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Zeiss Compact Prime vs ZF.2

zeiss zeiss cp.2 compact prime zeiss zf

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#1 Alex Lopez

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Posted 28 November 2014 - 12:14 AM

Good morning,

I'm having a hard time deciding between Zeiss CP2 vs ZF.2 to use on a 5D body. Lenses are optically identical but the Zeiss representative said that differences could be seen in the bokeh (14 aperture blades with CP.2 lenses vs. 9 aperture blades in the SLR lenses) and the better stray light reduction with CP.2 lenses. How noticeable could that be? Because I do not want to compromise the quality. The reason why I am considering ZF.2 is because of the considerably smaller size and wider aperture. The smooth cine-like focus ring on CP2 is great but can it become a huge burden if used by the cameraman himself with the camera mounted on a shoulder rig? That's my biggest concern because I do not have a lot of experience in using cine-type focus rings and I do not want to make the shooting hard, compromising the quality and maybe even physically impossible.

The sturdiness, build quality and features of CP2s are really great but can it cripple the cameraman if he's just operating alone and handheld? Or is there absolutely no reason to go with it if the production is more guerilla and smaller size and weigth could matter (if the quality is identical(?)) ? That response about different bokeh makes me wonder...because I liked it on the CP2 but I've never used ZF and do not have the chance to compare them.

Thank you very much in advance!
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#2 Dennis Couzin

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Posted 28 November 2014 - 12:29 PM

As an optics engineer I very much doubt that the f/2 CP.2 lens is "optically identical" to the f/1.4 ZF.2 lens.  Online pictures show the f/1.4 to have a larger front element.  So the lenses are not literally optically identical but having different irises.  It is conceivable that the f/2 design is the f/1.4 design with (at least) its front element shaved down, but has anyone verified this?  I suspect "optically identical" is optically ignorant marketing talk.  Get MTF data at corresponding apertures for the two lenses before making your decision.


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#3 Albion Hockney

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Posted 28 November 2014 - 12:33 PM

are you talking about buying or renting?

 

I would say the visual differences you will see in the resulting footage will be subtle. the bokeh being the biggest and maybe yea the CP2s coating performing a little better. The Cp2's are far more expensive so in my opinion the question is really about how to best spend your budget and where that money will go. If you can afford it get CP2's....or if this is to own I would think about the long term value stay and also if you plan to ren them out.

 

The Zf2 and Cp2 should have the same aperature's btw.... Zeiss released the Cp2 "super speeds" which have the wider stops ....although they are not sharp at those stops at all and neither are the zf's

 

 

as for as operating handheld alone....without a follow focus its easier for sure to pull off the barrell of a photo lens the long focus throw on the cp2s is good for critcal focus and narrative work and really needs a follow focus.


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#4 Albion Hockney

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Posted 28 November 2014 - 12:37 PM

As an optics engineer I very much doubt that the f/2 CP.2 lens is "optically identical" to the f/1.4 ZF.2 lens.  Online pictures show the f/1.4 to have a larger front element.  So the lenses are not literally optically identical but having different irises.  It is conceivable that the f/2 design is the f/1.4 design with (at least) its front element shaved down, but has anyone verified this?  I suspect "optically identical" is optically ignorant marketing talk.  Get MTF data at corresponding apertures for the two lenses before making your decision.

 

I think this is actually true for the most part dennis there may be some small differences but I think this phrase "optically identical" is not marketing talk as if anything Zeiss wants use to beleive the CP2's are optically better then the ZF lenses as they are far more expensive.

 

The Cp2's are known as rehoused ZF's ....they took the glass and put it in a bigger housing, put on new coatings, and added more blades to the aperature.

 

The reason the CP2 is T2. and ZF is 1.4 is because zeiss locked the aperature at t2 beacuse under T2 the lens just doesn't hold up......People complained about this and then Zeiss released the Cp2 "super speeds" which just have the aperature open up as wide as it did on the ZF's


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#5 Dennis Couzin

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Posted 28 November 2014 - 04:18 PM

Albion, go to http://matthewduclos...11/02/cp2vszf2/ and look at the photo over the caption "It may not be obvious, but these two 85mm primes are share the exact same optical design".  The f/1.4 has a much larger front element than the f/2.  To say that Zeiss "took the glass and put it in a bigger housing" and then "locked the aperture at T2" is not true.  Putting "the glass" into a bigger housing does not make the glass smaller.  Until someone verifies that Zeiss shaved down "the glass" and put it into a bigger housing, very unlikely from a design point of view, "optically identical" is marketing (or blogging) boloney.


