Home

Please support mflenses.com if you need any graphic related work order it from us, click on above banner to order!

SearchSearch MemberlistMemberlist RegisterRegister ProfileProfile Log in to check your private messagesLog in to check your private messages Log inLog in

lens coating: yellow vs. blue
View previous topic :: View next topic  


PostPosted: Fri Oct 25, 2013 9:06 pm    Post subject: Reply with quote

from what I remember having read I believe the lenses that have an aperture ring that not only has f stop marking but also markings 1 2 3 4 asf are the Pen-FT lenses, those with the 'normal' aperture ring are the Pen-F lenses. So far I have been thinking that the strong variation of fit of the rear caps don't go along that dividing line though, will try to verify that.

I don't have any precision measuring tool at hand, but a Macro lens Wink
to the left a lens on which the cap fits tight, and the right one where the same cap fits ( too ) loosely
( btw. the one to the left is a Pen-F, the one to the right a Pen-FT )

#1

#2

#3 both lenses turned abt. 180 deg.


From what I see I think it is safe to say that there clearly is a variation of construction of the Pen-F lens mount and that most likely this is why original caps fit tight on some and loose on others.

edit october 2014: photos had been lost, I just replaced two of them.
Files not with me now, taken from a site that I had allowed to use my photos: http://olypedia.de/Kategorie:PEN_F_System


Last edited by kuuan on Wed Oct 22, 2014 4:59 pm; edited 1 time in total


PostPosted: Sat Oct 26, 2013 7:19 am    Post subject: Reply with quote

I can measure my lenses and post here, but only next weekend.

Alex


PostPosted: Sat Oct 26, 2013 11:09 am    Post subject: Reply with quote

I have plannar 50 1,4 MM and AE by Contax. The AE is yellow and the MM is blue. I tested both and I prefer the Yellow one respect the blue one.

About Multi and single coating please note that Contax are both MC , so the lens color isn't related to MC or SC.

thanks


PostPosted: Sat Oct 26, 2013 3:39 pm    Post subject: Reply with quote

I have these two pairs: (from left to right)
Nikkor-H 28/3.5, Nikkor-H.C 28/3.5, Nikkor-S 50/1.4, Nikkor-S.C 50/1.4
I think the ones marked with "C" are multicoated version of the ones without "C".
In terms of colour reproduction the difference is minimal. I only see marginal differences in green channel contrast, being the multicoated more contrasty.
That said, the multicoated ones are probably from the same year (1973-74) and they show a completely different colour reflections from each other. The 28mm has a predominant green/purple, whereas the 50mm has a strong purple/amber with a faint green.



PostPosted: Sat Oct 26, 2013 5:24 pm    Post subject: Reply with quote

kds315* wrote:
Thanks a lot Calvin, this is a very good source, still complicated for many I guess.


This type of explanation is found all over the place. Unfortunately it is at best incomplete or misleading. At worst it is incorrect. I'll elaborate if you wish.

Quote:
Still I don't get it why not invest a little effort to learn and understand about that
using google, as it is all there for free... Guess I'm just too "old school", SIGHHH
http://en.wikipedia.org/wiki/Photographic_lens_design


Google is a great tool, the web is wonderful and an enormous amount of information is available. Unfortunately there are lots of contradictory reports and sometimes you need to be an expert to know which one is correct.


PostPosted: Sat Oct 26, 2013 8:18 pm    Post subject: Reply with quote

I have two identical 14x eyepieces by Lomo gomz from different production years - both are multicoated, one yellow-brownish, the other one blue. The yellow one shows better contrast, the blue one shows more natural colors.

So maybe it`s a matter of purpose and taste which one is better.


PostPosted: Sun Oct 27, 2013 4:56 am    Post subject: Reply with quote

sichko wrote:
kds315* wrote:
Thanks a lot Calvin, this is a very good source, still complicated for many I guess.


This type of explanation is found all over the place. Unfortunately it is at best incomplete or misleading. At worst it is incorrect. I'll elaborate if you wish.

Quote:
Still I don't get it why not invest a little effort to learn and understand about that
using google, as it is all there for free... Guess I'm just too "old school", SIGHHH
http://en.wikipedia.org/wiki/Photographic_lens_design


Google is a great tool, the web is wonderful and an enormous amount of information is available. Unfortunately there are lots of contradictory reports and sometimes you need to be an expert to know which one is correct.

