61 replies to this topic

[Dave Mitsky]

It also seems to blur a bit less toward the edges than my 30mm, but that could just be my imagination.

Simple five-lens-element widefield eyepieces based on the Erfle design are prone to the off-axis optical aberration known as astigmatism, especially when used in fast (i.e., low-focal-ratio) telescopes.  They do perform well in slow telescopes, such as f/10 SCTs, however.  Adding additional lenses to widefield eyepieces can counter astigmatism, at additional cost and weight, of course.  Such eyepieces are referred to as being well corrected.
 

Astigmatism is another off-axis effect that causes rays from a star to come to different focal points in the vertical and horizontal plane. It elongates images horizontally and/or vertically, making them look cross-like. Its effects are especially pronounced when racking a star’s images through focus. Astigmatism is more likely to be found in very fast optical systems. It’s usually corrected with additional lens elements that vary spacing and stop down the optics.
 

https://www.celestro...ign-aberrations
 

It's a bit out of date nowadays but the article at https://www.chuckhaw...ece_designs.htm describes most of the common types of eyepiece designs.

[Dave Mitsky]

Astrohopper is a free, open-source web app designed to locate celestial objects using a smartphone that you may want to try.
 

https://artyom-beili....io/manual.html
 

https://artyom-beili...strohopper.html

https://www.cloudyni...-1010-released/

[severencir]

yeah, i saw someone mention it so i looked it up and am looking forward to trying it out

[vintageair]

A 20x50 binocular would be quite difficult to hand hold and has a rather small field of view.  I certainly do not recommend one for surveying potential star hops.  A 10x50 is generally the maximum size recommended for hand-held use.

Yes, virtually impossible to use hand held, I had them on a tripod but even then it's difficult to look at anything higher than 45 degrees above the horizon. They are great for terrestrial viewing though.

[severencir]

It was very smokey tonight, so i cut my session short. I did get to try out that astrohopper though and it worked beautifully to find albireo. I think i will still want to learn to starhop properly, but that was really cool given how much i struggled to find it the first couple times. I took another look at the moon because it doesn't seem to care about transparency and i saw that the image was much less stable (i assume poor seeing). I did see that the lit part was much farther along the surface than last night. It actually seems to have gone so far that i feel like i could notice a difference over an hour or less. I'm going to try that on another night. Using my trick of aligning an adjustment screw. i ordered some nichrome wire to try to make myself a dew heater for cheap because spending another $50 for a dew heater for just my finder didn't seem appealing, and having some nichrome wire might become useful down the road too.

I realized looking through my images that i confused some craters and mare and it had not in fact traveled that far.

Edited by severencir, 31 May 2025 - 01:27 AM.

[EsaT]

It was very smokey tonight, so i cut my session short.

 

I took another look at the moon because it doesn't seem to care about transparency and i saw that the image was much less stable (i assume poor seeing).

It's not that smoky if you don't get "Venus simulation" and can't see sun during the day...

Though especially deep sky objects suffer fast from any gunk in the air, including high humidity.

 

But for stars bigger aperture's "brute force" helps.

Just like for the Moon being observable through thinner clouds.

(high level clouds seem to affect seeing more than low level fractocumulus/stratus)
 

 

Besides atmospheric seeing also telescope can be source of bad seeing:

If telescope's storage temperature is significantly above outside temperature, heat released by telescope during cooling causes thermals inside it.

Actually even shape of the mirror gets distorted by its edges cooling faster than center.

But that shows as static softness, instead of moving and varying blurring/distortions.

 

 

Couple hours is enough to make it or break it for some details of the Moon.

Though bigger aperture's capabilities give more leeway for many smaller details.

For example Rima Hadley next to Apollo 15's landing site can be distinguished farther from terminator.

 

 

Sky&Telescope's Field Map of the Moon is by far the best for learning to "locate yourself on the Moon."

Semi-perspective representation of libration zones makes it also excellent complement to any later more detailed atlas book.

Though for easier handling and better durability it's usefull to cut it to those four "quadrants" and laminate them.

