AstroShed:
Jeffery Richards:
AstroShed:
Jeffery Richards:
AstroShed:
This is what I get from My Esprit 100, here in the U.K., this was taken at -2.5 degrees, ...
Is that F or C?
C, I only use degrees C as in Uk..👍🏻
That's what I figured but wanted it to be clear for everyone. -2.5C is significantly different that -2.5F. I would expect most optics to operate fine at -2.5C.
Well clearly not as that is what this thread is all about, have you read the first post or not…? If so you will se that he is having issues at or just below 0 degrees C, and with the same optics I was saying that mine is good at these temps… And I stand by my statement that most optics should operate fine at those temps (as yours does).
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Jeffery Richards:
AstroShed:
Jeffery Richards:
AstroShed:
Jeffery Richards:
AstroShed:
This is what I get from My Esprit 100, here in the U.K., this was taken at -2.5 degrees, ...
Is that F or C?
C, I only use degrees C as in Uk..👍🏻
That's what I figured but wanted it to be clear for everyone. -2.5C is significantly different that -2.5F. I would expect most optics to operate fine at -2.5C.
Well clearly not as that is what this thread is all about, have you read the first post or not…? If so you will se that he is having issues at or just below 0 degrees C, and with the same optics I was saying that mine is good at these temps…
And I stand by my statement that most optics should operate fine at those temps (as yours does). “Should”, exactly, but that is of no help to the OP at all, I was trying to show that what he is seeing is NOT normal for these scopes, at these temps, and something else is amiss.
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"Should" is saying there is likely something wrong with his scope or something else in his setup. And sorry for getting your dander up for asking to verify which temperature scale you were using. I'll bow out…
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I've sent over a mail to FLO to hear what they say. Here's a crop of a more or less finished picture of M81-Bodes. Have deleted half of the subs, so this is 5h48min. I guess that one could live with it like this, but I'd really like a scope that produces perfect stars.  |
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This is an interesting effect and it’s not easy to completely explain where that pattern comes from. Sometimes I even see this kind of stuff that varies sub to sub from my 24” RC. In the refractors, I’m wondering if it might be due to birefringence in the one (or more) of the elements induced by mechanical stress. As the temperature goes down, any material with a positive CTE should decrease in size—not increase. That means that if mechanical stress is being applied to a lens, the lens cell must be getting smaller faster than the glass as the temperature decreases—and the manufacturers should account for that in their design. That may also be why a heater strap wrapped around the lens cell may be effective. If there is mechanical stress, that can induce birefringence in the glass, which conceivably could produce the kind of pattern that you folks are reporting—particularly if it’s happening in more than a single element. One way to test that theory would be to put a polarizer in front of the telescope and rotate it to see what happens. The other way would be to put a 1/2 wave plate in front of the sensor to see if the pattern disappears. The problem with either of those ideas is that you would need high optical quality components—and that’s hard (and expensive). Either way, it seems like the manufacturers of these scopes need to think a bit more carefully about how to better athermalize the cell design.
John
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John Hayes:
This is an interesting effect and it’s not easy to completely explain where that pattern comes from. Sometimes I even see this kind of stuff that varies sub to sub from my 24” RC. In the refractors, I’m wondering if it might be due to birefringence in the one (or more) of the elements induced by mechanical stress. As the temperature goes down, any material with a positive CTE should decrease in size—not increase. That means that if mechanical stress is being applied to a lens, the lens cell must be getting smaller faster than the glass as the temperature decreases—and the manufacturers should account for that in their design. That may also be why a heater strap wrapped around the lens cell may be effective. If there is mechanical stress, that can induce birefringence in the glass, which conceivably could produce the kind of pattern that you folks are reporting—particularly if it’s happening in more than a single element. One way to test that theory would be to put a polarizer in front of the telescope and rotate it to see what happens. The other way would be to put a 1/2 wave plate in front of the sensor to see if the pattern disappears. The problem with either of those ideas is that you would need high optical quality components—and that’s hard (and expensive). Either way, it seems like the manufacturers of these scopes need to think a bit more carefully about how to better athermalize the cell design.
John Thanks for your view ! I fulle agree, if this is due to temperature it should be possible to handle. So far I have only had the chance to test my scope two nights, both with temperatures between minus 6 - 9 C. Hope to to see temp well above freezing in order to check if problem still exists.