In fact, I want to quote this link but I think more people will think it is complicated to understand.
http://www.animations.physics.unsw.edu.au/jw/light/non-reflective-coatings.html

and there is a decent one in Wiki too:
http://en.wikipedia.org/wiki/Anti-reflective_coating

My English is not good to write precise explanation on this subject. It will be good to see your elaboration which should be more accurate and easy understand.


PostPosted: Mon Oct 28, 2013 1:58 pm    Post subject: Reply with quote

calvin83 wrote:
sichko wrote:
kds315* wrote:
Thanks a lot Calvin, this is a very good source, still complicated for many I guess.


This type of explanation is found all over the place. Unfortunately it is at best incomplete or misleading. At worst it is incorrect. I'll elaborate if you wish.

Quote:
Still I don't get it why not invest a little effort to learn and understand about that
using google, as it is all there for free... Guess I'm just too "old school", SIGHHH
http://en.wikipedia.org/wiki/Photographic_lens_design


Google is a great tool, the web is wonderful and an enormous amount of information is available. Unfortunately there are lots of contradictory reports and sometimes you need to be an expert to know which one is correct.

In fact, I want to quote this link but I think more people will think it is complicated to understand.
http://www.animations.physics.unsw.edu.au/jw/light/non-reflective-coatings.html

and there is a decent one in Wiki too:
http://en.wikipedia.org/wiki/Anti-reflective_coating

My English is not good to write precise explanation on this subject. It will be good to see your elaboration which should be more accurate and easy understand.


Hi Calvin. I think that you might be disappointed. My elaboration, such as it is, concerns problems with the explanation offered by Rick Oleson and others, rather than necessarily offering a better one. Anyway, for what its worth, lets start with the Wiki link which you provided. : http://en.wikipedia.org/wiki/Anti-reflective_coating , and look at the figure under the heading Interference Coatings.



This picture is reproduced with permission from "DrBob". See Wikimedia Commons : http://commons.wikimedia.org/wiki/File:Optical-coating-2.png

The description tells us .

For this type of coating a normally incident beam I, when reflected from the second interface, will travel exactly half its own wavelength further than the beam reflected from the first surface, leading to destructive interference. .. If the intensities of the two beams R1 and R2 are exactly equal, they will destructively interfere and cancel each other since they are exactly out of phase. Therefore, there is no reflection from the surface, and all the energy of the beam must be in the transmitted ray, T.

The description has been examined here : http://en.wikipedia.org/wiki/Talk%3AAnti-reflective_coating ...

This way of explaining things implies that part of the incident light is reflected and then "destroys" itself. The average well-informed reader may imagine two photons being reflected, one from each surface, and then "canceling each other," resulting in the loss of two photons.

If true, it makes no sense to me at least. In order to stop one photon from being reflected, so that it may be transmitted, we lose two photons by some other means. We stop the reflection but the loss of light is increased.

A second problem occurs when we have a low light source where the photons arrive one at a time with long intervals between them ? Does a photon corresponging to beam R1 sit around and wait for a second photon to generate R2 ? No. Its either transmitted or reflected. We can do the experiment and count single photons.

However what if the waves, as shown in the figure do not represent beams of light with (implicitly) many photons, but rather some sort of probability describing what happens when one photon meets an interface. Again from the second link

the quantum mechanical explanation is that the waves both go forward and go back, but they are probability waves that determine the likelihood that a photon will be detected at one place or another. If they interfere with themselves so that the probability of a photon being detected in front of the lens goes to zero or thereabouts, the probability that it goes forward is increased. So more photons get through.

To me at least this is understandable. So my complaint is that the Wiki description doesnt tell us what it means by the wavy lines the waves. In that sense I think that its incomplete or misleading.

If we are going to use the idea of probabilities we might as well go straight to Feynman. See : http://reasonbroadcast.blogspot.co.uk/2012/03/photons-corpuscles-of-light-by-richard.html and http://reasonbroadcast.blogspot.co.uk/2012/03/fits-of-reflection-and-transmission.html These lectures discuss the reflection at two surfaces such as those in a a pane of glass or a soap bubble, or those in the Newtons rings experiment. Reflections at the surfaces of a thin film anti-reflective coating are analogous. Feynman shows how the amount of refection varies as a function of the distance between the the two surfaces. But at one point he tells us ...

