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All my telescopes suffer the same loss of performance

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#1 Stewc14

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Posted 17 September 2021 - 03:37 PM

I have been keeping track of this for months. 
I primarily look at planets. I have started to develope interests in clusters and double stars.

I keep my scopes in a air conditioned garage. 72 to 78 degrees.

this is about 10 degree warm up when I put them out.

I just leave them sitting a couple hours . Prior to using them I take a few looks during cool down.

it can be quite sharp on good nights and I find myself using them during this temperature equalizing period .

then they start getting progressively worse when the planets are In their best position. 
even after 6 hours.

they don’t have cooling fans. Some of my scopes are listed below.

c14

tak. Mewlon 300 crs

TMB 228 mm

questar 7

 

i have not tried my rcos 16, unitron 160, Edmund 4” achro, Edmund 4.5 reflector 32” reflector, others.

I was going to start putting fans on them. Blowing don the tube??? On the refractor tube?? I was  going to put a screen over the open focuser end and point it up.

just looking for advice from more experienced individuals than me.

thank you for your advice in advance. Stewart 


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#2 ShaulaB

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Posted 17 September 2021 - 03:55 PM

Um, you do know you posted in the Beginners Forum, right? I do not know many Beginners with a C14 or any kind of Tak or a Questar.

Perhaps a different forum?
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#3 Sandy Swede

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Posted 17 September 2021 - 03:59 PM

This a complete shot in the dark, but don't you get a lot of rising air currents after sundown?  The release of radiant energy at this time of day may play havoc with air currents.  You are at approx 4,700 ft elevation, correct?



#4 MisterDan

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Posted 17 September 2021 - 04:12 PM

When are you putting them out to cool?  If you're setting up prior to sunset, then your scopes are heating up, first.

 

Septembers along the Front Range can see sharp temperature drops - some of the sharpest all year.  Days that end up in the mid-90s can cool down ~25 degrees in about two hours.  That can mean temperature drops of ~12 degrees per hour, which can leave even modest-sized telescopes significantly warmer than the ambient air temp.

 

Another thought:  has anything changed, in your observing area?  Is there a new driveway or paved parking lot just to your south?  A big slab of concrete or asphalt that soaks up sunlight all day long will radiate all that heat for hours.  A big heat island like that can keep your local air & sky quite turbulent.

 

Rather than waiting for larger scopes to cool down (especially cassegrains), you may want to try insulating them from the ambient temperature drops.  Many folks who insulate their scopes utilize aluminized bubble-wrap sheet (i.e. Reflectix, Cool Wrap, et.al), thin foam sheet (such as a yoga mat), or even corrugated cardboard.

 

Best wishes.

Dan



#5 wrnchhead

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Posted 17 September 2021 - 04:17 PM

I used reflectix on my C8 with great results. 

 

But the thing he's describing is that they function well during the temperature adjustment period, and after equilibrated, the performance decreases. I was thinking it may say something about the optics, but with those different scopes, it must be environmental somehow, some function of the localized climate. 



#6 barbarosa

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Posted 17 September 2021 - 04:24 PM

If you did not see this problem in the past, then what changed and what would effect all of your scopes regardless of design?

 

Smoke? Unusual high winds aloft (currently 56 knots at your location)? Local construction or paving that created new heat plumes? A persistent temperature inversion? A combination of any or all of these factors?

 

Is the problem general in all directions and altitudes?

 

I am not Newtonian owner but there is considerable information about using fans in the mirror cell and likewise a lot of information about fans in SCTs to speed cool down or reduce heat plumes. I have not seen the same posts about refractors. But if you need fans now the question is still what changed?



#7 happylimpet

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Posted 17 September 2021 - 04:25 PM

So if I understand, they start cooler than ambient, give great images, and then get worse when the surroundings cool (and the optics have warmed) to lower than the mirrors - a situation than persists until dawn in a desert climate.

 

This is exactly what one would expect. Cold mirrors arent too much of a problem, warm ones are a disaster.

 

Get fans. Blow them hard up the back on reflectors. Onto the face of the mirror if you can.



#8 happylimpet

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Posted 17 September 2021 - 04:26 PM

So if I understand, they start cooler than ambient, give great images, and then get worse when the surroundings cool (and the optics have warmed) to lower than the optics- a situation than persists until dawn in a desert climate.

