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I-d-b

300 budget scope for moon basic Astro and land / sea viewing

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Posted (edited)

I’m looking for a telescope around 300 that has good magnification and good optics so I can do basic astronomy and look at the boats in the sea (approx 3 miles from our house!)

I assume I need a refractor?

looked at the celestron nexstar xlt 102 at £349 and the sky-watcher star travel 

102mm £ 229.00 

120mm  £ 329.00 

 

Thoughts?!

also looked at the celestron ultimate 80 spotting scope at less than £200 (like the idea of zoom). 

All seem to have Chromatic aboration- any suggestions on alternatives in my price range please!

Edited by I-d-b

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Welcome

A mac would not have chromatic aberration and is also good on the Moon as higher magnification is it's thing.

something like this but you could look for a telescope and tripod bundle.

For da and night viewing an altaz mount would be easier (not equatorial)

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But a refractor with a longer focal length like this one would;d show less aberration then a startravel refactor.

evostar 90mm

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I had a little Meade ETX90 Maksutov about 20 years ago that I used for the Moon and daytime observing. I think a little Mak will be the only thing in budget that will show the image the correct way around top to bottom at least, and will show zero chromatic aberration. 

Celestron do a little 90mm Mak for about £170 leaving money left to mount it :) 

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Posted (edited)

The 102mm mak I linked to earlier has bigger aperture and is same price for OTA only.

The skywatcher mak  would need an erect image diagonal for day time observing if want specifically a right way up image. 45 degree angle is good for day time observing. 90 degree is more comfortable for night astro. The C90 comes iwth a 45 erect image but then these are not as comfortable for night time.

https://www.firstlightoptics.com/diagonals/skywatcher-45-erecting-prism.html

Edited by happy-kat

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Posted (edited)

To change magnification you can swap eyepiece or perhaps get an extra zoom eyepiece if after using your new telescope you want to add to the two that came with it.

Magnification is telescope focal length / eyepiece focal length.

The 10mm would give x130 and the 25mm x52 in the telescope linked above.

Maksutov telescopes by nature have a narrow field of view but take magnification well.

I'm not sure how practical a motorised mount is for day time viewing. 

 

Edited by happy-kat

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Thanks for the replies and advice.  Ring new to the idea of getting a scope I’m confused!!

mak or refractor options detailed above - whAt difference would I see?

is field of view important?

https://www.firstlightoptics.com/maksutov/skywatcher-skymax-102-ota.html

https://www.firstlightoptics.com/evostar/sky-watcher-evostar-90-az-pronto.html

https://www.firstlightoptics.com/optical-tube-assemblies/celestron-c90-mak.html

and do the maks give  a vertically mirrored image when the horizontal flip is. “Corrected” with the 45 erecting prism?

 

sorry for so many questions!!

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Where in the UK are you based? I ask as there is the Practical Astronomy Show at Kettering this coming Saturday (9th March). If you can attend (it's free admittance) you will be able to see and talk to most of the well renowned UK suppliers.
Good luck.

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I’m in West Sussex. 

The local (Worthing) ship suggested the ones on my original post but I’m now being drawn towards the mak style. 

Will this be a problem for terrestrial viewing with more limited field of view

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It is choices. The closer the object the more field of view might feel narrow, the further away terrestrial the more magnification could be useful. 

It depends on your viewing style, do you want to have more field of view and don't mind some chromatic aberration (or use a long focal length refractor like the Evostar 90 but it is long) or would a compact telescope like the mak which can take magnification suit.

The trade off is wider field of view, great for star gazing sweeps but less favourable on high contrast items where the CA can show. Or narrower field of view, compact, and can take magnification, no CA.

I will add that where the focal length is longer like on a mak, the exit pupil can get small when higher magnification eyepieces are used. This is the circle of light that the eye actually sees the telescope image in. eyepiece focal length / telescope focal length. A smaller exit pupil means placing your eye more exactly where it needs to be.

