Your best bargain?

Astronomically-related chat

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David Frydman
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Re: Your best bargain?

Post by David Frydman »

However, my 1000mm MTO of the first design with a serial number single digit something like 0004, I cannot remember, is the best quality photographic lens I ever tested. Perhaps over a thousand lenses tested.
Apparently, it resolves better than the theoretical limits. It completely outclasses a 3.5 inch Questar.
It is in a fitted wooden box.
I recall someone else who has one of these wooden box early ones.
The other strange thing is that it was supplied by possibly Sinclair?, who are situated maybe near Whitehall.
So this was made by the Soviets for photographing themselves.
Poetic justice, but it does not quite compensate for the 3 jet engines that Rolls Royce supplied to them, which was the basis of the outstanding Mig 15.
We were completely deluded by selling them these engines.
As we were by giving the Americans the Miles supersonic aircraft design.
They then quickly made the Bell X1 which immediately broke the sound barrier.
Out of interest someone made a half scale Miles design aircraft and that too went supersonic.
I think that we or our politicians are certifiable nutcases.
The only other comparable quality photo lens I tested was a Den Oude Delft Dutch 5.5 inch special military Maksutov. I tried to buy it but the owner would not sell although he had no use for it.
Visually, Saturn was amazing in it. The Dutchman I think maybe Bower independently invented something like the Maksutov, as did the Finn Vaisala in the 1930s I think. The Maksutov is a 1940 design I think.
I am told that there was a large quantity of 1/20th wave Maksutovs on some surplus Russian tanks, but the person trying to buy these was unsuccessful.
I think we have discussed before that the best optics are military, monetary cost of manufacture no importance.
Even 30 years ago £250,000 each for a 48 inch aspheric hand figured tele lens was the going rate.
And in the 1960s a super wide angle was £85,000.
These lenses mainly end up as junk on the rubbish tip, some deliberately chopped up. It did keep master craftsmen opticians in employment.
Unfortunately, if found, say in an Ex gov. auction, these military optics are often in bad condition, although sometimes one is lucky.

Regards, David
David Frydman
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Joined: Mon Jan 18, 2010 9:25 am
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Re: Your best bargain?

Post by David Frydman »

The person from whom I bought the MTO 1000 claimed it could resolve twice as well as the theoretical limit.
I confirmed this.
However, what we were seeing was I think explained by the Rayleigh limit.
I will check. It depends on wavelength but is I think around 5.6 arc seconds for a 1 inch aperture scope.
The Dawes limit is closer, maybe 4.5 arcseconds, again I will check,
What we were seeing can be explained by the Sparrow limit that I just found which is about half the Rayleigh limit. This is where you can see the stars are double without seeing them totally apart with a clear gap or just touching. You are seeing the dip between the two stars.
Also apparently using a USAF 1951 resolution chart of line pairs I have seen mention that the resolution is 60% of the Rayleigh limit for stars.
Again lines or wires have very different resolution limits to stars. In some cases wires have been seen 1.5 arcseconds wide with unaided eyes.
So essentially the MTO 1000 is perfect even accounting for the central obstruction.
In fact in some cases the resolution is improved by a central obstuction by moving the diffraction rings and placing very close double stars in the altered gaps.

The only real way to test various good lenses or scopes is to have them side by side.

And yes the MTO 1000 was one of the best bargains I have found.

Regards, David
Lady Isabella
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Re: Your best bargain?

Post by Lady Isabella »

The vast majority of the Tento 10x50 that I've seen were made by SOMZ (Salavatski Optiko Mekhanicheskii
Zabod), I've also seen in the flesh some that were made by ZOMZ Zagorsk.

Both companies still list this model, bodywork is the same, cannot comment on the optics as post-Soviet era ones
seem very, very thin on the ground in this country.
David Frydman
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Re: Your best bargain?

Post by David Frydman »

Talking about the same bodies in different makers binoculars.
I was surprised to find that the Japanese 20 x 65 Viper and the Japanese 20 x 60 Swallow have mostly identical body parts and maybe prisms also. The Swallow O.G. or optics are higher quality. The Viper maybe 4 element eyepieces. The Swallow 3 element but tiny star images for a binocular.
Yet these two binoculars seem to be made by different makers.
But these makers may be rather small workshops although I am not sure. The 20 x 65 Viper may be a larger enterprise as there are many seemingly identical 20 x 65s, but I have not seen any other 20 x 60s like the Swallow.
I understand there were many independent small workshops especially around Tokyo making astro eyepieces etc.
I think the T orthos and Kelners are still made in the same place for perhaps 40 years.
Some of the craftsmen must be well into their eighties and I wonder how their eyes are now to do the skilled work.

Regards, David
brian livesey
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Re: Your best bargain?

Post by brian livesey »

All very interesting stuff David. If Henry Wildey is anything to go by, those elderly Japanese opticians are probably "blind as a bat" by now; not that bats are really blind! :lol:
brian
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