Is Swift Osprey closer to 7x than 7.5x magnification? (1 Viewer)

The Swift Osprey was sold as a 7.5x42 binocular. But my pair (S/n: 844121) perform so close as to apparent magnification and depth of focus to a pair of Nikon Action VII 7x35 binoculars as to make me ask: Is the Swift Osprey closer to 7x than 7.5x magnification?

Incidentally I have never seen anyone on the Forum claim for 7x binoculars the great advantage in performance that they have over higher-powered binoculars when looking through imperfect window glass. I suppose that this is a function of depth of focus -- And the Swift Osprey does also match the performance of the Nikon Action when viewing through the same imperfect window glass that far more markedly mars my observation of garden birds through more powerful binoculars

Stephen Prower

Good double glazing takes up to 20 x 60 binoculars without degradation except for ghost images so long as you view at right angles to the glass or nearly so.
Good parts of the glass takes 60 x 80mm with no problems and special glass up to 400x or 500x with 200mm aperture scopes at a big angle.

We've still got quite a lot of the old 'wobbly' glass in our Victorian windows and you really can't use even a 6x through them. The modern float glass in the newer extension is generally fine.

David

I must admit that the excellent plate glass I used was 1960s and the double glazing 1980s.
It is surprising how reflections from the double glazing are not at all good but viewing through it especially through selected portions is excellent.
I did notice that for some reason a Tamron 200 mm camera lens changed focus through the plateglass window even though the photos were good.
Through the double glazing I can regularly use a really excellent 70 mm mirror lens spotting scope at all magnifications from 30 times to 120 times with excellent resolution and images at all powers especially during daylight.
The advantage of observing from indoors if the central heating is not on is that temperature variations are greatly reduced and for this reason alone the images can be better through window glass than outside.

Viewing the planet Mars with an 8 inch Maksutov telescope made by a master optician through his selected attic plateglass window probably tweaked by him and using 400 times or 500 times magnification was something nobody would believe unless they saw it for themselves. The detail seen was quite incredible. I certainly was amazed.

When I was young I mostly observed outdoors so any poor window glass experiences were denied to me.
I was though quite surprised at how bad some early Hoya filters were. They were actually worse than window glass. They seem better nowadays.
if I ever used filters they were by B&W which I think is actually Schneider. Or own makes such as Minolta, Nikon or Canon. Soviet filters are also good even the large ones for their 1000 mm F/10 Mirror lenses. you can buy a whole lens and 4 filters for less than the price of one large filter by another good maker.
also some military filters by Ross are good even though a ships telescope made by them was amazingly poor. Broadhurst Clarkson are normally much better even though the optics were basically handmade sometimes during the war from bombed out window glass found in the street.

As to the difference between a seven times binoculars and 7 1/2 times.
One might be 7.2 and the other 7.3. So it would be hard to tell them apart.

Thank you Binastro!

A friend too may welcome your information re filters for Russian 1000mm f10 Mirror lenses. Strange how coincidence works!

Stephen

Typo

1955 vintage Crittall windows and glass of same vintage here. I'm almost the last in the street. The double glazing salesmen don't even any longer treat Crittall windows as a 'mark'.

Stephen

Stephen Prower said:

Typo

1955 vintage Crittall windows and glass of same vintage here. I'm almost the last in the street. The double glazing salesmen don't even any longer treat Crittall windows as a 'mark'.

Stephen

Click to expand...

1955, would that be Shephall?

Crittall windows!! Wow! you must be a martyr to vintage design.

David

Typo

Bedwell Monkswood (Second phase). No central heating: Robinson Willey gas fire. Think get both High Plash and Monkswood Goldfinches on feeders. Must be 50 at least circulating around centre of New Town and surrounding area. Consumption horrific.

Enough local talk! Just bought Celestron Nature 8x30 'try at the shop before you buy' from Microglobe on basis may be truly per Henry Link 6.9x27. Since it took three years of 'which shall I reach for' comparisons with modern binoculars to realise how good optically and mechanically durable the Swift Osprey is, I don't comment on the Celestron. But certainly will test it on window glass tomorrow!

Stephen

Steven,

Don't tell the council or you will end up with a listed building. We occasionally get 15-20 Goldfinch descend on us, but we are definitely low on the pecking order. A neighbour has 15+ feeders and after a stop there I'd guess they are too fat to manage a couple more fences.