(here's scans you can use on PC)

[severencir]

Most of the stars i could see by eye were dimmer and had a reddish tint to them. Through the scope most of the stars were hardly noticeable and kept popping in and out (poor seeing again i assume). This continued to an hour agter being out there with the mirror fan on. 

Edited by severencir, 31 May 2025 - 10:50 AM.

[Dave Mitsky]

Click on http://astrostrona.pl/moon-map for an excellent online lunar map and http://www.ap-i.net/avl/en/start to download the free Virtual Moon Atlas. Visit http://time.unitariu...moon/where.html for current information on the Moon and https://www.fourmila.../lunarform.html for information on various lunar features.

[Dave Mitsky]

The articles at the following URLs discuss astronomical seeing:
 

http://www.damianpeach.com/seeing1.htm
 

http://www.damianpea...m/pickering.htm
 

https://skyandtelesc...ing-the-seeing/
 

https://www.skyatnig...nomical-seeing/
 

https://sentinelmiss...nomical-seeing/

[vintageair]

It hit 101 degrees yesterday and when I started viewing the Moon right after sunset the whole thing was going in and out of focus, way beyond the normal atmospheric shimmer, but it settled down later. The terminator was cutting across Mare Tranquliitatis right about the Apollo 11 site.

Edited by vintageair, 31 May 2025 - 01:24 PM.

[3C286]

Hi

 

What a lovely observation report of your first outing . 

 

With everything in place, i decided to just look around in the area of vega and see what was there. My first thing of note was that i had no idea what i was looking at, and i could only gesture broadly to the region of sky i was in. Even in the finder scope it was very difficult to get my bearing right. I decided to try practicing aligning my scope to vega and was able to do so a few times successfully, then decided to move on to something else. I turned the scope around and started looking at mars, as the only planet i could reasonably look at in outside of the bright penumbra right now. it took some effort, but i managed to get a decent view of a tiny redish disc. It wasn't too impressive, but i considered it a success. I then figured that if i can align to vega, i could probably try to see m57. It did not go well. I could align to vega, but once i tried finding the rest of lyra, i had difficulty. I was used to navigating by constellation because of naked eye observation, but that skill is only marginally helpful when you have about an 8 degree tfov in your finder and less than 2 at the eyepiece. I didn't yet have the knowledge i would eventually end up with either, and most importantly, i couldn't figure out how much of the sky i was actually seeing. I could calculate the tfov, but that doesn't really help me intuit what i am seeing and how much i need to move in which direction. Needless to say, i didn't end up finding m57 that night. I then figured that i would try aligning with another star and practice some basics first. I chose deneb because it was in a good part of the sky for my viewing location, somewhat close to the horizon so i didn't have to kill my back, and it was also fairly bright. It took me a long time looking down my scope and sweeping back and forth to find it, but i eventually did. When i tried seeing if i could align to arcturus and polaris, i started to realize how good of a choice vega was as a starting star. I failed to find them and it was getting late, so i packed up for the night.

 

You might find this YouTube tutorial on star hopping useful. It's a hop to M57 so I think you'll find the area familiar familiar:

 

https://www.youtube...._channel=MikeyJ

 

There are other ways of star hopping so this is one of many ways. The key thing with star hopping is to always know exactly where you are relative to your charts.

 

Regarding finding it hard to get your bearing, Star hopping using a planetarium software can be helpful because it rotates the charts to alt-az coordinates. I use a paid version of SkySafari on my phone with a dark red filter. You can create FOV circles for your finderscope which makes star hopping and "visual plate-solving" much easier. Many swear by paper charts though.

 

Another trick I read in one of John Isaac's posts is to rotate your RACI eyepiece so that the crosshairs run along the alt/az (kind of vertical/horizontal) axes so that they match the crosshairs in SkySafari. You'll need to insert a thin O-ring between the RACI and the crosshair eyepiece to get it to stay in place.

 

 

Hope that helps and do share your observations with us.

 

Tak

[severencir]

Hi

 

What a lovely observation report of your first outing . 