We dont understand a damn thing but we have described how it behaves.


PostPosted: Mon Oct 28, 2013 6:13 pm    Post subject: Reply with quote

I'm not sure why somebody would think the photons were destroyed. It would be like suggesting a humbucker pickup works by destroying electrons.


PostPosted: Tue Oct 29, 2013 3:51 am    Post subject: Reply with quote

I am not disappointed sichko. Smile

Photon(energy) cannot be destroyed but they can be absorbed by electrons.

Light(photon) have both wave and particle properties. It will be more complicated when we consider it as a particle. Both question you raised was discussed in the first link I mentioned above and the link here: http://www.animations.physics.unsw.edu.au/jw/light/coherence-length.html . For a more precise explanation, we need to know more about particle/quantum physics which is behind the scope of this thread.

I think we could say that the anti-reflective coating works by they reducing the chance of light reflection at the glass surface(use the idea of probabilities). If the reflection is minimized, most light is passed through the glass. The visible color on the coating is the sum of the visible light reflected back from the coating surface.


PostPosted: Fri Nov 01, 2013 11:38 am    Post subject: Reply with quote

Alex H wrote:
I can measure my lenses and post here, but only next weekend.

Alex


I am very sorry that this thread ended up to be about two subjects, it was entirely my fault. Nevertheless:

Alex I'd appreciate very much if you find time to measure the mounts of your Pen-F lenses! Maybe even - still - in a newly started thread?
I have been in conversation about this issue with the main contributor of the Pen-F pages at Olypedia: http://olypedia.de/Kategorie:PEN_F_System he is very interested and investigating too

thank you, andreas


PostPosted: Fri Nov 01, 2013 11:53 am    Post subject: Reply with quote

That mount size difference is still a miracle to me Andreas. How can that be and still fit the cameras?? Wouldn't also be there a problem?


PostPosted: Fri Nov 01, 2013 12:17 pm    Post subject: Reply with quote

Klaus please look at the photos I provided above:
One clearly can see that the 'mounting' parts of the lens bayonet of one lens has 'sharp' edges while those of another lens are 'slanted'. Now I suppose that this is the only difference and that this difference alone is responsible for the different fit of the caps. The slanting alone sure would not influence the fit on the camera.

Still, additionally, I'd love to verify if the mounting parts of various lenses really have the exact same thickness. It certainly would be surprising if they had not, but can imagine that the strong and 'deep' leaf springs inside the camera mount 'could' pull the lens towards the camera, before the lens locks, well enough to guarantee a tight fit of lenses even if their bayonet parts 'somewhat' differed in thickness.


PostPosted: Fri Nov 01, 2013 12:44 pm    Post subject: Reply with quote

Yes,. that's what I meant, not just that slant, but from the "Bottom" (Auflage) to that first step, it looks quite different (height) to me, left compared to right!


PostPosted: Fri Nov 01, 2013 1:03 pm    Post subject: Reply with quote

exactly!
There must be 'some' space between the lens and camera mounts when the slide against each other when mounting, right? So it must be the springs on the camera mount pulling the lens towards the camera + the locking mechanism that make for the tight fit. Well, at least that's my thinking, and that the springs could allow for some difference of thickness of the mounting parts of the lens.


PostPosted: Fri Nov 01, 2013 1:20 pm    Post subject: Reply with quote

Well, not quite. That bottom part (Auflage) hat to sit tight on the camera, as this is part is what defines the "lens register" (Auflagemass), 28.95mm in case of the Pen-F camera. The rest above (so to speak) "only" fixes the lens towards the body using springs or whatever method used by the manufacturer. Tolerances there are not as important as tolerances to that base plate. All my Pen-F lenses sit very tight with very little, if ever any, tolerances.


PostPosted: Fri Nov 01, 2013 2:30 pm    Post subject: Reply with quote

Once mounted and locked the lens resp. the outer flat ring of it's mount of course sits flush and tight against the outer surface of the camera mount and therefore at the correct register distance! However I wonder if slight variations of the thickness of the lens' mount parts seen in my photos and which, when mounted, rest inside the camera mount is feasible ̣̣̣̣̣and actual in the case of Pen-F lenses, that the lens gets pulled tight by the springs and locks tight, then of course at the correct register distance, regardless of that slight variation.


