Jump to content

  •  

CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.

Photo

Are there any reverse image atlases available?

  • Please log in to reply
13 replies to this topic

#1 Chris K

Chris K

    Messenger

  • *****
  • topic starter
  • Posts: 469
  • Joined: 20 Sep 2017
  • Loc: Long Island, Earth

Posted 25 September 2021 - 08:14 PM

The mental gymnastics of the right-reading paper atlases are too much for my tiny brain. Curious if there are reverse image paper atlases for use at the eyepiece.

 

Using a refractor with diagonal.


Edited by Chris K, 25 September 2021 - 08:58 PM.

  • Castor likes this

#2 Spikey131

Spikey131

    Vanguard

  • *****
  • Posts: 2,482
  • Joined: 07 Feb 2017

Posted 25 September 2021 - 08:40 PM

Sky Safari can reverse and flip charts.  

 

I don't know of any paper charts that do this.


  • Castor likes this

#3 gmiller123456

gmiller123456

    Vostok 1

  • -----
  • Posts: 185
  • Joined: 25 Dec 2020

Posted 25 September 2021 - 08:54 PM

If you don't use a diagonal, the image in the scope will be rotated 180 degrees, so it's just a matter of turning the chart upside down.



#4 Chris K

Chris K

    Messenger

  • *****
  • topic starter
  • Posts: 469
  • Joined: 20 Sep 2017
  • Loc: Long Island, Earth

Posted 25 September 2021 - 08:59 PM

Sky Safari can reverse and flip charts.  

 

I don't know of any paper charts that do this.

 

 

If you don't use a diagonal, the image in the scope will be rotated 180 degrees, so it's just a matter of turning the chart upside down.

Thank you. Should have specified I'm using refractors with diagonals and was referring to paper atlases.


  • Castor likes this

#5 lphilpot

lphilpot

    Vanguard

  • *****
  • Posts: 2,085
  • Joined: 15 Oct 2005
  • Loc: Central Lousiana, USA

Posted 25 September 2021 - 10:10 PM

I don't know of any existing paper atlases like that, but most planetarium software will allow you to flip / reverse charts so you could print specific areas as needed.


  • Castor likes this

#6 sanbai

sanbai

    Apollo

  • *****
  • Posts: 1,338
  • Joined: 18 May 2019
  • Loc: Baton Rouge, LA

Posted 25 September 2021 - 10:21 PM

Views through a diagonal (refractors and SCT) have an horizontal flip. It can be mimicked with SkySafari, but not (easily) with a printed chart. One would look into a mirror image or looking from behind the paper (using a transparent copy).

Newtonian telescopes offer a fully inverted image (horizontal and vertical flip). In that case rotating the chart 180 ° (book upside-down) shows the same view of the telescope. Also possible in SkySafari.

Edited by sanbai, 26 September 2021 - 09:34 AM.

  • Castor likes this

#7 Chris K

Chris K

    Messenger

  • *****
  • topic starter
  • Posts: 469
  • Joined: 20 Sep 2017
  • Loc: Long Island, Earth

Posted 26 September 2021 - 08:43 AM

I guess I can scan my Jumbo PSA page and print it backwards as needed. Thanks all.


  • Castor and sanbai like this

#8 PolyWogg

PolyWogg

    Messenger

  • -----
  • Posts: 455
  • Joined: 26 Jul 2017
  • Loc: Ottawa, Canada

Posted 28 September 2021 - 01:11 PM

I seem to recall Turn Left at Orion has multiple views and their "extra" views are freely downloadable...

 

Paul


  • Castor likes this

#9 Steve Cox

Steve Cox

    Surveyor 1

  • -----
  • Posts: 1,963
  • Joined: 19 Jan 2017

Posted 28 September 2021 - 04:14 PM

I've tried some of the reverse and inverted view lunar atlases and never found them very good for my use; same will apply for star atlases for me for the same reason.

 

Reason being that such an atlas is written to invert the view either N-S or E-W (depending on whether it's printed for a refractor/SCT or for a newt).  That decision by the author or publisher assumes your scope and eyepiece are always at the same orientation, which for a GEM and a non-rotating diagonal/focuser should work okay.  But for an alt/az mount, it doesn't work and here's why.  When an object is near the meridian, then the object's orientation wrt N-S and E-W matches the scope and alt/az mount orientation.  But moving either further E or W of the meridian, and the object orientation will "rotate" up to 90deg wrt the scope.  Suppose you have an atlas reversed E-W for a refractor/SCT, but if you're looking at the object toward the east or west horizon, the view in the eyepiece will really be flipped N-S, or worse yet, the image will be reversed but based on a 45deg angle difference, something that's nearly impossible to translate (at least for me).

 

This is why I have no use for these type atlases and maps and have preferred to train myself to invert the view in my head when translating between a standard atlas and the eyepiece.  Let me close by saying though to the OP, if you're not opposed to using a software atlas, then SkyTools eyepiece view is the most accurate and in fact only one I've found that will properly orient the reproduced image to match what I see in the eyepiece.  But for paper atlases, better to learn how to invert in your head.


