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Apo recommendations


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Hi stargazers!  I want to get start doing some AP.  I need help in finding the right scope for this endeavor.  Looking to spend from anywhere from $1000 to $1500 (Canadian dollars). I have a seller who wants me to sell a Zenithstar 70ED he says it's made in the USA before WO started to use Chinese manufacturers.  Is there a difference in lens optic quality?

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Do you have a picture of this telescope? William Optics are a Taiwanese company and as far as I know they have always used the Taiwanese manufacturer Long Perng to produce their telescopes. There may be slightly different optical designs in different editions of the same scope line but you would have to hunt down comparison reviews to find out if that makes any difference that can be seen.

If you were looking to buy a Celestron SCT then you could have the old built in USA vs new built in China scenario. I suspect the two histories have been confused. 

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13 hours ago, HaiXing said:

Is there a difference in lens optic quality?

Even if there is - you'll be hard pressed to see it in long exposure photography (where seeing dominates).

Regardless of the provenance of that scope - it is fast ED doublet (at F/6) - and it will show some residual CA, especially if you use OSC camera with it.

If you can live with that - then it is fine. If not - look into getting 80mm f/6 triplet scope.

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According to Company Seven:

William Optics Corp. was founded in 1996 as "Optical technology Limited" by brothers William and David Yang for the purpose of making astronomical telescopes for use by the more demanding amateur astronomer and birder. The company is based in Tapei, Taiwan, with optical production of their telescopes in Taiwan. William Optics has established offices and distributors overseas including in the USA. Unlike many other companies based in China or Taiwan at the time the Yangs set out to develop telescopes that are more refined in terms of performance and durable, with features that appeal to the more demanding amateur. The William Optics company subcontracts their designs for production by other companies, and also resells products that are sometimes marketed by other companies too.

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RC51 is the best astrograph out of the three simply due to the fact it’s a 4-element Petzval design. It does not show CA and has a very flat field over even a full frame sensor. Its edges will have coma and vignetting on a full frame sensor but honestly, so does every scope in that price range. It has an extremely wide field also, which is both a good and a bad thing depending on what you want to photograph. I love mine even if I have to crop basically every picture. 

It can have collimation problems which is quite painful to resolve if you get it. But FLO could help you with that.

Some users on Cloudy Nights claim that the Askar FRA400 is excellent for its price. Flat field, no CA, no collimation problems. At 1100 US it will be slightly out of your budget, and it’s bigger and heavier than the RedCat, but you are getting 72mm of aperture compared to 51mm. It’s something you might want to look at.

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On 17/10/2021 at 23:33, HaiXing said:

Hi stargazers!  I want to get start doing some AP.  I need help in finding the right scope for this endeavor.  Looking to spend from anywhere from $1000 to $1500 (Canadian dollars). I have a seller who wants me to sell a Zenithstar 70ED he says it's made in the USA before WO started to use Chinese manufacturers.  Is there a difference in lens optic quality?

If I remeber correctly that is a FPL51 doublet if that is correct then i would not chose it for astro photography with that sized aperture.

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