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Benefits of a 80mm refractor over a 127mm MAK ?

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#26 Jon Isaacs

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Posted 02 October 2020 - 01:49 AM

No that's a conceptual mistake.

 

It's an error probably all of us have made at some point.  But it's a point to be emphasized given how easy it is to fall into it.

 

At equal magnifications fields of view are identical.  (assuming the oculars have the same apparent field of view)  This is ALWAYS true.  A wide field scope is a *low magnification scope.*  At 100x with a 70 degree eyepiece your f/4 Dob Newt has EXACTLY the same field of view as my f/11 C14 at 100x with a 70 degree eyepiece.   Run the numbers.

 

Here is the thing: field of view is determined by two things:  telescope focal length and eyepiece field stop.  A shorter focal length yields a wider field of view. 

 

Lets run the numbers:

 

100X with a 3910mm focal length requires a 39mm eyepiece.  This is doable, barely. 

 

Now lets look at 58x with a 100 degree field of view.  This is possible with the 14 inch F/4 Dob using the 25mm Explore Scientific 100 degree eyepiece. 

This eyepiece has a 41mm field stop and yields a TFoV of 1.62 degrees.

 

With the C-14, 58X requires a 68mm eyepiece.  There are no 68mm 100 degree AFoV eyepieces. The longest focal length 100 degree eyepiece is 30mm.  

 

This is why faster scopes of the same aperture are capable of wider fields of view.  In theory, the field of view does not depend on focal ratio but in practice, it's a question of available eyepieces.  

 

If the AFoV is possible with the longer focal length at the desired magnification, then field of view does not depend on focal length.  That's the catch 22, the eyepieces do not exist. 

 

In reality, staying with 2 inch format eyepieces, the widest TFoV possible for a C-14, is 0.67 degrees.  In the 14 inch F/4, it's 1.65 degrees.  

 

In the discussion of the 80mm refractor:  I have three, F/5, F/6 and F/7.  I have owned a number of 80mm F/11s. The maximum TFoV's look like this:

 

F/5:  6.6 degrees

F/6:  5.5 degrees

F/7:  4.7 degrees

F/11: 2.9 degrees.

 

In terms of AFoV, the F/5 will do 100 degree AFoV with eyepieces I own (21mm Ethos) at 19x with a 5.2 degree TFoV.  The rest of the scopes are not able to provide that 100 degree AFoV at 19x.  The F/11 can only does 2.9 degrees at 22x with a 68 degree AFov.  

 

As the say, in theory, there is no difference between theory and practice, in practice, there is.

 

Jon


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#27 Redbetter

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Posted 02 October 2020 - 03:13 AM

I've been looking at Mars at over 200x alternately with my 127mm Mak and 80ED DS Pro Evostar. I prefer the 80ED. 

Must be a poor sample of Mak.  The 127mm Synta's actually run around 120mm effective aperture or a little less, but that still wouldn't explain it.  I've seen some individual reports of underwhelming optics in the Synta 127's, but some good ones as well.

 

My ED80 is a nice scope and has excellent contrast, but it is still an 80mm scope...and it begins to run out of gas well before 200x.  Tonight I had the seeing to support it, but not my large scopes at the level of detail I am after, so I pulled it and the 127 f/15 Mak out tonight.  The best views with the ED80 were coming at 150 to 171x, which is a very good night for the scope.  Using 171x was providing the last bit of image scale before diffraction did too much damage.  I employed a #23 filter to make the most of the contrast available.

 

By comparison, I was using 191x primarily with the 127 Mak, going up to 233x when the seeing would sharpen.  This was with a #25 filter. The detail was maxing somewhere in between, with 233x providing better scale, but more susceptible to deterioration of the seeing.   I've had steadier conditions with the Mak, but this wasn't bad.  

 

It isn't like there is a problem with my 80; performance wise it falls right in the sequence 60ED, 72EDII, ED80, then 127 Mak and finally 110ED.  On Jupiter the 127 Mak has been closer to the 110ED in detail than the 80ED.  The 127 shows things I've never heard anyone describe seeing with an 80mm.


