Jump to content

  •  

CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.

Photo

Orion 8" Classical Cass giving soft view - collimation?

  • Please log in to reply
44 replies to this topic

#1 rexowner

rexowner

    Viking 1

  • *****
  • topic starter
  • Posts: 606
  • Joined: 13 Aug 2017
  • Loc: SF Bay Area, California

Posted 21 July 2021 - 09:39 AM

I've been using mostly refractors, so bear with me.

 

With Jupiter and Saturn headed higher, I wanted more aperture, so I ordered the

8" Classical Cassegrain.  Props to Orion for prompt shipping.  I ordered it

Sunday evening they shipped it Monday, and arrived yesterday, Tuesday.

I guess I'm lucky that they ship from just a couple of towns over from

where I live.

 

During the day I pointed it at a distant cedar tree, which is far enough away

that I use it to get a rough set up for optics before the sunset. 

 

I would describe the daytime view through the eyepiece as "soft."  With other

scopes I can see detail on the bark and needles, but could not with the CC8.

Also, the range of focus with a 55mm Plossl, and a 25mm ES 100 were wide,

i.e. focus didn't change much as I moved the focuser, i.e. low speed would

be virtually unnecessary.  The diagonal was the same Tele Vue Everbrite used

with other scopes, so no problem with the rest of the equipment.

 

Later in the afternoon, I put in the included collimation cap and

was able to adjust the secondary to center the circle, but could

not see the ring of light supposedly indicating the primary's

collimation.  I ordered a Cheshire eyepiece which hasn't

arrived yet, and will give it a go.

 

I set it up at last night and viewed the Moon.  Same thing.  I set up my 5"

refractor with the similar magnifications of 44x and approx 100x, and

it wasn´t even close.  Tons of easily seen detail with the refractor, but

soft images lacking detail through the CC8.  Not even close.

 

 

 

The primary mirror looks fine from the outside, and nothing appears 

to be wrong with the scope.

 

Is this typical for a Cassegrain out of collimation, normal, or am I

missing something?


Edited by rexowner, 21 July 2021 - 09:41 AM.

  • shredder1656 likes this

#2 petert913

petert913

    Aurora

  • *****
  • Posts: 4,931
  • Joined: 27 May 2013
  • Loc: Silverton, OR

Posted 21 July 2021 - 09:58 AM

OOoooohh !  I am expecting delivery of my CC8 today.   Being an SCT guy, I was hoping the classic cassegrain would give me even sharper views.  I'll report on my experience as soon as I get it set up and operating.  Ugh.



#3 David Boulanger

David Boulanger

    Mariner 2

  • *****
  • Posts: 276
  • Joined: 25 Aug 2020
  • Loc: Naples, Florida

Posted 21 July 2021 - 10:10 AM

My CC 8 comes today also. popcorn.gif



#4 Bill Barlow

Bill Barlow

    Fly Me to the Moon

  • *****
  • Posts: 5,130
  • Joined: 03 Dec 2007
  • Loc: Overland Park KS

Posted 21 July 2021 - 10:16 AM

Did you check the collimation using a somewhat bright star about 45 degrees above the horizon at magnifications of 150-250X?  This is usually the reason for soft views in Cassegrain type scopes.

 

Bill


  • Medic002 likes this

#5 Medic002

Medic002

    Ranger 4

  • *****
  • Posts: 361
  • Joined: 27 Apr 2021
  • Loc: South Carolina Bortle Class 4

Posted 21 July 2021 - 10:37 AM

Just as Bill stated u need to check collimation using a star and then u will see the rings that u were expecting before. During daylight u won't see those rings but maybe more of a blurring in the view. Most sct's I have used will give sharp views once collimated and focused but maybe not as good as a refractor.



#6 rexowner

rexowner

    Viking 1

  • *****
  • topic starter
  • Posts: 606
  • Joined: 13 Aug 2017
  • Loc: SF Bay Area, California

Posted 21 July 2021 - 10:38 AM

Did you check the collimation using a somewhat bright star about 45 degrees above the horizon at magnifications of 150-250X?  This is usually the reason for soft views in Cassegrain type scopes.

 

Bill

Not yet, but I will try to do so tonight with the collimation cap, and will do so with the

Cheshire eyepiece when it arrives.  

 

Are there any other tools recommended for collimation?


