LS100THa Question.
- GUS
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LS100THa Question.
Had a chance to try the LS 100T today, noticed a ghost disk about half the diameter of low power field, and multi reflections (using the Lunt BF). Has any one else had a similar problem, particularly with the LS 100 SS and if so, how can it be minimized.
GUS.
GUS.
- swisswalter
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Re: LS100THa Question.
Hi GUS
sorry I can't help.Have only experience with a LUNT 100 PT
sorry I can't help.Have only experience with a LUNT 100 PT
Only stardust in the wind, some fine and some less fine scopes, filters and adapters as well. Switzerland 47 N, 9 E, in the heart of EUROPE
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- grimble_cornet
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Re: LS100THa Question.
Hi Gus. It may just be coincidence and totally unrelated but I got a very similar ghost image this morning when pushing my Lunt 60 CaK to ridiculously high exposures in an attempt to record CaK proms:
I have imaged CaK proms a few times before but have not seen this effect. I was using my ZWOASI120MM camera this time whereas my previous attempts at very high exposure for CaK proms have been with my DMK41 - not sure if this is relevant?
The ghost is clearly an image of the objective lens, complete with clips at 120 degree spacing. I can only assume it is caused by reflections between internal components which are normally too dim to show up at normal exposures? I positioned the limb with giant prom outside the ghost area in an attempt to record it.
Were you pushing the exposure when you got ghosting or were you observing visually? Was your ghost anything like the one in my image?
I have imaged CaK proms a few times before but have not seen this effect. I was using my ZWOASI120MM camera this time whereas my previous attempts at very high exposure for CaK proms have been with my DMK41 - not sure if this is relevant?
The ghost is clearly an image of the objective lens, complete with clips at 120 degree spacing. I can only assume it is caused by reflections between internal components which are normally too dim to show up at normal exposures? I positioned the limb with giant prom outside the ghost area in an attempt to record it.
Were you pushing the exposure when you got ghosting or were you observing visually? Was your ghost anything like the one in my image?
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Mike Garbett
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Mike Garbett
Selection of Solar and Deep Sky images on Flickr: https://www.flickr.com/photos/mikegarbett/
- GUS
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Re: LS100THa Question.
Hi Walter, I'm talking about the 100 PT, sorry I didn't put that in the title as I thought there was only one 100mm model, forgot about the Lunt engineering 100mm scope.
Thanks Mike,that's exactly what I'm talking about, but in the 100mm scope its visible at low powers, and seems to be a reflection of the ITF off the back of the re collimating lens, but not sure. This is seen using both Lunt BFs that I own, but is not visible in the Coronado BF10 that I use with this scope as well,so might have to do with the tilt angle of the ITF. At higher powers it is not seen in the lunt BFs.
Thought that maybe it could have been a focuser problem as the focuser was loose on arrival and had to be re tightened, and I didn't try to collimate it, but not sure about this scenario as well. Haven't noticed the ghost image on my LS60PT, at any powers, but figure that the image in the 100mm is so bright ,that it could be the reason its visible in it more compared to the 60mm. Just want to see if there is a way to minimize it at low power for visual, tried different filters, and got it to a point were it wasn't objectionable but the image was then very faint.
GUS.
Thanks Mike,that's exactly what I'm talking about, but in the 100mm scope its visible at low powers, and seems to be a reflection of the ITF off the back of the re collimating lens, but not sure. This is seen using both Lunt BFs that I own, but is not visible in the Coronado BF10 that I use with this scope as well,so might have to do with the tilt angle of the ITF. At higher powers it is not seen in the lunt BFs.
Thought that maybe it could have been a focuser problem as the focuser was loose on arrival and had to be re tightened, and I didn't try to collimate it, but not sure about this scenario as well. Haven't noticed the ghost image on my LS60PT, at any powers, but figure that the image in the 100mm is so bright ,that it could be the reason its visible in it more compared to the 60mm. Just want to see if there is a way to minimize it at low power for visual, tried different filters, and got it to a point were it wasn't objectionable but the image was then very faint.
GUS.
- grimble_cornet
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Re: LS100THa Question.
OK, well you now have a photograph to show people what you are seeing. I hope you find a solution Gus as I have just ordered the very same scope.
You have 2 months to solve the problem before mine is supposed to arrive
Mike
You have 2 months to solve the problem before mine is supposed to arrive
Mike
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Mike Garbett
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Re: LS100THa Question.
GUS,
There is only one thing that causes multiple, closely spaced ghost images that move when you tune the etalon, and that is a decontacted etalon.
If you had a picture of what you are seeing it would be much easier for me to offer my opinion. I have screwed them up just about every way you can.
grimble comet, that is the reflection of the mirrored end of the CaK module on your objective. It is supposed to be there. If you look on the objective while you are using it, you will see it from the other side.
There is only one thing that causes multiple, closely spaced ghost images that move when you tune the etalon, and that is a decontacted etalon.
If you had a picture of what you are seeing it would be much easier for me to offer my opinion. I have screwed them up just about every way you can.
grimble comet, that is the reflection of the mirrored end of the CaK module on your objective. It is supposed to be there. If you look on the objective while you are using it, you will see it from the other side.
Stephen W. Ramsden
Atlanta, GA USA
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Atlanta, GA USA
Founder/Director Charlie Bates Solar Astronomy Project
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Re: LS100THa Question.
after reading your other post though GUS, it sounds like you are also just getting the reflection from the ITF. It has to be close in order for it to work but deflected away in order for you not to see it. You must have been on extremely low power.
Stephen W. Ramsden
Atlanta, GA USA
Founder/Director Charlie Bates Solar Astronomy Project
http://www.solarastronomy.org
Atlanta, GA USA
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Re: LS100THa Question.