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John Hayes:
This is an interesting effect and it’s not easy to completely explain where that pattern comes from. Sometimes I even see this kind of stuff that varies sub to sub from my 24” RC. In the refractors, I’m wondering if it might be due to birefringence in the one (or more) of the elements induced by mechanical stress. As the temperature goes down, any material with a positive CTE should decrease in size—not increase. That means that if mechanical stress is being applied to a lens, the lens cell must be getting smaller faster than the glass as the temperature decreases—and the manufacturers should account for that in their design. That may also be why a heater strap wrapped around the lens cell may be effective. If there is mechanical stress, that can induce birefringence in the glass, which conceivably could produce the kind of pattern that you folks are reporting—particularly if it’s happening in more than a single element. One way to test that theory would be to put a polarizer in front of the telescope and rotate it to see what happens. The other way would be to put a 1/2 wave plate in front of the sensor to see if the pattern disappears. The problem with either of those ideas is that you would need high optical quality components—and that’s hard (and expensive). Either way, it seems like the manufacturers of these scopes need to think a bit more carefully about how to better athermalize the cell design.
John Hello John! Thank you for chiming in John! You are one of the people I most respect in this hobby. It is is greatly appreciated! Skywatcher is graciously accepting for me to send them back the telescope to check it out. But...(there is always one in this hobby, isn't it) after 5+ years in this hobby without big pockets to spend on high end equipment, overall I am very happy with this telescope. The color correction is really good, the field flattner works great....The only thing that bothers me is the shape of bright stars at low temperatures. As the temperature increases the shapes improve, but at +7 C I still see some of diffraction. It doesn't look the same across all filters...It is more noticeable on the red and green filters. The blue looks almost perfect! All of this makes me wonder if it is worth to take the risk to dismount such a big, heavy scope and send it via courier (risking falls and mishandling) hundreds of kilometers to SW's shop in Spain. Part of me says that I have to accept that this is the normal behavior of its three-element air spaced lens and there is not much more that can be done to fix this (I don't think they will redesign the lens cell just to fix my scope). Do you agree? I am processing an image I took of IC 405 (under less than ideal conditions) to decide whether or not I want to send the scope back.
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Hey, I'm a little late to this one, but as an Esprit 150 user, I can say I don't see this issue in my scope. I do however, have about a half hour of acclimation to go through after astro dark as it cools off where I do see some issues that look like pinched optics. Lately, it's been down into the teens farenheit, so I don't see any serious cold like some do.
I do want to ask though where your dew heater is placed. If it's directly over the lens cell, and its not evenly heating, I could suspect this may cause your issue. I keep my dew heater well in front of the lens cell, to the point where the back of the strap is even with the skywatcher letters on the cell… if that makes sense.
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Brian Puhl:
Hey, I'm a little late to this one, but as an Esprit 150 user, I can say I don't see this issue in my scope. I do however, have about a half hour of acclimation to go through after astro dark as it cools off where I do see some issues that look like pinched optics. Lately, it's been down into the teens farenheit, so I don't see any serious cold like some do.
I do want to ask though where your dew heater is placed. If it's directly over the lens cell, and its not evenly heating, I could suspect this may cause your issue. I keep my dew heater well in front of the lens cell, to the point where the back of the strap is even with the skywatcher letters on the cell... if that makes sense. Interesting. I also keep the dew heater on the "cap", and even with the letters. I have been advised though to keep it just shy of the "dew-cap" on the tube itself by a fellow astrophotographer who image at temperatures well below minus 20 C. I'm also advised to put a dewheater on the flattener as some say these flatteners also can cause similar stars. I'l have to test this, I guess.
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Gunder Strømberg:
I've sent over a mail to FLO to hear what they say.
Here's a crop of a more or less finished picture of M81-Bodes. Have deleted half of the subs, so this is 5h48min.
I guess that one could live with it like this, but I'd really like a scope that produces perfect stars.
