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Stupid question - any issues with using my scope "upside-down"?

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#1 Tulloch

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Posted 11 October 2019 - 05:23 PM

Hi all, in the spirit of "There is no such thing as a stupid question", I have one of my own which I'm pretty sure I know the answer to, but just wondering if anyone else has had it too and got the answer.

 

Since I've been taking images, I always found it difficult to use the focus knob on my SCTs, since it's below the camera and hard to reach without accidentally knocking the scope, the mount, the camera, the cables, whatever. Since an electronic focuser is not a necessity for me (yet) I'd like to use the scope the other way around (upside down, if you like), with the focus knob above the center barrel. Obviously this configuration isn't ideal for optical viewing as the eyepiece on the diagonal would be directly blocking the focus knob, but for imaging it shouldn't be a problem.

 

OK, stupid question time. Will my Celestron Evolution altaz mount care if it's pointing the "wrong" way after it's been aligned in that configuration? I don't believe it should, however you never really know with these things. I will try it tonight (if the clouds stay away), just wondering if anyone has any insights?

 

Thanks (in stupidity),

 

Andrew.


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#2 Sunspot

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Posted 11 October 2019 - 05:50 PM

No answer on that one, except isn't everything you do down there up side down anyway...lol.gif lol.gif lol.gif lol.gif lol.gif lol.gif

 

(j/k)


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#3 Tulloch

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Posted 11 October 2019 - 05:54 PM

No answer on that one, except isn't everything you do down there up side down anyway...lol.gif lol.gif lol.gif lol.gif lol.gif lol.gif

 

(j/k)

Heh heh, not on my map ... rofl2.gif

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  • map-of-world-in-correct-orientation.jpg

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#4 Kokatha man

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Posted 11 October 2019 - 06:16 PM

Heh heh, not on my map ... rofl2.gif

...& you can see why all those bits are falling down off the bottom edge of America..! :rofl:


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#5 junomike

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Posted 11 October 2019 - 06:37 PM

Hi all, in the spirit of "There is no such thing as a stupid question", I have one of my own which I'm pretty sure I know the answer to, but just wondering if anyone else has had it too and got the answer.

 

Since I've been taking images, I always found it difficult to use the focus knob on my SCTs, since it's below the camera and hard to reach without accidentally knocking the scope, the mount, the camera, the cables, whatever. Since an electronic focuser is not a necessity for me (yet) I'd like to use the scope the other way around (upside down, if you like), with the focus knob above the center barrel. Obviously this configuration isn't ideal for optical viewing as the eyepiece on the diagonal would be directly blocking the focus knob, but for imaging it shouldn't be a problem.

 

OK, stupid question time. Will my Celestron Evolution altaz mount care if it's pointing the "wrong" way after it's been aligned in that configuration? I don't believe it should, however you never really know with these things. I will try it tonight (if the clouds stay away), just wondering if anyone has any insights?

 

Thanks (in stupidity),

 

Andrew.

In order to have the Focuser knob at the top the OTA would  need to be flipped around, thus being mounted in the wrong side of the Evo arm.....This will AFAIK be an issue for Star Alignment and GOTO Tracking if changed after alignment.

 

The only real way to do this would be to mount a Dovetail on the top of the OTA.



#6 Sunspot

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Posted 11 October 2019 - 06:41 PM

lol.gif lol.gif lol.gif lol.gif



#7 Tulloch

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Posted 11 October 2019 - 07:13 PM

In order to have the Focuser knob at the top the OTA would  need to be flipped around, thus being mounted in the wrong side of the Evo arm.....This will AFAIK be an issue for Star Alignment and GOTO Tracking if changed after alignment.

 

The only real way to do this would be to mount a Dovetail on the top of the OTA.

Thanks Mike, I won't be flipping or changing the orientation of the OTA on the mount, just pointing it in the opposite direction (so the focus knob is on top, and the screw on the dovetail is on the bottom). Maybe "upside-down" was the wrong term?

 

I would align it in this configuration and use it straight away - no changes in orientation after alignment, but the "up" arrow would point the scope down? See image below, note the focus knob has a piece of black foam over it, so it's more difficult to see, and I spun the diagonal around 180* .

 

Andrew

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  • Evolution upside down small.jpg


#8 kevinbreen

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Posted 12 October 2019 - 04:55 AM

Andrew

 

Can the OTA be removed and re-fitted upside down? If so, no problem. But if it can't, and you head-over-heels rotate it upside down, then it's pointing backwards and that obviously screws up your tracking. The result will be that not only will the planet drift out of your FOV it will do so at twice the normal speed in both RA and DEC and in the wrong directions. You will effectively be living in a parallel universe where down is up, left is right, Santa comes in the winter and the only large hopping mammals are in zoos (and some Irish pubs): aka the Northern Hemisphere.

 

I'm not sure what solution you have in mind - but what about changing your gps coordinates to those of the location that is diametrically opposed to yours - somewhere east of Canada and south of Greenland? Would that do the trick?

 

Tired now

 

Kevin


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#9 Kokatha man

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Posted 12 October 2019 - 06:55 PM

Andrew

I'm not sure what solution you have in mind - but what about changing your gps coordinates to those of the location that is diametrically opposed to yours - somewhere east of Canada and south of Greenland? Would that do the trick?