 

 

You might find this YouTube tutorial on star hopping useful. It's a hop to M57 so I think you'll find the area familiar familiar:

 

https://www.youtube...._channel=MikeyJ

 

There are other ways of star hopping so this is one of many ways. The key thing with star hopping is to always know exactly where you are relative to your charts.

 

Regarding finding it hard to get your bearing, Star hopping using a planetarium software can be helpful because it rotates the charts to alt-az coordinates. I use a paid version of SkySafari on my phone with a dark red filter. You can create FOV circles for your finderscope which makes star hopping and "visual plate-solving" much easier. Many swear by paper charts though.

 

Another trick I read in one of John Isaac's posts is to rotate your RACI eyepiece so that the crosshairs run along the alt/az (kind of vertical/horizontal) axes so that they match the crosshairs in SkySafari. You'll need to insert a thin O-ring between the RACI and the crosshair eyepiece to get it to stay in place.

 

 

 

Hope that helps and do share your observations with us.

 

Tak

I actually rooted my phone so i could turn off the blue and green leds in my amoled display before receiving my scope. I even tested it with a 1000/mm diffraction grating. I've been using Stellarium, but i might switch for that feature. I might follow your advice about the crosshairs, but i am a bit timid to try to take my finder apart.

[severencir]

I went out for a couple hours tonight. I started with the moon again, but i haven't gotten into becoming familiar with its landmarks yet. I then did my usual practice with vega, and decided to move over to polaris. There was a lot of glow in the sky when i went to observe. I assume the moon was to blame. Still i managed to center on polaris, and for a challenge, find my way to the next star in the little dipper by referencing what i was seeing to stellarium. The best part is that i managed to do it without using my finder scope. 

I then moved over to zeta her because eta her was too dim for me to see while aligning my scope by eye at the time. i was able to confirm via stellarium that i was on zeta her, and was about to move away when i noticed it seemed almost like there was a hair's width black line through the middle of it. i switched to my 9mm and focused in, and turns out it was a binary. It was very clear in the 9mm. After that i panned left a decent bit and lost track of where i was, but found a shape in my eyepiece that was unique enough to try to get my bearings. It was a quadrilateral made by several stars that stellarium labeled as sao and hd with numbers. I was able to figure out where i was, so i moved it to the edge of my fov and looked for another shape. I found a long triangle made up of similarly named stars and saw that it's short base points directly where i wanted to go, and sure enough, i saw a bright fuzzy cloud.

I checked my finder because someone said i should be able to see it in the finder, but i only was able to notice it distinctly in the finder when i knew where to look and what to expect. Before having found it, i had likely had it in my fov on the finder several times and never noticed. I then switched to my 9mm to get a better look, as that was recommended to view some extended objects, and used 2 nearby stars to recenter my scope. It really changed the view. I was able to make out a bunch of faint individual stars. It was the densest collection of stars i had seen so far. I think i would love to see it on a moonless night. One thing of note is that it appeared grey and fuzzy on my 25mm, but more defined and mostly blue in my 9mm. I had been trying to find m13 since day 1 and i am happy that i succeeded, even if it was a bit janky. 

I tried going for m3 next, but that section of the sky had too much glow for me to navigate properly (i assume because it is closer to the moon). I was able to identify another bright binary as confirmed in my 9mm, but i couldn't figure out where i was when i found it. i know i was somewhere in the general area of bootes, but i couldn't seem to find arcturus and i'm unsure why. It was getting late again so i decided to pack up. I am loving the view my ad8 is giving me. Thank you to everyone who has recommended it so heavily that i couldn't go 3 pages in research without seeing it pop up.

[The Ardent]

I’m going to give you two exercises. Make sure your finder is lined up and use low power eyepiece, and be comfortably 

 seated. Moonlight may be a distraction but these can still be accomplished. 

