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Hairy Gazer

Are refractor images duller then reflector images?

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Does anyone know why the image seems to look duller through my new Sky Watcher Evostar 150 refractor than they do through my old Celestron Power Seeker 1000 (127) reflector?

I was looking at Albireo a few weeks ago and it seems to be slightly brighter and prettier (although not as sharp) through the power seeker. I was expecting it to look a lot nicer through the Evostar.

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Were you using similar magnification? I would expect them to be roughly similar with the frac a little brighter due to its aperture, and sharper too.

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I think you'd need to observe on a good number of different nights before drawing any conclusions. Just the clarity of the night, the elevation of the target, etc, may be at play here.

Olly

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In the case of the non-ED Evostar 150, chromatic aberration might cause issues. However, as others have said, much depends on conditions and magnification used. In any case, the PowerSeeker 127/100 is not a pure reflector, but a short-tube Newtonian with built-in Barlow, so it really is a catadioptric design, which can suffer a bit from chromatic aberration as well.

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ED or APO refractor images generally blow the doors off of matching aperture star images from reflectors or catadioptrics.  I'm assuming your refractor is an achromat with significant false color muting the color fidelity of Albireo.  Try defocusing Albireo in each (on each side of best focus) and watch the colors that spread out from the stars.  You'll probably see purple fringing in the refractor that is absent (or significantly reduced) in the Jones-Bird reflector.  You'll also see that red, green, and blue don't all focus at the same distance in the refractor which also mutes the color fidelity and image sharpness.  There's a reason folks pay big bucks for ED and APO refractors.

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It may be the viewing conditions as you guys have said, as I didn't try them at exactly the same time.  I used a 10 and 12 mm eyepiece on both scopes interchangeably.

The Evostar is an achromatic  Refractor, but I don't know about the significant false color part.

As it's a brand new scope, I was more worried about it being duller due a fault (but probably just a bit paranoid).

 

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10mm and 12mm in a 1000mm and 1200mm focal length refractor respectively should give the same mag. Try again on a different night I guess, and make sure the objective isnt dewed up on the frac!

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4 hours ago, Hairy Gazer said:

Does anyone know why the image seems to look duller through my new Sky Watcher Evostar 150 refractor than they do through my old Celestron Power Seeker 1000 (127) reflector?

I was looking at Albireo a few weeks ago and it seems to be slightly brighter and prettier (although not as sharp) through the power seeker. I was expecting it to look a lot nicer through the Evostar.

It might not be the brightness but the colour rendition of each scope. The 150 evostar will give brighter images, but the reflector will often show bluer -  perceived as brighter -  star images due to the aluminium coating on the mirrors. The evostar, because it is a short large aperture achromat, will lean towards the yellow. You'll notice this effect on Jupiter, which through the evostar will have a slightly yellow cast, where as in the reflector Jupiter will have a whiter/bluer cast. Looking at nebulous objects such as galaxies you'll notice the evostars aperture has the advantage, proving it gives the brighter view out of the two. 

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Thanks  Mike,

You've got it spot on, everything you said there is true (except I haven't had chance to see any galaxies with it yet).  It was the blue star in Albireo that made me think this in the first place, as the yellow one looked fine.

 

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