Startravel  10mm eyepiece / f5 gives 2mm exit pupil (this is x60 magnification)

a 5mm eyepiece would give 1mm exit pupil (x120 magnification)

Mak 10 mm / f13 = .75 (this is x130 magnification) 

20mm / f13 = 1.53 (x65 magnification)

Magnification is often theory as reality does not always allow us to use it, seeing and atmospheric conditions play a part.

I have both a small Mak 70mm and a StarTravel 80mm. I found the exit pupil size something I didn't like so much on the mak compared to the comfortable viewing in the ST. I use binoculars when wanting a really wide field of view.

When making choices it does help if you can get to a local astro meet and see different types of telescope and hopefully even look through them. I would see if you can find any reviews too and user experiences, the search on this forum is good too.

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I've created these two views. First image is using a 10mm eyepiece in st120 and a 20mm in the skymax102. Very similar magnification.

15519697574253.jpg.e0ca159b5ec259c2fd0266cde0798bce.jpg

This image is using a 32mm plossl in both and shows field of view difference of 2.77° (x18) versus 1.28° (x40).

You won't get much wider a view in a mak.

15519697573362.jpg.57962f170229d5ff0f4f3c167666e3af.jpg

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Hi @I-d-b and welcome to SGL. :hello2:

Just to give an idea of what the Moon looks like through a Meade ETX105 and 20mm Plossl, (I do not own the Skywatcher Skymax 102)... p3130001-enhanced.thumb.jpg.4d5cc4989d96b52e2bb88531e6f6e710.jpg

...this is Montes Apennius.

Apologies for the quality of the image as it was taken with a 2.1 megapixel digital compact camera a few light years ago.

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The Meades focal length is 1470 hence the magnification with a 20mm gives x73.5

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On 07/03/2019 at 13:34, happy-kat said:

It is choices. The closer the object the more field of view might feel narrow, the further away terrestrial the more magnification could be useful. 

It depends on your viewing style, do you want to have more field of view and don't mind some chromatic aberration (or use a long focal length refractor like the Evostar 90 but it is long) or would a compact telescope like the mak which can take magnification suit.

The trade off is wider field of view, great for star gazing sweeps but less favourable on high contrast items where the CA can show. Or narrower field of view, compact, and can take magnification, no CA.

I will add that where the focal length is longer like on a mak, the exit pupil can get small when higher magnification eyepieces are used. This is the circle of light that the eye actually sees the telescope image in. eyepiece focal length / telescope focal length. A smaller exit pupil means placing your eye more exactly where it needs to be.

Startravel  10mm eyepiece / f5 gives 2mm exit pupil (this is x60 magnification)

a 5mm eyepiece would give 1mm exit pupil (x120 magnification)

Mak 10 mm / f13 = .75 (this is x130 magnification) 

20mm / f13 = 1.53 (x65 magnification)

Magnification is often theory as reality does not always allow us to use it, seeing and atmospheric conditions play a part.

I have both a small Mak 70mm and a StarTravel 80mm. I found the exit pupil size something I didn't like so much on the mak compared to the comfortable viewing in the ST. I use binoculars when wanting a really wide field of view.

When making choices it does help if you can get to a local astro meet and see different types of telescope and hopefully even look through them. I would see if you can find any reviews too and user experiences, the search on this forum is good too.

I think I’m asking for the impossible! :

decent exit pupil size (so easy to view for whole family). 

No (or very low) CA

sharp optics

ability to be magnified

 naturally orientated image

good for planets / moon and looking at boats on the sea 3 miles away 

 

i dont mind if it’s a very long telescope - it won’t be travelling!

happy to increase my budget to £400 (would like a tripod included but I do have a manfrotto SLR tripod available)  

 

am am I asking the impossible?

 

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Posted (edited)
29 minutes ago, I-d-b said:

I think I’m asking for the impossible! :

decent exit pupil size (so easy to view for whole family). 

No (or very low) CA

sharp optics

ability to be magnified

 naturally orientated image

good for planets / moon and looking at boats on the sea 3 miles away 

 

i dont mind if it’s a very long telescope - it won’t be travelling!

happy to increase my budget to £400 (would like a tripod included but I do have a manfrotto SLR tripod available)  

 

am am I asking the impossible?

