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Flare control in multi-coated lenses of the Seventies
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PostPosted: Tue Jul 23, 2019 7:17 pm    Post subject: Flare control in multi-coated lenses of the Seventies Reply with quote
Flare control in multi-coated lenses chart from December 1973 issue of Popular Photography

http://www.aohc.it/testi.php?id_testi=59



PostPosted: Tue Jul 23, 2019 11:26 pm    Post subject: Reply with quote
Thank you for this chart.
Just to clarify - is better flare control with higher % or lower %?
Tom


PostPosted: Wed Jul 24, 2019 1:03 am    Post subject: Reply with quote
Quote:
According to Mr. Goldberg’s words, here is how the test works: the lens is placed at the opening of a large, hollow sphere containing several bright lights. With light flooding the front of the lens from every possible angle, a photomultiplier is used to measure the brightness of the detail-less image, and this measurement is considered to be 100 percent in the flare level. Next, a totally nonreflecting black target is placed at the side of the sphere opposite the lens. A lens with no flare will image the black target totally black, but a lens that has some flare will image the target as if it were some shade of gray. The amount of light present within the image of the black target is measured by the photomultiplier and expressed as a percentage of the first, all-white, 100-percent reading. In the simplest terms, the flare level of a lens is the percentage of light that intrudes into the image of a totally black target from a bright surrounding field of infinite size.


PostPosted: Wed Jul 24, 2019 6:40 am    Post subject: Reply with quote
Thank you once again for that clarification.
So, if I understand it correctly, the lower the percentage, the better.
Which makes the Topcor 35/2.8 one of the best of the bunch - better against flare than every Leica lens tested and most of the others.
Interesting
Tom


PostPosted: Wed Jul 24, 2019 7:27 am    Post subject: Reply with quote
Yes, with smc tak 50/1.4 leading followed closely by the other taks Smile


PostPosted: Wed Jul 24, 2019 7:42 am    Post subject: Reply with quote
visualopsins wrote:
Yes, with smc tak 50/1.4 leading followed closely by the other taks Smile


That was a very helpful chart - thanks again.
Just goes to show how good the SMC coatings from Pentax were.
Tom


PostPosted: Wed Jul 24, 2019 7:47 am    Post subject: Reply with quote
Interesting chart.

I never used my lenses on film, but on digital there is huge difference between bodies.
Between NEX-3N, NEX-3N+LTII and A7R you'll see three different behaviours.
Actually, with or without a booster flares are fairly identical, but some of the flares are cut off with plain adapter.
Between NEX-3N and A7R sensors, there almost no resemblance in flare intensity and patterns.

Than there are adapters, which can reflect internally and for some lenses adapter blackening does make a visible difference.

I think not only digital is nothing like film, one digital can be nothing like the other.


PostPosted: Wed Jul 24, 2019 9:53 am    Post subject: Reply with quote
visualopsins wrote:
Yes, with smc tak 50/1.4 leading followed closely by the other taks Smile


I find the other end of the scale interesting too.
I'm generally not keen on zooms of this period & looking at the zoomar we might see one of the reasons, nearly 10% flare at one point!
Surprisingly the Soligor zoom is much more similar to the typical primes & beating most of the Mirandas...


PostPosted: Wed Jul 24, 2019 10:23 am    Post subject: Reply with quote
What is also interesting is that the Canon FD 50mm f1.4 with SSC shows more flare than the Canon FD 50mm f1.8 with single coating.
Interesting
Tom


PostPosted: Wed Jul 24, 2019 11:09 am    Post subject: Reply with quote
...

Last edited by Blazer0ne on Tue Feb 22, 2022 7:12 pm; edited 1 time in total


PostPosted: Wed Jul 24, 2019 11:19 am    Post subject: Reply with quote
Blazer0ne wrote:
Topcor in MC! Really?


Clearly there are many lenses included in the list that are not multi-coated.
It is their performance that is interesting
Tom


PostPosted: Wed Jul 24, 2019 12:20 pm    Post subject: Reply with quote
...

Last edited by Blazer0ne on Tue Feb 22, 2022 6:19 pm; edited 1 time in total


PostPosted: Wed Jul 24, 2019 2:27 pm    Post subject: Reply with quote
Blazer0ne wrote:
Oldhand wrote:
Blazer0ne wrote:
Topcor in MC! Really?