Edited by Dennis Couzin, 28 November 2014 - 04:22 PM.

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#6 Dom Jaeger

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Posted 28 November 2014 - 09:30 PM

Albion, go to http://matthewduclos...11/02/cp2vszf2/ and look at the photo over the caption "It may not be obvious, but these two 85mm primes are share the exact same optical design".  The f/1.4 has a much larger front element than the f/2.  To say that Zeiss "took the glass and put it in a bigger housing" and then "locked the aperture at T2" is not true.  Putting "the glass" into a bigger housing does not make the glass smaller.  Until someone verifies that Zeiss shaved down "the glass" and put it into a bigger housing, very unlikely from a design point of view, "optically identical" is marketing (or blogging) boloney.


There is a front element mask on the f/2 85mm CP.2 which is removed on the super speed f/1.4 CP.2. The front element is the same size as the ZF lens. Hard to find a good pic of the front, but have a look at the picture on this site:
http://bob-productio.../arenda/item/82

There are f/1.4 and f/2 versions of the 35mm and 50mm ZF lenses, which are in fact different designs. The f/1.4 50 mm for example has 7 elements in 6 groups, while the f/2 version (which focuses much closer) has 8 elements in 6 groups, with a floating element group. But in the CP.2 versions there are the f/1.4 super speed, the f/2 "macro", and an f/2 standard which is a constrained version of the f/1.4.

While the standard and super speed versions of both 50mm and 85mm CP.2 s are the same size and weight, I suspect the 35mm f/1.4 super speed CP.2 is a different design to the standard f/2 version since it weighs more and is physically longer. The ZF data sheets have the f/2 as 9 elements in 7 groups, while the f/1.4 is 11 elements in 9 groups with an aspheric component. I have yet to work on a 35mm super speed CP.2 to confirm that however.
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#7 Dennis Couzin

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Posted 29 November 2014 - 12:04 AM

The original post compared an f/2 CP.2 with a "wider aperture" ZF.2.  The Matthew Duclos blog compared the f/2 85mm CP.2 with the f/1.4 85mm ZF.2.  Dom Jaeger mentions the Super Speed f/1.4 85mm CP.2, and links a picture, and yes, it is possible that the f/2 85mm CP.2 has a much larger front element in it than shows.  Like the earlier mentioned possibility of a shaved down front element, the question is: who has verified it?

 

Masking a front element and reducing maximum aperture by a full stop would reflect poorly on Zeiss manufacturing.  It would appear that they're building the f/1.4 lens, testing it at full aperture, and the losers are put in the f/2 bin for the restricted mounting.  That kind of trial-and-error manufacturing existed many years ago when lenses were sometimes binned f/1.8 vs. f/2.  But a full stop restriction, today, at Zeiss, is shocking (if true). The losers would probably be a little worse at f/2 too.  Owners of losers, carrying around the extra glass, would be ashamed of their lenses. 

 

So let's verify for the f/1.4 85mm CP.2 vs. the f/2 85mm CP.2.  It is not enough to learn that both these lenses are, e.g., 6 elements in 5 groups.  That would only suggest that they are in the same design family.  The simplest verification is from the typical entrance pupil, exit pupil, H, and H' locations, optical information Zeiss used to provide.  An optical shop that has disassembled the f/2 can also tell you. 


Edited by Dennis Couzin, 29 November 2014 - 12:05 AM.

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#8 Dom Jaeger

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Posted 07 December 2014 - 10:33 PM

The original post compared an f/2 CP.2 with a "wider aperture" ZF.2.  The Matthew Duclos blog compared the f/2 85mm CP.2 with the f/1.4 85mm ZF.2.  Dom Jaeger mentions the Super Speed f/1.4 85mm CP.2, and links a picture, and yes, it is possible that the f/2 85mm CP.2 has a much larger front element in it than shows.  Like the earlier mentioned possibility of a shaved down front element, the question is: who has verified it?

