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Newcomer second scope purchases, an expensive mistake?


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When you look for an eyepiece (on FLO’s site anyway) below the description it gives you a graphic where you can input your scope details, input your eyepiece etc and select a subject. It shows an idealised object through your scope with the selected eyepiece (after deleting all the ones you don’t want).  When I get a new ep I spend quite a while doing simulations to get a fl of ep that suits the scope and the objects I want to see.

12 dimensional string? Has a better simulator than the FLO Site. If you use the search tab under target the images are photographic and fill the ep simulated view. Rather than selecting M1 from the grid which shows a little box…

Simply changing your ep selection will change the display accordingly.

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1 hour ago, fwm891 said:

12 dimensional string? Has a better simulator than the FLO Site.

This is a really useful website (Astronomy - 12DString). I particularly like the 'Planetary orbit info' and the 'Planetary size and viewing info' pages. Very useful for those of us who are trying to get a good view of the planets and want to know when the likes of Mars and Venus will be at their largest (closest to Earth), and in the case of Venus, still mostly illuminated by the Sun.

By the way, I'm reading this thread as I've been wondering whether a fixed small FL EP (such as the Baader Morpheus 76deg 6.5mm or the ES 82deg 6.7mm) might give me a better view of the planets than my current Baader Hyperion Zoom at 8mm?

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Just purchased the collimation cap so I'll start there. Like a lot of budding new astronomers my expectation is usually based on the images users on this and other forums upload who have painstakingly processed and refined their original photo.

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2 minutes ago, sonicninja said:

Just purchased the collimation cap so I'll start there. Like a lot of budding new astronomers my expectation is usually based on the images users on this and other forums upload who have painstakingly processed and refined their original photo.

Not sure if anyone has pointed you here before, but if not, this will help you make realistic expectations::

 

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51 minutes ago, sonicninja said:

Just purchased the collimation cap so I'll start there. Like a lot of budding new astronomers my expectation is usually based on the images users on this and other forums upload who have painstakingly processed and refined their original photo.

Here are some collimation scenarios for you from my 130PS

Pic 1).

The secondary mirror is properly aligned with the primary mirror, because the outer parts of the mirror mount (the black circle) and the three mirror clips (with two Philips screws on each) are nice and concentric in the secondary mirror, and it looks like a circle as viewed through the collimation cap. Unfortunately the primary mirror is not correctly aligned - the refection of the hole in the collimation cap (the black dot in the centre of the photo) should be inside the white doughnut in the centre of primary mirror. This would indicate the primary mirror is looking directly at the centre of the secondary mirror and therefore directly at the middle of the focus tube and the collimation cap - as you can see below, it's not.

The green is a plastic bag I put the other side of the secondary mirror mount from the focuser to make the edges of the secondary mirror clear as otherwise it all gets confusing (for me!) 

image.png.e66edcae6fb95f5c5d401a043e7c454f.png

Pic2).

The secondary mirror is not correctly aligned. It looks a bit squashed (not a full circle) and the reflection of the primary mirror is not in its middle.  It does point at the middle of the primary mirror, but this will not result in sharp planets in the centre of the view - there will be a sharp spot off to one side somewhere which will be a fair bit smaller...  

image.png.17e78704b692181b1d7cafbdb73d5a8e.png

Pic 3).

This is what you should expect to see.  The clips in view around the outside so the primary mirror reflection is central,  and the dot is in the middle of the doughnut so everything is lined up.

image.png.fe78338afb7c384a08ed9f4cfb06845c.png

Edited by cwis
Horrific grammar
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Wow, thanks so much for all the replies. Lots to get my started here. I did spend an hour or so trying to find Uranus last night as it was clear. Unfortunately didnt see it (or al least I saw It and couldnt tell it apart from the surrounding stars). I'll keep looking, it'll make it all the more enjoyable when i do see it. Glad I didnt go for a GOTO mount in the end.

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Does this look about right?

Also, very quickly. Is it possibly to over-tighten the grub screw clutch on a telescope like this. My horizontal control seems to be either loose or ,once the clutch is tightened, completely unmovable. I wonder if Ive over tightened it at some point meaning I cant really use the precise controls

 

1629054060_130PSCol.thumb.jpg.a37b1881c8d69797c16231ae991dad6e.jpg

Edited by sonicninja
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22 minutes ago, sonicninja said:

Does this look about right?

Also, very quickly. Is it possibly to over-tighten the grub screw clutch on a telescope like this. My horizontal control seems to be either loose or ,once the clutch is tightened, completely unmovable. I wonder if Ive over tightened it at some point meaning I cant really use the precise controls

 

1629054060_130PSCol.thumb.jpg.a37b1881c8d69797c16231ae991dad6e.jpg

That looks pretty much OK!

You are looking for:

1).  The secondary mirror looks like a perfect circle and is bang in the middle of the focus tube.

It's a bit difficult to make out from the pic above but it might be a bit out - looks a little to the right and down from centre. But you be the judge - it could be the pic... Looks circular though - excellent!

2). The primary mirror reflection is centred so the three clips and maybe the mount for the primary (depending on how far the focus tube is racked out)  is concentric with the outside of the secondary mirror

I'd say - yup - looks good on that one.

3). With both the above satisfied, the black dot of the refection of the hole in the collimation cap is in the middle of the doughnut in the centre of the primary mirror.

Yup on that one.

So - check on point 1) - but it looks like it's fine.

Personally, even if it's a bit out with point 1). I'd leave it - it's probably better than the average eyeball at this point anyway.  Astrophotographers have to be far more picky with regard to collimation... 

Read up on doing a star test and do one next time you're out for the final check under real conditions.

 

 

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