Bad optics or bad eyesight?

14 years 2 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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14 years 2 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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14 years 2 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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14 years 2 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 http://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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14 years 2 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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14 years 2 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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14 years 2 months ago #30765 by Keenan
Replied by Keenan on topic Re: Bad optics or bad eyesight?
I have already had a look at Jupiter. I could see 3 moons and fancied I could see 4. Also had a look at Saturn a few weeks ago.

I have been out a couple of nights in winter - I have a solution for the cold nights - a patio heater. It keeps the frost off the scope and the observer!

I use the binoculars most of the time. It's so much handier than dragging out and setting up the scope, plus a lot easier to use.

Thanks for all the tips.

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14 years 2 months ago #30768 by ftodonoghue
Replied by ftodonoghue on topic Re: Bad optics or bad eyesight?
Just one other tip Keenan

If you are using a patio heater near the scope it will probably lead to an unsteady local atmosphere and cause shimmering of any images in the scope.

Cheers
Trevor

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14 years 2 months ago #30776 by Keenan
Replied by Keenan on topic Re: Bad optics or bad eyesight?
Thanks everyone for all the tips so far, maybe I'm getting hooked!

I've been looking at those photos again and I'm puzzled. I can see stars, looking like I would expect 9pinpricks of light), but then there's a big reddish-brown blob with a green halo which is the object in question.

This image is a typical example, one of a dozen where the same object appears, albeit looking different in each one - allowing for camera-shake and newbieness, is this capella?

The proportions look all wrong to me - any ideas?

Several other photos at http://www.propertyfile.net/astro [/url]

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14 years 2 months ago #30780 by dmcdona
Replied by dmcdona on topic Re: Bad optics or bad eyesight?
Keenan, I suspect that what you think are stars are in fact 'hot' pixels - electronic noise within your camera and nothing to be ashamed of :D

The only 'true' image recorded seems to be a bright star, albeit smeared over a small portion of the frame.

In order to diagnose it better, can you tell me what camera you're using and what was the exposure time?

Cheers

Dave

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14 years 2 months ago #30781 by michaeloconnell
Replied by michaeloconnell on topic Re: Bad optics or bad eyesight?
I think what Dave is saaying may be correct. My guess is that the camera has difficulty focusing as there's nothing to focus on , hence the blur. Also, as the sky is relatively dark, the exposure becomes long and the cmaera shakes in your hands while the shutter remains open.
Just my hunch...

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14 years 2 months ago #30783 by dmcdona
Replied by dmcdona on topic Re: Bad optics or bad eyesight?

IMy guess is that the camera has difficulty focusing as there's nothing to focus on


I didn't think of that :D Keenan - can you set your camera to manual focus on infinity? That'd help - autofocus would probably get very confused...

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14 years 2 months ago #30784 by Keenan
Replied by Keenan on topic Re: Bad optics or bad eyesight?
Ah, I think get it.

So if I compare several photos, I should see the "hot" pixels in all of them and in the same positions relative to the frame edges - but Capella will be in slightly different positions?

The camera is a Nytech ND5040 5 megapixel (from Lidl, where else) set on auto without flash. I'm just holding it up to the eyepiece and taking a 3 shot burst.

Hmm, time to read some of the astrophotography threads, I think.

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14 years 1 week ago #33052 by EPK
Replied by EPK on topic Re: Bad optics or bad eyesight?
That's your problem...it's just hand movement over the 3 second exposure...way too short for hot pixels to be an issue...but way enough to make the star images smear around instead of being points of light.
Anything over 1/60th sec exposure will start to show that shake....and any zoom will magnify it by the zoom amount as well.

Meade 16" Lightbridge
Tal 6" Newtonian
Meade LXD75 6" Newtonian
Tal 4" Refractor
Panoptic and Nagler eyepieces.
Attitude and Smartassery

For forever and a day I shall chase that white whale - Captain Ahab

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