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#28 Shorty Barlow

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Posted 02 October 2020 - 04:04 AM

I've had both Maks and small refractors, both achromatic and apo and prefer my small Apo over a small Mak because of my climate and locale, typical seeing conditions, etc. I can go from 13X for wide angle viewing incremementally to 200X plus on the moon, planets and doubles with a mere switch of an eyepiece. My scope( a Skywatcher Evo 72 ED Apo) has a beautifully figured objective and excellent mechanicals and internal baffling/blackening of the tube interior and delivers excellent views of the brighter deep sky objects, doubles, moon and planets. It doesn't leave my wanting for more aperture or anything else for that matter. It thermally acclimatizes quickly and is ready to go on a moment's notice with no hassle setup and transport. Contrast  is excellent and it's lightweight for these old, worn out bones!!

med_gallery_249298_10284_261607.jpg

 

 

I'm a big fan of the 72ED DS Pro. It's far more versatile than my 102mm Mak, and much sharper on the Moon. The Mak's easier for me to set up (I'm physically disabled), but a reflector is never going to be a refractor. I can live with the resolution loss of a smaller refractor as the contrast and sharpness more than compensate.

 

 

gallery_249298_5348_43823.jpg


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#29 Redbetter

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Posted 02 October 2020 - 04:54 AM

Nate, 

 

I am not sure what is the best fit for you.  You already have the Mak so this sounds like it primarily a comparison of the ST80 and 80ED rather than benefits over the Mak.  These two refractors are in different classes in terms of price and performance.

 

The ST80/Meade 80 f/5's main virtue is providing wide fields of view in 1.25", with a serviceable metal focuser, small overall size,and for a bargain price.  They are very forgiving of light mounts and provide the most basic grab-n-go.   

 

Optically the 80 f/5's suffer from large levels of CA, and quality of the the objective is hit or miss (I have one with a good objective and one that is not so good, but that does well at low power.)   Up to moderate powers they are competent scopes for DSO's and can provide some basic planetary detail.

 

The 80ED's/ED80's with FPL-53 generally are equipped with better 2" focusers, and some are dual speed.  If you go to 2" diagonal and eyepiece format you can get an even wider field than the ST80...unless you put a 2" focuser on the ST80.  The 80ED's make excellent wide field scopes that can provide a moderate amount of planetary detail without much fuss.

 

The negatives of the 80ED's are that they are pricier, heavier, have longer tubes due to focal length and are somewhat bulkier than they have to be due to fixed dew shields and oversized diameter tube.  They are somewhat more demanding of mount although a full set up is still quite portable.  

 

There is the separate question about whether an 80ED replaces the functions of your Mak.  That is tougher to say because for mid and high powers, the Mak has more capability, but not without caveats. 

  • For planets in decent seeing I'll take the 127Mak. Resolution/brightness and detail at high power win.
  • For planets at very low elevation or in poor seeing, the 80ED will be better.  This is particularly true when just trying to catch glimpses of Mercury or Venus low in the sky.  There are some aesthetic advantages as well, but that is not the same as maximizing detail.
  • Maks are more sensitive to thermals from rapidly falling temps.  They take longer to equilibrate and that can impact their grab-n-go characteristics. There are some ways to mitigate this--such as making a Reflectix blanket & dew shield (which I have done, blackened on inner dew shield portion.)  However I still employ mine as a mild/fair weather scope.
  • For medium to high power DSO's, the extra 0.5+ mag or effective throughput favors the 127 Mak (and that calc was for one operating at 120 effective aperture.)  The Mak will definitely have more punch on globulars and galaxies.
  • Low power favors the refractor, primarily due to the total size of field, but also for how well it can provide contrast for large diffuse nebulosity.

Have you lived with the Mak for a year of observing so that you know how it handles the seasons?  I have never relied on mine as a primary scope, and it basically sits idle during the wetter and/or "winter" months here (typically Nov. through March/April.)  

 

I guess one way to look at this is to go with the 80 f/5 since it is so inexpensive.  If you find your Mak lacking for part of the year in the roles you have it for, then you can always consider adding the 80ED or some other higher performance refractor later.  The extra cost of going to 2" and considering filters can also factor into whether you want to make a leap now, or hold off to make sure you want to do the rest later.