 

This is exactly what one would expect. Cold optics arent too much of a problem, warm ones are a disaster.

 

Get fans. Blow them hard up the back on reflectors. Onto the face of the mirror if you can.



#9 Stewc14

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Posted 17 September 2021 - 04:52 PM

This a complete shot in the dark, but don't you get a lot of rising air currents after sundown?  The release of radiant energy at this time of day may play havoc with air currents.  You are at approx 4,700 ft elevation, correct?

Yes , 4700 feet plus. I'm not sure about the severity of the currents but would it be a factor 6 hours plus later?

#10 Stewc14

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Posted 17 September 2021 - 04:59 PM

If you did not see this problem in the past, then what changed and what would effect all of your scopes regardless of design?
 
Smoke? Unusual high winds aloft (currently 56 knots at your location)? Local construction or paving that created new heat plumes? A persistent temperature inversion? A combination of any or all of these factors?
 
Is the problem general in all directions and altitudes?
 
I am not Newtonian owner but there is considerable information about using fans in the mirror cell and likewise a lot of information about fans in SCTs to speed cool down or reduce heat plumes. I have not seen the same posts about refractors. But if you need fans now the question is still what changed?

The problem has persisted from the beginning. I am going to go to fans and see if it helps.we do get smoke at times but I'm talking about regular clear nights. No construction or paving. Same problem with the refractor.

#11 Stewc14

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Posted 17 September 2021 - 05:02 PM

When are you putting them out to cool?  If you're setting up prior to sunset, then your scopes are heating up, first.
 
Septembers along the Front Range can see sharp temperature drops - some of the sharpest all year.  Days that end up in the mid-90s can cool down ~25 degrees in about two hours.  That can mean temperature drops of ~12 degrees per hour, which can leave even modest-sized telescopes significantly warmer than the ambient air temp.
 
Another thought:  has anything changed, in your observing area?  Is there a new driveway or paved parking lot just to your south?  A big slab of concrete or asphalt that soaks up sunlight all day long will radiate all that heat for hours.  A big heat island like that can keep your local air & sky quite turbulent.
 
Rather than waiting for larger scopes to cool down (especially cassegrains), you may want to try insulating them from the ambient temperature drops.  Many folks who insulate their scopes utilize aluminized bubble-wrap sheet (i.e. Reflectix, Cool Wrap, et.al), thin foam sheet (such as a yoga mat), or even corrugated cardboard.
 
Best wishes.

I thought about wrapping them. I do have a concrete driveway. I will try that too.
Dan



#12 Stewc14

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Posted 17 September 2021 - 05:27 PM

I used reflectix on my C8 with great results. 
 
But the thing he's describing is that they function well during the temperature adjustment period, and after equilibrated, the performance decreases. I was thinking it may say something about the optics, but with those different scopes, it must be environmental somehow, some function of the localized climate.

I am going to wait tonight till optimum viewing time to start. I don't take them out until sunset.my optics are all good and. Collimated.
We rarely get nights of better than average seeing. When we do it is a joy
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#13 nyairman

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Posted 17 September 2021 - 05:29 PM

The problem has persisted from the beginning. I am going to go to fans and see if it helps.we do get smoke at times but I'm talking about regular clear nights. No construction or paving. Same problem with the refractor.


If all of your scopes have this issue then I would say that it is your surroundings. It sounds like you are doing everything you can to take the correct precautions and procedures with your scopes.

I would bet they would all perform much better in another hospitable location, so to be sure, I would take a refractor and a reflector to a known good seeing location (if possible) and see how they perform.
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#14 Pat Rochford

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Posted 17 September 2021 - 06:40 PM

I have been keeping track of this for months. 
I primarily look at planets. I have started to develope interests in clusters and double stars.

I keep my scopes in a air conditioned garage. 72 to 78 degrees.

this is about 10 degree warm up when I put them out.

I just leave them sitting a couple hours . Prior to using them I take a few looks during cool down.

it can be quite sharp on good nights and I find myself using them during this temperature equalizing period .

then they start getting progressively worse when the planets are In their best position. 
even after 6 hours.

they don’t have cooling fans. Some of my scopes are listed below.

c14

tak. Mewlon 300 crs

TMB 228 mm

questar 7

 

i have not tried my rcos 16, unitron 160, Edmund 4” achro, Edmund 4.5 reflector 32” reflector, others.