Thanks for putting on the pressure mike. The detail through the scope is amazing visually, when the conditions are right the surface detail that can be seen in SS is amazing, and the proms and spicules are incredible. These scopes are all hand made and can behave differently to each other and I realize that reflections and ghosts are hard to eliminate, especially with something so bright,so in my case, visually the scope is great at medium to higher powers. were I do most of my obs. I still haven't tried it imaging wise, too busy trying visuals most of Saturday, was hoping to image Sunday but clouds rolled in.
GUS.
GUS.
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Re: LS100THa Question.
Hi Steven, the view through the scope is great, it tunes properly, and I can see Proms and surface at the same time in great detail. Figured it was reflections of the ITF off the RE collimating lens,as the ghost was quite large, and yes I was using about 30x mag, But if I try medium Mag, its not as noticeable. Thanks for the input Steven.
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Re: LS100THa Question.
Cheers Stephen, I only see this when I push the exposure to ridiculous levels in an attempt to image very feint proms in CaK. I can't complain as I'm pushing the envelope way beyond the design parameters
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Mike Garbett
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Re: LS100THa Question.
Hi GUS
now we come the riddle closer. I can produce the same ghost as MIKE showed us with the LUNT 100 PT. I see it only at low power and high gain. It is easely put out of the FOV while adjusting the PT knob. I have never bothered about it because it is not interacting with my pics. That said I can record the CaK ghost too, as Mike did, but that one is closer to the disc compared to the LUNT 100 ghost and it is harder to move it away
now we come the riddle closer. I can produce the same ghost as MIKE showed us with the LUNT 100 PT. I see it only at low power and high gain. It is easely put out of the FOV while adjusting the PT knob. I have never bothered about it because it is not interacting with my pics. That said I can record the CaK ghost too, as Mike did, but that one is closer to the disc compared to the LUNT 100 ghost and it is harder to move it away
Only stardust in the wind, some fine and some less fine scopes, filters and adapters as well. Switzerland 47 N, 9 E, in the heart of EUROPE
from 7 am - 7 pm http://www.nanosys.ch
from 7.01 pm - 6.59 am http://www.wastronomiko.com some times vice versa
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Re: LS100THa Question.
Hi Walter, what do you mean move it away with the PT tuner.The ghost takes up half my FOV, and is very bright at low power.Do you see the same thing visually, and is it as bright.
GUS.
GUS.
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Re: LS100THa Question.
Hi GUS
while turning the PT knob, the ghost moves away. I'm speaking only about Imaging. Never saw a ghost visually in the LUNT 100
while turning the PT knob, the ghost moves away. I'm speaking only about Imaging. Never saw a ghost visually in the LUNT 100
Only stardust in the wind, some fine and some less fine scopes, filters and adapters as well. Switzerland 47 N, 9 E, in the heart of EUROPE
from 7 am - 7 pm http://www.nanosys.ch
from 7.01 pm - 6.59 am http://www.wastronomiko.com some times vice versa
from 7 am - 7 pm http://www.nanosys.ch
from 7.01 pm - 6.59 am http://www.wastronomiko.com some times vice versa
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Re: LS100THa Question.
Mmmmmm... the plot thickens.
No pressure intended GUS, just my warped sense of humour. Guess I was still worrying a little bit about the weird ghost I had just seen in CaK.
Any chance you could take a picture of what you see - if only a snapshot at the eyepiece with a phone?
No pressure intended GUS, just my warped sense of humour. Guess I was still worrying a little bit about the weird ghost I had just seen in CaK.
Any chance you could take a picture of what you see - if only a snapshot at the eyepiece with a phone?
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Mike Garbett
Selection of Solar and Deep Sky images on Flickr: https://www.flickr.com/photos/mikegarbett/
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Mike Garbett
Selection of Solar and Deep Sky images on Flickr: https://www.flickr.com/photos/mikegarbett/
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Re: LS100THa Question.
I'll try for one on the next clear day Mike. Hope this doesn't put you off the idea of getting the LS100, as its a great scope. I'm coming at it from a different perspective, I'm a visual observer at heart, trying a little imaging at the moment, but much prefer to see with my own eyes than to take images( no disrespect to imagers intended), so I'm trying to get the best view I can visually,trying to minimize reflections, trying different BFs, polarizing filters, coloured filters,etc. I know imaging wise that you can eliminate/minimize the effects of reflections and ghosts so in your case they might not be a problem.
One thing I found is that the Coronado BF doesn't show the ghost image, the ITF must have more of a tilt compared to the Lunt BFs , thus throwing the ghost further out of the view.
GUS.
One thing I found is that the Coronado BF doesn't show the ghost image, the ITF must have more of a tilt compared to the Lunt BFs , thus throwing the ghost further out of the view.
GUS.
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Re: LS100THa Question.
Something really enigmatic. PT just change the pressure (refractive index) of the air - the space between etalon plates.swisswalter wrote:
while turning the PT knob, the ghost moves away.
No mechanical movements in the optical train. ??????????? Enigma!
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Re: LS100THa Question.
Hi Valery
enigmatic or not , that happens when you watch the ghost and turne the PT knob, at least on my LUNT 100
enigmatic or not , that happens when you watch the ghost and turne the PT knob, at least on my LUNT 100
Only stardust in the wind, some fine and some less fine scopes, filters and adapters as well. Switzerland 47 N, 9 E, in the heart of EUROPE
from 7 am - 7 pm http://www.nanosys.ch
from 7.01 pm - 6.59 am http://www.wastronomiko.com some times vice versa
from 7 am - 7 pm http://www.nanosys.ch
from 7.01 pm - 6.59 am http://www.wastronomiko.com some times vice versa