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How much does the quality of the eyepieces affect detail?

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#1 BLUSky

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Posted 28 November 2021 - 09:30 PM

Hi everyone,

I am using my SkyWatcher Heritage 130p to view Jupiter and Saturn with the 10mm SUPER eyepiece that comes with it. However, with this I could see the 2 main bands of Jupiter but they aren't very clear and I couldn't see the other bands. I read on amazon(https://www.amazon.c...e/dp/B00AWAT6BW) (although mine has "Long Eye Relief" on it) that I should invest in a better eyepiece because the better eyepieces give better detail? 

Does anyone using this eyepiece agree with this? Or perhaps I should buy a smaller focal length eyepiece/barlow to view more detail since it is more up close?

For a more general question: How significantly does the quality of the eyepieces affect how much detail you can see?

I apologize for any mistakes I have made in this post. 

Thanks


Edited by BLUSky, 28 November 2021 - 09:37 PM.

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#2 MellonLake

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Posted 28 November 2021 - 09:49 PM

More expensive eyepieces tend to give wider fields of view but are generally not sharper.

I have seen 5 moons of Saturn and cloud bands on Saturn in a cheap 6mm Plossl. Yes some eyepieces are better corrected in the periphery but in the centre of the field of view most eyepieces will perform well.

Jupiter is a long way away now and I suspect you may also have poor seeing.

Also ensure your collimation is good.
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#3 Echolight

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Posted 28 November 2021 - 09:53 PM

Inexpensive eyepieces will often be sharp on axis, when the object is centered in the field of view.

 

Some of the better eyepieces are more comfortable to look through. Making it possible to watch for longer, and allow you to be more likely to be viewing when a moment of exceptional seeing arrives.

 

“Seeing” refers to the condition of the atmosphere that we are viewing through. Which can become more stable for a second or a few at any given time. And when it becomes more stable you can possibly see greater details.

But keep in mind that Jupiter is a low contrast object itself. Although shadow transits can be very high contrast.



#4 Stellar1

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Posted 28 November 2021 - 09:59 PM

I’m not familiar with the 130P but I can bet dollars to donuts that if it is not collimated as well as possible, no matter what eyepiece you stick in it won’t matter. Have you had a look at the collimation? if not then start there before you jump on any eyepieces cause you may just get a surprise after collimating it.



#5 BLUSky

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Posted 28 November 2021 - 10:17 PM

I’m not familiar with the 130P but I can bet dollars to donuts that if it is not collimated as well as possible, no matter what eyepiece you stick in it won’t matter. Have you had a look at the collimation? if not then start there before you jump on any eyepieces cause you may just get a surprise after collimating it.

I have had a look at the collimation. But then I don't have a laser collimator or a Cheshire Eyepiece so I just stuck my eye in the focuser without the eyepieces and it seems to be okay as the circles are centered, and all three primary mirror clips are visible. Although I have not tested collimation by looking at a bright star yet.


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#6 vtornado

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Posted 28 November 2021 - 10:38 PM

Hi everyone,

I am using my SkyWatcher Heritage 130p to view Jupiter and Saturn with the 10mm SUPER eyepiece that comes with it. However, with this I could see the 2 main bands of Jupiter but they aren't very clear and I couldn't see the other bands. I read on amazon(https://www.amazon.c...e/dp/B00AWAT6BW) (although mine has "Long Eye Relief" on it) that I should invest in a better eyepiece because the better eyepieces give better detail? 

 

I would be very wary of reviews written on Amazon about technical subjects.   As others have said, a reasonable quality eyepiece will give you 95% of the

view of a premium eyepiece on axis.  On axis means generally in the center of the field of view.

 

I don't know what your budget is.  A paradigm dual ED 5mm eyepiece.  Is a great eyepiece, and will give you more eye relief and a larger field of view than you have

now.  They go for around $65. 

 

A 2x barlow and a 10mm eyepiece will work well too.

https://www.astronom...l.html?___SID=U

 

Your scope is an f/5 reflector.  Collimation is critical and so is focus.    Also it has a lot of coma.  This is an optical abberation in fast reflectors

as objects move toward the edge of the field they will distort.  It will be important to keep Jupiter centered.