Kevin

...would that be Ireland Kevin..?!? :rofl:



#10 kevinbreen

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Posted 13 October 2019 - 06:12 AM

...would that be Ireland Kevin..?!? :rofl:


Closer to Iceland!

#11 Tulloch

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Posted 13 October 2019 - 07:22 AM

Andrew

 

Can the OTA be removed and re-fitted upside down? If so, no problem. But if it can't, and you head-over-heels rotate it upside down, then it's pointing backwards and that obviously screws up your tracking. The result will be that not only will the planet drift out of your FOV it will do so at twice the normal speed in both RA and DEC and in the wrong directions. You will effectively be living in a parallel universe where down is up, left is right, Santa comes in the winter and the only large hopping mammals are in zoos (and some Irish pubs): aka the Northern Hemisphere.

 

I'm not sure what solution you have in mind - but what about changing your gps coordinates to those of the location that is diametrically opposed to yours - somewhere east of Canada and south of Greenland? Would that do the trick?

 

Tired now

 

Kevin

Yep, turns out you were right, I tried aligning it with the OTA pointing in the other direction and the alignment failed twice. The first time it said it aligned OK but then when I told it to go to Jupiter it pointed in the other direction, the second time I got a message saying the alignment failed. Looks like I need to use it the "right" way. 

 

It's strange, I thought it wouldn't have mattered too much, I figured that the alignment would be enough to calibrate the scope, and just because it's moving in the negative direction it wouldn't affect it. Oh well.

 

Andrew



#12 kevinbreen

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Posted 13 October 2019 - 07:54 AM

Yep, turns out you were right, I tried aligning it with the OTA pointing in the other direction and the alignment failed twice. The first time it said it aligned OK but then when I told it to go to Jupiter it pointed in the other direction, the second time I got a message saying the alignment failed. Looks like I need to use it the "right" way.

It's strange, I thought it wouldn't have mattered too much, I figured that the alignment would be enough to calibrate the scope, and just because it's moving in the negative direction it wouldn't affect it. Oh well.

Andrew


Yeah, it’s designed to track with the OTA upright!

#13 lakeorion

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Posted 12 November 2019 - 02:04 PM

So in the end you were right.  "There is no such thing as a stupid question."

 

Some ideas don't work as well as others however.

 

Is it possible to move the dovetail to the other side of the scope?  Wouldn't that accomplish the same thing?


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#14 Tulloch

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Posted 12 November 2019 - 03:40 PM

 

Is it possible to move the dovetail to the other side of the scope?  Wouldn't that accomplish the same thing?

Hmmm... scratchhead2.gif

 

Looking at the setup now, I think that would work perfectly! The C9.25 appears to have dovetail mounting points on both sides (I assume they are identical?), so it shouldn't matter which side is attached. The finderscope would be on the fork side, but that wouldn't be a major issue, the CPC mount system has forks on both sides (but I note with interest that the mounting points on the CPC are east-west, so the focuser is to the side of the rear port, not underneath).

 

Thanks for the insight and advice, I'll give this a go sometime applause.gif .

 

Andrew



#15 Tulloch

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Posted 12 November 2019 - 04:50 PM

However.....

 

Upon closer inspection, it appears that the dovetail mounting holes on the "right hand side" of the OTA are designed for the larger CGE dovetail, while the holes on the other side are for the smaller CG5 dovetail. This is probably not surprising, given that you can buy the same OTA with either dovetail from Celestron. Same tube, different mounting.

 

This will make swapping the dovetail over to the other side more problematic, a new dovetail, an adapter for the mount, probably not worth the effort. Shame really, that really should have worked...

 

Andrew


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#16 MikeMiller

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Posted 12 November 2019 - 04:56 PM

Yeah, for whatever reason the Celestron dovetails only go on one side or the other. However, the only difference is the knob being on the other side and the logo being upside down. When I was using the stock dovetails, there was Losmandy-D on one side and Vixen on the other.

 

So, depending on which mount I put the scope on, it was either a celestron edgehd or a pɥǝbpǝ uoɹʇsǝןǝɔ. smile.gif


Edited by MikeMiller, 12 November 2019 - 04:59 PM.

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#17 Kokatha man

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Posted 12 November 2019 - 06:00 PM

However.....

 

Upon closer inspection, it appears that the dovetail mounting holes on the "right hand side" of the OTA are designed for the larger CGE dovetail, while the holes on the other side are for the smaller CG5 dovetail. This is probably not surprising, given that you can buy the same OTA with either dovetail from Celestron. Same tube, different mounting.

 

This will make swapping the dovetail over to the other side more problematic, a new dovetail, an adapter for the mount, probably not worth the effort. Shame really, that really should have worked...

 

Andrew

Aaagh, but the spirit of adventure Andrew..!?! :lol:



#18 Tulloch

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Posted 12 November 2019 - 07:01 PM

Aaagh, but the spirit of adventure Andrew..!?! lol.gif

Maybe, but I think I've settled on getting the Celestron electric focuser once it's available again in Oz. It's more expensive, sure, but being able to focus hands-off with the one hand controller while still having enough room at the back of the scope to image at high elevations without using a diagonal or banging against the base of the mount is worth the extra cost I think.



#19 lakeorion

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Posted 12 November 2019 - 10:03 PM

Some ideas don't work as well as others however.

And now I'm right also - even my ideas...

lol.gif




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