I think that is deffo a bit of piching of the optics, the 6 points on the stars represent the 6 collimation screws around the lens cell, and as they are all a tad tight it causes this effect, not something you could really do yourself.. ☹️
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Wanda Conde:
John Hayes:
This is an interesting effect and it’s not easy to completely explain where that pattern comes from. Sometimes I even see this kind of stuff that varies sub to sub from my 24” RC. In the refractors, I’m wondering if it might be due to birefringence in the one (or more) of the elements induced by mechanical stress. As the temperature goes down, any material with a positive CTE should decrease in size—not increase. That means that if mechanical stress is being applied to a lens, the lens cell must be getting smaller faster than the glass as the temperature decreases—and the manufacturers should account for that in their design. That may also be why a heater strap wrapped around the lens cell may be effective. If there is mechanical stress, that can induce birefringence in the glass, which conceivably could produce the kind of pattern that you folks are reporting—particularly if it’s happening in more than a single element. One way to test that theory would be to put a polarizer in front of the telescope and rotate it to see what happens. The other way would be to put a 1/2 wave plate in front of the sensor to see if the pattern disappears. The problem with either of those ideas is that you would need high optical quality components—and that’s hard (and expensive). Either way, it seems like the manufacturers of these scopes need to think a bit more carefully about how to better athermalize the cell design.
John
Hello John! Thank you for chiming in John! You are one of the people I most respect in this hobby. It is is greatly appreciated!
Skywatcher is graciously accepting for me to send them back the telescope to check it out. But...(there is always one in this hobby, isn't it) after 5+ years in this hobby without big pockets to spend on high end equipment, overall I am very happy with this telescope. The color correction is really good, the field flattner works great....The only thing that bothers me is the shape of bright stars at low temperatures. As the temperature increases the shapes improve, but at +7 C I still see some of diffraction. It doesn't look the same across all filters...It is more noticeable on the red and green filters. The blue looks almost perfect! All of this makes me wonder if it is worth to take the risk to dismount such a big, heavy scope and send it via courier (risking falls and mishandling) hundreds of kilometers to SW's shop in Spain. Part of me says that I have to accept that this is the normal behavior of its three-element air spaced lens and there is not much more that can be done to fix this (I don't think they will redesign the lens cell just to fix my scope). Do you agree?
I am processing an image I took of IC 405 (under less than ideal conditions) to decide whether or not I want to send the scope back. Wanda, may I ask which country You live in, and which Sky-Watcher office that will handle Your guarantee ? I got three fellow Norwegian astrophotographers with the Esprit 150ED, and all three of them have imaged in temperatures between minus 6 and minus 30 with perfect stars. One of them imaged at minus 6 without heaterband, still perfect. So, I'm pretty sure I will have to return the scope for service in order to get it right. Gunder
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Gunder Strømberg:
Wanda Conde:
John Hayes:
This is an interesting effect and it’s not easy to completely explain where that pattern comes from. Sometimes I even see this kind of stuff that varies sub to sub from my 24” RC. In the refractors, I’m wondering if it might be due to birefringence in the one (or more) of the elements induced by mechanical stress. As the temperature goes down, any material with a positive CTE should decrease in size—not increase. That means that if mechanical stress is being applied to a lens, the lens cell must be getting smaller faster than the glass as the temperature decreases—and the manufacturers should account for that in their design. That may also be why a heater strap wrapped around the lens cell may be effective. If there is mechanical stress, that can induce birefringence in the glass, which conceivably could produce the kind of pattern that you folks are reporting—particularly if it’s happening in more than a single element. One way to test that theory would be to put a polarizer in front of the telescope and rotate it to see what happens. The other way would be to put a 1/2 wave plate in front of the sensor to see if the pattern disappears. The problem with either of those ideas is that you would need high optical quality components—and that’s hard (and expensive). Either way, it seems like the manufacturers of these scopes need to think a bit more carefully about how to better athermalize the cell design.
John
Hello John! Thank you for chiming in John! You are one of the people I most respect in this hobby. It is is greatly appreciated!
Skywatcher is graciously accepting for me to send them back the telescope to check it out. But...(there is always one in this hobby, isn't it) after 5+ years in this hobby without big pockets to spend on high end equipment, overall I am very happy with this telescope. The color correction is really good, the field flattner works great....The only thing that bothers me is the shape of bright stars at low temperatures. As the temperature increases the shapes improve, but at +7 C I still see some of diffraction. It doesn't look the same across all filters...It is more noticeable on the red and green filters. The blue looks almost perfect! All of this makes me wonder if it is worth to take the risk to dismount such a big, heavy scope and send it via courier (risking falls and mishandling) hundreds of kilometers to SW's shop in Spain. Part of me says that I have to accept that this is the normal behavior of its three-element air spaced lens and there is not much more that can be done to fix this (I don't think they will redesign the lens cell just to fix my scope). Do you agree?
