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Buying a refractor

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#1 astronomykiwi

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Posted 19 May 2019 - 06:24 AM

SkyWatcher Evostar 72ED

#2 astronomykiwi

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Posted 19 May 2019 - 06:26 AM

I am planning to buy a SkyWatcher Evostar 72ED in the near future, however, I have been told by many videos it has the focusing issue and needs a spacer, simple question, would it work just to use macro extension tubes to move the camera into focus or do I HAVE to invest in a pricey Focal reducer?

#3 dhaval

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Posted 19 May 2019 - 06:41 AM

Almost all refractors will require extension tubes to come to focus using a camera. You don't "need" a focal reducer unless you truly want to image using a faster F/ratio. And even then, you may still need extension tubes.

 

Depending on the size of the camera sensor, you may want to invest in a flat fielder. This will ensure round stars edge to edge. You can also crop the image if you don't use a flat field device. 

 

CS!


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#4 astronomykiwi

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Posted 19 May 2019 - 06:47 AM

Almost all refractors will require extension tubes to come to focus using a camera. You don't "need" a focal reducer unless you truly want to image using a faster F/ratio. And even then, you may still need extension tubes.

Depending on the size of the camera sensor, you may want to invest in a flat fielder. This will ensure round stars edge to edge. You can also crop the image if you don't use a flat field device.

CS!


Thanks! I use a apsc sized sensor in my canon 600D. people have had issues with round stars around the edges, I already own some macro extension tubes, 13mm 21mm and 31mm so I have many options, how much is usually a reasonably priced flattener? Sometimes stuff here in new zealand is highly overpriced! 😂

#5 dhaval

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Posted 19 May 2019 - 06:59 AM

The thing with flatteners is that unless they are specific to the scope, it makes it very difficult to find out which one will actually work. 

 

I haven't used the scope that you are looking to buy, so I can't answer the question of which FF will work for you. Sorry.

 

CS! 



#6 PirateMike

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Posted 19 May 2019 - 08:27 AM

You can contact SW to see what they suggest. I have heard that they are a friendly bunch and very willing to help their customers.

 

Support Center — Sky-Watcher.jpg

 

 

Miguel   8-)

 

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#7 terry59

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Posted 19 May 2019 - 09:03 AM

I am planning to buy a SkyWatcher Evostar 72ED in the near future, however, I have been told by many videos it has the focusing issue and needs a spacer, simple question, would it work just to use macro extension tubes to move the camera into focus or do I HAVE to invest in a pricey Focal reducer?

If a flat field with round stars is your objective then yes a flattener or reducer/flattener is needed. Since this scope has no matched flattener getting a perfectly flat field may not be possible. This review uses a William Optics flattener

 

https://astrophotons...GC_2024_Nebulae



#8 Stelios

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Posted 19 May 2019 - 11:28 AM

I can easily recommend the Hotech field flattener. And yes, you *will* need one, especially with a DSLR which has an APS-C sensor (or larger) (likely also with 4/3rds cameras such as the ASI294 and ASI1600). 




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