Finderscope upside down

[Neptune38]

Hi guys,

I've been out this afternoon for the first time in daylight and managed to 'finally' get some trees in the distance into focus (took a while, to get my eyes used to the eyepiece etc) , but when i look through my finderscope, the trees are upside down, i'm sure there is a logical explanation for this, can someone shed some light on this please. Thanks in advance.

[laudropb]

The image in the finder scope is always inverted unless it has a correcting prism. To get a correct way up image you need to use a RACI Finder, but do not worry you soon get use to the upside down image.

[Neptune38]

The image in the finder scope is always inverted unless it has a correcting prism. To get a correct way up image you need to use a RACI Finder, but do not worry you soon get use to the upside down image.

Thanks for that, i thought i was doing something wrong... i have a lot to learn!

[Bizibilder]

Refractors, like your finderscope, will always produce an inverted image (as do Newtonians and a few other types of scope) - some designs also reverse the image left -right as well.

In astronomy it doesn't really matter which way up you see an image as there are no points of reference (like the horizon or ground) to tell your brain that the image is indeed the "wrong way up".

To turn the image the right way up again involves putting an additional lens in the optical path - this presents two problems:  Firstly the additional glass will make the final image slightly fainter and secondly the additional two surfaces of the lens will never be perfect and will cause a tiny amount of additional image degredation.  Overall it is usual to live with the inverted image of slightly better quality and brightness.

[Dave In Vermont]

Good software-programs that people use to print out star-charts from have options of the view to account for different finder-views. Which can save one from pulling their hair out at the scope, I think Stellarium (Free) has this option.....Anyone? I use TheSkyX at my scope, so I'm not sure.

Don't worry, Neptune - you'll be answering these questions for someone else soon enough!

Dave

[rockystar]

https://youtu.be/VtAwdO0Dhnc

Check out this video, explains it all

[Astro Imp]

Good software-programs that people use to print out star-charts from have options of the view to account for different finder-views. Which can save one from pulling their hair out at the scope, I think Stellarium (Free) has this option.....Anyone? I use TheSkyX at my scope, so I'm not sure.

Don't worry, Neptune - you'll be answering these questions for someone else soon enough!

Dave

Yes Dave you can indeed orientate Stellarium any way you wish to suit your needs.

Here's how:-

Flip vertical:- control/shift/V

Flip horizontal:- control/shift/H

HTH

[Stub Mandrel]

I got a right-angle finder which turns the view the right way up but it's still left-right reversed.

The straight through finder is easy to use as all you have to do is turn the star map upside down and it all works like you expect.

[swamp thing]

To turn the image the right way up again involves putting an additional lens in the optical path - this presents two problems:  Firstly the additional glass will make the final image slightly fainter and secondly the additional two surfaces of the lens will never be perfect and will cause a tiny amount of additional image degredation.  Overall it is usual to live with the inverted image of slightly better quality and brightness.

I don't think a few extra lenses will effect the faintness or quality of the image Roger. We use eyepieces with up to nine elements in them these days with no detrimental effects on image brightness or loss in quality. The real reason standard finders show an inverted image is obvious.....Cost. It's cheaper to make one without adding the correction lenses.

[acey]

What did the trees look like through the main scope? If it's a Newtonian (e.g. dob) they would have been inverted too. If it's a refractor with mirror diagonal you would have seen them upright but left-right inverted. Every mirror in the system introduces a left-right reversal: a Newt has 2, so they cancel.

The inversion in a finder is dealt with by turning your map around to match the view.

[spaceboy]

This is the hobby for you. Upside down, back to front, in fact anything to help confuse you trying to find those night sky objects while standing freezing your baubles off

[Stub Mandrel]

Why not make finders with Galillean eyepieces?

[acey]

Why not make finders with Galillean eyepieces?

A Galilean refractor (convex objective, concave eyepiece, upright image) has a relatively narrow field of view. It was the first kind of telescope that was invented. Once people started looking at the sky it was realised that the inverted image of a Keplerian refractor (convex objective and eyepiece) was offset by the wider field of view. The Galilean type continued to be used for terrestrial applications where correct orientation is important. Opera glasses, made from a pair of Galilean refractors, were widely available in the l9th/20th centuries. They were smaller, lighter and generally cheaper than binoculars (which use prisms to create an upright image) and often served as beginners' instruments for astronomy.

For a finder, the most important thing is that it matches the map you're using. I once tried using a refractor with mirror diagonal as finder, but the left-right reversal made map-reading very hard. I also tried a prismatic monocular, which was fine once I found a way to mount it that allowed for fine adjustment. I've tried lots of things. In the end I went back to using whichever finder comes supplied with the scope. Far more important than the finder is choosing the right map and learning how to use it. Insufficient detail means you can't get close enough to target objects without guesswork. Too much detail is confusing.