I am processing an image I took of IC 405 (under less than ideal conditions) to decide whether or not I want to send the scope back.
Wanda, may I ask which country You live in, and which Sky-Watcher office that will handle Your guarantee ?
I got three fellow Norwegian astrophotographers with the Esprit 150ED, and all three of them have imaged in temperatures between minus 6 and minus 30 with perfect stars. One of them imaged at minus 6 without heaterband, still perfect.
So, I'm pretty sure I will have to return the scope for service in order to get it right.
Gunder I am currently living in Portugal, but I purchased the telescope through a store in Spain. I made the claim through the store because the telescope is still under warranty. I think SkyWatcher has a service shop in Barcelona, but I do not exactly where it is located. You may want to find out through your dealer in Norway where is the nearest service shop for you. Wanda
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Wanda Conde:
I am currently living in Portugal, but I purchased the telescope through a store in Spain. I made the claim through the store because the telescope is still under warranty. I think SkyWatcher has a service shop in Barcelona, but I do not exactly where it is located. You may want to find out through your dealer in Norway where is the nearest service shop for you.
Wanda Ok thanks. Mine is under warranty as well, my dealer is located in England, so will eventually have to be shipped with DHL or UPS. Would be nice to know what happens next with your scope, hope you update this post as soon as SkyWatcher comes to a conclusion ?  |
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Gunder Strømberg:
Wanda Conde:
I am currently living in Portugal, but I purchased the telescope through a store in Spain. I made the claim through the store because the telescope is still under warranty. I think SkyWatcher has a service shop in Barcelona, but I do not exactly where it is located. You may want to find out through your dealer in Norway where is the nearest service shop for you.
Wanda
Ok thanks. Mine is under warranty as well, my dealer is located in England, so will eventually have to be shipped with DHL or UPS.
Would be nice to know what happens next with your scope, hope you update this post as soon as SkyWatcher comes to a conclusion ? My experiences with SkyWatcher's customer service have been second to none. My mount (EQ8R) came with some backlash issues which they fixed under warranty, and now they are fixing the pinched optics of my refractor. That's something you just hear about high end manufacturers. I will post the outcome once my scope is back. I hope you can get yours fixed too.
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Wanda Conde:
John Hayes:
This is an interesting effect and it’s not easy to completely explain where that pattern comes from. Sometimes I even see this kind of stuff that varies sub to sub from my 24” RC. In the refractors, I’m wondering if it might be due to birefringence in the one (or more) of the elements induced by mechanical stress. As the temperature goes down, any material with a positive CTE should decrease in size—not increase. That means that if mechanical stress is being applied to a lens, the lens cell must be getting smaller faster than the glass as the temperature decreases—and the manufacturers should account for that in their design. That may also be why a heater strap wrapped around the lens cell may be effective. If there is mechanical stress, that can induce birefringence in the glass, which conceivably could produce the kind of pattern that you folks are reporting—particularly if it’s happening in more than a single element. One way to test that theory would be to put a polarizer in front of the telescope and rotate it to see what happens. The other way would be to put a 1/2 wave plate in front of the sensor to see if the pattern disappears. The problem with either of those ideas is that you would need high optical quality components—and that’s hard (and expensive). Either way, it seems like the manufacturers of these scopes need to think a bit more carefully about how to better athermalize the cell design.
John
Hello John! Thank you for chiming in John! You are one of the people I most respect in this hobby. It is is greatly appreciated!
