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Old 09-06-2014, 04:20 PM
209herschel (Herschel)
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Moon/Planetary EP advice

Hi everyone,

I've just gotten my 10" dob and it came with a 30mm 2" ep, and a 9mm, 15mm and 25mm plossl. I've read that the 9mm plossl can really be improved upon and that the moon and planets can be a lot clearer.

I'm very excited to get a good Moon/Planet ep that my son will find very impressive! I'm undecided between the Hyperion 5mm, the Explore Scientific 6.7mm and the Orion Stratus 8mm. If you'd recommend something else completely, I'd love to hear the advice.

Thanks very much.
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Old 09-06-2014, 05:36 PM
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dannat (Daniel)
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i think the 5mm will be pushing to much mag on most nights -almost the ES 6.7 also (if you have an f5 10" you should be ok) -so id choose the stratus 8mm, also check out bst explorer from telescopes & astronomy in SA.
a 7 or 7.5mm ep would also be good, any of the orthos will give very sharp views
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Old 09-06-2014, 06:47 PM
N1 (Mirko)
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Congrats. 7mm or slightly above will work in this scope on most decent nights, but do yourself a favour and check your copies of the GSO Plossls during an actual observing session before you decide. Who knows- the 9mm may be a better one than I got. Plus you will get a rough idea what each focal length will do in this scope.
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Old 09-06-2014, 08:27 PM
David Niven (David Niven)
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The Celestron Xcel 9mm is a great planetary performer.
One of those ep that will not leave a hole in your pocket.
I wouldn't buy any expensive eyepiece till you spend more time getting to know your scope and stuff.
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Old 09-06-2014, 10:54 PM
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Varangian (John)
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Originally Posted by dannat View Post
i think the 5mm will be pushing to much mag on most nights -almost the ES 6.7 also (if you have an f5 10" you should be ok) -so id choose the stratus 8mm, also check out bst explorer from telescopes & astronomy in SA.
a 7 or 7.5mm ep would also be good, any of the orthos will give very sharp views
I'm not sure the 8mm Stratus / Hyperion is the best choice EP at this price point. I have owned the 8 Stratus and Hyperion in fast scopes and I must say the original Burgess TMB and the ES 82 degree 8.8mm were superior in this type of scope.
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Old 10-06-2014, 11:13 AM
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AG Hybrid (Adrian)
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I find that the ES 6.7mm is a stunning lunar eyepiece. Craters and mountains everywhere in the eyepiece. Because the moon is so large, you can bump up the magnification even on a night of average seeing due to the lunar features being so large compared to features - lets say on Mars which are tiny and easily lost in average seeing.

It gives me 223x magnification and has yet to let me down on the moon. Unless of course a gale force wind is blowing.

Dynamic criticisms? Eye relief is a bit on the short side. Some kids don't like that I'm told. But, easy for a teenager/adult without glasses.
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Old 16-06-2014, 09:19 AM
209herschel (Herschel)
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Congrats. 7mm or slightly above will work in this scope on most decent nights, but do yourself a favour and check your copies of the GSO Plossls during an actual observing session before you decide. Who knows- the 9mm may be a better one than I got. Plus you will get a rough idea what each focal length will do in this scope.
Thanks very much for the advice. I've had the scope out a couple of times now, using the 9mm on the moon. While it looks amazing, I'm really keen to get that additional magnification from a 6mm as compared to the 9mm. It also seems that a large FOV would be amazing. I find it more comfortable to keep my glasses on while viewing so I'm also looking for good eye relief!

One other question I had was how much magnification would be needed to say, for eg, see the rings of Saturn? My seeing conditions have not been good but I could see that saturn had width to it but at best focus, I couldn't really make out the rings. Also, would additional mag give mars a fair bit more volume. I love seeing it as a small sphere but I'd also love to see it as even larger. I guess it's all about still learning as much as I can right now. Cheers.
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Old 16-06-2014, 10:50 AM
N1 (Mirko)
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Hmm. Large FOV, shortish FL, longish ER - you're asking a lot. I think you'll find most EPs that do all this will not come cheap. An option might be to look at a barlow - that's if you are considering longer focal length EPs also.

Saturn. I have seen its rings in a Russian made 25x spotting scope years ago and had an absolute ball when I did. More power will show ever more detail until you hit the seeing limit (that usually happens before the scope is exhausted).