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#30 Shorty Barlow

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Posted 02 October 2020 - 06:39 AM

I read your entire post. It's just that what was written is incorrect. This is what you wrote:

 

"You can't compare refractors with reflectors. Even with a greater resolving power (R = 11.6/D D in centimetres, R in arc seconds) the Mak' can only effectively magnify to 127x. Anything over 127x will be bigger but will show no more detail than at 127x."

 

A 1mm exit pupil does not result in the maximum resolving power.  Consider double stars, a common measure of resolving power.  No one splits Dawes limit doubles at a 1mm exit pupil. 

 

Jon

I don't really care what you and your mates think. I just prefer refractors over reflectors. Either way, I prefer the sharpness and contrast of a smaller refractor to a larger reflector. 

 

As I said before; swings and roundabouts. I like my reflectors, I like my refractors. I probably like my refractors a bit more for their sharpness and contrast. 

 

I have a fairly severe physical disability. I use what is the most convenient and easy for me at the time. 

 

As I said. I don't really care what you and your mates think. 


Edited by Shorty Barlow, 02 October 2020 - 06:40 AM.

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#31 barbie

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Posted 02 October 2020 - 12:38 PM

I find the images a refractor produces more aesthetically pleasing than those produced by a reflector. A large reflector may have the ability to dig deeper, but I still prefer the razor sharp images my small refractor provides. I too have a physical disability so large reflectors and their benefits for going deeper and showing brighter images are a non starter for me now that I'm older. That said, I do have fond memories of my most recent large reflector( a 10" F8 Cave Astrola) from 15 years ago. It was a fantastic performer on all objects but was a bear to set up for me, even back then. Hardly portable, it never left the confines of my front yard under what were then dark skies. For me, circumstances have changed and evolved over time and I now prefer my small ED Apo over anything larger, Newt, Mak, or otherwise.  I also find images in the small ED Apo to be sharper than in any of the 4 or 5 inch Maks I've had over the last 15-20 years, my most recent being a 4" Mak last summer. As I stated previously, my small refractors have consistently shown me sharper images of the moon, planets, and doubles because they don' t suffer from the thermal issues the Mak design does. My temperature deltas can range from 20-30 degrees from day to night, especially this time of year here in Northern Ohio and this is now an issue for me because I can no longer store my scopes in an unheated garage or shed like I used to. When I had my 20" Classic Cassegrain 30 years ago, it was permanently housed in a small observatory which I drove an hour East of Cleveland to get to. At that time, I thought this was the best arrangement. 30 years later, age and newly evolved observing habits are now a reality and small ED refractors are the ideal fit for me now that my observing sessions are only about 90 minutes long. I don't want to wait for cool down of a Catadioptric, large or small either!! I keep my observing goals modest and know what my small refractor does well and simply stick to those objects which it excels at showing.


Edited by barbie, 02 October 2020 - 12:52 PM.

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#32 Shorty Barlow

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Posted 02 October 2020 - 01:01 PM

I find the images a refractor produces more aesthetically pleasing than those produced by a reflector. A large reflector may have the ability to dig deeper, but I still prefer the razor sharp images my small refractor provides. I too have a physical disability so large reflectors and their benefits for going deeper and showing brighter images are a non starter for me now that I'm older. That said, I do have fond memories of my most recent large reflector( a 10" F8 Cave Astrola) from 15 years ago. It was a fantastic performer on all objects but was a bear to set up for me, even back then. Hardly portable, it never left the confines of my front yard under what were then dark skies. For me, circumstances have changed and evolved over time and I now prefer my small ED Apo over anything larger, Newt, Mak, or otherwise.  I also find images in the small ED Apo to be sharper than in any of the 4 or 5 inch Maks I've had over the last 15-20 years, my most recent being a 4" Mak last summer. As I stated previously, my small refractors have consistently shown me sharper images of the moon, planets, and doubles because they don' t suffer from the thermal issues the Mak design does. My temperature deltas can range from 20-30 degrees from day to night, especially this time of year here in Northern Ohio and this has always been an issue for me because I can no longer store my scopes in an unheated garage or shed like I used to.