I was going to start putting fans on them. Blowing don the tube??? On the refractor tube?? I was  going to put a screen over the open focuser end and point it up.

just looking for advice from more experienced individuals than me.

thank you for your advice in advance. Stewart 

 

Did you just recently move to this location?  Or have you accumulated all of these high dollar telescopes since you've lived there?  I know it's none of my business, but if it's the latter I'm just wondering why you've gotten this deep into equipment if local conditions won't allow you to observe with any of them.  I hope you're able to find some kind of workaround.  



#15 teashea

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Posted 17 September 2021 - 07:11 PM

I have been keeping track of this for months. 
I primarily look at planets. I have started to develope interests in clusters and double stars.

I keep my scopes in a air conditioned garage. 72 to 78 degrees.

this is about 10 degree warm up when I put them out.

I just leave them sitting a couple hours . Prior to using them I take a few looks during cool down.

it can be quite sharp on good nights and I find myself using them during this temperature equalizing period .

then they start getting progressively worse when the planets are In their best position. 
even after 6 hours.

they don’t have cooling fans. Some of my scopes are listed below.

c14

tak. Mewlon 300 crs

TMB 228 mm

questar 7

 

i have not tried my rcos 16, unitron 160, Edmund 4” achro, Edmund 4.5 reflector 32” reflector, others.

I was going to start putting fans on them. Blowing don the tube??? On the refractor tube?? I was  going to put a screen over the open focuser end and point it up.

just looking for advice from more experienced individuals than me.

thank you for your advice in advance. Stewart 

They should perform well - you have some very nice telescopes.



#16 teashea

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Posted 17 September 2021 - 07:14 PM

Could it be atmospheric conditions?  smoke, etc.?



#17 Stewc14

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Posted 18 September 2021 - 03:56 AM

Did you just recently move to this location?  Or have you accumulated all of these high dollar telescopes since you've lived there?  I know it's none of my business, but if it's the latter I'm just wondering why you've gotten this deep into equipment if local conditions won't allow you to observe with any of them.  I hope you're able to find some kind of workaround.


I moved here and when I retired I wanted to get back into astronomy after a long departure from it.I had saved and had the money stashed away.my plan was to go to star parties and join the local club.i hoped to get advice from others.
Well ,Covid happened and everything was shut down. I did however get to go to one star party.(such as it was). People were stand offish and not so friendly. I was told y someone I met later that the club was dead. I decided to sell my80 mm stellar view and buy a bass boat. The person that came to buy it talked me into staying the course.
I spoke to him and someone he had put me in touch with. His advice was ," buy a bunch of different scopes and eyepieces and try them out.sell what you don't like.
I have sold most of them.most of what's left I like for one reason or another. I did not realize my area was prone to the type of seeing due to air disturbances that would keep me from pushing the scopes to their limits.
Now I'm saving for a van to carry a couple to better areas and expand my chances of better seeing. I still enjoy my time with them. I have no one to share them with which is what I hoped to find along the way.
Some of life's boulders have been in the way lately and slowed things a bit but I keep on pushing through.
Thanks to people here I have been slowly learning.
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#18 CHASLX200

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Posted 18 September 2021 - 06:08 AM

I have been keeping track of this for months. 
I primarily look at planets. I have started to develope interests in clusters and double stars.

I keep my scopes in a air conditioned garage. 72 to 78 degrees.

this is about 10 degree warm up when I put them out.

I just leave them sitting a couple hours . Prior to using them I take a few looks during cool down.

it can be quite sharp on good nights and I find myself using them during this temperature equalizing period .

then they start getting progressively worse when the planets are In their best position. 
even after 6 hours.

they don’t have cooling fans. Some of my scopes are listed below.

c14

tak. Mewlon 300 crs

TMB 228 mm

questar 7

 

i have not tried my rcos 16, unitron 160, Edmund 4” achro, Edmund 4.5 reflector 32” reflector, others.

I was going to start putting fans on them. Blowing don the tube??? On the refractor tube?? I was  going to put a screen over the open focuser end and point it up.

just looking for advice from more experienced individuals than me.

thank you for your advice in advance. Stewart 

Any big temp drops will make planets look bad. Here in FL it is still 82 to 87f at 10pm with no drop at all. Plus planets are way south even for me so that also don't help with seeing.