 

1. Try aiming your scope using both finder and sighting along tube at the seven stars of the Big Dipper. Go from 

 one end to the other five times successfully . We call this “Dancing along the Bear” 

 

2. Later in the evening try the same with the six main stars or Lyra. Being closer together, it’s easy to center the wrong one. Each star has a distinct appearance in the eyepiece. Try to write a short description of each star explaining the distinctive feature of each . We call this “The Truth of the Lyre” 

 

The six main stars are labeled in the pic. 

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[severencir]

I’m going to give you two exercises. Make sure your finder is lined up and use low power eyepiece, and be comfortably 

 seated. Moonlight may be a distraction but these can still be accomplished. 

 

1. Try aiming your scope using both finder and sighting along tube at the seven stars of the Big Dipper. Go from 

 one end to the other five times successfully . We call this “Dancing along the Bear” 

 

2. Later in the evening try the same with the six main stars or Lyra. Being closer together, it’s easy to center the wrong one. Each star has a distinct appearance in the eyepiece. Try to write a short description of each star explaining the distinctive feature of each . We call this “The Truth of the Lyre” 

 

The six main stars are labeled in the pic. 

So i went out tonight, astrospheric said there was 0% cloud cover, but the moon was clearly blocked by clouds. I couldn't see stars in half the sky and many of the stars i could see were quite dim. I did the vega challenge, and i learned that aside from vega and sulafat they all are doubles, or double looking. Sheliak and zeta lyr look quite similar, but all the others were quite distinct. I also checked out m57 again because it was on the way. Once again, it was only really noticeable with averted vision and not visible in my finder.

The big dipper was very hard to see. Even in my scope, i could only make out maybe 5 stars max in the area with a 1.5 degree fov. i tried navigating it, but i just couldn't bear it so i gave up. I planned this session to be a bit later since i don't have to be up as early, and i got to get my first quite fuzzy dim look at m31 on the horizon. It was bright enough to see directly with my 9mm and 25mm, but i could barely see it with averted vision in my scope. I am eager to contrast that with a clear dark night when it's higher in the sky. Finding it was difficult because it was, in an area of the sky i could barely see like the big dipper was. This was to the point that when i decided to pack up, i couldn't even make out the cup of the big dipper or any of cassiopeia by eye. I was determined to try to find it though or at least point my scope where it should be because i scheduled this session specifically to get a look at it. When pleides stops hanging out with the sun like almost all the planets are, i will have another high priority target. Like many cultures and a car company, it's one of my favorite night sky objects. 

I would still call this night a success, challenges and all.

Edited by severencir, 02 June 2025 - 02:47 AM.

[MikeTahtib]

I checked my finder because someone said i should be able to see it in the finder, but i only was able to notice it distinctly in the finder when i knew where to look and what to expect. Before having found it, i had likely had it in my fov on the finder several times and never noticed. 

Yes, this is exactly how I use my finder scope.  Many of the targets do not stand out, but are perceptible if you are looking for them.  This is also why I don't think binoculars and small telescopes are the greatest fit for beginners who want to see DSOs.  While visible, you can't really see what they look like as you can through a bigger scope.  When the Pleiades are around again, though, your best view will probalby be through your finder scope.

[Dave Mitsky]

So i went out tonight, astrospheric said there was 0% cloud cover, but the moon was clearly blocked by clouds. I couldn't see stars in half the sky and many of the stars i could see were quite dim.

Much of the United States was covered with wildfire smoke.  The sky where I live was "clear" last night, but I could only see a bright pass of the Tiangong space station, the Moon, and Arcturus naked eye.

[Dave Mitsky]

The smoke will be even worse in my area tonight.

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[severencir]

So tonight was the first chance in a week or so to observe because it's been very weather lately. I got my telrad during the downtime and added it to my scope. It makes a massive difference. After my collimation and aligning my finder and telrad, i decided to start with my usual practice navigating lyra. i then decided to use my telrad to find the couple objects i was already familiar with as a test and i quickly navigated to m57, then just lined up to m13 and was basically right on it. I decided to just leave my 9mm in and leave the navigating mostly to the telrad. I was easily able to find m92 and decided to try something in a less familiar region of the sky and went for m12. This one was a bit harder as i wasn't sure exactly where to line up yet, but i got it in the general area, saw a unique looking set of stars, found it in my app, and used it to easily navigate to m12. I then tried to check out m107 because it is close, and i found where i should be looking based on other unique looking star patterns, but i didn't see anything there. The glow was very bright though, so i assume it was just how close it was to the moon.

