Вчера смог оценить угол, поле зрения самодельного бинокля "Найкон 2х54"
из двух телеконвертеров по звёздам (в очках). Ниже детали:
It was a clear night yesterday (01-02 March 2018), and even through my light-polluted
and dirty window I could see stars up to, let's say, 2nd magnitude.
So I used this opportunity to measure the real FOV of my 2x54 "constellation binoculars"
constructed from two Nikon TC-E2 afocal teleconverters.
-a- Looks like I could place Vega and Deneb at the very edges of my field even when wearing
glasses. From their coordinates the central angle calculates to 23.847 degrees or about 24 degrees
-b- Distance between Vega and the "left eye" of Dragon calculates to 22.253 degrees - and they did
fit in the binoculars' FOV with a small margin left
-c- The angular distance between Arcturus and Alcaid (which is the tail of the Big Dipper) is
30.568 degrees, when calculated from their coordinates. They are too wide apart to get in the
same view through the bins (wearing glasses), and to my eye it looked I needed about 5 degrees
extra
THEREFORE my conclusion is:
WHEN wearing glasses, with lenses almost exactly 10mm from my pupils, and holding the bins
so that my improvised eyepieces (which are 5mm above the rear lens edge, it's a concave lens)
touched the lenses, WE OBTAIN 24-25 degrees true Field Of View with theses "Nikon 2x54 binoculars".
WITHOUT GLASSES my measurements have been less precise, but I consistently seem to hit the
28-30 degrees in my estimations.
NOT BAD AT ALL
Yours truly etc.
Это было сообщние от Трутня.
------P.S.-------
-1- Sharpness at night can be amazing - if one centres the lenses precisely, which process can be a bit
fiddly. And the FOV is also affected by the piece position.
But given that you've done it properly, the field is uniformly sharp - and even at the very edges
where colouring (not visible with stars at night, I know it's there from the day views)takes effect,
it visibly "squeezes" the star point and it looks even sharper.
When used at day time, the binoculars are as amazing - centred properly, they can provide edges
without coloured fringes - even of crow heads against the sky, in full sunlight, or of other sharp
edges. Colouring does appear at the very edges of the field (as with all optical systems), but will be
invisible for normal objects - I had to use very contrasty roof outlines to check for its presence.
SO: it's a good, usable device.
-2- Прочие теленасадки также будут работать как широкоугольные монокуляры/бинокли,
если они "афокальные". Выше давали наводку на насадку для узко-форматной кинокамеры
Кварц (СССР) - и я видел отзывы о теленасадках для современных видеокамер.