Re: [ap-gto] [ap-ug] A colorful Southern Sky Beauty


ROBERT WYNNE
 

Did a little more research on the quality of pre-1990 lens fabrication. The running theme is that almost all camera lenses were figured with particular attention paid only the about the center third of the lens. Everything beyond that is poorly figured. Today's lenses are figured to a much higher standard to conform (as you stated) to CCD pixel geometries. Here I have to wonder if each camera's CCD even though sold as an equal to its market is precisely as equal as we may demand. -Best, Robert  

On 05/01/2021 11:53 AM Roland Christen via groups.io <chris1011@...> wrote:
 
 
Ne ver seen one but probably a very good lens.
 
Rolando
 
 
 
-----Original Message-----
From: ROBERT WYNNE <robert-wynne@...>
To: main@ap-ug.groups.io; Roland Christen via groups.io <chris1011@...>
Sent: Sat, May 1, 2021 1:13 pm
Subject: Re: [ap-gto] [ap-ug] A colorful Southern Sky Beauty

Any opines on fluorite lenses from 40 years ago. I have what at the time was a fairly expensive Canon fluorite telephoto lens that was specifically designed to "eliminate" chromatic aberration. -Best, Robert
On 05/01/2021 10:00 AM Roland Christen via groups.io <chris1011@...> wrote:
 
 
I have studied lenses and lens design for a generation. What is possible today versus 40 years ago is an order of magnitude improvement. The reason is that back then we did not have fluorite based low dispersion glass (ED and SD glass) available. Development of real glass with fluorite as the main ingredient was the breakthrough that was needed to make high resolution possible. It was not lanthanum because that was always around since day1. It was not fluorite crystal either since that was always available but had many drawbacks for mass production (high cost, fragile during processing).
 
The main driving force for ED lenses was sports photography and digital color television along with the flat screens that replaced the old cathode ray tubes. All of a sudden flat screen TV images were of high enough resolution that you could see the effects of chromatic aberration when the cameras zoomed in on the players down on the field. Camera manufacturers scrambled to produce higher performance lenses to meet the new resolution requirements. If you look at any old TV shows from the '60s you will see the green and purple fringing when the camera zoomed in on a subject.
 
Rolando
 
-----Original Message-----
From: Alan Friedman <alan@...>
To: main@ap-ug.groups.io
Sent: Sat, May 1, 2021 11:20 am
Subject: Re: [ap-gto] [ap-ug] A colorful Southern Sky Beauty

One of the old film lenses that was designed for sharpness over a wide field at maximum aperture was the Noct-Nikkor 58 f1.2. It was made in relatively small numbers with a hand-aspherized front surface element. The goal of the design as I understand it was to minimize coma in point sources of light to the corners of the frame. I used it a little last summer to photograph the comet… never got a good sense of its potential from the city location I was shooting from. 
 
I don’t have experience with medium format systems but in 35mm format lens designs for digital are all over the place. Leica is reissuing historic designs that bring intentional softness wide open. They are also introducing f2 lenses with apo-asph designations that are said to deliver remarkable correction across the full frame. These small manual focus lenses are $8000+ - I haven’t tried one. Cosina in Japan is producing several lenses with a similar goal under the Voigtlander name. I have used these Apo-Lanthar lenses and at f2 they are incredibly sharp. Chromatic aberration is very well controlled into the corners of the frame. There is vignetting wide open which improves at f2.8. About 1/8 the cost of Leica - an interesting option to pair with a 61mp 24x36mm sensor. 
 
 
Alan Friedman

On May 1, 2021, at 11:08 AM, Roland Christen via groups.io < chris1011@...> wrote:

 
I have seen MANY stunning results taken with very humble equipment (ex Canon EOS 70-200/f4L)
Sure, I agree, but that is not one of the old lenses made for film cameras. The original question was how good those old film camera lenses were. The answer that I got from my Pentax lens was - basically horrible at full aperture. Stopped down to near pinhole size - ok but very little light gathering power. Compared to a cheap and cheerful Rokinon that i bought for Milky way imaging, the old lens doesn't come close. The Rokinon is sharp even wide open. Take a look at my recent image that i posted of the Zodiacal Light. That was taken with the Rokinon at F2.
 
I have old Nikon lenses, including the original all-around 50mm F1.4 lens that most people used with their 35mm Nikon film cameras. Wide open it gathers a lot of light. Unfortunately that light is spread out over a huge blur circle, especially in the blue and red end, so that bright stars all have huge halos. These lenses were basically achromats, and fast achromats have horrible chromatic aberrations.
 
Rolando
 
 
 

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