olyacme,
Thank you for bringing up some interesting points.
After reading this thread, I feel like I have a better understanding of apochromatism.
I'm not surprised that manufacturers/marketers cheat when trying to sell lenses by associating their product with a desirable characteristic...even if it barely qualifies or doesn't qualify at all. I have known that some lenses are sold as apo's that clearly aren't - but didn't realize that even some of the lens that qualify as apo's don't start to exhibit those qualities until stopped down, and as you point out - some have to be stopped down severely, to the extent that it becomes a joke.
I didn't know how strict the original definition was or understand how much it has been watered down. I agree with you that manufacturers/marketers shouldn't use the label of 'apo' if their product doesn't qualify, and that there should be some commonly acceptable way of quantifying how 'apo' a given lens is, perhaps as you suggest by stating at what "f-stop" the lens is truly apo. When we as consumers are paying good money for lenses that are reportedly apo - they should be. Now I'm wondering just how apo my Leica-R 90/2 apo summicron asph really is.
Anyway, thanks for sharing your knowledge, and for remaining patient, persistent and unflappable even while being insulted.
Cheers,
Scott
I can certainly agree with you guys regarding regulating the use of the term and requiring manufacturers to state at which aperture it becomes "truly APO" according to the definition that olyacme has presented. This would assist me in judging at which aperture it might be "APO" according to my less rigid definition.
So, there are a lot of people out there disappointed with the performance of their APO marked lenses? I think there must be some performance differences are there would be a huge outcry. No doubt there are some really inexpensive zooms that should not be marketed as APO but I have yet to hear from anyone who uses Zeiss, Leica or Voigtlander APO marked lenses that is disappointed by the performance of the lens.
Tariq Gibran wrote:
I have yet to hear from anyone who uses Zeiss, Leica or Voigtlander APO marked lenses that is disappointed by the performance of the lens.
Clearly there are some makers whose standard for using the APO label is higher than for other makers. I certainly haven't been disappointed with most of the Leica APO lenses I've used, but it's the performance that matters, not the label.
Hi Tariq,
I didn't read anyone on this thread say that "there are a lot of people out there disappointed with the performance of the APO marked lenses". I think that olyacme is simply bringing up some good points relating to the APO terminology/performance in an educational manner.
Reading through Lloyd Chambers' various articles on DigLloyd...he has pointed out that some lenses he has tested (and he doesn't dwell on inexpensive zooms) are not true APO's. It's worthy of mention and it's worthy of discussion, and I don't think it's a matter of making a mountain out of a molehill :-)
I like to learn about and know stuff like this - it makes me a better educated consumer - doubt if it'll ever make me a better photographer though :-)
As digital camera sensors with ever-increasing pixel-densities resolve more and more detail...they also highlight weaknesses in lenses. Real APO lenses are bound to do better in some circumstances as newer sensors exploit those weaknesses.
Will I ever be able to notice differences in my images? I don't know, but I do know that I enjoy learning about this stuff.
Cheers,
Scott
Tariq Gibran wrote:
No doubt there are some really inexpensive zooms that should not be marketed as APO but I have yet to hear from anyone who uses Zeiss, Leica or Voigtlander APO marked lenses that is disappointed by the performance of the lens.
+1, but they apparently only satisfy an "incomplete" definition of APO.
It's always frustrating when marketing takes a term with a definition, soaks it in plasticizer, and slaps it across everything for sale. Instead of APO, short for a term that already has a meaning, they should have used RA ("reduced aberration") or something similar. It'd have the same marketing appeal to those who don't care for the details but enjoy acronyms when they purchase gear-- and it would preserve apochromat. Further, for truly high end lenses that move in the direction of being apochromatic, the lens makers could put up some kind of fun chart-- kinda like MTF-- that all the gearheads can drool over, debate, and make mash-ups of in order to compare lenses.
Cogi: I say we go one step further-- instead of when it becomes "truly apochromatic" why not have makers produce a chart showing which aberrations it clears as the lens is stopped down?
olyacme: Thank you for doing all the reading so I don't have to bother, my knowledge of the elusive definition of APO has taken a quantum leap. Superb macro shots by the way, very impressive stuff.
justruss wrote:
It's always frustrating when marketing takes a term with a definition, soaks it in plasticizer, and slaps it across everything for sale.
I don't know how many makers have claimed that 'APO' and 'apochromatic' are synonymous but that seems to be what many buyers have assumed. You know what happens when we assume... as far as I know there is no 1:1 correspondence between the two terms.
telyt wrote:
I don't know how many makers have claimed that 'APO' and 'apochromatic' are synonymous but that seems to be what many buyers have assumed. You know what happens when we assume... as far as I know there is no 1:1 correspondence between the two terms.
