TheSkySearchers

Many beginners wonder what that celestial thingy will look like in their telescope. Maybe they’ve looked at something, and they think it’s the thing but they’re not sure.

I recall on Astronomy Forum, someone linked to a website with a telescope simulator at astronomy.tools. You tell it your scope, eyepiece, Barlow or reducer, and the object, and it shows you what you might expect.

I’m linking that one and another one, Stelvision, I found. Stelvision doesn’t have very many objects, but it does a good job with realistic views.

http://astronomy.tools/calculators/field_of_view/
https://www.stelvision.com/en/telescope-simulator/

—Russmax

I'd add sketches from various fora and web sites, "Turn Left at Orion" and its web site, and possibly some of the bino observing books. Rod Mollise and Tony Flanders have posted their impressions of the Messier objects through different scopes and at different locations like urban versus suburban.

Since posting this, I played with "Scope Display" feature in SkySafari. It gives you FOV, but not really what the view will look like. Really helpful for picking EPs while viewing.

To use this, tap "Observe" at the bottom of the screen. Define your astronomy setup in "Equipment" and pick your setup in "Scope Display" You'll get a FOV circle for each selection defined and chosen.

--Russmax

Easy! It will look like a faint fuzzy.

I find many descriptions are too optimistic because they assume an experienced observer under great conditions. Most of us observe from urban and suburban locations. Also, the viewing conditions vary quite considerably from one day to another and objects are much fainter near the horizon, as they need to pass through more of Earth's atmosphere.

I test the conditions using binoculars on well-known deep sky objects. When clear of the horizon, the Pleaides (Seven Sisters, M45) are a good test. If you can see more stars than average, great. Using myself and 15x70 binoculars as an example, if I can see 10 stars, it is a poor night, 40-50 average and 80 up and I need to make the most of the night as truly great nights only happen about once per month where I live.

russmax wrote: ↑Fri Jan 24, 2020 6:32 pm Since posting this, I played with "Scope Display" feature in SkySafari. It gives you FOV, but not really what the view will look like. Really helpful for picking EPs while viewing.

To use this, tap "Observe" at the bottom of the screen. Define your astronomy setup in "Equipment" and pick your setup in "Scope Display" You'll get a FOV circle for each selection defined and chosen.

--Russmax

I find this to be a helpful feature with star hopping also. A circle representing the view through my finder scope facilitates this. I also have a smaller circle displayed showing the approximate FOV of the eyepiece/scope combo. it has worked really well for my star hopping.

If you have Stellarium (Who doesn't?), simply set up the Ocular View with your scopes and various eyepieces.

Here's a quick (partial) screen shot from five minutes ago in Vegas. Left-click for larger view.

I have my SS+ set up with FOV circles for the two EPs I use the most. Very handy.

My SS+ software is probably going to start rotting though - this is about Day 5 of overcast skies and there's no break forecasted for at least another 5 days. <sigh>

It is not easy to describe what you might see. Each person sees things differently, one's night vision may be below average, another might be color blind, and still another's color night vision may be exceptional. Some, like one guy I knew who is dyslexic spotted the streaks formed by M31s spiral structure with ease. After all, dyslexic people have incredible powers of observation. Then comes what you can see after several hours at the eyepiece. A beginner will see M31 in my 8" as just an oval bright patch of light. But I can see some structure after choosing the right magnification for the conditions. Speaking of which, seeing can affect what things look like, near a city the structure in M31 is gone no matter how much experience you have. What you see is very subjective and interpreted very differently by different people and changes with transparency, seeing and sky glow. This is not something you can pin down in a forum but must discover on your own at most being "coached" like below.

There are some things you can do while coaching viewers at a public star party on their own path of discovery. Don't tell them what you see until they tell you what they see. For example, showing M31, the viewer initially sees the oval patch of fuzzy light. Verbally guide them, say for example, "Look to the lower left of the field but don't stare hard. What do you see?" "Why, I see a slightly darker streak." "Very good, upper right closer the the brighter area?" "Yes, there is another." Then show them the photo of the spiral structure and they instantly know they saw exactly the same things, though very subtly. And, they will never see another photo of M31 the same way again. Running a viewing at your telescope this way relieves you of the responsibility of being subjective. It turns the night sky into an actual laboratory rather than just a museum. In other words, guide them with a narrative of not what you see, but of their own discovery.