I couldn't agree more. There's nothing wrong with any of my reflecting telescopes, I just prefer the crisper, sharper, more contrasted views of a decent ED refractor. 

 

I recently compared my 127mm Mak with my 80ED DS Pro on Mars. The image with the Mak seemed bigger and brighter (glare was a problem), but it wasn't as sharp or as contrasted as the Evostar. I thought the Acidalia Planitia was a bit easier to see, but I don't think the extra resolving power of the Mak gave me significantly more detail (if any).

 

I like my 102mm Mak as it is compact and I can carry it and the AZ5 down my garden in one journey. I tend to use it predominantly for lunar observing and sometimes Mercury/Venus.

 

The 72ED DS Pro gives a sharper image though and on a good night I've pushed it to 210x on the Moon and more recently Mars. 

 

The 102mm Mak copes well up to around 170x and can often do 200x or more. It's a great little portable scope, but it isn't as sharp or as crisp as the 72ED. Regardless of any slight resolution increase. 

 

A good ED refractor can push 70~80x per inch fairly effortlessly on a good night. In my experience a reflector can't do it so well. 


Edited by Shorty Barlow, 02 October 2020 - 01:04 PM.

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#33 barbie

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Posted 02 October 2020 - 08:17 PM

For me, it's the consistently average to below average seeing and transparency conditions here in northeast Ohio that usually limit me to 50X per inch although, last Sunday I was able to push my 72 ED to 75x per inch on Jupiter and the moon. Saturn however was too influenced by the glare from the then waxing gibbous moon to allow me to take advantage of the rare above average seeing and transparency that night but other times I've had Saturn to 210x and it was spectacularly sharp.  I think your 72ED and 127mm Mak will continue to serve you well!! I'd like to observe Mars but I'm now entering a 6 month long stretch of cloudy weather, but who knows, I may yet get a peek at the red planet in the coming weeks! I'll wait and see.


Edited by barbie, 02 October 2020 - 08:23 PM.

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#34 jcj380

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Posted 03 October 2020 - 07:10 AM

Bought an ST120 for my reentry into the hobby (old C8 stayed in storage).  After a year, I got an ST80 to see what it could do on deep sky and for even easier GnG than the 120.  Then I bought a 90mm Mak for inexpensive lunar GnG.

 

I'm happy with my choices.  YMMV.  Maybe  I'll upgrade one of these days, but I feel no pressing need to do so right now.


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#35 Shorty Barlow

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Posted 03 October 2020 - 10:10 AM

For me, it's the consistently average to below average seeing and transparency conditions here in northeast Ohio that usually limit me to 50X per inch although, last Sunday I was able to push my 72 ED to 75x per inch on Jupiter and the moon. Saturn however was too influenced by the glare from the then waxing gibbous moon to allow me to take advantage of the rare above average seeing and transparency that night but other times I've had Saturn to 210x and it was spectacularly sharp.  I think your 72ED and 127mm Mak will continue to serve you well!! I'd like to observe Mars but I'm now entering a 6 month long stretch of cloudy weather, but who knows, I may yet get a peek at the red planet in the coming weeks! I'll wait and see.

I find that when the Moon's high the sky's literally the limit with the ED72. Of course seeing/transparency has to be good as well. I've regularly got 210x on Mars this year, but Saturn and Jupiter would be more difficult at higher magnifications.

 

med_gallery_249298_10131_105925.jpg

 

The TV 5x Powermate is a permanent feature of my 72ED grab & go kit. With it a 15mm EP will give 140x (50x per inch), 12.5mm (60x per inch) and 10mm (75x per inch). The 72ED can often give a sharp and well defined and contrasted image at 75x per inch of aperture. I've never experienced this with a Maksutov.



#36 Jon Isaacs

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Posted 03 October 2020 - 11:41 AM

I don't really care what you and your mates think. I just prefer refractors over reflectors. Either way, I prefer the sharpness and contrast of a smaller refractor to a larger reflector. 

 

As I said before; swings and roundabouts. I like my reflectors, I like my refractors. I probably like my refractors a bit more for their sharpness and contrast. 

 

I have a fairly severe physical disability. I use what is the most convenient and easy for me at the time. 

 

As I said. I don't really care what you and your mates think. 

