Can you observe through glass?

[fullmoon]

Hi all, so as the title states.  Can you observe through glass? Or can you without it effecting what you see through your scope too much? So my scope is set up in my bay window which is pretty much west. And it's been generally a good position for moon, Jupiter, Mars, Venus and orion lately. Well not the last 4 weeks due to cloud. But generally  I get quite a good range from South to West through my lounge window. And it saves me lugging my setup outside. Probably won't mind so much in the summer, but when I look out and it's 10.30pm and I get a brief chance of clear sky, I quickly set up my scope and view what I can. So will viewing through the glass really impact what I'm seeing through my scope too much, or is it not that big of a deal? Cheers

 

Rich

[Franklin]

No, you need to bite the bullet and get your scope outside under the stars. Ordinary glass is optically imperfect and will destroy the view through any scope, not only that but observing from the house will impede the view because of warm air currents. 

[malc-c]

IMO no.  The idea is to have stable air to get the clearest views that the precision optics, be that a mirror or lens used in the scopes construction so it can produce clarity and details.  The only way to do that is to place the scope outside otherwise the reflections and imperfections in the glass used in the window will spoil the results

[bosun21]

Exactly what these gentlemen said 👆.

[NGC 1502]

As above…..  About the only exception could perhaps be with binoculars.  You would need the room lights off to prevent reflections.

The late great George Alcock used binoculars through glass as he got older. If you’re elderly and poor health makes heading outside in the cold a tough call, then the compromise of viewing through glass would be better than no views at all.

[Franklin]

1 minute ago, NGC 1502 said:

perhaps be with binoculars

Maybe for looking at the sparrows on the bird feeder but for astronomy it won't work. When focusing on stars they will not reduce to pin-points of light as there will be gross astigmatism caused by the imperfections of the glass window and dispersion from the non-optical glass will greatly increase chromatic aberration, not to mention the double image created by double glazed windows. I know it's nice and warm inside but to see the universe at night you've got to get outside. Preferably away from streetlights, security lights, houses and any other kind of buildings that generate heat. When viewing through a scope, the heat that rises from the roof of a house WILL spoil the view.

[NGC 1502]

On 25th March 1991, George Alcock aged 78, using 10x50 binoculars through double glazing, made his final discovery.

Nova V838 Her.

Confirmed by Denis Buczinski

[Tomatobro]

I would try it and then decide if the results are not worth the effort. Nothing to loose if it does not work out

[Cosmic Geoff]

Reflections of the sun etc from double glazing reveal that the glass is quite distorted.

My house has some original Victorian glass and the view through that looks wonky even to the naked eye.

[Louis D]

Sure you can observe through glass.  Can you observe well through ordinary window glass, no.  Generally, you can still pick out the high contrast details like the positions of Jupiter's moons and the features along the moon's terminator.

If you go to the trouble of replacing your glass with optical glass polished flat to within 1/10th wave or better and coat it with anti-reflective multicoatings, you'd stand a much better chance of being able to do critical observing of low contrast objects.

Consider this.  I don't know of a single observatory, professional or otherwise, that observes through glass of any type.  The scope is always open to the elements.

[fullmoon]

So, I think you've all answered my question haha. And tbh I probably knew that was coming. Think I'll reposition my scope to the kitchen so it's easier to get out of the patio doors and out into the garden. 

Thanks all.

[Nyctimene]

You can, with some restrictions, if your window panes are of decent quality. I've done this several times in winter with a small tabletop Dobsonian (Skywatcher Infinity 76, 76/300, "Blue Penguin"), and posted the results on here. As long as you keep the magnification low (30x with the Penguin), the views are rather good, esp. for open clusters, brighter galaxies, even the moon. The sky area is  rather limited; darkening the room is a must; and you should keep the scope's view as perpendicular as possible to the window. Of course, it's a substitute, but still better than to watch TV.

Here's my report about an observation of Luna five years ago:

Posted March 2, 2018 (edited)

When I woke up unplanned at 2 a.m., the full moon looked through some fast travelling clouds, indicating that the strong gusty wind, paired with low temperatures of about -7° C, still not had calmed down. Under these conditions, I was too lazy to put out any gear; so I grabbed the "Blue Penguin", a Skywatcher Infinity 76, (small, but decent 76/300 dobsonian Newton, designed for children), and put it on the sideboard under the south facing kitchen window. The kitchen is well warmed by an underfloor heating, so I simply stayed with pyjamas and slippers. Additional warming up was provided by stroking our cat Tabby, a trusty nightly companion. Through the double-glazed window (very good build quality), I got nice, crisp and almost undistorted views at mag 30x. I started with the Grimaldi basin at the moon's western limb; at it's SE rim, a bright area was very obvious. The walled plain Riccioli could be made out easily to the NW. Lohrmann A, a small (12 km) crater appeared as a bright tiny patch without any details (IIRC, Lohrmann A was/is, for the reason of it's brightness, part of an observing schedule (list of 30 craters), the "Berlin System", used for the evaluation of total lunar eclipses). Grimaldi C, 10 km diam. was less bright. To the SW, the triangle of craters Crüger, Rocca and Sirsalis/A followed. W of Kepler, the albedo phenomenon Reiner Gamma stood out clearly. The three large lunar ray systems of Tycho, Kopernikus and Kepler were very distinct, as always with full moon. I meandered across the lunar disc for some more minutes and spotted the 20 km crater Pytheas N of Kopernikus, Plato, the Apennines and Alpes regions. After 40 minutes, the moon slowly hid behind the roof top, and I returned to bed, being pleased by a satisfying winter session, and still warm feet!