 

I spoke with a contact at Zeiss who confirmed that the Super Speed 85 and 50 CP.2s share the same optical systems as their T2.1 versions. The only difference is in the diameters of the front and rear openings and of course the maximum aperture, but the elements are the same size, just masked down on the standards. Reducing the ray bundle diameters blocks some aberrated rays, leading to better sharpness and contrast figures even though the elements are exactly the same. 

 

Masking a front element and reducing maximum aperture by a full stop would reflect poorly on Zeiss manufacturing.  It would appear that they're building the f/1.4 lens, testing it at full aperture, and the losers are put in the f/2 bin for the restricted mounting.  That kind of trial-and-error manufacturing existed many years ago when lenses were sometimes binned f/1.8 vs. f/2.  But a full stop restriction, today, at Zeiss, is shocking (if true). The losers would probably be a little worse at f/2 too.  Owners of losers, carrying around the extra glass, would be ashamed of their lenses. 

 

My understanding is that the aperture restriction was done in order to have a uniform set of T2.1 (f/2) lenses - at least down to 25mm - which is more desirable for cinematography than for still photography. Mechanically restricting the aperture and masking the front and rear of the 2 faster lenses in the set was the simplest, cheapest way of achieving that goal.  When an f/1.4 35mm was developed, Zeiss then re-introduced the f/1.4 50mm and 85mm to create a sort of mini lens set of 3 CP.2 Super Speeds.

 

I don't think there's any reason to assume that the 50 and 85 T2.1 versions are made from high speed ZF lenses that didn't pass muster, if anything the cine lens series needs to be more uniform than the stills series. But it's likely that the Super Speed CP.2s are subject to stricter quality control, since maintaining tighter tolerances for element centration and other factors during assembly would be more critical with those lenses. Which would explain why the 85 and 50 Super Speeds are slightly more expensive than essentially the same lenses as T2.1 versions.


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#9 Albion Hockney

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Posted 08 December 2014 - 12:09 PM

...I mean it does reflect poorly on zeiss though. I think the cp2's are over priced and the zeiss and canon both rushed to fill a spot in the market without developing new lenses to do it.

 

when looking at lenses in this price range the schneider xenons are much more interesting


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#10 Dennis Couzin

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Posted 08 December 2014 - 12:22 PM

As I understand you, Zeiss is assembling f/1.4 lenses, excepting their irises, and then selecting some of them to become f/1.4 cine lenses, some to become f/2 cine lenses, and some to become f/1.4 still lenses.  Ask your contact at Zeiss how this selection process works.  For example:

  1. Those with best f/1.4 become the f/1.4 cine lenses. 
  2. Of the others, those with best f/2 become the f/2 cine lenses. 
  3. The rest become f/1.4 still lenses.

In this scenario the f/1.4 cine lenses are probably a bit better at f/2 than the f/2 cine lenses, and my reference to "owners of losers" applies.

 

Try a little design exercise: a one element lens for one wavelength, for a certain glass index, using just spherical surfaces, for a certain focal length, for on-axis performance.  When designing the lens for f/1.4 you try to optimize the image quality at f/1.4. When designing the lens for f/2 you try to optimize the image quality at f/2.  Use a good sophisticated measure of image quality.  You find that your f/2 design comes out different from your f/1.4 design -- different curvatures, different thickness -- not just a shaved-down or masked-down version.  And you find your f/2 design is a little sharper at f/2 than your f/1.4 design is at f/2.  

 

The heuristic exercise is limited to spherical aberration, and it's a big extrapolation to the two Zeiss cine lenses, but it's scary and sad if Zeiss has chosen a "simplest, cheapest way" of making their f/2 cine lenses.