Glad you managed to find Microglobe. Are they still as chaotic as they used to be? Hope you enjoy the Celestrons. Good for the money as I recall, but I think they are rather fragile. One place I tried them picked up three that rattled before that found one that worked. The Opticron/Leupold/Kowa 6x30s cost a little more but have a very good reputation.

Enjoy!

David

Typo

1. Think by now I must have been using Microglobe for four
years. They always know what stock they hold: The problem is
sometimes finding it.

Six items of the latest bubble-wrapped Olympus 7x21 Classic
('The weight-meanie cyclist's choice': They now have better
coatings, but cost £29 instead of £21) recently managed to
hide themselves successfully from the searching staff for two
weeks. But they were hunted down and found in the end.

No lazy flanneling the punter that 'they must be out of stock'.

I enjoy my visits!

2. I think--Touch wood!--that I am OK with the Celestron Nature
8x30.

They have certainly brought me luck: Yesterday a Stock dove and
two to three Redwing foraging at 20 yards in Golders Hill Park
(They've also got two captive Stone curlews in the free zoo! But
it would be a cheat to photograph them). Today cycling around
Weston: two Black squirrels and feeding flocks of
Fieldfare/Redwing; Fieldfare/Starlings; and Common Gulls.

But as everybody else has said about them: More emphatically
than other purchases: 'Read up everything on the web, and then
try before you buy!'


Stephen

Typo

I forgot: For obvious reasons, also ideally visit when there are several pairs of Celestron 8x30s in stock!

Stephen

Only been there the once and the shutters were down, doors locked, and lights off, but once you'd uttered the password.... "customer", the owner was charming and very helpful. How on earth they managed to track down the models I asked to try in the apparent chaos was beyond me, but they did and I left happy.

We've had several Fieldfare/Redwing flocks rest up in the trees at the bottom of the garden this winter which I've not noticed before, but they are regulars along the Bean valley. Scarcely seen a Starling.

Enjoy the Celestrons. Did they work with the windows?

David

Typo

[As you say: I have seen Redwing/Fieldfare flocks the
last two maybe three Winters on the fields West (and
this Winter a eek or so ago, also East) of Astonbury
Farm. The farmer's wife at White Hall Farm a year or two
ago also talked of the Fieldfares I was looking at in
the canopy as familiar visitors].

1. Like I said, it took me three years of comparisons to
fully appreciate how the Swift Osprey still punches its
weight alongside modern binoculars. If a heavy
non-waterproof '7x42' plus lightweight ditto 10x25 suits
as a field combination, it remains definitely on.

I'm afraid I jumped the gun in expecting at least a
quick final answer from the window test of the
Celestron. Sorry!

2. In fact the test yielded inconsistent, and ultimately
totally confusing results, presumably as a result of my
eyes getting tired.

Thus my Nikon Action VII 7x35s, which I have
always experienced over the past four or so years as
handling window glass better than any of my other
binoculars, in the end seemed to perform no better than
an old pair of 8x 'kitchen' binoculars.

Yet over the time I have owned both, I have always
reached for the Nikon without question whenever the view
through window glass has bugged me.

3. I shall just over the issue of window glass, as over
other aspects of performance, like I did with the
Osprey, have to take my time to reach final conclusions.

4. Yet, I immediately part swallow those fine words!

Frank D, as I recall from when I scanned the Forum,
talked of the field performance of the Celestron in the
same terms as the performance of the Nikon Action. I
thought: That's high praise ... !

Now also owning both, I understand: You lose a bit of
blurred field out towards the periphery of the field of
view with the Celestron; but you also lose a substantial
amount of weight. The Celestron maintains the same
distinctive quality of view as the Nikon in the part of
the field that remains.

I already find that a very good deal.

Dreams already--IF the build of the Celestron survives
shakedown!--of possessing the just luggable working
combination of field binoculars of not too heavy 7x27
and ordinary 10x42 specification!


Stephen

Stephen,

We've strayed quite a long way from Swifts. I'll reply in a PM.

David

Also gone mad. me that is.
8 x 30 Celestron. Microglobe. 8.30 degree field. Approx. 6.7x mag. Distortion free eyepieces. Edges quite good but varies depending which edge.
Crescent Moon and Earthshine very nice this evening.
Will test further.
Can they really be waterproof?