Thanks for reading

There was a discussion in the CloudyNights forum about this; have a look:

https://www.cloudynights.com/topic/857938-observing-from-inside/

Give it a go, and let us know!

Stephan

Edited April 1, 2023 by Nyctimene

[PeterW]

Depends on the glass. Went to Rye Nature Reserve recently, lovely big visitor centre with seats round the edge. Tried using my spotting scope through the window… ugh, not crisp at all, had to go back out into the wind to get the best views.

However I’ve enjoyed lunar views with my 12x binoculars whilst lying on the sitting room floor through a window.

peter

Edited April 2, 2023 by PeterW
Addition

[bosun21]

As a young teenager I used to lazily try and observe through my bedroom window. Even at this young age I realized that the views were substandard, and that I had to brave the elements to get what I determined to be decent results. This was probably more so, due to my young mind saying that more magnification equals better. 

[Sunshine]

Ah the classic observe through a window, don’t do it, it’s pointless and will only leave you questioning your telescope.

[skyhog]

You already have the answers to your question.

This does remind of an advert that appeared regularly in old s&t magazines. You could buy a film that effectively sealed the slit in an observatory dome. I think it was mylar. Not seen that since though...

[doublevodka]

6 hours ago, skyhog said:

You already have the answers to your question.

This does remind of an advert that appeared regularly in old s&t magazines. You could buy a film that effectively sealed the slit in an observatory dome. I think it was mylar. Not seen that since though...

Similar stuff is still available - https://www.baader-planetarium.com/en/turbofilm-127-x-51-cm-nd-01.html

 

As for the original question, technically yes, pitfalls are all listed above, but you'd be missing out on the best bit, being out under the stars! Very few things are more relaxing to me than being out on a clear and quiet night 🔭

[Jim L]

7 hours ago, skyhog said:

You already have the answers to your question.

This does remind of an advert that appeared regularly in old s&t magazines. You could buy a film that effectively sealed the slit in an observatory dome. I think it was mylar. Not seen that since though...

Baader sells an optical monomer film that is an uncoated version of their solar film which they call TurboFilm, and which they claim to be optically equal to a 1/10 wave plane parallel optical window.  Perhaps a frame to hold the film and that could slip into a window opening would be a worthwhile step in the right direction.  Here’s a link:

https://www.baader-planetarium.com/en/turbofilm-127-x-51-cm-nd-01.html

[skyhog]

Yes, that would be the same thing. My only thought would be that it would be difficult to fully heat seal an observatory and the only reason for doing this in the first place would be to sit in comfort against the outside elements. I've been doing that so long it's almost part of the experience, though, to be fair we don't have the winters a lot of our fellow forum members endure...😁

Edited April 3, 2023 by skyhog

[Paz]

Observing through glass will significantly compromise quality but I will admit I observe from indoors from time to time with a small scope. 

Most recently only a couple of days ago I was observing indoors because I've got covid (again) and am too ill to lug a set up outside and sit out there in the cold.

If the aperture is small and the magnification is low those things help to make the best of it.

A couple of other things... the more square on to the glass the scope is pointing the better, so whilst when outdoors a high moon is better, indoors a lower moon is better. The other point is radiators, which are often located under windows, if you have windows without heaters under them those are likely better prospects.

[ollypenrice]

On 01/04/2023 at 01:01, NGC 1502 said:

On 25th March 1991, George Alcock aged 78, using 10x50 binoculars through double glazing, made his final discovery.

Nova V838 Her.

Confirmed by Denis Buczinski

Fair point but, perhaps, slightly misleading. What Mr Alcock needed for this discovery was a knowledge of previous apparent magnitude to compare with present apparent magnitude. The quality of the view would not greatly affect this observation, especially since the comparison stars would be in the same field, or very nearly. In a similar way, a 'good' stellar view is not necessary for splitting doubles, which is why double star observers will sometimes 'over magnify' since what they are looking for is information rather than a pleasing view.

I suggest the OP simply make a comparative test. I'm confident that the result will indicate that observation is possible through a window but that the image is significantly degraded. How much this matters to an observer will vary from person to person.

Olly

[Macavity]

We always SAY "Starlight is Parallel"... But then recalling the
*Apparent forward displacement* diagram from Physics?!? 😬



They also say: "We leave it as an "Exercise for the Reader"! 😅

Edited April 6, 2023 by Macavity

[Stu1smartcookie]

hmmm... firstly taking the OP exactly as he wrote , then YES .. its possible , but , the principle of adding an imperfect glass pane will introduce all sorts of bizare distortions . However its down to the individual to determine if its bothersome or not . Stars are only points of light in the best and largest telescope of course , but the idea is to see them as precisely as possible . 

For some people , viewing through a small window is the only possibility . ie in a small flat in a high rise building with no balcony . Astronomy is a hobby that can be enjoyed by everyone , to varying degrees. From what i gather the OP can move the scope to a place where he is able to view outside ..so  its a no brainer really . There is a YouTube channel ( hertfordshire allotment) where the guy in his early days did view through an OPEN window . Still not ideal , but it kind of worked . 

 

[Louis D]

10 hours ago, Stu1smartcookie said:

Stars are only points of light in the best and largest telescope of course

Not necessarily.

[Stu1smartcookie]

45 minutes ago, Louis D said:

Not necessarily.

Care to elaborate Louis , for the record .