  • Medic002 likes this

#7 rexowner

rexowner

    Viking 1

  • *****
  • topic starter
  • Posts: 606
  • Joined: 13 Aug 2017
  • Loc: SF Bay Area, California

Posted 21 July 2021 - 10:40 AM

Just as Bill stated u need to check collimation using a star and then u will see the rings that u were expecting before. During daylight u won't see those rings but maybe more of a blurring in the view. Most sct's I have used will give sharp views once collimated and focused but maybe not as good as a refractor.

Do I understand that this would be done with a star test, i.e. no special tool,

just moving in and out of focus?

 

Thanks in advance, sorry to be a little slow here.  Collimating my small Newtonian

was quite easy.  I used to have a 127 Mak that never needed collimation, so this

skill is a little new to me.



#8 SocalAstro

SocalAstro

    Explorer 1

  • *****
  • Posts: 54
  • Joined: 21 Sep 2007
  • Loc: Corona, CA

Posted 21 July 2021 - 10:43 AM

Here's an excellent procedure for collimating the GSO CC's that I used with good results when I had the 8".

 

https://www.cloudyni...cal-cassegrain/

 

Cheers,

Leon


  • rexowner and Medic002 like this

#9 Medic002

Medic002

    Ranger 4

  • *****
  • Posts: 361
  • Joined: 27 Apr 2021
  • Loc: South Carolina Bortle Class 4

Posted 21 July 2021 - 10:49 AM

Do I understand that this would be done with a star test, i.e. no special tool,

just moving in and out of focus?

 

Thanks in advance, sorry to be a little slow here.  Collimating my small Newtonian

was quite easy.  I used to have a 127 Mak that never needed collimation, so this

skill is a little new to me.

yes u just get any star in your view and keep it out of focus a little and u will see the rings no special tools. then u turn the small collimation screws a small fraction maybe quarter turn in the right direction to get all the rings concentric. once u have rings all concentric u focus the star and see if your viewing is better.



#10 Medic002

Medic002

    Ranger 4

  • *****
  • Posts: 361
  • Joined: 27 Apr 2021
  • Loc: South Carolina Bortle Class 4

Posted 21 July 2021 - 10:57 AM

here is a video start to finish collimating an sct.

 

https://www.bing.com...7BF06&FORM=VIRE


  • Illinois and rexowner like this

#11 rootsabove

rootsabove

    Sputnik

  • -----
  • Posts: 30
  • Joined: 28 Feb 2015
  • Loc: SW Ohio, USA

Posted 21 July 2021 - 11:05 AM

I received mine yesterday after ordering it on February 12th. Initially I had the same soft view, popped in the collimating cap and it looked fine. Went and put in my Cheshire, and could immediately see the collimation was whacked. 2 ever so slight adjustments and it looks dead center. I focused on a tree line about 1/4 of a mile away and was pleased with what I saw, nice detail. The thing I did not expect was to have to use all 3 spacers to come to focus. It achieves focus pretty quickly, so the last 1” spacer is barely needed. I assume the need for all the spacers is based on using a 1-1/4” prism diagonal. I used Tak LE eyepieces, 24mm and 12.5, they appear relatively parfocal. The accompanying manual says backfocus from the end of the 2” focuser collar (which adds about 75mm to the rear of the tube) is 166mm. So I guess it all pretty much adds up. One other thing is the dust cap…popped it out and then when putting it back in, it was loose. Gave it a little twist and it was tight. Nice little design. 
So far I’m very pleased, balances well on my Sirius EQ-G, and vibration was minimal. Focuser seems very nice; I’m totally a visual user. 


Edited by rootsabove, 21 July 2021 - 11:05 AM.


#12 rexowner

rexowner

    Viking 1

  • *****
  • topic starter
  • Posts: 606
  • Joined: 13 Aug 2017
  • Loc: SF Bay Area, California

Posted 21 July 2021 - 11:43 AM

I was surprised how loose the dust cap was too.  Noticed that rotating it to a certain angle made the

fit tighter.  Since there wasn't any extra material, I took this to mean the inside edge of the tube and

the dust cap aren't exactly round.  Hoping my collimation works out....



#13 rmollise

rmollise

    ISS

  • *****
  • Posts: 23,512
  • Joined: 06 Jul 2007
  • Loc: US

Posted 21 July 2021 - 12:42 PM

I've been using mostly refractors, so bear with me.

