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Leon-Fleet

Which Scope - ED 72 or other!

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So I am looking to get my first scope, one that I can put on the Star Adventurer. 

I'm aware the max load capacity for the SA is 5kg. Both scopes I ahve found will come in under that; but I eventually plan on adding Camera (Nikon D90), guide scope.... 

So I need a compact, light weight scope. 

I've come across these two, by way of recommendations and trawling through websites. 

I have also been told that I should get a refactor instead of a reflector for imaging, is this the correct advice? 

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

https://www.firstlightoptics.com/sky-watcher-starquest/sky-watcher-starquest-102r-f49-achromatic-refractor-telescope.html

The 72 ED is potentially what I am leaning towards now but the 102r comes with many of the accessories that the 72ED doesn't. 

If any of you are already using this scope or similar with the Star Adventurer I'd love to hear of your experience with it.

Can someone advise me which one would be better for Imaging? 

Thanks in advance for your comments and by all means jump in with a "I wouldn't choose either of those I'd choose..." answers. My budget is around the £250 mark. 

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The starquest is an achromatic so liable to show chromatic aberration, the ED72 is an APO so less likely to show CA.

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If you already own camera lenses with your Nikon why not start with them.

If factoring in weight consider the weight of your camera and bits as well.

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I didn't know that about the scopes so thanks! 

I have got some lenses but none are of particularly good quality. 

I also thought achieving focus on the scope would be easier than with the lenses. 

I've always struggled to get pin sharp stars. 

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Have you tried using a bahtinov mask to help focus your lenses, or make a simple Y mask to check focus though you'll need a live view screen to check focus.

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The ED 72 is a better scope, but be aware you still have to buy a diagonal, a finder scope and eyepieces before you can use it for observing. It will work out a fair bit more expensive.

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1 hour ago, happy-kat said:

Have you tried using a bahtinov mask to help focus your lenses, or make a simple Y mask to check focus though you'll need a live view screen to check focus.

I've used Bahtinov Masks, 10x zoom on the live view, taped the lens etc. bit can never get it right. 

I almost gave up last year. 

I keep thinking there must be something wrong with my kit... 

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27 minutes ago, laudropb said:

The ED 72 is a better scope, but be aware you still have to buy a diagonal, a finder scope and eyepieces before you can use it for observing. It will work out a fair bit more expensive.

I thought the ED 72  must be better, I would be using it for imaging mostly so can use my other Konouspace scope for visual. 

however someone has just said to me that I should just stick with lenses, and not get a scope at all. 

I'm pretty confused as what to do now! 

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10 minutes ago, Leon-Fleet said:

I thought the ED 72  must be better, I would be using it for imaging mostly so can use my other Konouspace scope for visual. 

however someone has just said to me that I should just stick with lenses, and not get a scope at all. 

I'm pretty confused as what to do now! 

There is one for sale in the ads section. Has all the bits with it.

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I'd also use your widest shortest focal length lens as well so you get a nice wide field image as well as any telescope you may buy. Could try picking a star that is on a third intersection and focus on that, also stop the lens down a stop or two. 

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With an unmodded Nikon DSLR you should be fine with the 72ED, and it'd be a good match for the mount in terms of size. It struggles badly with RGB filters on a mono camera (below about 420nm it just doesn't focus), but the DSLR will not suffer excessive chromatic aberration.

On the other question, it depends what lenses you have. With an 0.85 focal reducer/flattener you will get 357mm at about f4.9. Having used and compared a budget (c. £80) Sigma 70-300mm zoom at f5.6, my money would be on the Sigma. Yes, the zoom bit and the less than friendly manual focusser are a pain, but optically it's clearly better.

Economies of scale - can't beat em!

Billy.

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1 hour ago, billyharris72 said:

It struggles badly with RGB filters on a mono camera (below about 420nm it just doesn't focus)

ED72 / William optics 0.8 reducer / ZWO 1600 mono / ZWO filter wheel ...

 

Heart _Hubble_palette.jpg

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Ah, shouldn't post so quickly ... Just realised what Billy might have meant ! It is fairly hard to get enough inwards focus travel with the Skywatcher reducer hence my use of the William optics reducer.

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The 72ED is the scope of the two for imaging.

If used for viewing you will need a diagonal and a few eyepieces, you will find 3 will be adaquate to get started. Which ones you purchase is a case of budget mainly.

The Skywatcher focuser does have a lot of travel, so can cause a few problems. If you buy a 2" diagonal then it may be impossible to get enough inward travel. A 2" diagonal looks good on it so if you decide on one research the mechanical size of it for the optical path involved. There are low profile diagonals but not sure how low profile they are.

For imaging you do not need the diagonal, you attach straight through with a T-ring for the DSLR or whatever attachment is required for an AP camera.

Hold off of buying a guide scope. You cannot fully guide with the mount as it does not have a declination motor so there is no way you can control that aspect. Which means is it worth purchasing a guide scope and camera. I would not, however your decision. It seems to be a case that having a guide port makes you think you can guide fully whereas you cannot. So a guide port does not mean you can guide, at least fully.

The focuser on the skywatcher 72ED does not feel very solid. You may need to take it apart to understand how it fully operates. Mine I found I just could not adjust correctly until I had taken it apart to see what exactly was happening and then understand it more. Slightly extreme maybe, but it worked, asI now know what is going on.

The scope is flexible in that you can add diagonal and eyepiece and view, remove diagonal and add attachments and DSLR and image, you can also add a solar filter or herschel wedge and solar view.

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21 hours ago, knobby said:

ED72 / William optics 0.8 reducer / ZWO 1600 mono / ZWO filter wheel ...

Hmmmm, point taken - that's nice! Makes me wonder if I've got something else wrong with my setup. I seem to be able to go both sides of focus, so it's not that, but have bloated stars in luminance and in blue. We're talking really bad here, like a blue fuzzy ring around each star. Removing it in processing leaves the stars looking almost white.

I fitted an additional Astromimic UV/IR cut filter, a bit more aggressive than the stock filters. That cleans it up quite a bit - but now I seem to have the focus issue you mention. Only way to get focus is to put the flattener way too close to the chip.

Wonder if it's just a QC issue.

Billy.

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Maybe, I'm probably cheating a bit as the Heart image is narrowband which may hide the blue fringing ?

Ha Oiii Sii

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