Skywatcher is graciously accepting for me to send them back the telescope to check it out. But...(there is always one in this hobby, isn't it) after 5+ years in this hobby without big pockets to spend on high end equipment, overall I am very happy with this telescope. The color correction is really good, the field flattner works great....The only thing that bothers me is the shape of bright stars at low temperatures. As the temperature increases the shapes improve, but at +7 C I still see some of diffraction. It doesn't look the same across all filters...It is more noticeable on the red and green filters. The blue looks almost perfect! All of this makes me wonder if it is worth to take the risk to dismount such a big, heavy scope and send it via courier (risking falls and mishandling) hundreds of kilometers to SW's shop in Spain. Part of me says that I have to accept that this is the normal behavior of its three-element air spaced lens and there is not much more that can be done to fix this (I don't think they will redesign the lens cell just to fix my scope). Do you agree?
I am processing an image I took of IC 405 (under less than ideal conditions) to decide whether or not I want to send the scope back. Hi Wanda, I just returned from the SPIE conference in San Fransisco where I had a chance to speak informally to Russell Chipman about your issue and my response. Russell is a former professor at the Wyant College of Optical Sciences and he now works at Meta. He is probably the world's foremost expert on polarization and he virtually invented the field of polarization aberrations. He generally agreed with my assessment of the likelihood of stress induced birefringence as the cause of the problem. We agreed that if the lens mount has some sort of three point contact in the cell, that could be the cause of the fairly regular 6-point diffraction-like spikes in the pattern. Russell pointed out my mistake in saying that a half wave plate could be used to diagnose the problem. You actually would need a half-wave plate along with a polarizer. Either way, I think that you should continue to push the manufacturer to see if they can fix it. As I've said, they should be able to design their scopes to avoid this kind of thermal problem. If they can't do anything about it, you may just have to use a heater strap to keep it from getting cold. That solution is pretty easy and if it works, it's worth doing. Good luck with it! John
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Brian Puhl:
Hey, I'm a little late to this one, but as an Esprit 150 user, I can say I don't see this issue in my scope. I do however, have about a half hour of acclimation to go through after astro dark as it cools off where I do see some issues that look like pinched optics. Lately, it's been down into the teens farenheit, so I don't see any serious cold like some do.
I do want to ask though where your dew heater is placed. If it's directly over the lens cell, and its not evenly heating, I could suspect this may cause your issue. I keep my dew heater well in front of the lens cell, to the point where the back of the strap is even with the skywatcher letters on the cell... if that makes sense. Thanks for chiming in. I placed the dew heater exactly where you say. Unfortunately it didn't help much. Since the telescope is still under warranty, I decided to ship it back to SkyWatcher. The people at the shop where I got it say that they are very positive that the problem will be fixed completely. We'll see...
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John Hayes:
Wanda Conde:
John Hayes:
This is an interesting effect and it’s not easy to completely explain where that pattern comes from. Sometimes I even see this kind of stuff that varies sub to sub from my 24” RC. In the refractors, I’m wondering if it might be due to birefringence in the one (or more) of the elements induced by mechanical stress. As the temperature goes down, any material with a positive CTE should decrease in size—not increase. That means that if mechanical stress is being applied to a lens, the lens cell must be getting smaller faster than the glass as the temperature decreases—and the manufacturers should account for that in their design. That may also be why a heater strap wrapped around the lens cell may be effective. If there is mechanical stress, that can induce birefringence in the glass, which conceivably could produce the kind of pattern that you folks are reporting—particularly if it’s happening in more than a single element. One way to test that theory would be to put a polarizer in front of the telescope and rotate it to see what happens. The other way would be to put a 1/2 wave plate in front of the sensor to see if the pattern disappears. The problem with either of those ideas is that you would need high optical quality components—and that’s hard (and expensive). Either way, it seems like the manufacturers of these scopes need to think a bit more carefully about how to better athermalize the cell design.
John
Hello John! Thank you for chiming in John! You are one of the people I most respect in this hobby. It is is greatly appreciated!
Skywatcher is graciously accepting for me to send them back the telescope to check it out. But...(there is always one in this hobby, isn't it) after 5+ years in this hobby without big pockets to spend on high end equipment, overall I am very happy with this telescope. The color correction is really good, the field flattner works great....The only thing that bothers me is the shape of bright stars at low temperatures. As the temperature increases the shapes improve, but at +7 C I still see some of diffraction. It doesn't look the same across all filters...It is more noticeable on the red and green filters. The blue looks almost perfect! All of this makes me wonder if it is worth to take the risk to dismount such a big, heavy scope and send it via courier (risking falls and mishandling) hundreds of kilometers to SW's shop in Spain. Part of me says that I have to accept that this is the normal behavior of its three-element air spaced lens and there is not much more that can be done to fix this (I don't think they will redesign the lens cell just to fix my scope). Do you agree?
