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Whats this spotlight i am seeing?

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#1 HowardK

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Posted 29 January 2013 - 05:58 PM

Can anyone explain why on bright objects like Jupiter i see the object bathed in a bright light a bit like a spotlight?

Outside this spotlight space is nice and black
Only happens on real bright stars or planets
I use Baader mk v's with a pair of 17.3 Delos on a TEC 140mm APO
Something to do with reflection?
Is this normal?

#2 DaveJ

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Posted 29 January 2013 - 06:17 PM

Can anyone explain why on bright objects like Jupiter i see the object bathed in a bright light a bit like a spotlight? Outside this spotlight space is nice and black Only happens on real bright stars or planets I use Baader mk v's with a pair of 17.3 Delos on a TEC 140mm APO Something to do with reflection? Is this normal?


Could it be dew or condensed moisture from your breath on the eyepieces? I've seen this on rare occasions and that's always been the cause. I have nearly the same equipment as you, except for the Delos eyepieces. Are you using any of the GPCs (Glass Path Correctors)? If not, you're only operating at a magnification of 57x

#3 HowardK

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Posted 29 January 2013 - 06:22 PM

Yes i am using a denk powerswitch with its OCS to reach focus.

I am operating at about x90 or at x120

Could be moisture
Will check that next time

#4 GlennLeDrew

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Posted 29 January 2013 - 06:25 PM

How about your eyes? At 50, I do get a bit of 'halo-ing' that I didn't when rather younger.

#5 HowardK

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Posted 29 January 2013 - 06:38 PM

Glen

Its a very bright spotlight

Dont think its my eyes

#6 johnnyha

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Posted 29 January 2013 - 07:25 PM

Whenever that happens to me it's moisture, I back off and fan my hand in front of the eyepiece, and when I go back to the eyepiece I try to control my breath because it's usually my breath fogging up the eyepiece.

#7 Eddgie

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Posted 30 January 2013 - 09:11 AM

Of course it is not easy at all to tell what a "Spotlight" exactly describes.

In many cases, glaring off of an eyepeice can be caused by reflections of the light source off of the observer's own eye. It happens sometimes with specific eyepeices.

The easiest thing to do is to change to a different set of eyepeices and see if you can repeat this.

The other thing... I have Mark Vs also, and when there is a bright object in the field, I do sometimes see a small bright spot in the field as well. Some kind of internal reflection. It always appears when the target is high and right in the field, and the little spot will be low and left. If I move the target in the field, the spot will track at right angles to it and in the opposute direction.

It is very small, but it appears to be very slightly rectangular if I look closely at it.

It is pretty bright is the target is pretty bright, but once the target is in the center of the field, I don't see it anymore.

And when I do see it, it is always low and left in the field.

I have never thought to see if it was coming from both eyepieces or one. If both, then it would seem to be something with the beam splitter, but again, it has never concerned me enogh to troubleshoot.

So, if you are seeing something like this, then perhaps it is some kind of reflection in the Mark V.

#8 HowardK

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Posted 30 January 2013 - 01:23 PM

Ok

It is moisture from my breath

I use a hoodie type thing and my breath cant escape well
Small blast with warm hair dryer clears it.

#9 panhard

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Posted 30 January 2013 - 10:07 PM

Well you have that one figured out. :grin:

#10 HowardK

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Posted 31 January 2013 - 11:27 AM

Yup

#11 gustave

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Posted 31 January 2013 - 10:55 PM

Now that you have the spotlight problem solved here is another glaring problem.
Tonight I was viewing with my 11” F5 Dob using WO bino’s, TV 2” Big Barlow, and Brandon 24 ep’s. I was trying this set up on Jupiter and OC’s.The views were bright, with high contrast and sharp detail far exceeding my expectations. The issue was twin cones of light streaming out horizontally from bright stars and Jupiter. Reminded me of images of black hole jets. Is this flaw a result of using a 2” barlow with the WO bino’s or something else in this optical train set up?

#12 HowardK

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Posted 01 February 2013 - 08:24 AM

Hmmmm

Yes i get this on bright objects with my refractor, power switch with Denk OCS and Baader mk5 .....its not too extreme though

I live with it

#13 johnnyha

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Posted 01 February 2013 - 05:07 PM

Sounds like typical spider vane diffraction.

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#14 HowardK

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Posted 01 February 2013 - 05:34 PM

Eye placement

Get the eyes positioned right and the two beams of light disappear






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