 

With Jupiter and Saturn headed higher, I wanted more aperture, so I ordered the

8" Classical Cassegrain.  Props to Orion for prompt shipping.  I ordered it

Sunday evening they shipped it Monday, and arrived yesterday, Tuesday.

I guess I'm lucky that they ship from just a couple of towns over from

where I live.

 

During the day I pointed it at a distant cedar tree, which is far enough away

that I use it to get a rough set up for optics before the sunset. 

 

I would describe the daytime view through the eyepiece as "soft."  With other

scopes I can see detail on the bark and needles, but could not with the CC8.

Also, the range of focus with a 55mm Plossl, and a 25mm ES 100 were wide,

i.e. focus didn't change much as I moved the focuser, i.e. low speed would

be virtually unnecessary.  The diagonal was the same Tele Vue Everbrite used

with other scopes, so no problem with the rest of the equipment.

 

Later in the afternoon, I put in the included collimation cap and

was able to adjust the secondary to center the circle, but could

not see the ring of light supposedly indicating the primary's

collimation.  I ordered a Cheshire eyepiece which hasn't

arrived yet, and will give it a go.

 

I set it up at last night and viewed the Moon.  Same thing.  I set up my 5"

refractor with the similar magnifications of 44x and approx 100x, and

it wasn´t even close.  Tons of easily seen detail with the refractor, but

soft images lacking detail through the CC8.  Not even close.

 

 

 

The primary mirror looks fine from the outside, and nothing appears 

to be wrong with the scope.

 

Is this typical for a Cassegrain out of collimation, normal, or am I

missing something?

Don't fiddle with the collimation anymore until you check it on a star. A magnitude 2 or so one is good--Polaris will work. Defocus just until you can see diffraction rings--not too much. The star should look like a little bullseye target. Are the rings concentric, or do they look squished on one side? If they do the scope is out of collimation. Otherwise...

  • Daytime views are poor gauges of the quality of larger aperture telescopes. The seeing caused by the heated ground is responsible. Images in smaller telescopes at lower power will look better.
  • The same goes for sky objects on nights of poor seeing.
  • With a telescope like this, it is important it be allowed to acclimate to outdoor temperatures if it is to perform its best. Half an hour, at least, is needed when going from a cool house to a warm outdoors or vice versa.

If all the above is accounted for, it's time to do a star test (maybe getting help from a local observer experienced with that) to check the quality of the telescope's optics. 

 

Good luck... :)


  • Medic002 likes this

#14 Bill Barlow

Bill Barlow

    Fly Me to the Moon

  • *****
  • Posts: 5,130
  • Joined: 03 Dec 2007
  • Loc: Overland Park KS

Posted 21 July 2021 - 01:43 PM

In these CC scopes, could you avoid using so many extension tubes/spacers by using a 2" diagonal?



#15 Daniel Mounsey

Daniel Mounsey

    Vendor (Woodland Hills)

  • *****
  • Vendors
  • Posts: 8,063
  • Joined: 12 Jun 2002

Posted 21 July 2021 - 01:48 PM

I've been using mostly refractors, so bear with me.

 

With Jupiter and Saturn headed higher, I wanted more aperture, so I ordered the

8" Classical Cassegrain.  Props to Orion for prompt shipping.  I ordered it

Sunday evening they shipped it Monday, and arrived yesterday, Tuesday.

I guess I'm lucky that they ship from just a couple of towns over from

where I live.

 

During the day I pointed it at a distant cedar tree, which is far enough away

that I use it to get a rough set up for optics before the sunset. 

 

I would describe the daytime view through the eyepiece as "soft."  With other

scopes I can see detail on the bark and needles, but could not with the CC8.

Also, the range of focus with a 55mm Plossl, and a 25mm ES 100 were wide,

i.e. focus didn't change much as I moved the focuser, i.e. low speed would

be virtually unnecessary.  The diagonal was the same Tele Vue Everbrite used

with other scopes, so no problem with the rest of the equipment.

 

Later in the afternoon, I put in the included collimation cap and

was able to adjust the secondary to center the circle, but could

not see the ring of light supposedly indicating the primary's

collimation.  I ordered a Cheshire eyepiece which hasn't

arrived yet, and will give it a go.