I am processing an image I took of IC 405 (under less than ideal conditions) to decide whether or not I want to send the scope back.
Hi Wanda,
I just returned from the SPIE conference in San Fransisco where I had a chance to speak informally to Russell Chipman about your issue and my response. Russell is a former professor at the Wyant College of Optical Sciences and he now works at Meta. He is probably the world's foremost expert on polarization and he virtually invented the field of polarization aberrations. He generally agreed with my assessment of the likelihood of stress induced birefringence as the cause of the problem. We agreed that if the lens mount has some sort of three point contact in the cell, that could be the cause of the fairly regular 6-point diffraction-like spikes in the pattern. Russell pointed out my mistake in saying that a half wave plate could be used to diagnose the problem. You actually would need a half-wave plate along with a polarizer. Either way, I think that you should continue to push the manufacturer to see if they can fix it. As I've said, they should be able to design their scopes to avoid this kind of thermal problem. If they can't do anything about it, you may just have to use a heater strap to keep it from getting cold. That solution is pretty easy and if it works, it's worth doing.
Good luck with it!
John Hi John, Today I sent the scope back to SkyWatcher. Tech team told me that the lens is held in place by 3 screws. These screws are threaded into the lens cell (a massive piece of machined aluminium). I these screws are too tight, the metal contracts and the glass tightens a bit. If that's the case all they have to do is loosen the screws (and in the process, you will also collimate the tube). Whether the solution is that simple or not remains to be seen. In any case I will keep pressing on until the issue is fixed. Thanks again for taking the time to look into this. Wanda
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Wanda Conde:
Gunder Strømberg:
Wanda Conde:
I am currently living in Portugal, but I purchased the telescope through a store in Spain. I made the claim through the store because the telescope is still under warranty. I think SkyWatcher has a service shop in Barcelona, but I do not exactly where it is located. You may want to find out through your dealer in Norway where is the nearest service shop for you.
Wanda
Ok thanks. Mine is under warranty as well, my dealer is located in England, so will eventually have to be shipped with DHL or UPS.
Would be nice to know what happens next with your scope, hope you update this post as soon as SkyWatcher comes to a conclusion ?
My experiences with SkyWatcher's customer service have been second to none. My mount (EQ8R) came with some backlash issues which they fixed under warranty, and now they are fixing the pinched optics of my refractor. That's something you just hear about high end manufacturers. I will post the outcome once my scope is back. I hope you can get yours fixed too. I have tried "a new option", i.e. using three dew-heaters, one on the dew shield, one next to the dew-shield and one on the flattener. At minus 4 degrees Celcius i looks like this did the trick. Hoping for a clear night with minus 10 to see if it still produces round stars. These are screen shots of single subs, 600s   |
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Wanda Conde:
Hi John,
Today I sent the scope back to SkyWatcher. Tech team told me that the lens is held in place by 3 screws. These screws are threaded into the lens cell (a massive piece of machined aluminium). I these screws are too tight, the metal contracts and the glass tightens a bit. If that's the case all they have to do is loosen the screws (and in the process, you will also collimate the tube). Whether the solution is that simple or not remains to be seen. In any case I will keep pressing on until the issue is fixed.
Thanks again for taking the time to look into this.
Wanda Hi Wanda, So that completely explains why there were 6 spikes. Loosening those screws should fix the problem. Good luck with it and let us know how the fix works. John
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From what I'm reading here it seems that consistency in manufacturing could be an issue. I've used my SW Esprit 100 down to -25 C and have not noticed this - However I have been using a dew strap BUT only around the dew shield not the lens cell; maybe it still provides enought heat anyway?