 

That TMB228 APO would do 700x easy on my best nites and that Tak 300 could do 800x and a great C14 that is sharp 900x.  Plus your state has a problem with steady seeing. 


Edited by CHASLX200, 18 September 2021 - 06:09 AM.


#19 WadeH237

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Posted 18 September 2021 - 08:10 AM

In your signature, I see that you are in Pueblo, Colorado.  The leeward side of a mountain range can have pretty poor seeing much of the time.

 

I live in Washington State.  For most of my life, I have lived on the west side of the Cascade mountains.  For the last 20 years, I was in Snohomish and had quite good seeing.  My problem there was that clear nights were rare.  I retired last year and moved to Ellensburg, which is on the east side of the Cascades.  I now get lots more clear nights (and far less light pollution), but the seeing is very noticeably worse.  We do get some nights of steady seeing, but on a typical night, my stars are a bit bloated compared to what I used to get.


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#20 Notdarkenough

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Posted 18 September 2021 - 11:51 AM

In your signature, I see that you are in Pueblo, Colorado.  The leeward side of a mountain range can have pretty poor seeing much of the time.

 

I live in Washington State.  For most of my life, I have lived on the west side of the Cascade mountains.  For the last 20 years, I was in Snohomish and had quite good seeing.  My problem there was that clear nights were rare.  I retired last year and moved to Ellensburg, which is on the east side of the Cascades.  I now get lots more clear nights (and far less light pollution), but the seeing is very noticeably worse.  We do get some nights of steady seeing, but on a typical night, my stars are a bit bloated compared to what I used to get.

That is some interesting information. I live on the other side of the Rockies from Pueblo and the OP. I have been searching for information about Seeing relative to topography, orographic effect; basic geography. Some posters here on CN are educated in astronomy and others in meteorology; any of you remember a good textbook, or university course, that covers this dynamic?

 

Sorry OP! I don't mean to hijack your thread, but I think a better understanding of Seeing and the Rockies will help both you and me, and lots of us who live near mountains. Best wishes-

Mike 



#21 Stewc14

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Posted 18 September 2021 - 12:30 PM

Any big temp drops will make planets look bad. Here in FL it is still 82 to 87f at 10pm with no drop at all. Plus planets are way south even for me so that also don't help with seeing.

 

That TMB228 APO would do 700x easy on my best nites and that Tak 300 could do 800x and a great C14 that is sharp 900x.  Plus your state has a problem with steady seeing. 

Maybe I need to move there!



#22 CHASLX200

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Posted 18 September 2021 - 02:46 PM

Maybe I need to move there!

You would hate the weather. But a warm winter nite and i have done over 1000x easy.



#23 Stewc14

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Posted 19 September 2021 - 02:38 AM

You would hate the weather. But a warm winter nite and i have done over 1000x easy.

I lived in Sarasota and newsymrna beach for a couple years bu couldn't afford a telescope then

#24 Stewc14

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Posted 19 September 2021 - 02:52 AM

Did you just recently move to this location?  Or have you accumulated all of these high dollar telescopes since you've lived there?  I know it's none of my business, but if it's the latter I'm just wondering why you've gotten this deep into equipment if local conditions won't allow you to observe with any of them.  I hope you're able to find some kind of workaround.

When I got back into it covid hit. No chance to go to star parties or meetings. I had no clue about the seeing here. I was advised to buy a bunch of different scopes and try them out. Sell what I don't like,so I did. I wanted an AP but couldn't find one for sale . Ill get one one day". I had no real astronomy "friends" to bounce things off of. I am going to get me a van so I can travel and experience better locations. I'm still going to put up an observatory at home.l bought a 10'4" ash dome that is in storage

#25 WadeH237

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Posted 19 September 2021 - 07:28 AM

I have been searching for information about Seeing relative to topography, orographic effect; basic geography. Some posters here on CN are educated in astronomy and others in meteorology; any of you remember a good textbook, or university course, that covers this dynamic?

There is tons of material about the effect of geography on turbulence and other weather phenomenon that affect aviation.   Just search for mountain turbulence.

 

What airplanes experience as turbulence is the same thing that we experience as poor seeing.

 

Edit:  I do notice that there is even a lot of stuff out there specific to Colorado and the Rocky Mountains.


Edited by WadeH237, 19 September 2021 - 07:30 AM.



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