 

I set it up at last night and viewed the Moon.  Same thing.  I set up my 5"

refractor with the similar magnifications of 44x and approx 100x, and

it wasn´t even close.  Tons of easily seen detail with the refractor, but

soft images lacking detail through the CC8.  Not even close.

 

 

 

The primary mirror looks fine from the outside, and nothing appears 

to be wrong with the scope.

 

Is this typical for a Cassegrain out of collimation, normal, or am I

missing something?

 

 

Many users think collimation will solve these problems and that's often not the case with exposed optics like this. You could have perfect collimation and still get very soft views exactly the way you describe and it's very common.  An "open tube" is far more prone to thermal currents because the optics are openly exposed to the outside air without being shielded. It's like flying in a passenger plane at twenty thousand feet and the windows are open all the sudden. There's no harmony between the two environments and this is precisely what happens when glass substrates, tubes, open tubes etc are exposed to a different environment. Fuzz and softness often have to do with "thermal behavior".

 

Some very important history.

https://www.astro-ph...fractorland.pdf

 

Also, I don't know how many are aware of the this, but classical cat designs are extremely difficult to manufacture because of the complexity of the secondary.  So, do you want to know if it's collimation? Do you want to know if it's thermals? Do you want to know if it's the optics by observing the spherical correction? The best way by far to determine that is to observe the Fresnel patterns or diffraction patterns witnessed by observing stars and even seeing if planets flare to one side. Taking astrophotos will not reveal these issues unless a camera is used in a specific way and even then, it's often questionable. These drawing provide "realistic" impressions of what some of the artifacts may appear like through an eyepiece. 

 

https://www.bbastrod...tarTesting.html



#16 pweiler

pweiler

    Vostok 1

  • *****
  • Posts: 159
  • Joined: 20 Oct 2020
  • Loc: Chicago, IL, USA

Posted 21 July 2021 - 03:15 PM

Rexowner,
I bought an Orion CC8 this year too. I don’t have a quick and simple answer, but I might have some useful comments. My eyesight is not the greatest so I find collimation with reflectors more of a challenge. When I first setup the CC8, I tried to do indoor artificial star collimation and focus tests on trees across the street with a 56mm EP. Due to the long focal length of scope, I was not able to see much of anything. With good / bright indoor lighting I was able to collimate the scope with a Cheshire EP. But, believe it or not the crosshairs of both of my Cheshire EPs slightly cover up the small pinpoint area of the center of the concentric circles enough to make it feel like a little bit of blind guess work. The primary was nearly perfect and the secondary needed a slight adjustment probably from shipping. I was not 100% convinced that I had done the job right and ordered, based on some CN advice here - a Tak collimator and 2” adapter, which is nearly half the price of the scope!! Using the Tak collimator’s small magnification and later night field tests, I was able to verify that the Cheshire did the job. I now only use the Tak for collimation. For visual use, I had the 2” extender in the back of the scope/focuser for several months and it brought most of my range of EPs used into focus, but on one clear night I finally got a chance to jack the power up above 300x and discovered that it would not focus until I switched to using only the 1” extender, which can bring to focus all my EPs 56mm to 7mm (no barlows or powermates used. TV 2” diagonal is used) into focus. Hope some of this helps. Also, my dust cap twists the same way that you described, which I believe is normal.

Edited by pweiler, 21 July 2021 - 03:42 PM.


#17 Bean614

Bean614

    Vanguard

  • *****
  • Posts: 2,094
  • Joined: 05 Nov 2015
  • Loc: Mass.

Posted 21 July 2021 - 06:01 PM

here is a video start to finish collimating an sct.

 

https://www.bing.com...7BF06&FORM=VIRE

The OP hast a Classical Cassegrain,  not an SCT!  They are quite different!


  • Asbytec likes this

#18 jgraham

jgraham

    ISS

  • *****
  • Posts: 22,367
  • Joined: 02 Dec 2004
  • Loc: Miami Valley Astronomical Society

Posted 21 July 2021 - 09:55 PM

If you don’t touch the primary, then the collimation is the same, and I would be very reluctant to touch the primary unless it were absolutely necessary. I have both the CC8 and RC8 and they both give very sharp, high contrast views. Love’m!


