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Feel the intensity, not your equipment. Maximum image quality. Minimum weight. The new ZEISS SFL, up to 30% less weight than comparable competitors.

More to Close-Focus (1 Viewer)

Maljunulo

Well-known member
...Perhaps it's experience with cameras that makes close focus seem a no-brainer. True macro lenses are indeed a specialty, but those focus to inches/cm. Camera lenses are designed to higher optical standards than binoculars, yet most focus (internally these days) under 1m, and even telephotos to 2m or so. No one argues about who does that how often, or calls it unnecessary complexity or expense.
I am not convinced that is a valid comparison.
 

Binastro

Well-known member
Firstly, a stereo camera should be compared to a binocular.

Secondly, cameras and binoculars are different devices.

It is clear that some lenses focus close and far with good detail.

It is clear that some binoculars can work quite close and far with good detail.

In both cases some areas are relaxed to achieve this.
The magnification changes with distance.
The distortions change with distance.

A small Maksutov Cassegrain has massive changes in focal length depending on whether it is used for astro with inverted image or terrestrially with a prism.
In addition it works close up.
This is despite the fact that it is computed at infinity with the shortest focal length.
But they are slow devices.

The Sigma complex 500mm f/4 mirror lens only gives tolerable images at one distance, from memory a rather close distance.
At long and very close the image is awful.

The rather simple Nikon 500mm f/5 mirror lens is much better.

I am not convinced that internal focus maintains aberrations at all distances.

Regards,
B.
 

Patudo

Well-known member
I don't understand the argument of this post at all. This definition is a dinosaur from the era of Porro prisms, and if you find internal focusing somehow impure you can keep using those.

...and those saurian bellowings (bleatings, more like) would have a modicum of amusement value had they not been repeated ad nauseaum. One wonders how the self-declared "curmudgeons" of former decades might have railed against trends like longer eye relief and center focusing - and heck, watching birds itself must once have been seen as every bit as much a fringe activity as watching insects is today.

If one finds short close focus so frickin' objectionable - well there are plenty of binoculars out there that won't do that. A car to me is purely a conveyance for getting me from point A to point B, but far be it for those like me to rail at those who wish to get from point A to point B at speed, or in style and comfort...
 

Pinewood

New York correspondent
United States
It is clear that some lenses focus close and far with good detail.

It is clear that some binoculars can work quite close and far with good detail.

In both cases some areas are relaxed to achieve this.
The magnification changes with distance.
The distortions change with distance.

...

...

I am not convinced that internal focus maintains aberrations at all distances. Agreed

Regards,
B.
Hello Binastro,

It is my recollection that either the 50 or the 60mm lens for the Hasselblad, had a floating element with three settings to optimize performance at various distances. To achieve something similar in a binocular with internal focussing would requite either a change in the settings of the internal focussing elements or a mechanically sophisticated device to do so automatically. The latter would not come cheap.

Stay safe,
Arthur
 

Maljunulo

Well-known member
Arthur, you have brought back memories of how much I wanted a Hasselblad in my younger days.

When I visited the Nordic countries, they cost $1400 US, which was beyond my grasp. I can’t remember if that was body only, or with the normal lens. (which I think was something like either 65mm or 85mm)

Then life got in the way, but I never did manage it.
 
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Binastro

Well-known member
Hi Arthur,

My Zeiss lens expert is even older than I am, and I am not sure he would remember.

I had not known this.

Maybe it is a 60mm Hassleblad lens.
I think the 50mm may have been the Zeiss well known wide angle.

I have the Zeiss Jena 50mm for Pentacon Six, and this has no settings for distance.

Some of the finest lenses, say for making digital components, are strictly one distance and may be also for monochromatic light.
Price in the several $100,000.

The anamorphic movie lenses can be really complex.

However, some of the simplest macro lenses have been around for a very long time, and work well close and far.

Regards,
B.
 
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