 

What I care about is an accurate representation of reality. You state the limit of the 127 mm Mak at 127x, that's simply not the case. More magnication can show more detail.  

 

As far as sharpness, I consider my 10 inch Dob as sharper than my 120 mm ED refractor. Double stars that are nicely resolved in the 10 inch are seen as nothing more than a slightly elongated star..

 

Jon



#37 Shorty Barlow

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Posted 03 October 2020 - 11:54 AM

What I care about is an accurate representation of reality. You state the limit of the 127 mm Mak at 127x, that's simply not the case. More magnication can show more detail.  

 

As far as sharpness, I consider my 10 inch Dob as sharper than my 120 mm ED refractor. Double stars that are nicely resolved in the 10 inch are seen as nothing more than a slightly elongated star..

 

Jon

I was told this about aperture size in millimetres a long time ago. If it's incorrect, it's incorrect. More magnification can show more detail because it's easier to see. But a 127 Mak has a definite resolution limit, and that limit will be higher than anything less than a 127mm aperture. Unless the laws of physics have changed recently.

 

I've never known any reflector be as sharp as a refractor. 

 

And I eat Marmite sandwiches.



#38 gwlee

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Posted 03 October 2020 - 12:14 PM

You seem to have a realistic understanding of the benefits of a small refractor as well as the benefits of owning multiple scopes. If the scope you have now meets your needs, I don’t see much reason to add another scope


Edited by gwlee, 03 October 2020 - 01:19 PM.

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#39 Nate1701

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Posted 03 October 2020 - 01:21 PM

You seem to have a realistic understanding of the benefits of a small refractor as well as the benefits of owning multiple scopes. If the scope you have now scope meets your needs, I don’t see much reason to add another scope

Ya - I'm leaning that way. The Mak is small enough / portable but still Packs a PUNCH!

And i so enjoy planets. Which is what a long FL is really best for.

If i want low power wide view - it's hard to beat binoculars. Which in the past 1.5 year has been my primary tool. With the gorgeous procession of planets this summer and fall i havent touched the 'Nocs at all. Its been telescope only.

I think a 32mm plossl would be wide enough and large enough exit pupil i could want out of a scope. OR so i think - i've never done 2 inch wide field on a scope. But i still tend to think that 16x80 on a scope would struggle to match 15x50 with two eyes. Nevermind 25x100.

 

BUT... But... But... 2 things really nag at me. what would ~40x80 show me? I think that is where i will run a comparison soon with my Mak@ 50x127 vs 25x100 on some clusters.That should tell me what the extra mag  over 25x will show while still retaining some exit pupil.

 

And... and ... and I would 'almost' be content with the Mak alone EXCEPT the above posts and conversations about the Sharpness, Clarity and Contrast of an ED scope really have my curiosity piqued...

especially billP's comment here on a similar vein...

https://www.cloudyni...tor/?p=10547141

https://www.cloudyni...tor/?p=10550468

 

P.S. Jon, Shorty and Barbie - thanks for the insightful comments as well.


Edited by Nate1701, 03 October 2020 - 01:23 PM.


#40 Shorty Barlow

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Posted 03 October 2020 - 01:28 PM

You're welcome Nate. I can often push my 2.8" Evostar refractor to 75x per inch aperture and over. I can't do that with my 4" Mak. That's the difference.



#41 barbie

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Posted 03 October 2020 - 01:57 PM

You're welcome Nate.



#42 gwlee

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Posted 03 October 2020 - 02:48 PM

Ya - I'm leaning that way. The Mak is small enough / portable but still Packs a PUNCH!

And i so enjoy planets. Which is what a long FL is really best for.

If i want low power wide view - it's hard to beat binoculars. Which in the past 1.5 year has been my primary tool. With the gorgeous procession of planets this summer and fall i havent touched the 'Nocs at all. Its been telescope only.

I think a 32mm plossl would be wide enough and large enough exit pupil i could want out of a scope. OR so i think - i've never done 2 inch wide field on a scope. But i still tend to think that 16x80 on a scope would struggle to match 15x50 with two eyes. Nevermind 25x100.

