I remember all to well the giant improvement in closeup image quality when nikon upgraded their wideangle designs from non floating element to floating element. I simply will never forget, 2 decades ago (or more) when I film tested wideangle lenses from nikon and canon FD mounts (non floating versus floating element) versions. The floating element versions were so much better it wasn't even funny.
I would find it a little incredulous if a lens maker like zeiss, in the 21st century, would design a wideangle lens with real close focusing and no floating element.
I have read somewhere that Cosina lacked the ability to manufacture wide angle lenses with floating elements which is why the ones with that feature are still made in Germany. I do not think the ZF 25mm has Floating Elements.
The ZF 25mm makes no mention of using a Floating Element either on B&H Nor anywhere in the description or Catalog from Zeiss. If it did, Zeiss would state it as they do with every lens which uses a Floating Element.
Does this lack of floating element (be it in the zeiss zf 25 or any other lens) only affect its performance in close up images as opposed to infonity focus such as landscape use.
If so up to what kind of distances are we talking about here...?
Does the canon 24mm L series have them..or is that a dumb question with it being an autofocus lens?
marcwilson wrote:
Does this lack of floating element (be it in the zeiss zf 25 or any other lens) only affect its performance in close up images as opposed to infonity focus such as landscape use.
If so up to what kind of distances are we talking about here...?
Yes, close up performance is where the most benefit is seen. Should not matter with distant landscapes and I would think we are talking about a few feet to inches for the greatest benefit of the use of a floating element. One of my 50mm FLE Distagons for my Hasselblad had floating elements which one positioned manually with a secondary focus ring. If I remember correctly, it had adjustments up to about 12 feet and closer. 12 feet and infinity put the floating element in the same position so with that lens, the adjustement was only used for less than 12 feet/ 4 meters.
Although, there are certain non-floating-element, wide-angle lenses that have surprisingly good close-up performance. Hubsand mentions this about the Zuiko 21/3.5, and I agree.
AFIAK, the ZF 25mm has no floating element, but I also don't think this is reason to condemn it to the firey depths of Hell. Not yet, anyway
It is simply not a given that floating element designs ONLY benefit closeup performance. In fact the whole idea behind the floating element is that the element moves in the most optimal position for best image quality at whatever point it is focused. Floating element is of great benefit for the entire range of the lens. Lens without this type of design, like the 28mm F2.8 distagon tend to perform optimally in a narrow range only. In the 28mm F2.8 distagon, for example, this is the infinity position. I LOVE the 28mm F2.8 distagon, but as great as it is at infinity, quality drops off long before it gets to the close focusing distance.
I do not agree with this. Floating elements in wide angle lenses is not needed for better infinity performance. I am sure the narrow range, how you call it, where the 28mm Distagon performs best is enough for 99% of all photographs
Close up performance "suffers" much more from narrow DOF, there is no ultimate need for this to make a high performance lens. Macro lenses benefit from the FLE for the reason I mentioned before and because they are corrected for close up and many people would use them also for other typs, like landscape photos. The advantage not to have a FLE is that most lenses without this feature are hard to kill.
ambystoma wrote:
It is simply not a given that floating element designs ONLY benefit closeup performance. In fact the whole idea behind the floating element is that the element moves in the most optimal position for best image quality at whatever point it is focused. Floating element is of great benefit for the entire range of the lens. Lens without this type of design, like the 28mm F2.8 distagon tend to perform optimally in a narrow range only. In the 28mm F2.8 distagon, for example, this is the infinity position. I LOVE the 28mm F2.8 distagon, but as great as it is at infinity, quality drops off long before it gets to the close focusing distance. ...Show more →
cogitech wrote:
AFIAK, the ZF 25mm has no floating element, but I also don't think this is reason to condemn it to the firey depths of Hell. Not yet, anyway
That doesn't mean that it doesn't have a floating element. Zeiss doesn't often talk freely about elments of its lens design. There is also no mention anywhere about aspheric elements or ultra-low dispersion glass, or anything else. Zeiss not mentioning a design element doesn't necessarily mean that it doesn't have that element. It's just typical that they not say anything about it.
Zeiss does claim that the lens "incorporates the latest optical design". They also claim, and this is supported by the published MTF's, that the ZF 25mm Distagon, "features the very highest image sharpenss to the very edges of the image format even at full aperture".
Given the considerable divergence in the test images from this claim, we can possibly only conclude one of two things, 1) Zeiss is blantantly lying about its lens (unlikely), 2) there is a problem with the test (whether it be a bad sample, adapter problems, or test methodology). Are there really any other possibilities here?
The MTF for the 25 is flat, drops a bit as you move away from center, then spikes up towards the edges, similar to what the MTF for the CZ 21 does. Whether or not only a floating element can cause this, I do not know. There could be other types of mechanisms such as internal focusing, or rear element focusing that cause the elements to move in different places relative to eachother that may not technically be called "floating element design", but none-the-less help the edge sharpness.
Lotusm50 wrote:
That doesn't mean that it doesn't have a floating element. Zeiss doesn't often talk freely about elments of its lens design. There is also no mention anywhere about aspheric elements or ultra-low dispersion glass, or anything else. Zeiss not mentioning a design element doesn't necessarily mean that it doesn't have that element. It's just typical that they not say anything about it.
Zeiss does claim that the lens "incorporates the latest optical design". They also claim, and this is supported by the published MTF's, that the ZF 25mm Distagon, "features the very highest image sharpenss to the very edges of the image format even at full aperture".