  • petert913 likes this

#19 quilty

quilty

    Mariner 2

  • -----
  • Posts: 230
  • Joined: 07 Oct 2019

Posted 22 July 2021 - 04:10 AM

I think there's nothing wrong with your CC. First of all I recommend to everyone to check if the mirrors are lose. They happen to be. Then normal collimation procedure starting with the primary mirror will do if necessary. I've heard from no one who didn't succeed in getting sharp views through such CCs or RCs

Watching trees in daytime at high power usually won't give an impression on how these scopes perform. And yes, a good 6 inch refractor would outperform these scopes at contrast and resolution


Edited by quilty, 22 July 2021 - 04:14 AM.

  • petert913 likes this

#20 Tomcatf14

Tomcatf14

    Lift Off

  • -----
  • Posts: 17
  • Joined: 29 Jun 2021

Posted 24 July 2021 - 10:20 AM

I've been thinking about 1 of these scopes or an orion mak, has anyone figured out the soft view issue yet.



#21 rexowner

rexowner

    Viking 1

  • *****
  • topic starter
  • Posts: 606
  • Joined: 13 Aug 2017
  • Loc: SF Bay Area, California

Posted 24 July 2021 - 11:00 AM

I've had the scope out a few times, but not tested it thoroughly yet.

 

There is nothing wrong with the scope.  I think my expectations were too high. 

 

Did the star test, and collimation is OK, but not perfect.  Out of focus star presents a very

*slightly* oval ring, and in focus stars look good, with the expected diffraction spikes

on bright stars.  I'm planning to try to improve this before I give up and send the

scope back to Orion.

 

I was expecting the additional aperture vs. my 5" refractor to make more of a difference.

E.g. my 127mm refractor views are way better than my 102mm, which is way better than my

85mm..., but in the limited time I've spent with the scope, I'm not seeing a benefit in

going to 200mm.  Might be better with a binoviewer because of the large backfocus,

but then this scope is best in high magnifications.

 

The 3 extension rings are provided for good reason.  Depending on my diagonal, eyepiece

and filter set up, I've used 1, 2 or all 3 of them to achieve proper focus.  Not really

unexpected, but something may have to manage depending on how one uses the scope

If I keep it, I'm probably going to use it parfocal lenses to minimize swapping extension

rings.  To be honest, I don't understand the exact technical reason for the focus needing

different extensions, but they are indeed required even in the limited variations of

configurations I've tried.


Edited by rexowner, 24 July 2021 - 11:01 AM.


#22 rexowner

rexowner

    Viking 1

  • *****
  • topic starter
  • Posts: 606
  • Joined: 13 Aug 2017
  • Loc: SF Bay Area, California

Posted 24 July 2021 - 11:16 AM

FWIW some notes for someone reading this thread considering buying this scope.

 

It´s made by GSO, and Orion relabels it.  As far as I can tell it is not identical to the

8" GSO sold by others, which might not be obvious.  The difference is the focuser

the Orion comes with a *Linear Bearing* Crayford focuser, whereas it looks to me

like the others come with a regular Crayford focuser.  In theory, the Linear Bearing

is "better" because it can carry heavier loads - the standalone focuser is more

expensive than the regular Crayford, and the better focuser justifies at least some

of Orion´s higher price.

 

The disadvantage of the Linear Bearing is that it has 2" of travel, whereas I blv

the regular Crayford has 3".   Considering that one may have to reconfigure the

3 extension rings for different setups, the extra inch of travel in the focuser

would be nice to have.  From what I´ve read from knowledgable CN folks 

elsewhere, the regular Crayford is plenty robust, and for visual, would

certainly be more than adequate.

 

Like others, I bought the Orion because it was available immediately, whereas

the other GSO 8" CC´s were "more on the way."  If availability were the same,

I would have strongly considered the slightly less expensive versions with

the regular Crayford.



#23 rmollise

rmollise

    ISS

  • *****
  • Posts: 23,512
  • Joined: 06 Jul 2007
  • Loc: US

Posted 24 July 2021 - 01:19 PM

I've had the scope out a few times, but not tested it thoroughly yet.

 

There is nothing wrong with the scope.  I think my expectations were too high. 

 

Did the star test, and collimation is OK, but not perfect.  Out of focus star presents a very

*slightly* oval ring, and in focus stars look good, with the expected diffraction spikes

on bright stars.  I'm planning to try to improve this before I give up and send the

scope back to Orion.

 

I was expecting the additional aperture vs. my 5" refractor to make more of a difference.