PostPosted: Sun Nov 03, 2013 12:11 pm    Post subject: Reply with quote

kuuan wrote:
Alex H wrote:
I can measure my lenses and post here, but only next weekend.

Alex


Alex I'd appreciate very much if you find time to measure the mounts of your Pen-F lenses! Maybe even - still - in a newly started thread?
I have been in conversation about this issue with the main contributor of the Pen-F pages at Olypedia: http://olypedia.de/Kategorie:PEN_F_System he is very interested and investigating too

thank you, andreas


Here You go: http://forum.mflenses.com/lens-mount-variability-in-olympus-pen-f-ft-lenses-t62556.html


PostPosted: Mon Nov 04, 2013 12:40 am    Post subject: Re: lens coating: yellow vs. blue Reply with quote

kuuan wrote:
in front of me I have two copies of the same lens. The glass of one has a yellow tint, the other a blue/purple tint.
my question: does the color of the coating tell me which 'should' be the later, the 'better' coating?

well, I should try to find out be testing, resp. suppose that the one with the higher serial number, being the later, may have the better coating, but nevertheless I am curious if the color of the coating can tell us anything.

thank's


I also think the purple/ blue is newer than yellow/ amber and is multi coated but you can check if you have 2 copies of the same lens with different colors by compare the brightness of the reflections , the lens with brighter reflections will be the single coated one.


PostPosted: Mon Nov 04, 2013 10:07 am    Post subject: Re: lens coating: yellow vs. blue Reply with quote

Nordentro wrote:
kuuan wrote:
in front of me I have two copies of the same lens. The glass of one has a yellow tint, the other a blue/purple tint.
my question: does the color of the coating tell me which 'should' be the later, the 'better' coating?

well, I should try to find out be testing, resp. suppose that the one with the higher serial number, being the later, may have the better coating, but nevertheless I am curious if the color of the coating can tell us anything.

thank's


I also think the purple/ blue is newer than yellow/ amber and is multi coated but you can check if you have 2 copies of the same lens with different colors by compare the brightness of the reflections , the lens with brighter reflections will be the single coated one.


the question of coatings also surfaced in the other thread Alex had started about lens mount variability of Pen-F/FT lenses: http://forum.mflenses.com/lens-mount-variability-in-olympus-pen-f-ft-lenses-t62556.html

I also believe that in the case of Pen-F/FT lenses resp. their coating that tjose that rather looks 'amber' are of earlier make than those that look blue / purple. However from what I observe looking at my Pen-F lenses I believe that 'amber' not necessarily must means single coated.

During the period when Pen-F lenses were made development of multi coating was taking place, classifying in single or multi-coated may be simplifying and difficult: Some lenses will have single coating, others 2 or 3 layers of coating, some very late lenses possibly more layers than that. I even imagine that a lens could have individual single coated elements with different colors each or that there are lenses that could have some elements with single coating and other elements with more than one layer of coating.



..........

This ideas stem from articles I have read about the Super Multi Coating introduced by Pentax in 1971. Some say Pentax invented multi coating, other say that it had been around and used by a number of producers before but that it had not occurred to them to name it as such, that the introduction of the S-M-C was a mere marketing stunt by Pentax.

Truth seems to be a mix of the above and my personal take is as follows: Multi layer coating had been around long before the introduction of the S-M-C but until then other producers used 2 or 3, maximum 4 layers of coating while S-M-C had 7, some say 9 layers. Offering that at a commercial level for their all their SLR lenses was an achievement, advertizing their coating technology, which at the time most likely had an edge over that of their competitors, and giving it a name certainly was clever marketing by Pentax. Other producers were forced to catch up and later offered lenses touting their own naming of multi coatings.

this thread at Fred Miranda is quite good with many insights: http://www.fredmiranda.com/forum/topic/704895


PostPosted: Mon Nov 04, 2013 1:58 pm    Post subject: Re: lens coating: yellow vs. blue Reply with quote

This is very interesting, thx for sharing. I have also read that the OM-series who came later had both single and multi coating, and there was also a price difference on these lenses. Some where consumer made and some for PRO with multi coating.

Olympus also had the FTL series for a short period between the PEN F and OM, so can it be that maybe all PEN F lenses was Single coated? but with different coating material and thickness in the periode?!? It's really difficult to find any information about this topic. Surprised