Given the considerable divergence in the test images from this claim, we can possibly only conclude one of two things, 1) Zeiss is blantantly lying about its lens (unlikely), 2) there is a problem with the test (whether it be a bad sample, adapter problems, or test methodology). Are there really any other possibilities here?...Show more →
I disagree with this in regards what Zeiss state and promote about their lenses. I have a Zeiss lens Catalog featuring Hasselblad lenses put out in the early 90's where they specifivally mention the use of Floating elements and their benefit. If you also look at many of the PDF's at the Zeiss site for the lenses they make and have made for just about every lens mount/camera brand, they often talk about the use of special types of optical glass used(such as in the Contax N Zoom lenses) as well as the use of Floating Elements. Such technical abilities put into production is one of the things which Zeiss has built their reputation upon so they talk about it and state it often in their marketing material.
Given I used to work in camera repair and have taken about MANY lenses with floating elements, nikon, canon, mamiya, hasselblad, I can state that floating element does not inherently make a lens more suspectible to damage when being dropped. Fact is many lenses have different elements group moving in different ways. Not all elements and element groups that move are floating element. Floating element simply refers to an element in the specific position that helps optimize it for a specific object difference. A lens like the 28mm distagon is optimized for infininty work. While you might think that makes it suitable for 99% of photos a photographer shoots I can assure you it doesn't. Many photographers just not myself will use a 28mm lens to shoot scenes where we might want objects from, say 15 feet to infinity, or maybe 7 feet to 15 feet in sharp focus. As good as the 28mm distagon is there is a WHOLE world of photos out there that don't involve setting a lens on infinity and shooting. Floating elements will help distance, mid range and closeup performance.
I also don't see or understand how depth of field has anything at all to do with wide angle lens performance. It is irrelevant. It is a given that a photographer is capable of selecting the most advantageous apeture and focus point to allow their lens to perform at its optimum and any given object distance or magnification. DOF in and of its self has not impact on image quality.
ambystoma wrote:
It is simply not a given that floating element designs ONLY benefit closeup performance. In fact the whole idea behind the floating element is that the element moves in the most optimal position for best image quality at whatever point it is focused. Floating element is of great benefit for the entire range of the lens. Lens without this type of design, like the 28mm F2.8 distagon tend to perform optimally in a narrow range only. In the 28mm F2.8 distagon, for example, this is the infinity position. I LOVE the 28mm F2.8 distagon, but as great as it is at infinity, quality drops off long before it gets to the close focusing distance. ...Show more →
In most Floating Element designs used for Wide Angle lenses by Zeiss, the floating element(s) only float in close up focusing postions as in the Distagon 50mm FLE for the Hasselblad. I strongly disagree that Floating elements are of great benefit for the entire range. In fact, Zeiss themselves re-designed that Distagon mentioned above for the Hasselblad, put it in their classic series, and re-moved the Floatin Element design mentioning how technically difficult it is to produce AND how it really only benefits close up work where this lens is not often used, therefore no longer needed.
ambystoma, maybe you are right floating elements like to get droped from time to time, never worked in a camera repair shop so I cant really tell
What I want to say with the DOF comment is, before you can benefit from high close up performance, you need to have it in DOF.
Zeiss stated that the Distagons FLE is helping to keep the flatness of field on the best possible level in the close up range. I could not find any statements about further improvements with FLE by Zeiss.
If there are any I am glad to learn them. link in German only
Tariq Gibran wrote:
I disagree with this in regards what Zeiss state and promote about their lenses. Such technical abilities put into production is one of the things which Zeiss has built their reputation upon so they talk about it and state it often in their marketing material.
You haven't read alot of Zeiss materials. Contax materials only rarely spoken about a optical design element. Go and read all the ZF lens materials -- they say NOTHING about the elements in their optical designs, nothing about flaoting elments, nothing about ultra-low dispersion glas, nothing about ashpheric elements, nothing. Zeiss has been using aspheric elements since the 1930's yet never ever really mentioned it -- and they still really don't. Zeiss doesn't have to shoot about how they designed the lens -- the proof is in the performance. That is what matters, that is what they talk about and that is how they sell their lenses -- not whether it has 2 or 3 aspheric elements and one that floats. Your Hassy materials are a rare case when they did talk about an optical element. It is a very lonely exception to a very long standing practice -- a practice that continues today.
Lotusm50 wrote:
You haven't read alot of Zeiss materials. Contax materials only rarely spoken about a optical design element. Go and read all the ZF lens materials -- they say NOTHING about the elements in their optical designs, nothing about flaoting elments, nothing about ultra-low dispersion glas, nothing about ashpheric elements, nothing. Zeiss has been using aspheric elements since the 1930's yet never ever really mentioned it -- and they still really don't. Zeiss doesn't have to shoot about how they designed the lens -- the proof is in the performance. That is what matters, that is what they talk about and that is how they sell their lenses -- not whether it has 2 or 3 aspheric elements and one that floats. Your Hassy materials are a rare case when they did talk about an optical element. It is a very lonely exception to a very long standing practice -- a practice that continues today. ...Show more →
Regarding the floating element design, at least in the case of C/Y lenses, Zeiss mentioned it in every lenses that have it. At least it is benificial in commercial sense, and isn't much leaking technically by just mentioning it.
As to aspherical lens as early as 1930's, forgive my ignorance, but that's the first time I heard about it.
Edited by Cinstance on Jan 30, 2007 at 09:18 PM GMT
bathman wrote:
FLE is more expensive and can fail when the lens drops >Kaput
Hmmm. I think you missed the point of the question. The question was addressing the issue of the inconsistency between the test results and published lens information and data. It had nothing to do with whether the lens has floating elements or not.