E.g. my 127mm refractor views are way better than my 102mm, which is way better than my

85mm..., but in the limited time I've spent with the scope, I'm not seeing a benefit in

going to 200mm.  Might be better with a binoviewer because of the large backfocus,

but then this scope is best in high magnifications.

 

The 3 extension rings are provided for good reason.  Depending on my diagonal, eyepiece

and filter set up, I've used 1, 2 or all 3 of them to achieve proper focus.  Not really

unexpected, but something may have to manage depending on how one uses the scope

If I keep it, I'm probably going to use it parfocal lenses to minimize swapping extension

rings.  To be honest, I don't understand the exact technical reason for the focus needing

different extensions, but they are indeed required even in the limited variations of

configurations I've tried.

I would be concerned about "oval". If it is noticeably oval, and the major axis rotates 90 degrees when you go to the other side of focus, that is astigmatism (which can be in your eyes or your eyepiece, too, of course).


  • rexowner likes this

#24 rootsabove

rootsabove

    Sputnik

  • -----
  • Posts: 30
  • Joined: 28 Feb 2015
  • Loc: SW Ohio, USA

Posted 24 July 2021 - 01:59 PM

Took mine out last night for the first time. I live in a condo community lit up like a prison yard, so my plan is to use this mainly for planets, the moon, and double stars. Anyway, last night was still, but not super clear. About 11:00 to 12:30 I was checking out the rising full moon, Jupiter, and Saturn. First light is always Vega, a la Leslie Peltier. Gorgeous sharp image with spikes, excellent concentric patterns on both sides of focus. Found out that I only needed 2 of the spacers, focuser racked out to 34mm. Jupiter, although slightly boiling as it was about 10 degrees over the roofs showed a wealth of detail in my 12.5 mm ep. Definitely more detail than my FC100DF. Also very satisfied with the detail on Saturn. Cassini well defined, more subtle shading on the globe than I’m used to. Even the full moon, after my pupils adjusted, was very entertaining to hop around. 
Fully satisfied with these optics, and looking forward to using it at the darker site as soon as I can. It also behaved well on my Sirius mount, although I took care to balance it properly. The scope leaves me excited, my 62 year old eyes, not so much ;-)

mine only required 2 to 3 tweaks to the collimation out of the box, each time barely turning until I heard a slight creak. 


  • RAKing and Gen 1:16 like this

#25 pweiler

pweiler

    Vostok 1

  • *****
  • Posts: 159
  • Joined: 20 Oct 2020
  • Loc: Chicago, IL, USA

Posted 24 July 2021 - 02:53 PM

I've had the scope out a few times, but not tested it thoroughly yet.

There is nothing wrong with the scope. I think my expectations were too high.

Did the star test, and collimation is OK, but not perfect. Out of focus star presents a very
*slightly* oval ring, and in focus stars look good, with the expected diffraction spikes
on bright stars. I'm planning to try to improve this before I give up and send the
scope back to Orion.

I was expecting the additional aperture vs. my 5" refractor to make more of a difference.
E.g. my 127mm refractor views are way better than my 102mm, which is way better than my
85mm..., but in the limited time I've spent with the scope, I'm not seeing a benefit in
going to 200mm. Might be better with a binoviewer because of the large backfocus,
but then this scope is best in high magnifications.

The 3 extension rings are provided for good reason. Depending on my diagonal, eyepiece
and filter set up, I've used 1, 2 or all 3 of them to achieve proper focus. Not really
unexpected, but something may have to manage depending on how one uses the scope
If I keep it, I'm probably going to use it parfocal lenses to minimize swapping extension
rings. To be honest, I don't understand the exact technical reason for the focus needing
different extensions, but they are indeed required even in the limited variations of
configurations I've tried.

For visual use, what EP’s are you using? I am using 56mm to 7mm without having to swap extensions. The EPs are a mix of 50’, 82’, and 44’ othros. The focus is sharp on the moon, open clusters, globular clusters, and a few diffuse objects, Galaxies are a challenge from bortle 8 and an 8” scope.

Correction above the 56mm does not come to focus and I use a 2” extender threaded to just that EP, which I rarely use from my bortle 8 backyard. It’s mostly been used at darker sky sites. From bortle 8 my lowest power/finder EP is 40mm.

Edited by pweiler, 24 July 2021 - 04:27 PM.



CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.


Recent Topics






Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics