Why do we still show the images upside down?

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  • #575047
    Peter Tickner
    Participant

    I can understand that it was convention in the days when most scopes showed a visual South up Jupiter and Saturn to show the images that way up too but I have a SCT and camera combination (as with all my last four planetary cameras and three SCTs going back more than a decade) that shows me visually and on camera a view the right way up and the right way round (I don’t use a diagonal to view). 

    I have rather rebelliously decided that I would like to present my images the way I took them and not turn them upside down when they weren’t in the first place.  Am I overstepping/offending? Any reason apart from kit orientation for doing otherwise?

    Peter 

    #584687
    Chris Dole
    Participant

    Peter, I’m totally in agreement with you on this. I fully understand where the south up convention comes from but for decades now I would say that most observers have been using equipment that shows a north up image.

    When I submit observations I have to deliberately turn everything upsidedown which seems odd and is just irritating. Surely it’s time to move to a global north up standard?

    Chris

    #584688
    Martin Lewis
    Participant

    Hi Peter,
    It’s good to have a convention to make images easier to compare images and can’t see a reason not to stick with the existing arbitary one rather than change it after several centuries. Jupiter with a GRS at the bottom and a Mars with Syrtis Major at the bottom – to me they just don’t look right.

    It is arbitary whether it has been chosen to be north up or south up but south up is the existing astronomical convention. In the northern hemisphere that’s the view in an inverting telescope but from the southern hemisphere that is the view in an non-inverting set up. There is no such thing as the right way up or wrong way up just the conventional way up and the unconventional way up.

    I am intruiged by your comment that you see visually a view with North at the top when you view through an SCT with no diagonal. Surely an SCT with two mirrors should give an inverted view. I though it was only through a diagonal that  you would get a non-inverted view but it would be mirrored L-R.

    Cheers, Martin

    #584689
    Paul Leyland
    Participant

    I understand the reasoning behind why planetary images are generally shown “upside down” but (with one major exception) most everything else these days is displayed with north to the top and east to the left. Look at any major atlas, either on paper or on-line, and it will follow this convention. As far as I can tell, most images in the BAA gallery are similarly aligned though, to be sure, some are not but those exceptions seem to show no particular pattern.

    My own images are generally N-up, E-left but that is primarily because that is the result of SWarp’s stacking algorithm rather than any conscious choice of mine. The raw subs are at whatever angle the camera happened to be at the time but a single sub is rarely of much use except perhaps for photometry where the angle and parity doesn’t matter for reporting purposes.

    Now the major exception;: M31.  Images generally appear East-up & South-left or NE-up & SE-left. My favoured explanation is that some people prefer to see the galaxy in a landscape view rather than portrait. Hubble’s famous frontispiece to The Realm of the Galaxies adheres to the N-up & E-left convention.

    #584690
    Chris Hooker
    Participant

    For what it’s worth, in most cases I don’t think it matters which way up an image or an observation is presented, provided the directions are indicated (or obvious). The exception, I would say, is the Moon, which we in the northern hemisphere see as north up without optical aid. Presenting lunar images or drawings with south up is just being contrary for no good reason, although observers in the southern hemisphere would no doubt say the opposite! The argument that we should stick to the tradition is very weak, given that the instruments and techniques in use nowadays are far beyond what those who established the tradition could even have dreamed of.

    #584691
    Paul Leyland
    Participant

    provided the directions are indicated”.  A very very important point.  Thank you for drawing it to our attention.

    #584692
    Nick James
    Participant

    I don’t have a view on whether planetary observers should have north or south up but I do wish that they would be consistent. When I’m doing Sky Notes I either have to have some slides with the original caption text upside down or the planet just flips back and forth in an irritating way.

    Don’t get me started on the random orientations and even mirror imaged views that you see for Deep Sky objects (and also comets if truth be told).

    #584693
    Peter Tickner
    Participant

    Thank you all for your considered comments to date.  I’m glad I am not yet in a minority of one! 

    I note with interest Marin’s views and it reminds me that I really must pay attention when looking visually and just check I am seeing what my brain is telling me I do see.   Chris has summed it up for me, the convention comes from an era that probably pre-dates photography and we have come a long way since then.  But it is important to be clear when presenting an image to avoid any potential audience misunderstanding, so as long as the direction is obvious either from the image or the information provided with it then that is sufficient.  I’m happy to accept that directors of sections may prefer their images presented conventionally and to go along with those that do, but otherwise I will gently continue to presnt them the way that seems as logical to me as the way we present images of the Moon.

    Peter 

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