wondering if there is any difference at all in the optical formulas between them and the new Loxia lenses? I'm looking at the 35 f2 and 21 f2 at the moment. Has anyone had both or done any research to see if the Loxia are just re-housed ZM versions or not? Prices and specs seem to be very similar.

I'd also be curious how the Batis lenses compare optically with the others.

Steve

The ZM wa lenses use a Biogon design which doesn't fit well with the short flange distance of the A7r. You get smeared corners or colored vignetting. May be a little less with the new A7r2 BSI sensor, but there is still a problem. The Loxia 21mm was designed especially for the A7 series and it shows, the IQ is better, but it isn't a Biogon design. The 35mm Loxia is a Biogon design and from what I have read the results aren't stellars in the corners. I think it is OK for travel photography where you get people in the middle of the frame, but less adapted to landscape. Zeiss say that they worked to adapt the 35mm Biogon design to the A7 series, but it isn't as good as the 50mm. And there is a reason why the 21mm isn't a Biogon.

 

[kxl]

For WA lenses to be used exclusively with A7* bodies, stick with lenses designed for that mount. I would go with the Batis 25mm, which displays that beautiful Zeiss color and micro contrast that gives images that 3D pop. And you get AF.

Personally, I use adapted ZM lenses but ONLY because I always carry a Zeiss ZI film body with my A7R so I need lenses that I can mount on both bodies. To mitigate smeared corners, I had my A7R upgraded by Kolari Vision with their thin filter upgrade (along with the full spectrum IR conversion, but that's entirely another matter).

 

[ShooterSteve]

The ZM wa lenses use a Biogon design which doesn't fit well with the short flange distance of the A7r. You get smeared corners or colored vignetting. May be a little less with the new A7r2 BSI sensor, but there is still a problem. The Loxia 21mm was designed especially for the A7 series and it shows, the IQ is better, but it isn't a Biogon design. The 35mm Loxia is a Biogon design and from what I have read the results aren't stellars in the corners. I think it is OK for travel photography where you get people in the middle of the frame, but less adapted to landscape. Zeiss say that they worked to adapt the 35mm Biogon design to the A7 series, but it isn't as good as the 50mm. And there is a reason why the 21mm isn't a Biogon.

Very disappointing that the new Zeiss Loxia 35 is not a stellar performer but good to hear the 21 is good. I don't mind going with the Batis but didn't really want AF. I wonder why they would ever bother designing lenses specifically for the E mount that aren't perfect? Bummer to hear the ZM's are not the answer as they offer so many nice focal lengths for landscapes...

Are the Leica M lenses having the same issues as the Zeiss M on the Sony???

Thanks for the info!

 

[Vivek]

Are the Leica M lenses having the same issues as the Zeiss M on the Sony???

From the known reports, the modern M lux' (21,24,28)should do well.

The ZM lenses are from the film era and are relics of a distant past. Do not be fooled by the blue tag!

 

[chrisjmitchellphotography]

It seems that if you get a good Loxia 35 then its really good (even in the corners) but there does seem to be more sample variation than there is with the 50mm.

 

[ErikKaffehr]

My reflection, from what I have read

Hi,

Very clearly, digital cameras will have issues with Biogons designed for film. There are many problems, including vignetting, colour shift and "crosstalk".

One of the main issues is the cover glass, however. The cover glass induces astigmatism. That astigmatism can be corrected in optical design. The Zeiss 35 ZM is an example of that. The original ZM lens has a lot of smearing at corners, while the Loxia has much less as the optical design was changed to take cover glass into account.

Still, symmetric wide angle designs don't play well with digital sensors, so the new 21/2.8 from Zeiss is a "Distagon" design.

One issue with user reports is that different users have different expectations, so what for one user may be barely usable could be an excellent lens for another.

Best regards
Erik

 

[ShooterSteve]

Re: My reflection, from what I have read

Hi,

Very clearly, digital cameras will have issues with Biogons designed for film. There are many problems, including vignetting, colour shift and "crosstalk".

One of the main issues is the cover glass, however. The cover glass induces astigmatism. That astigmatism can be corrected in optical design. The Zeiss 35 ZM is an example of that. The original ZM lens has a lot of smearing at corners, while the Loxia has much less as the optical design was changed to take cover glass into account.

Still, symmetric wide angle designs don't play well with digital sensors, so the new 21/2.8 from Zeiss is a "Distagon" design.

One issue with user reports is that different users have different expectations, so what for one user may be barely usable could be an excellent lens for another.

Best regards
Erik

Great to have this wisdom on this forum. I'm just not sure why Zeiss would bother offering lenses designed for a specific camera and sensor, at very high prices that are not excellent. My Leica R lenses seem to perform very well but I have not done any serious analysis, just pixel peeping with great results so far. I'm guessing the SLR film lenses perform better than the RF variety because of the lens-sensor distance where the sensor cover glass has less of an issue? I just find the R lenses very heavy and large for the small Sony body. However, certainly not larger than the Sony 35 1.4 or Sigma, Canon etc.

If the Batis are the winners, I guess it may be the only good option?

Thanks for the feedback.

Steve

 

[Vivek]

Steve, check this out: http://photo.net/leica-rangefinders-forum/00M5ag

The original post from Brian Caldwell on this topic.