 

 

 

 


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#11 Dom Jaeger

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Posted 11 December 2014 - 10:42 PM

...I mean it does reflect poorly on zeiss though. I think the cp2's are over priced and the zeiss and canon both rushed to fill a spot in the market without developing new lenses to do it.
 
when looking at lenses in this price range the schneider xenons are much more interesting


Why does it reflect poorly on Zeiss? They were the first to provide properly housed cine lenses for the DSLR filmmaking community at a reasonable cost, and they set the bar pretty high. Compact Primes were a huge step up from still lenses, and allowing for interchangeable mounts really changed the game. It made perfect sense to rehouse ZF glass to keep costs down while still providing very decent optics.

Schneider HAD to design a new range because they didn't already have a modern line of Full Frame 35mm still lenses to adapt like Zeiss and Canon. Just because they are new designs doesn't mean there won't be compromises, to match the Zeiss/Canon price point there have to be some corners cut, it will just be a different flavour of compromise. More than four years after Zeiss pioneered the field you still can't get a full set of Schneider Xenons, whereas precisely because Zeiss "rushed in" to meet this market they now have the most versatile range of focal lengths, mount choices, macro and high speed options and matching compact zooms of any manufacturer. Seems like smart business to me.

The speculation about lens selection and "loser lenses" is waffle, each lens type would have its own quality control specs which are either met or the element/housing/lens is reworked/discarded. You don't completely assemble, calibrate and test a lens "without an iris" in order to assess it, then disassemble it and put it in different baskets for reassembly in a different housing with different irises, that would be a monumental waste of time and effort. Each element and housing goes through its own series of quality control tests before a lens is assembled, adjusted and tested. If it passes the specs for that particular lens it goes to market. My impression as a long time lens technician for the film industry is that Zeiss have very good quality control standards, even for their lower budget lines.

I should mention that I'm not affiliated with Zeiss in any way (in fact I generally prefer Cookes), but I've always been impressed with how they do things.
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#12 Albion Hockney

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Posted 12 December 2014 - 04:05 PM

I hear your points ....I guess I was little overly harsh.... I still feel for the price point and what they are doing the Zeiss stuff is a little over priced they are 4-5k/lens and the still lenses are like 1-2k /lens the the benefits of the cine lenses don't seems to quiet match the price when the optics are so close. I mean the reason they have so many focal lengths is because they already had the optics designed for the still lenses so its a much quicker process. That said I think they are nice lenses and if they were maybe a couple thousand dollars less a lens I think they would be a great option ....with the price point at what it is I would rather rent Cooke panchros which are optically far superior and usually 20-25$ a day more to rent.

 

the all said if you look at tests between the cp2 and the xenons the xenons out peform them for sure and have a nice look....the cp2s are not super consistent across the range optically some are better then others and wide open the super speeds are pretty terrible.

 

 

xenons have 18, 25, 35, 50, 75, 100 .....pretty close to full set. not sure if the 18 is out though actually .....they just need a 135 or 150 and its pretty full up.


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#13 Thomas J Tyler

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Posted 21 January 2015 - 07:50 PM

I own a set of the new CP.2s 25mm & 135mm at T2.1 and the Super speeds at 35, 50 & 85mm at T1.5. - The entire set was in the$25K range, Which I think was pretty fantastic.

 

I can say the newer CP.2 lenses are much sharper (for better or worse) than the older Zeiss CP.2 lenses, at identical aperatures.  Zeiss says all of theirs lenses are optically identical - that's a statement about their color matching and coatings. Technically anything in the CP or ZF families are "matched".

 

The biggest noticable difference if we are talking ZF lenses is the focus ring.  Nothing you do will let you roll focus as easily, accurately, and smoothly on the still lenses.  The questions is where you want to spend your money.  You know your clients, your work and your wants.  Gear purchase roulette, we all play it and then we eventually pull the trigger. 

 

I did a bunch of testing in my own workflow.  I'm a fan of the Cooke lenses but they were significantly more expensive (and backordered for quite a while),  the Schneider Xenons stacked up nicely, but at the time of my purchase nothing beyond 100mm and they were a big pricier for a few objective differences over Zeiss.  I went Zeiss because the previous generation worked well for me in the past. I work in a mostly Sony,  Raw/S-log work flow, I felt I was getting the best tools for my style of shooting.

 

Also, Please buy your lenses a nice case - no matter which you decide on.


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