lens coating: yellow vs. blue

Alex H · Joined: 25 Dec 2011 Posts: 344

I would think that the lens caps, being made from plastic and having high probability to be worn out, would not be the best way to measure the precision of the lens mounts.

Alex

kuuan · Expire: 2014-12-26

kds315* · Expire: 2021-03-09

Metal mounts also wear out Andreas, especially lenses being 20+ years old (or more)... Laughing

kuuan · Expire: 2014-12-26

Alex H · Joined: 25 Dec 2011 Posts: 344

Yep, it is not as simple as it may seem. I hope You will find the right answer. I only have one adapter to use Pen F lenses on NEX and it worked acceptable with all Pen lenses I had tried. None of them was too stiff, although some might have been a little looser than the others. I tried two 20/3.5, one 25/4, two 38/1.8 single coated, one 38/1.8 multi coated and one 40/1.4 single coated. I still have most of them, except the two single coated 38/1.8, so I can check the serials later on. I know some of the lenses that I have are of later design and have Olympus own aperture markings - the so called "through the lens numbers" (from 0 to 6 or 7), while some others do not, or have a special sticker with these markers attached to the lens. As far as I understand, these lenses were designed to work with later camera, like FT, comparing to an earlier model F. But I might be mistaken. Unfortunately, the only lens that had issues with fitting the other type of adapter (too tight) is no longer with me and all I can remember is that it was single coated 38/1.8. I do not have pictures of it any more, so I can not check if that particular lens had ordinary F-stop markings, or "through the lens numbers".

Just look for Pen-F and Pen-FT instruction manuals to see the difference.

I am currently on the trip, so I have no access to any of my Pen-F/FT lenses to check how they look.

Alex

kuuan · Expire: 2014-12-26

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

Alex H · Joined: 25 Dec 2011 Posts: 344

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

Alex

malsano · Joined: 27 Nov 2012 Posts: 93 Location: Dubai

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

flaviomaia · Joined: 15 Jan 2013 Posts: 120 Location: Portugal

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.

sichko · Joined: 20 Jun 2008 Posts: 2475 Location: South West UK

ForenSeil · Joined: 15 Apr 2011 Posts: 2726 Location: Kiel, Germany.

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.

calvin83 · Joined: 12 Apr 2009 Posts: 7553 Location: Hong Kong

sichko · Joined: 20 Jun 2008 Posts: 2475 Location: South West UK

Mos6502 · Joined: 20 Jun 2011 Posts: 961 Location: Austin

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

calvin83 · Joined: 12 Apr 2009 Posts: 7553 Location: Hong Kong

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.

kuuan · Expire: 2014-12-26

kds315* · Expire: 2021-03-09

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?

kuuan · Expire: 2014-12-26

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.

kds315* · Expire: 2021-03-09

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!

kuuan · Expire: 2014-12-26

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.

kds315* · Expire: 2021-03-09

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.

kuuan · Expire: 2014-12-26

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.

Alex H · Joined: 25 Dec 2011 Posts: 344

Nordentro · Expire: 2015-01-29

kuuan · Expire: 2014-12-26