 

BUT... But... But... 2 things really nag at me. what would ~40x80 show me? I think that is where i will run a comparison soon with my Mak@ 50x127 vs 25x100 on some clusters.That should tell me what the extra mag  over 25x will show while still retaining some exit pupil.

 

And... and ... and I would 'almost' be content with the Mak alone EXCEPT the above posts and conversations about the Sharpness, Clarity and Contrast of an ED scope really have my curiosity piqued...

especially billP's comment here on a similar vein...

https://www.cloudyni...tor/?p=10547141

https://www.cloudyni...tor/?p=10550468

 

P.S. Jon, Shorty and Barbie - thanks for the insightful comments as well.

Satisfying your curiosity about the capabilities of another instrument is probably as good a reason as any to buy another one. 


Edited by gwlee, 03 October 2020 - 02:49 PM.


#43 barbie

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Posted 03 October 2020 - 03:27 PM

What works well for one observer may not for another. There are many factors to consider such as the seeing conditions at one's locale and cooldown time. Horses for courses.


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#44 Escape Pod

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Posted 14 October 2020 - 12:02 AM

An ED80 will not give as wide field of views as the ST80. HOWEVER, you also won't get CA and will have an easier time finding EPs that work (f/5 scopes can be picky on EPs, thus gets things like "beaning").   Also Daystar Quark solar filters prefer ~f/6 or slower refractors (if solar is a possibility).

 

So you will have to decide, what objects are you doing and what field of view do you really need.  

 

If seeing star fields (like Double Cluster in Perseus, M45, etc.) crisply and without added color is your thing, go with an ED.

 

The f/7.5 600mm FL Evostar or Orion ED80 will give about 2.9 degrees without any CA and you can use your pick of EPs, inexpensive ones will work fine.  And if you want wider, can always go to 2" EP (and all set for solar).

 

If you really need 4 degrees with 1.25" EPs, are looking primarily to view nebula, galaxies or globular clusters, which will be hazy/whispy by their nature, and are willing to buy Pentax, TV, or ES eyepieces, especially for brighter targets, then go with the ST80 (and can get a semi-apo baader filter to control the CA if it is bothersome).

 

Now, not to throw you off, if you decide you are going the achro route, have you thought of a 120ST?...gets you more aperture, still f/5 so still get as wide a field of view as an ED80, less expennsive than an ED80, and it is only 6 lbs so also can be put on light weight mounts.  Currently I am thinking that may become my future low mag, nebula/"Milky Way sojourning" scope mounted on a VersaGo II (or Vixen Porta II) mount.

 

RE: focuser comment above, on both the ST80 or 120ST it is very common to do the GSO dual speed focuser upgrade.  Gets you 2" capability with the ST80, uses compression rings (stock versions are set screws only), it is a better focuser mechanism, and has capability to hold two finder scopes.  I did this on my ED80.

 

BTW, my 150mm Mak outperforms my ED80 on everything...in its field of view.  And that is the rub, I can easily put all the Pleiades and all of M31 (that I can see) in my ED80 which has its own "WOW" factor, I can't do that in the Mak. But as mentioned above nothing splits a double star, gives views of Mars or sees smaller DSOs like a good Mak and that also has its "WOW" factor.

 

Here's to the Mak and Frac combo!!

 

ABQJeff

Jeff, you’ve arrived at my dream setup. After exhaustively (and excitedly) deciding the Orion ED80 was the perfect scope for me to return to astronomy with, I started adding up the costs of tripod, eye pieces, diagonals, etc and got a little spooked. I’d love a StarSeeker IV for it, but purchased separately they are $350. Right in the midst of this, a 150mm Orion Mak popped up in the classifieds.

 

Perhaps predictably, my initial draw back was the planets and moon. Obviously the Mak is the way to go here.  But the more homework I’ve done, the more intrigued I am by wide field cruising the deep sky as well. And then I read about people having to wrap their Maks in glorified tinfoil to deal with temp swings?