I have had a look at the collimation. But then I don't have a laser collimator or a Cheshire Eyepiece so I just stuck my eye in the focuser without the eyepieces and it seems to be okay as the circles are centered, and all three primary mirror clips are visible. Although I have not tested collimation by looking at a bright star yet.

 

Doing this you have gotten the secondary fairly well aligned, but ... the most import aspect is getting the primary aligned.

The cheapest way is with a collimation cap.  Did your scope come with one?

https://agenaastro.c...t-eyepiece.html

 

You can also use a barlowed laser.

http://www.smartavtweaks.com/RVBL.html

 

The most important factor in planetary detail is the atmospheric "seeing".  View Jupiter when it is highest in the sky (due south).

Let your scope cool for half an hour.

Keep trying some nights the atmosphere very turbulent, others it is calm.  Usually calm atmosphere

occurs when the temps are stable for several days, and storms have left the area for a day.
 


Edited by vtornado, 28 November 2021 - 10:42 PM.

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#7 cookjaiii

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Posted 28 November 2021 - 10:40 PM

I have the same telescope, and the stock eyepieces are not bad.  They have a narrow field of view compared to more expensive eyepieces, but the more expensive eyepieces are not significantly sharper than the ones you are using.

 

This telescope has a focal ratio, f/5, which makes it very sensitive to mis-collimation. You need to be more accurate than you can get by eyeballing it.

 

The Heritage used to come with a Cheshire eyepiece to use for collimation.   If it does, invest in some time learning how to use it.  If you have access to someone with experience to help you, that would be best, but you can do it yourself if you take your time.

 

A laser collimator is a nice tool, but they only work if they are themselves collimated.  My experience with the less expensive laser collimators is that a lot of them "don't shoot straight" even when brand new.   

 

Congrats on the new scope.  It's a great instrument to start in a fantastic hobby.  You will have a ball with it.


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#8 BLUSky

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Posted 28 November 2021 - 10:52 PM

 

Hi everyone,

I am using my SkyWatcher Heritage 130p to view Jupiter and Saturn with the 10mm SUPER eyepiece that comes with it. However, with this I could see the 2 main bands of Jupiter but they aren't very clear and I couldn't see the other bands. I read on amazon(https://www.amazon.c...e/dp/B00AWAT6BW) (although mine has "Long Eye Relief" on it) that I should invest in a better eyepiece because the better eyepieces give better detail? 

 

I would be very wary of reviews written on Amazon about technical subjects.   As others have said, a reasonable quality eyepiece will give you 95% of the

view of a premium eyepiece on axis.  On axis means generally in the center of the field of view.

 

I don't know what your budget is.  A paradigm dual ED 5mm eyepiece.  Is a great eyepiece, and will give you more eye relief and a larger field of view than you have

now.  They go for around $65. 

 

A 2x barlow and a 10mm eyepiece will work well too.

https://www.astronom...l.html?___SID=U

 

Your scope is an f/5 reflector.  Collimation is critical and so is focus.    Also it has a lot of coma.  This is an optical abberation in fast reflectors

as objects move toward the edge of the field they will distort.  It will be important to keep Jupiter centered.

I have had a look at the collimation. But then I don't have a laser collimator or a Cheshire Eyepiece so I just stuck my eye in the focuser without the eyepieces and it seems to be okay as the circles are centered, and all three primary mirror clips are visible. Although I have not tested collimation by looking at a bright star yet.

 

Doing this you have gotten the secondary fairly well aligned, but ... the most import aspect is getting the primary aligned.

The cheapest way is with a collimation cap.  Did your scope come with one?

https://agenaastro.c...t-eyepiece.html

 

You can also use a barlowed laser.

http://www.smartavtweaks.com/RVBL.html

 

The most important factor in planetary detail is the atmospheric "seeing".  View Jupiter when it is highest in the sky (due south).

Let your scope cool for half an hour.

Keep trying some nights the atmosphere very turbulent, others it is calm.  Usually calm atmosphere

occurs when the temps are stable for several days, and storms have left the area for a day.
 

 

My telescope did not come with a collimation cap. I think I will get a cheshire eyepiece. Thanks



#9 TOMDEY

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Posted 28 November 2021 - 11:13 PM

Well, you're probably already near the limit of your telescope there. At F/5 and that aperture... fancy eyepieces aren't going to improve resolution. On the other hand, a good premium eyepiece or two will be more comfortable and pleasing --- but would exceed the cost of your entire kit --- by a lot! At some point you may want to consider upgrading everything... including the telescope itself. I'd say enjoy what you have there for at least a full cycle of the seasons (a full year). By then you will know what more you may want, or to just stick with what you have.     Tom


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#10 Dave Mitsky

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Posted 28 November 2021 - 11:16 PM

Premium eyepieces can produce large apparent fields of view that are corrected for astigmatism when used in fast telescopes, enhanced eye relief, or both attributes.  Premium "planetary" eyepieces yield views with high contrast and lack of scatter.  They often have small AFsOV.


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#11 Tony Flanders

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Posted 29 November 2021 - 07:03 AM

I am using my SkyWatcher Heritage 130p to view Jupiter and Saturn with the 10mm SUPER eyepiece that comes with it. However, with this I could see the 2 main bands of Jupiter but they aren't very clear ...


That's because Jupiter is quite low in the sky for observers at mid-northern latitude. The culprit is the atmosphere; the contribution from your eyepiece is negligible.
 

For a more general question: How significantly does the quality of the eyepieces affect how much detail you can see?


A whole lot less than eyepiece aficionados like to imagine -- assuming that you're comparing two respectable eyepieces. When it comes to the pieces of junk -- sometimes with plastic lenses -- that are still occasionally bundled with scopes at the true bottom of the market, all bets are off.

At least in the center of the field, the difference in sharpness, contrast, and brightness between the inexpensive 3-element eyepiece bundled with the Heritage 130P and the world's best planetary eyepiece would probably be invisible to the average beginner.


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#12 rhetfield

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Posted 29 November 2021 - 09:49 AM

I have the same scope.

 

The laser collimator is more useful on larger scopes so that you can see collimation without looking through the eyepiece.  That way you can play with the collimation screws.  It is less important on the heritage because you can reach the collimation screws while looking through the eyepiece.

 

Look at the following for collimation:

https://garyseronik....to-collimation/

https://garyseronik....pe-collimation/

 

Note that collimation should be done at a higher magnification than what you view at.  I fine tune mine using a 4.5mm eyepiece and 2x barlow.

 

The 10mm that came with the scope is not very good.  It is sharp in the middle but fuzzy at the edges.  That is not your main issue. 

 

In addition to confirming collimation (getting it perfect is very important for planetary viewing with the heritage) and seeing Jupiter as high in the sky as possible (at sunset at this time of the year), one needs to take a look at magnification.

 

The 10mm gives 65x magnification.  That does not lend itself to much detail on the planets.  A 2x barlow with the 10mm eyepiece will get you up to 130x with the heritage.  That will make a big difference.

 

I have two barlows.  One is a Celestron Omni.  The other is a celestron x-cel.  The Omni lets you take the lens out to screw into an eyepiece to function as a 1.5x magnifier.  The X-cel just give crisper views.

 

I also have a celestron x-cel 5mm eyepiece.  This one is really a clone of a 4.5mm meade eyepiece.  It is my main planetary eyepiece.  It gives me 144x and crisp views.  I use the x-cel barlow for star collimating (and splitting doubles) at 288x.  The 4.5mm with the 1.5x lens element gives me 216x.  On a good night, Saturn and Mars (won't be close again until late next year) will look spectacular, but it is often too much for Jupiter.

 

I would look at getting either the x-cel 5mm or the astrotech paradigm 5mm as a planetary eyepiece and getting good at collimation.  This will get you much more than you are seeing now.  I have been able to see 4-6 bands on Jupiter, the red spot, moon crossings, Saturn's Cassini division, and the martian polar cap.


Edited by rhetfield, 29 November 2021 - 01:21 PM.

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#13 sevenofnine

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Posted 29 November 2021 - 02:38 PM

The link you posted says your eyepiece is a Kellner undecided.gif  You will definitely see some improvement with good eyepieces and a well collimated scope. One of the cost cutting measures these days is to put really cheap eyepieces in the telescope kits. You don't have to spend big bucks though. The AstroTech Paradigm Dual ED's from our sponsor are fine 60 degree eyepieces that get great reviews from C/N members. Agena Astro Starguider's are the same eyepieces re-branded. At $65 each, they are a real bargain. A 5mm would be about max for your scope so I recommend trying an 8mm first then add more if you like it. There are no mistakes in this line. They are all good. Best of luck to you and your choices! borg.gif


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#14 SteveG

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Posted 29 November 2021 - 06:06 PM

I have had a look at the collimation. But then I don't have a laser collimator or a Cheshire Eyepiece so I just stuck my eye in the focuser without the eyepieces and it seems to be okay as the circles are centered, and all three primary mirror clips are visible. Although I have not tested collimation by looking at a bright star yet.

If you buy a combo tool (Cheshire) make sure it has a smooth barrel that can fully insert into the focuser, like this:

https://www.svbony.c...ating-eyepiece/

 

I strongly recommend a collimating cap as well. This does the same as the cheshire portion of the combo tool, only it's far easier to read:

https://agenaastro.c...gEaAt8vEALw_wcB


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#15 BLUSky

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Posted 29 November 2021 - 08:57 PM

I have the same scope.

 

The laser collimator is more useful on larger scopes so that you can see collimation without looking through the eyepiece.  That way you can play with the collimation screws.  It is less important on the heritage because you can reach the collimation screws while looking through the eyepiece.

 

Look at the following for collimation:

https://garyseronik....to-collimation/

https://garyseronik....pe-collimation/

 

Note that collimation should be done at a higher magnification than what you view at.  I fine tune mine using a 4.5mm eyepiece and 2x barlow.

 

The 10mm that came with the scope is not very good.  It is sharp in the middle but fuzzy at the edges.  That is not your main issue. 

 

In addition to confirming collimation (getting it perfect is very important for planetary viewing with the heritage) and seeing Jupiter as high in the sky as possible (at sunset at this time of the year), one needs to take a look at magnification.

 

The 10mm gives 65x magnification.  That does not lend itself to much detail on the planets.  A 2x barlow with the 10mm eyepiece will get you up to 130x with the heritage.  That will make a big difference.

 

I have two barlows.  One is a Celestron Omni.  The other is a celestron x-cel.  The Omni lets you take the lens out to screw into an eyepiece to function as a 1.5x magnifier.  The X-cel just give crisper views.

 

I also have a celestron x-cel 5mm eyepiece.  This one is really a clone of a 4.5mm meade eyepiece.  It is my main planetary eyepiece.  It gives me 144x and crisp views.  I use the x-cel barlow for star collimating (and splitting doubles) at 288x.  The 4.5mm with the 1.5x lens element gives me 216x.  On a good night, Saturn and Mars (won't be close again until late next year) will look spectacular, but it is often too much for Jupiter.

 

I would look at getting either the x-cel 5mm or the astrotech paradigm 5mm as a planetary eyepiece and getting good at collimation.  This will get you much more than you are seeing now.  I have been able to see 4-6 bands on Jupiter, the red spot, moon crossings, Saturn's Cassini division, and the martian polar cap.

Hello, thanks for the reply. Can you perhaps explain more on how much crisper the views get with the Celestron X Cel Barlow compared to the Celestron omni? Have you tried the Celestron X Cel Barlow and the X Cel 5mm eyepiece on the Heritage 130p? Because I'm afraid they won't fit(like an Svbony 2x barlow with the AWB Onesky I read somewhere). Do you recommend I purchase the X Cel Barlow or the X Cel 5mm eyepiece? Thanks.



#16 SteveG

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Posted 30 November 2021 - 01:41 PM

Hello, thanks for the reply. Can you perhaps explain more on how much crisper the views get with the Celestron X Cel Barlow compared to the Celestron omni? Have you tried the Celestron X Cel Barlow and the X Cel 5mm eyepiece on the Heritage 130p? Because I'm afraid they won't fit(like an Svbony 2x barlow with the AWB Onesky I read somewhere). Do you recommend I purchase the X Cel Barlow or the X Cel 5mm eyepiece? Thanks.

I have the AWB scope and have used many different eyepiece barlow combinations over the years. The bottom line it the difference between any of them is subtle at best. What really will provide "crisp" views are better seeing conditions and lower powers. With your scope, I would not use any higher power that a 5 mm eyepiece, but some might use a touch more. Do not plan on using a 5 mm and a barlow - it's simply too much magnification even if seeing is perfect, which is rare.

 

The X-Cel barlow gets excellent reviews, as does the 60 deg AFOV X-cel eyepieces, as does many SvBony low-cost eyepieces and barlows. The X-Cel won't be more "crisp" than any other eyepiece or barlow. If an eyepiece or barlow/eyepiece combination doesn't work with a scope, it is typical due to lack of focuser drawtube range.

 

Your local seeing is what gives you mushy, unclear views. When seeing improves, all of you scopes and eyepieces will provide sharper views (provided the scope is properly collimated).


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#17 BLUSky

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Posted 30 November 2021 - 10:09 PM

If you buy a combo tool (Cheshire) make sure it has a smooth barrel that can fully insert into the focuser, like this:

https://www.svbony.c...ating-eyepiece/

 

I strongly recommend a collimating cap as well. This does the same as the cheshire portion of the combo tool, only it's far easier to read:

https://agenaastro.c...gEaAt8vEALw_wcB

Hello, by smooth barrel do you mean the entire thing has no "corners"(i don't know what you call them)? If so, can you tell me why I should make sure the Cheshire eyepiece has a smooth barrel?

There is one I can buy in here with minimal costs, but it looks like this:
 

Attached Thumbnails

  • cheshire.png


#18 rhetfield

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Posted 01 December 2021 - 01:28 AM

Hello, thanks for the reply. Can you perhaps explain more on how much crisper the views get with the Celestron X Cel Barlow compared to the Celestron omni? Have you tried the Celestron X Cel Barlow and the X Cel 5mm eyepiece on the Heritage 130p? Because I'm afraid they won't fit(like an Svbony 2x barlow with the AWB Onesky I read somewhere). Do you recommend I purchase the X Cel Barlow or the X Cel 5mm eyepiece? Thanks.

I would get the x-cel 5mm first. You would use that more than the Barlow. An alternative would be to get the Barlow and a 7mm or 9mm eyepiece. If getting the 7mm, get a Barlow that converts to 1.5x.

The x-cel Barlow and 5mm eyepiece will work together with the heritage. It is heavy though. I use that combination most for collimation and splitting doubles. The tight doubles appear just a little less fuzzy with the x-cel Barlow than with the Omni Barlow, but the 1.5x option with the 5mm gets more use.

#19 radiofm74

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Posted 01 December 2021 - 07:50 AM

I have had a look at the collimation. But then I don't have a laser collimator or a Cheshire Eyepiece so I just stuck my eye in the focuser without the eyepieces and it seems to be okay as the circles are centered, and all three primary mirror clips are visible. Although I have not tested collimation by looking at a bright star yet.

As others pointed out, that does not help. You need a collimation tool to make sure at the very least that your eye is in the right position … A combined Cheshire + sight tube works perfectly well and is inexpensive. 



#20 PeterAB

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Posted 01 December 2021 - 10:09 AM

Hi,

 

The stock 10mm eyepiece that comes with this telescope is okay.    The magnification of 65 it provides is a reasonable medium-high power that should work in all viewing conditions.     Two issues are a fairly narrow field of view and short eye relief.   The narrow view is not a issue for planets.   Eye relief needs depend completely on the observer.    If the eyepiece is comfortable and you can see the sharp field stop edge, all is good for you. 

 

Was Jupiter shimmering, changing shape and going in and out of focus when you were observing?   If it was, that is bad seeing and there is nothing to do but to look again later or try a different viewing location.

 

At a magnification of 65 times, Jupiter should look small and sharp in this telescope.  You will be wanting to add magnification to make it bigger.   I often use my 6.5mm eyepiece for a 100x magnification.    The planets should still be sharp depending on seeing.    My impression is that with more magnification than 100x, the planets get bigger, but, also more fuzzy at the same time.    I do sometimes go with magnifications as high as 144 (4.5mm EP)  in this telescope.   I start to see my eye floaters and the shimmering atmosphere  most nights at this magnification.   

 

The most often used eyepiece for me in this telescope is a 12mm.    This is medium power that works the best and puts up the sharpest images with most eyes.

 

I agree that your collimation is a touch off.

 

Peter


Edited by PeterAB, 01 December 2021 - 10:13 AM.


#21 vtornado

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Posted 01 December 2021 - 05:53 PM

In doing a Jupiter Shoot out between the GSO 2x and GSO 3 element 2.5, I prefered the  2x.  Not a lot more, just some.  I tried the same eyepiece in both barlows, and also

tried a longer eyepice in the 2.5 to try an equal out any magnification differences.

 

Seeing changes in a minute around here.  One has to keep repeating and repeating

to make sure it is not a sudden change in seeing.

 

A lot of these two close to call things, may be because of sample variance,

and personal preferences which it is very hard to remove self-bias from the

experiment.  It may also involve what telescope you are using. 

 

I used an 100/f9 and 80 f/7.5 EDs.   Perhaps things are different in an f/5 scope.

 

It is important to not put too much weight in the plastic focuser.

It can sag a bit.

 

There are lots of variables to control.

 

I summary  I would say just pick one and be happy.  


Edited by vtornado, 01 December 2021 - 06:12 PM.

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#22 BLUSky

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Posted 01 December 2021 - 07:23 PM

Hi,

 

The stock 10mm eyepiece that comes with this telescope is okay.    The magnification of 65 it provides is a reasonable medium-high power that should work in all viewing conditions.     Two issues are a fairly narrow field of view and short eye relief.   The narrow view is not a issue for planets.   Eye relief needs depend completely on the observer.    If the eyepiece is comfortable and you can see the sharp field stop edge, all is good for you. 

 

Was Jupiter shimmering, changing shape and going in and out of focus when you were observing?   If it was, that is bad seeing and there is nothing to do but to look again later or try a different viewing location.

 

At a magnification of 65 times, Jupiter should look small and sharp in this telescope.  You will be wanting to add magnification to make it bigger.   I often use my 6.5mm eyepiece for a 100x magnification.    The planets should still be sharp depending on seeing.    My impression is that with more magnification than 100x, the planets get bigger, but, also more fuzzy at the same time.    I do sometimes go with magnifications as high as 144 (4.5mm EP)  in this telescope.   I start to see my eye floaters and the shimmering atmosphere  most nights at this magnification.   

 

The most often used eyepiece for me in this telescope is a 12mm.    This is medium power that works the best and puts up the sharpest images with most eyes.

 

I agree that your collimation is a touch off.

 

Peter

Hi, Jupiter was not shimmering, it was not changing shape and going in and out of focus when I was observing. As a matter of fact, in my location, when I observed yesterday, Jupiter was pretty close to the zenith and that specific location of Jupiter was in a gap without clouds. I could still only observe the same amount of detail which is the 2 bands. No Great Red Spot, no other bands. Or maybe it's just my eyesight(it's relatively bad without glasses)? 



#23 Tony Flanders

Tony Flanders

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Posted 01 December 2021 - 08:06 PM

Hi, Jupiter was not shimmering, it was not changing shape and going in and out of focus when I was observing. As a matter of fact, in my location, when I observed yesterday, Jupiter was pretty close to the zenith and that specific location of Jupiter was in a gap without clouds. I could still only observe the same amount of detail which is the 2 bands. No Great Red Spot, no other bands. Or maybe it's just my eyesight(it's relatively bad without glasses)? 

That's pretty much normal for 65X. You definitely need at least 100X -- and preferably more -- to take advantage of the aperture and quality of a Heritage 130P.

 

The visibility of the other belts varies greatly; occasionally one or more of them is quite prominent but usually they're fairly subtle. I haven't seen them much during this apparition. I usually need more than 65X to see the Great Red Spot. In any case, the Great Red Spot is only visible for about 2 hours out of every 10-hour Jupiter rotation, so the chances that it will be visible at any given moment are pretty small.

 

The planets are not easy to observe; they always look a lot smaller through a telescope than you wish they would. And usually a lot fuzzier than you wish, too.


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#24 SteveG

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Posted 02 December 2021 - 12:40 PM

Hello, by smooth barrel do you mean the entire thing has no "corners"(i don't know what you call them)? If so, can you tell me why I should make sure the Cheshire eyepiece has a smooth barrel?

There is one I can buy in here with minimal costs, but it looks like this:
 

By smooth I mean the insertion tube is 1.25" all the way up to the cheshire head of the tool. This tool pictured does not allow full insertion:

Orion.jpg

 

I have that much shorter combo tool you show a picture of. First read this:

 

There are 3 main Steps in collimation:
1. Center the secondary mirror under the focuser – done with a site tube or “combo tool”.
2. Align the focuser axis (secondary tilt) – done with a site tube w/cross hairs (combo tool), or thin beam laser.
3. Align primary axis – done with a Cheshire or collimating cap, combo tool (Cheshire portion), or barlowed laser.

 

Note that many combo tools are sold as “Cheshire eyepiece” or “collimating eyepiece”, but they are all 3 in 1 combo tools. They will only be as accurate as their fit in the focuser, which can be very sloppy.
A collimating cap is a derivative of a Cheshire – they both do the same thing.

 

The short combo tool that you posted a picture of sort of works, but has issues. For each of the above steps, that tool does the following:

 

Step 1. It works poorly to center the secondary. I'm not sure why but I can't get a good reading from it. It's too short as well, so you have to pull it out of the focuser, which causes a possible tilt in the tool. I get inconsistent readings from this short tool.

 

Step 2. It works poorly for aligning the focuser axis (secondary tilt). This is due to the very thin crosshairs they used. The crosshairs so thin that the tool will arrive with them slightly bent, and if you touch them they will bend further. They are too thin to get a good reading, even if they actually cross at the center.

 

Step 3. It works okay for aligning the primary. Most of these tools don't work well for step 3 because the newer center spots that are etched in the mirror are very small and black. So you are attempting to place a black ring under a black donut. The precision level is very poor with this method.

 

I'm using a sheet of green paper behind the secondary. You want to see the secondary through the tool, surrounded by a thin green circle (from the green paper). Getting this requires you to lift the tool out of the focuser a bit.

 

This is the short tool inserted but lifted out of the focuser by about 15 mm:

short tool - pulled out.jpg

 

This is the view through that tool. The crosshairs are bent, and the "read" is very poor:

Short tool view - lifted.jpg

 

This is the SvBony tool I posted a link to, lifted out of the focuser to center the secondary:

Svbony pulled.jpg

 

The view through the lifted SvBony. Note that you can see a nice ring of green around the secondary, but you can't fully see the primary mirror. Ignore the crosshairs for this step:

svbony.JPG

 

Here we have it almost fully inserted, in order to see the edges of the primary mirror:

svbony - inserted.JPG

 

The view of the SvBony tool inserted fully in the focuser. This shows the full primary, and now the crosshair align with the center of the primary:

svbony - in.JPG

 

Finally the collimating cap view. Note that you can see the center spot (donut), and a black dot (the cap pupil) centered within the donut. This gets you far better precision when aligning the primary mirror (step #3).

Col Cap.jpg


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