The fact that you could not even see the rings as such indicates extremely poor seeing, a scope that hadn't cooled properly, or was in need of collimating. Or a combination of these.

The attached pic shows Saturn near the Moon. It was taken handheld through the EP from a city location through thin high cloud and seeing conditions that were average at best. Power was 101x.

Edit: The Saturn pic was taken through a 60mm refractor. Just to give you an idea what it might look like at around 100x
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Last edited by N1; 16-06-2014 at 11:34 AM.
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Old 16-06-2014, 02:32 PM
209herschel (Herschel)
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Originally Posted by N1 View Post
Hmm. Large FOV, shortish FL, longish ER - you're asking a lot. I think you'll find most EPs that do all this will not come cheap. An option might be to look at a barlow - that's if you are considering longer focal length EPs also.

Saturn. I have seen its rings in a Russian made 25x spotting scope years ago and had an absolute ball when I did. More power will show ever more detail until you hit the seeing limit (that usually happens before the scope is exhausted).

The fact that you could not even see the rings as such indicates extremely poor seeing, a scope that hadn't cooled properly, or was in need of collimating. Or a combination of these.

The attached pic shows Saturn near the Moon. It was taken handheld through the EP from a city location through thin high cloud and seeing conditions that were average at best. Power was 101x.

Edit: The Saturn pic was taken through a 60mm refractor. Just to give you an idea what it might look like at around 100x
Thanks very much for the information. I bought a Cheshire collimator when I bought the scope last week I and spent a couple of hours on it. It was my first time collimating but all the rings seemed to show good collimation. I'm in my backyard and my neighbour's outdoor lights are visible and it was pretty bright to be honest. The moon was very bright two nights ago and it looked really great. It's a 10" dob and I guess I'm not quite sure what I'm supposed to be able to see. I used my phone to show where Mars and Saturn were and then I used the scope. I've looked at stars and they seem to be a good, clear point so I'm hoping collimation is good. Thanks again.
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Old 16-06-2014, 03:51 PM
N1 (Mirko)
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If details on the Moon look really sharp at mid to high powers, then you absolutely will see Saturn's rings too, assuming it's sufficiently high in the sky. Things turn crap when your target is low in the sky. A dark sky will improve things but is not a must for this. In good seeing, the 10" will bring out some beautiful details, such as the Cassini Division or the planet's shadow on the rings. Not sure what went wrong there. Perhaps the dew you mentioned in another thread was screwing things up somewhere in your optical path? I know it might sound silly, but it happened to me.

Mars, however, can be a difficult target. A stable atmosphere is pretty much essential for enjoyable views there. Plus it must be reasonably close to us. Its distance to Earth varies immensely. Now is still a good time to see it, although it's moving away already (or Earth is, I should say). I understand there are some filters which will improve things further, but haven't tried those yet.

Last edited by N1; 16-06-2014 at 04:03 PM.
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Old 16-06-2014, 05:20 PM
209herschel (Herschel)
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If details on the Moon look really sharp at mid to high powers, then you absolutely will see Saturn's rings too, assuming it's sufficiently high in the sky. Things turn crap when your target is low in the sky. A dark sky will improve things but is not a must for this. In good seeing, the 10" will bring out some beautiful details, such as the Cassini Division or the planet's shadow on the rings. Not sure what went wrong there. Perhaps the dew you mentioned in another thread was screwing things up somewhere in your optical path? I know it might sound silly, but it happened to me.

Mars, however, can be a difficult target. A stable atmosphere is pretty much essential for enjoyable views there. Plus it must be reasonably close to us. Its distance to Earth varies immensely. Now is still a good time to see it, although it's moving away already (or Earth is, I should say). I understand there are some filters which will improve things further, but haven't tried those yet.
Thanks very much for the information. The moon definitely looks sharp. I start with the 25mm plossl that will allow the entire moon and a little more in the FOV and it looks great. Not the craters of the 9mm but you see the contrast of dark and light, the streaks from ancient crater impacts - really great. The 9mm FOV is much smaller but then the detail increases. Everythingstill looks pretty sharp. The Cheshire collimator is showing all rings and reflections are pretty much centered. I'll try the star test tonight. I'm leaving the scope outside for at least a couple of hours before trying it.
I was wondering if it was possible I wasn't actually looking at Saturn? I'm pretty sure I was looking at Mars though - the red tinge was clear. I've been looking at things I can see with the naked eye, just trying to learn as much as possible. I only just found out I could focus the finderscope! Is the next to do to try to find objects of range of the naked eye? I'm sorry for these basic questions. I just want to stay patient so I can learn this well before trying anything too drastic. Thanks again.
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Old 16-06-2014, 06:37 PM
noeyedeer (Matt)
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viewing a large moon usually results in loss of detail, because there is no shadowing, and the smaller it becomes the more detail appears along the terminator and the limb. have a squizz when it's half or cresant and you'll be amazed.