 

in all honesty, I’ll probably arrive at your setup in a couple years. The problem before me now is where do I spend my first $1,000? Mak or Frac, as you say :)

 

cheers,

 

Don


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#45 ABQJeff

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Posted 14 October 2020 - 04:18 AM

Jeff, you’ve arrived at my dream setup. After exhaustively (and excitedly) deciding the Orion ED80 was the perfect scope for me to return to astronomy with, I started adding up the costs of tripod, eye pieces, diagonals, etc and got a little spooked. I’d love a StarSeeker IV for it, but purchased separately they are $350. Right in the midst of this, a 150mm Orion Mak popped up in the classifieds.

 

Perhaps predictably, my initial draw back was the planets and moon. Obviously the Mak is the way to go here.  But the more homework I’ve done, the more intrigued I am by wide field cruising the deep sky as well. And then I read about people having to wrap their Maks in glorified tinfoil to deal with temp swings?

 

in all honesty, I’ll probably arrive at your setup in a couple years. The problem before me now is where do I spend my first $1,000? Mak or Frac, as you say smile.gif

 

cheers,

 

Don

Don, yes it has been a great combo.  Loads of fun, and has been enjoyable letting neighbors who stop by take a look, especially with Mars in conjunction and Pleiades (M45) coming up by ~ 9:30 pm...have a perfect target for each scope. 

 

(BTW, don't be put off by the relfectix insulation for the Mak, it's cheap (like $20).  Sold at Lowes, Home Depot, I just used some mounting tape, others use velcro, to hold the first bit and then used reflectix tape to finish it off.  No thermal issues.)

 

If you are budget limited and need to start with one scope between these two (ED80 or Mak), I would go with an ED80, and I would look at the Skywatcher version (Evostar 80).  It is also a Synta telescope, but is a bit less expensive as they include the rings, dovetail, diagonal, etc.  All you would need to get is the mount and EPs.

 

Any of the various 600mm FL ED80s can get you wide field, just not as wide as an ST80 or as bright and resolved as ST120 achros...but the ED80s can also do doubles,  moon and planets with no CA to ~200x because of FPL-53 optics, but not the 300x+ that a 150Mak (or even 127Mak) can give you (also without CA).  The ED80 is kind of like the middle between an ST80/120 and a 127/150 Mak, not the best on wide field, not the best on doubles/planets/moon...but can do both while those other two ends of the spectrum will have struggles trying to do the other role (btw struggles may be too harsh, some people are totally fine with some CA in their moon or planet views or like seeing only 0.8 degree detailed portions of big nebula or M31, each to their own).   And Fracs and Cats can all do terrestrial (although with Maks you will be looking into neighbors' windows in another county).

 

The ED80 is also a great starter AP scope, if there is the possbility of going in that direction.

 

As the wide field companion to the Mak, I purchased the ED80 vs the 120ST to start with in order to 1) have a single travel scope that could do a bit of everything well 2) give me a good option for AP 3) be a good fit for solar (my Gemini H-alpha arrives in a week or so). 

 

But that was to start with. As indicated above, I am looking at someday getting the other bookend in this discussion (120ST)...hmmm, wife is already asking me to make my Christmas list laugh.gif .

 

Of course many would say for one scope, get a Newtonian reflector (either Dob or mounted), 6" or 8".  Newts get you most aperture for the dollar, and also don't have CA. But they have their own considerations (open tube telescope, bigger telescopes, don't take to being jostled around a lot, diffferent optical issues, like coma, not ideal for H-alpha solar, can't be used for terrestrial).

 

There is no one perfect telescope, except the one you are using right now (and the one you want to buy next lol.gif).  


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#46 Escape Pod

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Posted 14 October 2020 - 07:55 AM

Don, yes it has been a great combo.  Loads of fun, and has been enjoyable letting neighbors who stop by take a look, especially with Mars in conjunction and Pleiades (M45) coming up by ~ 9:30 pm...have a perfect target for each scope. 

 

(BTW, don't be put off by the relfectix insulation for the Mak, it's cheap (like $20).  Sold at Lowes, Home Depot, I just used some mounting tape, others use velcro, to hold the first bit and then used reflectix tape to finish it off.  No thermal issues.)

 

If you are budget limited and need to start with one scope between these two (ED80 or Mak), I would go with an ED80, and I would look at the Skywatcher version (Evostar 80).  It is also a Synta telescope, but is a bit less expensive as they include the rings, dovetail, diagonal, etc.  All you would need to get is the mount and EPs.