 

[ErikKaffehr]

Re: My reflection, from what I have read

Hi,

Yes, SLR lenses all have significant distance between outlet pupil and sensor, SLR lenses don't used to be problematic.

The cover glass is not the only issue. As the pixels have a certain depth, oblique rays may be able to reach the photo sensitive parts of the sensel. That causes shading effects, and for some reason also colour shift. In addition the oblique rays may cross over to other pixels, so say a part of green light hits the red pixels.

To that comes the microlenses, which are designed to work bet with some outlet pupil distance.

Leica has gone a long way to support their M-lenses. They developed a sensor with shallow wells and microlenses that work well with different beam angles. In addition Leica uses very thin cover glass, 0.8 mm in the M9 but only 0.5 mm in the M8. Most other makes use around 2 mm while 4/3 uses 4 mm.


Leica also has coding on the lenses and guesses aperture. This is used to make an automatic correction of colour shift and vignetting. Leica M-s would have major issues without these optical corrections.

Sony A7r have been modified to be more compatibe with Leica M glass, using thinner cover glass. But, Diglloyd who has tested this found that some A7 native lenses lost a lot of corner performance with the thinner Leica cover glass.

This, is a complex issue. In reality, the optical glass in the light path needs to be taken into account in the lens design. But in general, "biogon" type lenses will not play well digital sensors, especially not with small pixel sensors.

This video is quite informative: http://petapixel.com/2014/09/21/video-fascinating-lens-design-101-interview-zeiss-master/

You can check this inf from Carl Zeiss on the issues:

http://lavidaleica.com/assets/reviews/zms/en_CLN41_Nasse_LensNames_Distagon.pdf

The issues are discussed on pages 11-13.

Best regards
Erik

Great to have this wisdom on this forum. I'm just not sure why Zeiss would bother offering lenses designed for a specific camera and sensor, at very high prices that are not excellent. My Leica R lenses seem to perform very well but I have not done any serious analysis, just pixel peeping with great results so far. I'm guessing the SLR film lenses perform better than the RF variety because of the lens-sensor distance where the sensor cover glass has less of an issue? I just find the R lenses very heavy and large for the small Sony body. However, certainly not larger than the Sony 35 1.4 or Sigma, Canon etc.

If the Batis are the winners, I guess it may be the only good option?

Thanks for the feedback.

Steve

 

[LCT]

I have no experience with Loxia lenses but my ZM 35/2.8 works fine on the A7s Kolari so far. F/2.8, focus on the top right corner.

 

[iiiNelson]

I'm looking for a few wide angle lenses for my Sony A7R and R2. I have been watching a few ZM lenses on ebay and wondering if there is any difference at all in the optical formulas between them and the new Loxia lenses? I'm looking at the 35 f2 and 21 f2 at the moment. Has anyone had both or done any research to see if the Loxia are just re-housed ZM versions or not? Prices and specs seem to be very similar.

I'd also be curious how the Batis lenses compare optically with the others.

Steve

There are some hands on reports of the Loxia's and Batis' on here. In short I'd choose either over the ZM lenses for a variety of reasons. Most notable are the closer focusing distances compared to the ZM lenses. I own both Batis lenses and the only issue I really have with them is that the 85 hunts for focus at times in lower light (I'm on the original A7/A7R bodies so it's possible to have improved performance with the newest bodies.) I'd check out Flickr and the web for downloads to see if the lens meets your desires if you can't rent or buy one.

 

[ShooterSteve]

Re: My reflection, from what I have read

Hi,

Yes, SLR lenses all have significant distance between outlet pupil and sensor, SLR lenses don't used to be problematic.

The cover glass is not the only issue. As the pixels have a certain depth, oblique rays may be able to reach the photo sensitive parts of the sensel. That causes shading effects, and for some reason also colour shift. In addition the oblique rays may cross over to other pixels, so say a part of green light hits the red pixels.

To that comes the microlenses, which are designed to work bet with some outlet pupil distance.

Leica has gone a long way to support their M-lenses. They developed a sensor with shallow wells and microlenses that work well with different beam angles. In addition Leica uses very thin cover glass, 0.8 mm in the M9 but only 0.5 mm in the M8. Most other makes use around 2 mm while 4/3 uses 4 mm.

Leica also has coding on the lenses and guesses aperture. This is used to make an automatic correction of colour shift and vignetting. Leica M-s would have major issues without these optical corrections.

Sony A7r have been modified to be more compatibe with Leica M glass, using thinner cover glass. But, Diglloyd who has tested this found that some A7 native lenses lost a lot of corner performance with the thinner Leica cover glass.

This, is a complex issue. In reality, the optical glass in the light path needs to be taken into account in the lens design. But in general, "biogon" type lenses will not play well digital sensors, especially not with small pixel sensors.

This video is quite informative: http://petapixel.com/2014/09/21/video-fascinating-lens-design-101-interview-zeiss-master/

You can check this inf from Carl Zeiss on the issues:

http://lavidaleica.com/assets/reviews/zms/en_CLN41_Nasse_LensNames_Distagon.pdf

The issues are discussed on pages 11-13.

Best regards
Erik

Yes, I remember all the issues with the M8 and also understand the issue with digital sensors and wide angle M lenses. I guess I was hoping that it was some how fixed with the Sonys, but I guess not... it's interesting that the consensus is that some of the Leica M lenses perform better than the Zeiss ZM's do from the same era.