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Bad optics or bad eyesight?

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17 years 11 months ago #30755 by Keenan
Bad optics or bad eyesight? was created by Keenan
Hi all,
I may be about to embarrass myself so be gentle.
I'm neither an astronomer nor a photographer but I have the Skylux scope and the Bresser binoculars from Lidl.

Sitting on the deck these warm evenings, I noticed a twinkling star in the NE. When I looked through the binos it looked red and green so I though "Doh, it's a plane, dummy", so I thought no more about it.
... except it's there for hours, and it's there every night.

I took out the scope and eventually managed to get it in the eyepiece. It still looks red and green.

So my question: Is there a star that looks red and green, is this a problem with the optics of both the Bresser glasses and the Skylux scope or is it time to revisit my optician?

I did manage to get a few (bad) photos with a digital camera but I'm really not sure what they show. I'll upload them somewhere if anyone thinks it might help.

Thanks

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17 years 11 months ago #30756 by vindictive
Replied by vindictive on topic Re: Bad optics or bad eyesight?
gday keenan

it possible youve seen capella


i went thru the same thing a few years ago

At Present

7x50 Binocs

700mmx60mm Refractor

12 Inch Dob

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17 years 11 months ago #30757 by albertw
Replied by albertw on topic Re: Bad optics or bad eyesight?
Hi,

First off welcome to the site!

Sitting on the deck these warm evenings, I noticed a twinkling star in the NE.


I think that sentence might explain everything. This star is fairly low down right? I'd imagine its a star called Capella and should be the brightest star in the northeast at the moment.

Twinkling of stars is caused by changes in the Earths atmosphere through which the starlight is passing. So if the star is low down then there is more atmosphere for the light to pass. Given the warm evenings the air near the ground can be very turbulent which can make stars twinkly more than usual. Though stars will still twinkle on freezing winter nights too. This twinkling looks as if the star is rapidly changing colour.

No telescope will be able to remove this twinkle, so even through expensive telescopes you'll still see this happening.

So before planing to visit your optician have a look at the stars that are straight above. There should be a bright star at this time of year almost directly above you but a little to the south. Thats Vega, a very bright star. Have a look at that through your binoculars and scope and you should see it as a fairly steady white or blue colour. Since the air is warm and moving it may still twinkle a bit, but not anywhere near as much as the star near the north east horizon.

Without wanting to bore you I'll just mention that stars do come in different colours. Vega, on still clear nights has an obvious blue tinge. Arcturus, which you can see roughly west about 30 degrees up around midnight at the moment is an orange star. These colours will look a bit more obvious in a telescope or binoculars that are slightly out of focus. The colours depend purely on the temperature of the star the hotter they are the bluer they look.

Feel free to post the pics, and we can check exactly what you are looking at.

hth,
~Albert

Albert White MSc FRAS
Chairperson, International Dark Sky Association - Irish Section
www.darksky.ie/

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17 years 11 months ago #30758 by Keenan
Replied by Keenan on topic Re: Bad optics or bad eyesight?
Thanks Guys, for the info, the welcome and the reassurance.

Yes, if I look at object more directly overhead, they don't have the red/green colours so I guess the optics (and the eyes) are OK!

The warm air and low elevation explanation makes perfect sense now that you mention it. I've had a look at Stellarium (the sky simulator) and Capella does look like it's in the right place for what I'm looking at.

At the risk of being told I have dirt on my lens and a shaky hand, I've uploaded a few photos to www.propertyfile.net/astro .
The crops are just the interesting bit of larger photos. The image.jpg files are full size uncropped in case it helps to locate the object. It is curious looking if you view the images full size.

Anyhow, thanks for the input - this astronomy stuff could be interesting!

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17 years 11 months ago #30759 by ftodonoghue
Replied by ftodonoghue on topic Re: Bad optics or bad eyesight?
Hi Keenan

Next night you are out, why not turn the skylux on the brightest "star" in the sky. This is the planet Jupiter and you will find it in the SW low down as it is getting dark.

you should have no problem picking up some of its moons and may even see some cloud belts..

Cheers
Trevor

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17 years 11 months ago #30760 by Seanie_Morris
Replied by Seanie_Morris on topic Re: Bad optics or bad eyesight?
Welcome aboard Keenan! The guys above me here all gave you sound advice. Another piece I will add is that I would hope you would be brave enough to take your Skylux and binos out on the most frigid winters night, and you will be amazed by the clarity these same stars exhibit! Summer, while more comfortable for astronomy, is also the worst time for it! Barely any proper dark nights, lots of haze about, turbulent atmosphere (as you saw already!), and waiting for ages before it is dark enough to bring out the equipment. Winter is more flexible, albeit less comfortable because it is colder! But, there are ways around that too!

Still, glad to have you aboard! Hope you find our site useful!

Seanie.

Midlands Astronomy Club.
Radio Presenter (Midlands 103), Space Enthusiast, Astronomy Outreach Co-ordinator.
Former IFAS Chairperson and Secretary.

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