Orientation help

[BoisBlancBoy]

Ok first off I want to tell everyone this was the first time I have ever used a telescope and I had a blast! I used my Bushnell 700mm focal length, f/9.2, 76mm objective lens. Well I happened to have a few minutes to look at Saturn and even saw its rings!! It was pretty small but I was pretty excited. I also looked at the double Alya, pretty awesome!

Ok now that I have that out, I know all my images being reversed is normal but what I don't understand is if I set the scope parallel to the earth and look at an object, the object appears at an angle to the earth. Shouldn't it appear upside down? Because of this it makes it extremely hard to locate targets.

Thanks!

[Schorhr]

Do you use an image errector, included with many entry level telescopes?

Also keep in mind the focuser is a bit at the side.

Also set up a virtual telescope in Stellarium to simulate the view. There is one set up (8" newton iirc), but you can manually set flip and mirror image.

ctrl+o, alt+o

:-)

After a bit of observing the brain adjusts to the different view in the telescope.

Sadly the 76/700 does not take 2" eyepieces, but a. 30mm Plössl with a apparent view of field of about 50 degree should help locating objects, as the finder is pretty small.

In the long term a red dot finder, better a telrad or Rigel, will make oerientation and finding things in the night sky much easier.

Even the basic ones for 20-30€ beat the small optical 5x24, 6x30 (etc) finderscopes.

The red dot/circle finders will project against a acrylic glass and the dot/circle seems to project against infinity/the night sky. So it does not matter if you don't look through it straight as long as you see the dot.

With bought or printed star maps that have the circles on them, all you have to do is to align the stars on the circles the same way as shown on the map. Use a red light to preserve night vision.

When you did that, the object (star cluster, nebula) will be visible in a low or medium magnification eyepiece. Without searching (so called "star hopping") and upside down views.

[bingevader]

Ok now that I have that out, I know all my images being reversed is normal but what I don't understand is if I set the scope parallel to the earth and look at an object, the object appears at an angle to the earth. Shouldn't it appear upside down? Because of this it makes it extremely hard to locate targets.

Thanks!

You have the 'scope parallel to the earth, do you have the focuser parallel too or perpendicular?

If the 'scope were parallel and the focuser perpendicular (sticking straight up, might make viewing tricky ) then things would appear upside down.

If the 'scope were parallel and the focuser parallel (sticking straight out the side towards you) then the image would be reversed (the chimney on the left of the house your focused on would then be on the right in the image).

With the 'scope parallel but the focuser anywhere in between horizontal and vertical you'll get the image reversed through that angle.

Cheers

[BoisBlancBoy]

With the scope parallel to the earth the focuser is at roughly a 45 degree angle.

It's just making it very tricky since, as I'm looking at the target, I have to move the scope up for down and etc. but with things at a 45 degree angle it's making it not as simple as inverting X and Y. Am I stuck with this?

[LukeSkywatcher]

I prefer to observe using an erect prism "diagonal". It shows thing the correct way up and the image is not flipped horizontally either.

[BoisBlancBoy]

Do most scope view like mine does? Or do you just need to be up in the more expensive scope?

[John]

Refractors used with a star diagonal show a right way up view but left and right are reversed. With no diagonal they show an upside down view with left and right reversed which is the same as newtonian reflectors show. It's more normal to use a refractor with a star diagonal as it means less contortions getting to the eyepiece. These are the normal views that scopes deliver and you do get used to them.

You can get an erecting prism or eyepiece which gives a right way up, left and right as normal view but these are not normally recommended for astronomy purposes.

[NGC 1502]

Do most scope view like mine does? Or do you just need to be up in the more expensive scope?

Do most scope view like mine does? Or do you just need to be up in the more expensive scope?

Don't worry, your telescope is quite normal. After a while, the south-up view in a Newtonian will be easy to deal with, as will the 'angled' view if the focuser is at an angle to the ground.

Regards, Ed.

[LukeSkywatcher]

Refractors used with a star diagonal show a right way up view but left and right are reversed. With no diagonal they show an upside down view with left and right reversed which is the same as newtonian reflectors show. It's more normal to use a refractor with a star diagonal as it means less contortions getting to the eyepiece. These are the normal views that scopes deliver and you do get used to them.

You can get an erecting prism or eyepiece which gives a right way up, left and right as normal view but these are not normally recommended for astronomy purposes.

John, i'm curious. Why are erecting prisms not recommended for astronomy purposes?. My 70mm refractor travelscope came with one and i use it with my 8se. I cant detect any visual faults with it.

My 8se came with a bog standard star diagonal which most scopes come with.

Paul.

[John]

John, i'm curious. Why are erecting prisms not recommended for astronomy purposes?. My 70mm refractor travelscope came with one and i use it with my 8se. I cant detect any visual faults with it.

My 8se came with a bog standard star diagonal which most scopes come with.

Paul.

To get a fully corrected image requires several additional reflective surfaces. Each surface needs to be coated to a high quality, accurately polished and accurately aligned with the other surfaces involved. Unless the prism is made too very high tolerances (therefore = expensive) there is much more scope for errors to be introduced that will degrade the image to some extent.

A mirror diagonal has a single surface to be ground polished and aligned with the optical axis so less chance of error for a reasonable budget.

Viewing astronomical objects well is a very exacting business, more so that terrestrial viewing in my opinion, so I feel it's best to maintain the highest optical quality in the optical train as possible at all times.

[LukeSkywatcher]

To get a fully corrected image requires several additional reflective surfaces. Each surface needs to be coated to a high quality, accurately polished and accurately aligned with the other surfaces involved. Unless the prism is made too very high tolerances (therefore = expensive) there is much more scope for errors to be introduced that will degrade the image to some extent.

A mirror diagonal has a single surface to be ground polished and aligned with the optical axis so less chance of error for a reasonable budget.

Viewing astronomical objects well is a very exacting business, more so that terrestrial viewing in my opinion, so I feel it's best to maintain the highest optical quality in the optical train as possible at all times.

Thanks for that. I am pretty sure the erect prism that came with my 70mm travel scope is not of the highest quality. I am happy with it,as i like the views it provides and to me that is the main thing.

Im sure it would drive many people crazy.

[John]

Thanks for that. I am pretty sure the erect prism that came with my 70mm travel scope is not of the highest quality. I am happy with it,as i like the views it provides and to me that is the main thing....

That is the most important thing Paul

[LukeSkywatcher]

That is the most important thing Paul

I agree. I have checked out the prices of them online and i wont pay those prices. Im more then happy with the stock one i got and thats that.

[BoisBlancBoy]

Thanks guys I appreciate the explaination. I was just hoping to avoid that angular & backwards corrections to try and get in target. Maybe it's me just being new at it but it seems when trying to narrow down a DSO that it will just make it increasingly harder to do.