Clearly there are many lenses included in the list that are not multi-coated.
It is their performance that is interesting
Tom


Would it be correct to say:

At half the flare performance the older Super-Takumar 50mm f1.4 has twice as much character as the definitive SMC Takumar 50mm f1.4.


No.


PostPosted: Wed Jul 24, 2019 2:52 pm    Post subject: Reply with quote
Oldhand wrote:
Blazer0ne wrote:
Topcor in MC! Really?


Clearly there are many lenses included in the list that are not multi-coated.
It is their performance that is interesting
Tom


Next to the coating quality there are enough aspects in the optical design and finishing that can affect flare.
Number of elements. Baffles. Barrel interior finish. Element edges painted or not. Optics deep in the barrel like macros often have. I think the position of the aperture can have an influence as well.

Pity that there are so few Rokkors in the list. At home I must have PP and MP lens tests with more flare numbers. Might add them later on.


PostPosted: Wed Jul 24, 2019 5:23 pm    Post subject: Reply with quote
Blazer0ne wrote:
Ernst Dinkla wrote:
Oldhand wrote:
Blazer0ne wrote:
Topcor in MC! Really?


Clearly there are many lenses included in the list that are not multi-coated.
It is their performance that is interesting
Tom


Next to the coating quality there are enough aspects in the optical design and finishing that can affect flare.
Number of elements. Baffles. Barrel interior finish. Element edges painted or not. Optics deep in the barrel like macros often have. I think the position of the aperture can have an influence as well.

Pity that there are so few Rokkors in the list. At home I must have PP and MP lens tests with more flare numbers. Might add them later on.



Degraded or poor quality optical cement can also cause this test case to fail. I have seen it in the Topcor 35mm f2.8 silver, actually, with a doublet on the way out. Also with a Kilar 40mm f2.8 (Tessar type). Having good and poor copies of each available.

Something to consider on vintage lenses as the culprit could not be seen without removing the block and holding it at an angle. Then you have a lot of older lens elements with edge paint that has nearly completely flaked off.

Unlike resolving power, if the lens condition is not at least good to excellent, then these values can be seen as a stretch.

What percent loss could someone expect with an ordinary amount of internal dust?


@Ernst Dinka, to be comparable with the chart values those other tests have to be made using identical setup.

@BlazerOne, the chart was made in 1972...lenses were relatively new compared to now.


PostPosted: Wed Jul 24, 2019 5:49 pm    Post subject: Reply with quote
The Hexanon 135/3,2 is very good among tele lenses too


PostPosted: Thu Jul 25, 2019 10:21 am    Post subject: Reply with quote
More to the point, these results are so close to each other,

Can anyone tell the physical difference between 0.5% and 2% flare? Unlikely i'd wager.


PostPosted: Thu Jul 25, 2019 10:55 am    Post subject: Reply with quote
Ernst Dinkla wrote:
Oldhand wrote:
Blazer0ne wrote:
Topcor in MC! Really?


Clearly there are many lenses included in the list that are not multi-coated.
It is their performance that is interesting
Tom


Next to the coating quality there are enough aspects in the optical design and finishing that can affect flare.
Number of elements. Baffles. Barrel interior finish. Element edges painted or not. Optics deep in the barrel like macros often have. I think the position of the aperture can have an influence as well.

Another, quite important factor: The radii of the lenses. The Minolta AF 2.8/50mm Macro was famous for its last, concave lement which - around 1:3 - was reflecting quite a lot of light from the entire sensor back to the center of the sensor, causing a bright spot. Especially visible when you had a dark object in center of the image, surrounded by bright

Look e. g. at the Kern Switar 18mm 1:0.9 lens for Apollo 11: It had to be re-calculated with different radii because of too much flare.



tromboads wrote:
More to the point, these results are so close to each other,

Can anyone tell the physical difference between 0.5% and 2% flare? Unlikely i'd wager.


The difference can be quite visible (in dark parts of the image) or nearly meaningless (in bright parts of the image). In dark parts, the 2% flare is four times (!) stronger than the 0.5% flare.

Stephan
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