Unfortunately, as i was starting to aim in a darker portion of the sky, i noticed fast moving clouds (cirrocumulous i think based on a quick google), easily visible in the nearly full moon's light, had rolled in and blocked half of my sky. I decided to wait a bit for it to clear up, checking out the moon in the meantime. It did a bit, but i saw more clouds coming in. I didn't feel like trying to work around them, so i decided that i'd pack up. Astrospheric shows good opportunities (though it hasn't been very accurate about cloud cover) for the next several days, and they're on days that work better for me. That telrad is amazing though. It bridges my experience with naked eye observing with the ability to use the scope.

[EsaT]

...I then tried to check out m107 because it is close, and i found where i should be looking based on other unique looking star patterns, but i didn't see anything there. The glow was very bright though, so i assume it was just how close it was to the moon.

Unfortunately, as i was starting to aim in a darker portion of the sky, i noticed fast moving clouds (cirrocumulous i think based on a quick google), easily visible in the nearly full moon's light, had rolled in and blocked half of my sky.

Any light pollution starts fast degrading and completely blocking visibility of "surface" objects.

For point sources like stars, magnification increases contrast between background and them, but for surface sources that doesn't help.

(for emission nebulae radiating all of their energy at few wavelengths narrow band filters help)

 

Visible movement speed of clouds depends heavily on their distance to you.

High level clouds (like cirrocumulus) would need very high wind speeds, like jet stream, to show clear movement and usually you need minutes long observing to see much any movement.

So those were propably at most medium level clouds you saw.

[FiddleHead Galaxy]

Any light pollution starts fast degrading and completely blocking visibility of "surface" objects.
For point sources like stars, magnification increases contrast between background and them, but for surface sources that doesn't help.

This is very true, though with some exceptions. Take M33 for example, in my bortle 6, bordering on bortle 5 skies, I can just barely make out the Triangulum galaxy with my 30mm. However, NGC 604, a gigantic nebula within M33, can be seen MUCH more easier than M33 itself. With a 9mm at about 135x magnification, it appears as a fuzzy star, decently visible in direct vision, but greatly enhanced with averted vision. Also, I find the cores of M31 and M33 can take more magnification with the 9mm. So yes I wouldn't be trying to use high magnification on these larger dimmer objects a majortiy of the time, but you would certainly be missing out on some things here and there. Considering you are in bortle 4, with enough experience and time, your views should be even better than mine.

Also, speaking from my own experience as a beginner, in many ways I still am, please dont restrict yourself to what others suggest can and cannot be done. And no, I dont mean ignore the many years of experience that many here on the forums have...but if you really want, bump up the magnification, look for that "impossible" object. The moments where those efforts succeed may very well be few and far between, but when they DO work, they are very rewarding. Trust me, an 8-inch is WAY more capable than you think.

[Nerd1]

That went way better than my first two attempts,  I started the hobby like an idiot. A 125mm Apo on a goto eq mount.  It took me a week of nights before I got that thing pointing in the right direction,  on a consistent basis. I find Stellarium the best tool for learning,  you just slide the bar and watch the sky progress.  Skysafari is excellent as well, I have both on all my devices. 

 

Clear skies! 

[MikeTahtib]

Trust me, an 8-inch is WAY more capable than you think.

Very true!!

[vintageair]

... That telrad is amazing though. It bridges my experience with naked eye observing with the ability to use the scope.

Yea I really like the Telrad but no so much of a fan for the mount. I 3D printed an adapter that lets me mount it onto a standard wedge.

 

[stanleymcmahan]

I really really really enjoyed this post. What a great telling of your experience.

Please continue to post, I know it takes a long time, but it sure was an enjoyable read.

Thank you and happy observing!