as for ep, I prefer to use a 6mm tmb planetary II for close up moon features and planets in my 10" dob. the eye relief is better then the 9mm plossol for me and the clarity seems clearer as well. a Barlow will help in your longer length ep while keeping the same eye relief.

matt

Last edited by noeyedeer; 17-06-2014 at 02:43 PM.
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Old 16-06-2014, 08:28 PM
N1 (Mirko)
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209, I would not rule that out, especially if you weren't 100% sure yourself. From what you say in the earlier post, I think you may well have been looking at Mars. I've seen it as a fuzzy ball a few times, said oh well & moved on to Saturn . It's hard to say though, I wasn't there. What I do know is that with the kind of detail the scope showed on the Moon, you should have got more out of Saturn than you did. Anyway - do go back to Mars regularly. It will reward you eventually. Maybe next week, maybe in 2016

With the Moon waning, DSOs should be moving up on your list too.
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Old 17-06-2014, 07:31 AM
209herschel (Herschel)
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Originally Posted by AG Hybrid View Post
I find that the ES 6.7mm is a stunning lunar eyepiece. Craters and mountains everywhere in the eyepiece. Because the moon is so large, you can bump up the magnification even on a night of average seeing due to the lunar features being so large compared to features - lets say on Mars which are tiny and easily lost in average seeing.

It gives me 223x magnification and has yet to let me down on the moon. Unless of course a gale force wind is blowing.

Dynamic criticisms? Eye relief is a bit on the short side. Some kids don't like that I'm told. But, easy for a teenager/adult without glasses.
I'm very keen on this one but I'm concerned the 6.7mm is possibly too much with my seeing conditions in the yard. I'm leaning toward the 8.8mm now and possibly getting a barlow for when conditions are great or when I'm able to get to a dark site. Thanks very much.
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Old 17-06-2014, 07:40 AM
209herschel (Herschel)
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I want to thank everyone for the advice. It looks like I'll be going with the 8.8mm ES and I'll then get a barlow down the track for perfect conditions when I'm out. I'm very happy to say that last night was a big improvement. I was out till late and started looking for Saturn when I was again disappointed by the small image with no definition. Then I decided to just look in the area with the finder scope and investigate anything a little bright. And suddenly I saw Saturn! In the 25mm, it was a small disc with clear separation of the band around it. Moving up to the 15mm and finally the 9mm, I got an excellent clear look. I couldn't see any separation in the rings though. Could this be down to the conditions or perhaps a 6mm would give me the extra magnification to bring more out? The moon was incredible last night also. I think that's excellent advice in the DSOs - at one point I looked with the naked eye and saw a couple of stars, used the finderscope and then the 25mm and saw a rich band of stars that was completely surprising. Really amazing, even though I'm not sure what I was looking at! Thanks again.
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Old 17-06-2014, 09:02 AM
astro744
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I want to thank everyone for the advice. It looks like I'll be going with the 8.8mm ES and I'll then get a barlow down the track for perfect conditions when I'm out. I'm very happy to say that last night was a big improvement. I was out till late and started looking for Saturn when I was again disappointed by the small image with no definition. Then I decided to just look in the area with the finder scope and investigate anything a little bright. And suddenly I saw Saturn! In the 25mm, it was a small disc with clear separation of the band around it. Moving up to the 15mm and finally the 9mm, I got an excellent clear look. I couldn't see any separation in the rings though. Could this be down to the conditions or perhaps a 6mm would give me the extra magnification to bring more out? The moon was incredible last night also. I think that's excellent advice in the DSOs - at one point I looked with the naked eye and saw a couple of stars, used the finderscope and then the 25mm and saw a rich band of stars that was completely surprising. Really amazing, even though I'm not sure what I was looking at! Thanks again.
Note the 8.8mm will give similar magnification to your 9mm. If you 2x Barlow either later you effectively get 4.4 or 4.5mm which would be good for only the best of nights. I've not used ES eyepieces and cannot comment on whether they would be better than the GSO Plossl but may I suggest that rather than a Barlow you do get the 6.7mm since it gives you an ideal high power in your telescope for nights of reasonable but not necessarily exceptional seeing.

