2.1x42 Any use for birds? (1 Viewer)

I have 7x35 rangemasters, very nice. The 2x54 are these Nikon based models.. no cheap low quality! https://www.cloudynights.com/topic/536652-home-built-nikon-2x54-widefield-binos/

Cheers

PeerW

Hi Peter.
I see. Maybe they are as is, no extra optics needed.

I thought that you meant you used 2x Barlow, Nikon teleconverters as eyepieces and added objectives.

Your way is much more elegant.

P.S.
From memory the end stars of the Big Dipper might be 25.1 deg or 25.7 deg apart. I can't remember.

I have ordered some Nikon TC-E2, so will see if it works for me.
I may need to use my Minolta viewfinder correction dioptres, although my left eye might be O.K. without, at least at night.
I don't know if I can make the two converters truly parallel.

Afocal adaptors seem difficult to make well.
Zeiss resorted to radioactive glass for a 1.7x Mutar??, the only use by Zeiss of such glass that I found.

I had a Panagor?? fish eye adaptor that worked very well with stopped down lenses on my Minolta.
This is the only lens that ever cracked in minus 25C to minus 30C weather. The Minolta lenses were fine.
I think that the metal front cell contracted and broke the very curved front element.

16mm f/2.8 Minolta full frame fisheye lenses and probably others seem to have more or less front afocal lenses.

The rangefinder cameras with leaf shutters had 35mm, 45 or 50mm and 85mm lenses using interchangeable front halves. Never as good as a good fixed lens.
The 1950s Minolta 50mm f/1.8 or 45mm f/1.8 rangefinder lens was staggeringly good. Possibly a Minolta A?? camera.

Just received the Nikon TC E2s. Mint minus as described £15 each plus postage.

1 1/2 hour power cut restored, so I can see now indoors. Our emergency lighting did not work, battery probably. Should be checked every 3 months.

Unfortunately, being longsighted with little accommodation I cannot use these as is.
However, the Minolta Vn eyepiece correctors, of which I seem to have many, fit perfectly into the rear 'eyepiece' recess. The glass of the corrector is 8mm x 12mm.
Even so the field is less than with no corrector.
With reading glasses they work perfectly, but the field is further reduced.
One needs young or neutral eyes or both.

Coatings good and seem to be the same on both Nikon afocal units, but Minolta eyepiece correctors uncoated. My glasses are multicoated plastic.
I also have somewhere a Minolta dealers eyepiece corrector full unit. This is a slide with 9 correctors that is used to find the customers required dioptre. Very neat, and was quite low cost as an oddity.

Just looked at Orion with my reading glasses and one Nikon teleconverter.
The field is about 1.5x vertical Orion, Betelgeuse to Rigel.
Approx 25 degrees.
Stars sharp and I see stars not visible without the unit.
Edge performance is quite good.

Without glasses probably 30 degrees but not in focus so useless for me.

My pilot friend with excellent eyes cannot focus it without correction. He is probably a bit far sighted.

I think that these are probably optimum for minus 1 dioptre short sight.
And for younger folk with good accommodation.

The nice crescent moon is not good for me as my pupils are about 5.5mm, when they don't work well nowadays.

I will probably use one as a monocular with the Minolta Vn corrector.

The Dowling and Rowe 4x22 independent eyepiece focus binocular is better for me with its 16.5 degree easy field.

A simplified calculation gives 18.4 degrees for the angle between Betelgeuse and Rigel.
A map measure about 18.35 deg or 18.4 deg.
But I haven't done an exact calculation.

In daylight with rested eyes the image was sharper with old distance glasses.
At night reading glasses were better and Orion stars were sharp.
I think my eyes change focus night or day and if tired or not.

P.S.
Taking star positions for 2017.5, a simplified but more accurate calculation gives a maximum of 18.62 degrees.
One can do this because the two stars straddle the celestial equator and are not far from it.

However, The University of Texas at Arlington, Planetarium gives 18.56 degrees, which seems correct.

The trouble with measuring maps is especially difficult as the pages fold at the equator, although digital maps are better.

The Minolta Eyepiece Corrector 1000 (1985 onwards) also works on the Nikon teleconverter, but is not a perfect ft. The glass is 9x12 mm.
I prefer the Minolta Eyepiece Corrector Vn (1966 to 1985 I think).

Before 1966 they were circular.

I think the DSLRs have correctors inbuilt with a small wheel adjuster.

Many other camera systems had eyepiece correctors.

Nikon TC-E2 Mono.

For me.
Using reading or computer glasses the field measures vary from 24.75 deg to 25.75 deg.

Using the Minolta Vn eyepiece corrector the field is about 27.3 degrees.

Orion stars are nice and the whole constellation is visible, at least the brighter stars.

However, I think that for me the Vixen 2.1x42 would be much preferable as it can focus.
It is unlikely I will get one because of the cost.