 

102 Mak? https://stargazerslounge.com/topic/331810-300-budget-scope-for-moon-basic-astro-and-land-sea-viewing/?do=findComment&comment=3612977

Money left for two BST eyepieces ... ;)

If you can stretch for 127 mak even better and better mount! https://www.firstlightoptics.com/maksutov/sky-watcher-skymax-127-az5-deluxe.html

 

Edited by heliumstar
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The current "long" achromats are not that long.  This is a long-focus achromat, and with a focal-length similar to that of a Maksutov...

https://stargazerslounge.com/uploads/monthly_11_2014/post-33902-0-80153000-1415559339.jpg

The current, longish achromats are actually of a medium length, rather.  With a 90mm f/10, there would be minimal false-colour, but only when viewing the brighter and brightest objects in the sky.  You might see some during the day as well.  Given its moderate focal-length, respectably low powers with widish fields-of-view are quite possible; moreso than with a Maksutov, although a Maksutov is a worthy contender nonetheless.  If at all possible, if you go with a Maksutov, get a 127mm, as that's the "sweet spot" among the design's varying apertures...

https://www.firstlightoptics.com/maksutov/skywatcher-skymax-127-ota.html

...although the focal-length does increase as one goes up in aperture, per the design.  You would perhaps not need that much aperture during the day, as the Sun's out, albeit behind the clouds on occasion, but at night, the more aperture the better.

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For lunar and land & sea viewing its a difficult choice as for lunar a narrow field enough to see the full lunar disk and increase magnification from there is optimum and for land and sea lower magnification and wider fields will make objects easy to follow and better see through daytime thermal distortions wich can seriously hamper viewing even with a low mag wide field instrument. So the mid focal length refractor will be a much better land and sea scope but for the moon the maksutov with no chromatic aberration or false colour will be optimum.

The refractor should come with an aperture reduction cap build in it's objective lens cap and using it should make such a scope virtually colour free although by reducing aperture, personally I'd get the refractor because it is most likely the best compromise for all your viewing requirements.

                Best of Luck ?

                       Freddie...

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The evostar 72ED is a lovely small redactor you link to by all accounts on the forum. You'll find plenty posts on it and it most likely will show monimal to no chromatic aberration and is highly portable. There's been some observing reports with it on here may even have been a Jupiter one last year.

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31 minutes ago, happy-kat said:

The evostar 72ED is a lovely small redactor you link to by all accounts on the forum. You'll find plenty posts on it and it most likely will show monimal to no chromatic aberration and is highly portable. There's been some observing reports with it on here may even have been a Jupiter one last year.

I do agree, this is a Great alternative likely getting better colour correction than the formentioned midfocus achromatic doublet of greater aperture stopped down and for land and sea it ticks all the marks even portability. This is really a nice solution for those looking to use a telescope as a spotting scope.

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Posted (edited)
19 hours ago, I-d-b said:

Thanks. 

Reviews of this keep coming up

https://www.firstlightoptics.com/pro-series/sky-watcher-evostar-72ed-ds-pro-ota.html

though not sure what I’d need to buy on top?!

 

You would also need eyepieces say one low powered and one mid to high power or perhaps one zoom eyepiece, though 2 inch eyepiece can be a bit more pricey. You would need a 2 inch diagonal erect image one. Plus you would need to be able to mount it on your tripod assuming your tripod is sturdy enough, a ball head and a means to connect to the telescope dove bar can give an alt az motion. Plus say a red dot finder assuming there is a mounting shoe for one.

Edit: please research further to make sure the telescope meets your need's and can reach focus with an erect image diagonal.

Edited by happy-kat
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Posted (edited)

That’s the scope then!

now for eyepieces for the skywatcher 72ed!!

thinking initially something like 20x magnification up to around 80x. 

I assume 2 eyepieces with a Barlow 2x would be a good idea?

anything good around £100 total for 2 good eyepieces and a Barlow 2x?

 

happy to go with 2” or 1.25” with the step down  - best quality for £!

 

Edited by I-d-b

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