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Wanda Conde:
My experiences with SkyWatcher's customer service have been second to none. My mount (EQ8R) came with some backlash issues which they fixed under warranty, and now they are fixing the pinched optics of my refractor. That's something you just hear about high end manufacturers. I will post the outcome once my scope is back. I hope you can get yours fixed too. Hope it's ok to ask, I am a bit curious to hear if You got the Esprit back from Sky-Watcher, and if the problem got fixed? Regards Gunder
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Well for those of you interested in how it all ended, here is an update: Last week I received the telescope back. It took longer than expected as bad weather in Spain didn't allow the repair team to perform the last check which has to be done out in the field. The temperature has increased as the Winter is over and Spring arrived. Luckily as soon as the telescope arrivedthe temperature at the observatory dropped around 0 C and I was able to take some frames of the same cluster where I noticed the problem back in January. At 0 C the improvement is remarkable. How will it hold below 0C will have to wait until next Winter. I have high hopes because the issue was still noticeable around 7C. Here is a comparison where you can see the difference:  I have to mention that while the "Before" image was taken on a crisp, clear night with great seeing, the "After" image was taken on a night with terrible seeing, high clouds, etc... as bad as a night can get. Like I said before, the final test will take place next Winter...Until then I am quite happy with what I got. CS everyone! Wanda
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Wanda Conde:
Well for those of you interested in how it all ended, here is an update:
Last week I received the telescope back. It took longer than expected as bad weather in Spain didn't allow the repair team to perform the last check which has to be done out in the field. The temperature has increased as the Winter is over and Spring arrived. Luckily as soon as the telescope arrivedthe temperature at the observatory dropped around 0 C and I was able to take some frames of the same cluster where I noticed the problem back in January. At 0 C the improvement is remarkable. How will it hold below 0C will have to wait until next Winter. I have high hopes because the issue was still noticeable around 7C. Here is a comparison where you can see the difference:
I have to mention that while the "Before" image was taken on a crisp, clear night with great seeing, the "After" image was taken on a night with terrible seeing, high clouds, etc... as bad as a night can get. Like I said before, the final test will take place next Winter...Until then I am quite happy with what I got.
CS everyone!
Wanda Thanks for the update, that looks much better. As I mentioned earlier I have added dewheaterbands both on, and next to the dewshield, as well as on the flattener, and my stars got much better. I have had same trouble with bad weather, so final tests will have to wait til September. Regards Gunder
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Wanda Conde:
Well for those of you interested in how it all ended, here is an update:
Last week I received the telescope back. It took longer than expected as bad weather in Spain didn't allow the repair team to perform the last check which has to be done out in the field. The temperature has increased as the Winter is over and Spring arrived. Luckily as soon as the telescope arrivedthe temperature at the observatory dropped around 0 C and I was able to take some frames of the same cluster where I noticed the problem back in January. At 0 C the improvement is remarkable. How will it hold below 0C will have to wait until next Winter. I have high hopes because the issue was still noticeable around 7C. Here is a comparison where you can see the difference:
I have to mention that while the "Before" image was taken on a crisp, clear night with great seeing, the "After" image was taken on a night with terrible seeing, high clouds, etc... as bad as a night can get. Like I said before, the final test will take place next Winter...Until then I am quite happy with what I got.
CS everyone!
Wanda Thanks for the follow up Wanda! I suspect that you may need better seeing to know for sure, but that result looks very promising. John
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Wanda Conde:
Well for those of you interested in how it all ended, here is an update:
Last week I received the telescope back. It took longer than expected as bad weather in Spain didn't allow the repair team to perform the last check which has to be done out in the field. The temperature has increased as the Winter is over and Spring arrived. Luckily as soon as the telescope arrivedthe temperature at the observatory dropped around 0 C and I was able to take some frames of the same cluster where I noticed the problem back in January. At 0 C the improvement is remarkable. How will it hold below 0C will have to wait until next Winter. I have high hopes because the issue was still noticeable around 7C. Here is a comparison where you can see the difference:
I have to mention that while the "Before" image was taken on a crisp, clear night with great seeing, the "After" image was taken on a night with terrible seeing, high clouds, etc... as bad as a night can get. Like I said before, the final test will take place next Winter...Until then I am quite happy with what I got.
CS everyone!
Wanda The stars are much bigger and softer now, which would mask any issues anyway, I don’t think the focus is bang on, or they have made adjustments to soften the stars to mask the issue, which is what Askar do with there scopes, as they are well known for larger more bloated stars, which cover a multitude of sins, I am really not convinced that they have sorted the issue for you, just hidden it, time will tell 🤔
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