  • Castor and steveincolo like this

#10 Castor

Castor

    Surveyor 1

  • *****
  • Posts: 1,708
  • Joined: 26 Mar 2008

Posted 29 September 2021 - 01:14 AM

Hi,

 

I’m not aware of commercial reverse image paper star atlases, but when I’m too tired or don’t want to deal with the mental gymnastics, I simply use a 90-degree erecting (correct) prism diagonal with my small refractors for casual, low and medium power deep-sky observing.  Good quality amici prisms are expensive, so in general, the more you are willing to spend on one, the better the quality that you get.  Unfortunately, most 1.25” erecting prism diagonals have a restricted clear aperture (because of the small size of the prism) so you can’t use your lowest power wide-field eyepieces without experiencing some vignetting.  2-inch erecting prism diagonals are better in this respect but most still have smaller clear apertures than traditional mirror star diagonals.  Also, due to the complex optical path of erecting prisms and the exacting manufacturing requirements, correct diagonals can cause optical artifacts (like spikes) that limit their use at high magnification and can also add chromatic aberration on fast refractors.

 

IMO using a 90-degree erecting (correct) prism diagonal is an expensive and less than perfect solution (from the strict optical standpoint) to the mental gymnastics issue while navigating the night skies with a refractor or a cassegrain telescope and printed star charts, but it can make the difference between a relaxing evening observing with your telescope, or no observing at all.

 

Here’s a picture of my little 60mm refractor with a William Optics 1.25” 90-deg erecting prism diagonal and one of my 76mm refractor with a William Optics 2” 90-deg erecting prism diagonal.  Both diagonal models are discontinued, but you can find similar current products from William Optics, APM Telescopes and Baader Planetarium.

Attached Thumbnails

  • TV60+William_Optics-1.25in-90-deg-Erecting_Prism_Diagonal-950x570_131158.jpg
  • TV76+William_Optics-2in-90-deg-Erecting_Prism_Diagonal-1000x600_135245.jpg

  • Crusty99 likes this

#11 The Ardent

The Ardent

    Fly Me to the Moon

  • *****
  • Moderators
  • Posts: 5,509
  • Joined: 24 Oct 2008
  • Loc: Virginia

Posted 29 September 2021 - 01:33 AM

Correct image diagonal with refractor makes using paper atlases a breeze. I  enjoy wide field viewing and identifying the stars visible compared to the atlas. 
 

For planets and double stars it doesn’t matter . 
 

I use four correct image instruments:

1. Eyes 

2. binocular 

3. RACI finder

4. refractor with Amici prism

 

It’s nice when they all correspond to the chart, and to each other. 
 

Before I had Amici diagonal, I did enjoy the S&T mirror image moon map. 


  • Castor, jcj380 and Crusty99 like this

#12 PolyWogg

PolyWogg

    Messenger

  • -----
  • Posts: 455
  • Joined: 26 Jul 2017
  • Loc: Ottawa, Canada

Posted 29 September 2021 - 08:31 AM

I didn't mention it earlier, as I assumed it was obvious to most people, but a conversation with some other astronomers last night made me think it wasn't. Anyway, I'll mention an option FWIW.

 

If you have a map format you like, and it doesn't have the right orientation, you can always take a pic of the section you're using on your phone and then edit the photo by either rotating it or flipping it (or both) on the screen.  The lettering won't work if flipped vertical/horizontal although a friend says he has no trouble reading it mirrored if just flipped across the vertical access.

 

You were mentioning your map didn't work after a meridian flip, but if you can find a format you like for the rest, this might be good enough after a flip...

 

Paul


  • Castor likes this

#13 lphilpot

lphilpot

    Vanguard

  • *****
  • Posts: 2,085
  • Joined: 15 Oct 2005
  • Loc: Central Lousiana, USA

Posted 29 September 2021 - 09:15 AM

Reading the various workarounds folks (including myself) have mentioned kinda reminds me of why I don't worry about reversed / flipped charts. For me it's easier to do the minor mental flips needed to relate eyepiece to chart, than to create specialized charts that are relevant in only a specific context. In particular with a RACI finder, the only time it's even a factor is in the eyepiece itself, at relatively higher magnifications. At that point I just use geometric shapes to hop around, which can easily be mentally flipped, rotated, etc. But as always, YMMV.

 

In all fairness, my observing time is split between refractors (with diagonals) and Dobnewts. So roughly half the time for me, the view in a Newtonian is technically right-reading, just simply rotated. Then it's just a matter of rotating the chart to match.


  • Castor and Steve Cox like this

#14 jcj380

jcj380

    Mercury-Atlas

  • *****
  • Posts: 2,506
  • Joined: 08 Jul 2014
  • Loc: Hellinois

Posted 29 September 2021 - 09:30 AM

Correct image diagonal with refractor makes using paper atlases a breeze. I  enjoy wide field viewing and identifying the stars visible compared to the atlas. 
 

For planets and double stars it doesn’t matter . 
 

I use four correct image instruments:

1. Eyes 

2. binocular 

3. RACI finder

4. refractor with Amici prism

 

It’s nice when they all correspond to the chart, and to each other.

Geez, I thought I was the only heretic to use CI diagonals for all my frac and Mak observing.  All have RACI finders except for one vintage 8x50.  Took me awhile to find a correct image moon map that I like though.


Edited by jcj380, 29 September 2021 - 09:31 AM.

  • Castor likes this


CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.


Recent Topics






Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics