Beginner Question About Optical Reflections When Observing Near Moon
Last night I was trying to catch views of Praesepe with some binoculars. The moon was near the field of view. When viewing, I started getting strange reflections from the moon in my view. Waiting 30 minutes for the moon to move fixed the problem. Did I see strange optical reflections of the moon because I have low end binoculars, or because any optical system is prone to this problem? Is waiting for the moon to get out of the way the only solution? In photography I'm familiar with the idea of a lens flare, but this seemed much more pronounced than just a loss of contrast. It was a distorted image of the moon in the side of the area of view. Please let me know if asking so many beginner questions is a problem for the group. If there is a better forum or method for me to seek understanding I will gladly do it. I don't want to waste everyone's time asking questions like this. Besides, it is quite intimidating. Does SLAS have a mentoring program? -Ryan
Hi Ryan, What you are describing sounds like stray light. With many optical systems they will have baffles, longer tubes, flocking and other means used to reduce this. This is a bit tougher to do with binoculars - because the lenses are usually near the end of the tube. Basically, with stray light as I understand it, some of the light from an object that is outside of your main field of view finds a way to your eyepiece. Off axis lighting can pass through the lens then reflect off the inside of your binoculars, etc. Clear skies, Dale. -----Original Message----- From: utah-astronomy-bounces@mailman.xmission.com [mailto:utah-astronomy-bounces@mailman.xmission.com] On Behalf Of Ryan Simpkins Sent: Tuesday, April 08, 2014 12:39 PM To: Utah Astronomy Subject: [Utah-astronomy] Beginner Question About Optical Reflections When Observing Near Moon Last night I was trying to catch views of Praesepe with some binoculars. The moon was near the field of view. When viewing, I started getting strange reflections from the moon in my view. Waiting 30 minutes for the moon to move fixed the problem. Did I see strange optical reflections of the moon because I have low end binoculars, or because any optical system is prone to this problem? Is waiting for the moon to get out of the way the only solution? In photography I'm familiar with the idea of a lens flare, but this seemed much more pronounced than just a loss of contrast. It was a distorted image of the moon in the side of the area of view. Please let me know if asking so many beginner questions is a problem for the group. If there is a better forum or method for me to seek understanding I will gladly do it. I don't want to waste everyone's time asking questions like this. Besides, it is quite intimidating. Does SLAS have a mentoring program? -Ryan _______________________________________________ Utah-Astronomy mailing list http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Send messages to the list to Utah-Astronomy@mailman.xmission.com The Utah-Astronomy mailing list is not affiliated with any astronomy club. To unsubscribe go to: http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Then enter your email address in the space provided and click on "Unsubscribe or edit options".
Ryan, your question(s) are totally valid for this list. We've discussed the whole gamut here, from technical stuff way over most of our heads to the most basic beginner stuff, even straying off topic (OT) at times. Stray light is often a problem observing, and is often not easily apparent at first where the problem source may be. One reason why many open-truss dobs have fabric shrouds, and refractors usually have a "dew" shield (that doubles as a stray-light shield). I actually had my binos out last night as well. In my case, the neighbor to the north was the source of more aggravation than the moon -- he was out doing something in is yard with his horses and had the back floods on. /R ________________________________ From: Ryan Simpkins <astro@ryansimpkins.com> To: Utah Astronomy <utah-astronomy@mailman.xmission.com> Sent: Tuesday, April 8, 2014 12:38 PM Subject: [Utah-astronomy] Beginner Question About Optical Reflections When Observing Near Moon Last night I was trying to catch views of Praesepe with some binoculars. The moon was near the field of view. When viewing, I started getting strange reflections from the moon in my view. Waiting 30 minutes for the moon to move fixed the problem. Did I see strange optical reflections of the moon because I have low end binoculars, or because any optical system is prone to this problem? Is waiting for the moon to get out of the way the only solution? In photography I'm familiar with the idea of a lens flare, but this seemed much more pronounced than just a loss of contrast. It was a distorted image of the moon in the side of the area of view. Please let me know if asking so many beginner questions is a problem for the group. If there is a better forum or method for me to seek understanding I will gladly do it. I don't want to waste everyone's time asking questions like this. Besides, it is quite intimidating. Does SLAS have a mentoring program? -Ryan _______________________________________________ Utah-Astronomy mailing list http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Send messages to the list to Utah-Astronomy@mailman.xmission.com The Utah-Astronomy mailing list is not affiliated with any astronomy club. To unsubscribe go to: http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Then enter your email address in the space provided and click on "Unsubscribe or edit options".
It may be related to cheap binoculars. In my opinion a good pair of binocs is a good investment and a good quality pair can be less money than high end eye-pieces.
Last night I was trying to catch views of Praesepe with some binoculars.
The moon was near the field of view. When viewing, I started getting strange reflections from the moon in my view. Waiting 30 minutes for the moon to move fixed the problem. Did I see strange optical reflections of the moon because I have low end binoculars, or because any optical system is prone to this problem? Is waiting for the moon to get out of the way the only solution? In photography I'm familiar with the idea of a lens flare, but this seemed much more pronounced than just a loss of contrast. It was a distorted image of the moon in the side of the area of view.
Please let me know if asking so many beginner questions is a problem for the group. If there is a better forum or method for me to seek understanding I will gladly do it. I don't want to waste everyone's time asking questions like this. Besides, it is quite intimidating. Does SLAS have a mentoring program?
-Ryan
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All optical systems are prone to lens flares on bright objects like the moon, Jupiter, Venus, and Mars near opposition as it is now. Searching for a system that doesn't have them is a long, futile and ultimately expensive journey. Your binoculars are likely just fine for any purpose you choose to use them for. No optical system is perfect, no matter how expensive. DT
________________________________ From: Erik Hansen <erikhansen@thebluezone.net> To: Utah Astronomy <utah-astronomy@mailman.xmission.com> Sent: Wednesday, April 9, 2014 8:54 AM Subject: Re: [Utah-astronomy] Beginner Question About Optical Reflections When Observing Near Moon
It may be related to cheap binoculars. In my opinion a good pair of binocs is a good investment and a good quality pair can be less money than high end eye-pieces.
Last night I was trying to catch views of Praesepe with some binoculars.
The moon was near the field of view. When viewing, I started getting strange reflections from the moon in my view. Waiting 30 minutes for the moon to move fixed the problem. Did I see strange optical reflections of the moon because I have low end binoculars, or because any optical system is prone to this problem? Is waiting for the moon to get out of the way the only solution? In photography I'm familiar with the idea of a lens flare, but this seemed much more pronounced than just a loss of contrast. It was a distorted image of the moon in the side of the area of view.
Please let me know if asking so many beginner questions is a problem for the group. If there is a better forum or method for me to seek understanding I will gladly do it. I don't want to waste everyone's time asking questions like this. Besides, it is quite intimidating. Does SLAS have a mentoring program?
-Ryan
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I believe all optical systems will show this to a certain extent. Better light baffling will only make the effect less, but not eliminate it. The effect can actually be useful when trying to locate brighter objects in the sky. On Wednesday, April 9, 2014 9:00 AM, Erik Hansen <erikhansen@thebluezone.net> wrote: Last night I was trying to catch views of Praesepe with some binoculars.
The moon was near the field of view. When viewing, I started getting strange reflections from the moon in my view. Waiting 30 minutes for the moon to move fixed the problem. Did I see strange optical reflections of the moon because I have low end binoculars, or because any optical system is prone to this problem? Is waiting for the moon to get out of the way the only solution? In photography I'm familiar with the idea of a lens flare, but this seemed much more pronounced than just a loss of contrast. It was a distorted image of the moon in the side of the area of view.
Please let me know if asking so many beginner questions is a problem for the group. If there is a better forum or method for me to seek understanding I will gladly do it. I don't want to waste everyone's time asking questions like this. Besides, it is quite intimidating. Does SLAS have a mentoring program?
-Ryan
participants (6)
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Brent Watson -
Dale Hooper -
daniel turner -
Erik Hansen -
Richard Tenney -
Ryan Simpkins