Magnification at f.l.=1270mm

GSO 9mm = 141x
ES 8.8mm = 144x
2x Barlowed GSO 15mm = 169x
ES 6.7mm = 189x
2x Barlowed GSO 9mm = 282x
2x Barlowed GSO 8.8mm = 288x

I personally find the 150x magnification tantalisingly close to ideal but not quite just there for planets. You will find 170x to 220x your most useful power range. That's not to say 150x is no good and on many nights it will be sharper than the higher powers but you cannot get sharper and larger at the same time even on nights of good seeing although on such nights you will likely see more in the larger image.

My first and most useful high power eyepiece was a Vixen 5mm Ortho and it gave me 170x in my 6" telescope and although I craved for something larger at times I learned how to see small low contrast detail on planets which if you can master and you will with time will give you a skill that forms the basis of the art of observing planets.

Note and this is very important; the ability to see very fine detail on planets is greatly enhanced when the object is being tracked and does not move across the field of view. That's not to say that you wont see detail on a non-tracked telescope but for long duration study of a planets features tracking is highly beneficial. Ultra wide field higher power eyepieces can help with non tracked viewing at some extra expense but the object is still moving and the brain needs lock onto the image and not the edge of field to overcome the motion until again the telescope needs to be nudged to bring the object back. I'm speaking from my personal experience and others may have different opinions on the matter.
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Old 17-06-2014, 10:12 AM
209herschel (Herschel)
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Note the 8.8mm will give similar magnification to your 9mm. If you 2x Barlow either later you effectively get 4.4 or 4.5mm which would be good for only the best of nights. I've not used ES eyepieces and cannot comment on whether they would be better than the GSO Plossl but may I suggest that rather than a Barlow you do get the 6.7mm since it gives you an ideal high power in your telescope for nights of reasonable but not necessarily exceptional seeing.

Magnification at f.l.=1270mm

GSO 9mm = 141x
ES 8.8mm = 144x
2x Barlowed GSO 15mm = 169x
ES 6.7mm = 189x
2x Barlowed GSO 9mm = 282x
2x Barlowed GSO 8.8mm = 288x

I personally find the 150x magnification tantalisingly close to ideal but not quite just there for planets. You will find 170x to 220x your most useful power range. That's not to say 150x is no good and on many nights it will be sharper than the higher powers but you cannot get sharper and larger at the same time even on nights of good seeing although on such nights you will likely see more in the larger image.

My first and most useful high power eyepiece was a Vixen 5mm Ortho and it gave me 170x in my 6" telescope and although I craved for something larger at times I learned how to see small low contrast detail on planets which if you can master and you will with time will give you a skill that forms the basis of the art of observing planets.

Note and this is very important; the ability to see very fine detail on planets is greatly enhanced when the object is being tracked and does not move across the field of view. That's not to say that you wont see detail on a non-tracked telescope but for long duration study of a planets features tracking is highly beneficial. Ultra wide field higher power eyepieces can help with non tracked viewing at some extra expense but the object is still moving and the brain needs lock onto the image and not the edge of field to overcome the motion until again the telescope needs to be nudged to bring the object back. I'm speaking from my personal experience and others may have different opinions on the matter.
Thanks very much for all of that information, I really appreciate it. When looking at Saturn last night with the 9mm plossl, it's a very yellow colour and I see the band almost as thick as the disc. I don't think I really saw any separation in the band at all. The image is still pretty small in the eyepiece. I don't currently have any eyepiece to try any higher magnification but am I right that a 6mm would make the object larger in the FOV but perhaps lose clarity? Would it mean that I'd have a better chance of seeing the split in the bands at some points? I'm just trying to get an idea of what it would look like assuming my scope is well collimated and viewing conditions are my inner west of sydney backyard but it doesn't seem too bad late at night and if the neighbour's lights are off. Cheers and thanks again.
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Old 17-06-2014, 10:52 AM
astro744
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I can see the Cassini division in my Tele Vue 60 with my 2-4 and 3-6 Nagler zooms. I'll have a closer look again and see at exactly what magnification the division becomes visible for me. Note the Cassini division will become easier as the ring plane opens up and more difficult as it closes.

You should easily see the Cassini division with your telescope and 9mm eyepiece. You should also see subtle bands on the planet itself ranging from yellow to tan in colour.

Any ambient light from your neighbour's light should be blocked directly from line of sight but once blocked will not interfere at all with planetary observing.

Do not expect planets to be 'BIG'. Even with your 6mm eyepiece you will get an image only 1.5x bigger than with the 9mm eyepiece.

I think perhaps before you invest in eyepieces you first get (or borrow if you can) a reasonable quality 2x Barlow and see what type of image you get with your 15mm when Barlowed. Then ask yourself is the image 'big' enough for your liking? Is there plenty of detail there? Then try this with your 9mm when Barlowed. Is the image now too soft and any detail you saw before is just not there?

You will find that with your telescope even 1mm differences in eyepiece focal length under 10mm make a big difference to what the image is like and at higher powers even 0.5mm focal length difference is very noticeable. You may even find adding a quality 3x Barlow and also 20mm eyepiece will give you plenty of magnification range.

Note Barlows are great for fine tuning magnification provided you have suitable focal lengths to play with. Once you have determined that you get best performance from a particular focal length most of the time then you can invest in an eyepiece of just that focal length should you feel you need to or just stick with observing with Barlows.

This is what you can get with the following for example:

Tele Vue 25mm, 20mm, 15mm Plossl and Tele Vue 2x & 3x Barlow.

25mm
20mm
15mm
12.5mm
10mm
8.3mm
7.5mm
6.7mm
5mm

I mention Tele Vue because I know the glass to be good. You may get good results with GSO eyepieces and Barlows in the same combination.

Note at your higher powers you will get a comfortable eye lens and eye relief since you are viewing through longer focal length eyepieces when using Barlows.
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Old 17-06-2014, 11:16 AM
astro744
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Further to my previous messages and more to the point of your original post I think you would get more 'WOW' from the ES6.7 both from a magnification point of view for planets and also an apparent field point of view, (82 degrees is very nice!). You could then complement this eyepiece with the ES8.8 which would be fantastic with your telescope on globular clusters, planetary nebulae and galaxies. I don't think it is one or the other but both and I think you'll get the most out of the 6.7mm first but since both are useful it then doesn't really matter what order you buy them in.

However I cannot comment on the performance of ES in your Newtonian but can say that I use both my 7mm and 9mm Naglers on my 10.1" f6.4 as often one is either too much magnification or just not quite enough depending on the object and seeing conditions. (I get 182x and 234x). Of course there are times when I can go a lot higher than 234x and you will find this too and depending on how often this is and how much you want to observe at even higher power will be a deciding factor in whether you get even shorter focal length eyepieces.
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Old 17-06-2014, 12:07 PM
209herschel (Herschel)
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Further to my previous messages and more to the point of your original post I think you would get more 'WOW' from the ES6.7 both from a magnification point of view for planets and also an apparent field point of view, (82 degrees is very nice!). You could then complement this eyepiece with the ES8.8 which would be fantastic with your telescope on globular clusters, planetary nebulae and galaxies. I don't think it is one or the other but both and I think you'll get the most out of the 6.7mm first but since both are useful it then doesn't really matter what order you buy them in.

However I cannot comment on the performance of ES in your Newtonian but can say that I use both my 7mm and 9mm Naglers on my 10.1" f6.4 as often one is either too much magnification or just not quite enough depending on the object and seeing conditions. (I get 182x and 234x). Of course there are times when I can go a lot higher than 234x and you will find this too and depending on how often this is and how much you want to observe at even higher power will be a deciding factor in whether you get even shorter focal length eyepieces.
Thanks again. I don't think I saw bands and I'mpretty ccertain I didn't see the division in the band. I was pretty confident tha my collimation was correct but iit's slightly off, could that be the issue? I've only had the scope a week and taken it out twice. I'd just like to knowiit's working properl. I looked at the mirror using my phone torch and I saw a couple of parts in the cell of the mirror that wasnt perfectly uniform. There seem to be three parts that are not uniform in the circle. This is right on the edge and the surface of the mirror is pristine. Any thoughts on how to check my scope is working correctly would be greatly appreciated. Thanks again. I like the idea of both the es pieces. Thanks again
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