Perhaps some manufacturers have substituted an acronym there...
Anon Moss wrote:
Hi Tariq,
I didn't read anyone on this thread say that "there are a lot of people out there disappointed with the performance of the APO marked lenses". I think that olyacme is simply bringing up some good points relating to the APO terminology/performance in an educational manner.
Reading through Lloyd Chambers' various articles on DigLloyd...he has pointed out that some lenses he has tested (and he doesn't dwell on inexpensive zooms) are not true APO's. It's worthy of mention and it's worthy of discussion, and I don't think it's a matter of making a mountain out of a molehill :-)
I like to learn about and know stuff like this - it makes me a better educated consumer - doubt if it'll ever make me a better photographer though :-)
As digital camera sensors with ever-increasing pixel-densities resolve more and more detail...they also highlight weaknesses in lenses. Real APO lenses are bound to do better in some circumstances as newer sensors exploit those weaknesses.
Will I ever be able to notice differences in my images? I don't know, but I do know that I enjoy learning about this stuff.
Cheers,
Scott...Show more →
I agree with olyacme, as said earlier in the thread, that manufacturers should provide objective measurements and be specific when they use the term "APO". My remark about performance was in response to Telyt's post that the current use of the term "APO" is pure marketing and has no relationship to performance. Clearly, that is not the case either with the use of the term by companies such as Zeiss, Leica and Voightlander. There is a middle ground here.
S
"APO" has been abused but I do think we can reasonably rely on the term as used by the better manufacturers. Erwin Puts, in the Leica Lens Compendium, goes into a fairly detailed description of the history of apochromats and the use of different glass types to correct chromatic aberrations. With regard to Leica, he states:
"There is no agreed upon definition of what constitutes a ‘true’ apochromatic correction. Leica will designate a lens as an apochromat as both errors{red/green and blue/violet type chromatic aberrations} are corrected at full aperture, and over most of the image field."
Tariq Gibran wrote:
"There is no agreed upon definition of what constitutes a ‘true’ apochromatic correction. Leica will designate a lens as an apochromat as both errors{red/green and blue/violet type chromatic aberrations} are corrected at full aperture, and over most of the image field."
That works for me.
Yes, at least they published the definition (weak as it may be) that they're working under. It also permits explanation of the large amounts of Coma the Apo-Summicron 90/2 ASPH shows when wide open.
Tariq Gibran wrote:
My remark about performance was in response to Telyt's post that the current use of the term "APO" is pure marketing and has no relationship to performance.
TWEEETTT! Time out! Nowhere did I write that the APO term is pure marketing. What I wrote is that there is not a 1:1 correspondence between APO and apochromatic, that different makers have different standards for using the term, and that performance is more important than the label.
Nikon doesn't use the APO label, instead they use ED. ED is their high index/low dispersion glass that is used in many of their high-performance lenses. In several respects the optical performance of the original 300mm f/4.5 Nikkor*ED (the non-IF model) is the equal of the Leica 280mm f/4 APO-Telyt-R's performance, yet it does not carry the APO label.
telyt wrote: TWEEETTT! Time out! Nowhere did I write that the APO term is pure marketing. What I wrote is that there is not a 1:1 correspondence between APO and apochromatic, that different makers have different standards for using the term, and that performance is more important than the label.
Nikon doesn't use the APO label, instead they use ED. ED is their high index/low dispersion glass that is used in many of their high-performance lenses. In several respects the optical performance of the original 300mm f/4.5 Nikkor*ED (the non-IF model) is the equal of the Leica 280mm f/4 APO-Telyt-R's performance, yet it does not carry the APO label....Show more →
Sorry if I misinterpreted what you wrote here: "The APO label is used more a marketing tool than as a guarantee of performance." I guess I took it too far. I did not get from it what you have clarified above which I agree with. Looking through both the Nikon and Canon lens catalog, indeed I do not find any "APO" lenses listed.
Hi Tariq,
I was wondering whether Canon had any 'apo' named lenses too. I couldn't recall any, and your look through the catalog answers that question. Canon has many excellent lenses (mostly what I shoot along with a few alts) and I would assume that they must be going to a lot of effort to apo correct their lenses. How well corrected Canon's better lenses are relative to say Leica's designated 'apo' lenses - I don't know. I'm curious about how close Canon's better lenses are to being 'apo' (and at approx what 'f' stop), and if some of them do qualify (which I suspect they do)...it's interesting that Canon has chosen not to push that aspect in the marketing.
Scott
Superb macro shots by the way, very impressive stuff.