 

Any of the various 600mm FL ED80s can get you wide field, just not as wide as an ST80 or as bright and resolved as ST120 achros...but the ED80s can also do doubles,  moon and planets with no CA to ~200x because of FPL-53 optics, but not the 300x+ that a 150Mak (or even 127Mak) can give you (also without CA).  The ED80 is kind of like the middle between an ST80/120 and a 127/150 Mak, not the best on wide field, not the best on doubles/planets/moon...but can do both while those other two ends of the spectrum will have struggles trying to do the other role (btw struggles may be too harsh, some people are totally fine with some CA in their moon or planet views or like seeing only 0.8 degree detailed portions of big nebula or M31, each to their own).   And Fracs and Cats can all do terrestrial (although with Maks you will be looking into neighbors' windows in another county).

 

The ED80 is also a great starter AP scope, if there is the possbility of going in that direction.

 

As the wide field companion to the Mak, I purchased the ED80 vs the 120ST to start with in order to 1) have a single travel scope that could do a bit of everything well 2) give me a good option for AP 3) be a good fit for solar (my Gemini H-alpha arrives in a week or so). 

 

But that was to start with. As indicated above, I am looking at someday getting the other bookend in this discussion (120ST)...hmmm, wife is already asking me to make my Christmas list laugh.gif .

 

Of course many would say for one scope, get a Newtonian reflector (either Dob or mounted), 6" or 8".  Newts get you most aperture for the dollar, and also don't have CA. But they have their own considerations (open tube telescope, bigger telescopes, don't take to being jostled around a lot, diffferent optical issues, like coma, not ideal for H-alpha solar, can't be used for terrestrial).

 

There is no one perfect telescope, except the one you are using right now (and the one you want to buy next lol.gif).  

 

Many thanks, Jeff. I guess I’m suffering from the conceit of trying to answer questions that have no substitute besides experience. What does it fee like to cruise the deep sky in a wide field? How much time do I want to spend on a clear night just zooming in on a lunar mountain range?

 

More fundamentally, I think I’m struggling most with two questions.

 

Does a 127/150mm Mak close too many doors to deep sky, or does it just see them differently? I really appreciated the OPs question about adding a wide view EP to his Mak to squeeze out more deep sky capability? Have you ever tried that with your Mak? Does it play well with a 2” diagonal?

 

And if you’re a snooty photographer who will probably drift into Astrophotography, is an ED refractor just *that* much better at working out details? What are the tradeoffs of better contrast etc at lower magnification versus having Jupiter filling more of your proverbial windshield?

 

I guess it’s probably time for me to stop trolling the forum and get in the field :)

 

Many thanks again,

 

Don


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#47 gnowellsct

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Posted 14 October 2020 - 08:37 AM

One of the advantages of small refractors is that they provide full or very nearly fully illuminated views of starfields. This gives the eyepiece view a very brilliant appearance on wide open clusters or rich star fields in the milky way.

At apertures under 8 in lose field illumination so the view at the edge is not quite as bright as at the center. When you get to 5-in and smaller apertures the effect becomes noticeable if you've spent a lot of time with refractors or larger aperture telescopes.

When I rehabbed my 4.25-in Newtonian from my childhood the lack of full illumination was readily apparent to me since I had been using wide field refractors for years at that point. When I was a kid I never noticed it.

It did give me the chance to play with secondary sizing programs and it was very interesting to see that no matter what I did with focal ratio or size of the secondary the problem would not go away.

Varying the aperture does have an effect on field illumination and this forms one of the many reasons to recommend an 8-inch Newtonian over a 6 or 5-in even though the smaller scopes have certain advantages.

I'm with Jon on this one I don't see why one would fret about the difference between an 80 mm refractor and a 127 mm mak when the 100 to 110 mm ED options are sitting there to be had.

I don't consider a 5-in anything to be a planetary scope although there are many factors which might get them recruited to that purpose. I myself look at planets in smaller apertures.

But it can get tiresome in comparison to what an 8-in or larger aperture has to offer.
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#48 Echolight

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Posted 14 October 2020 - 12:28 PM

After having an ED80(SW) for 6 nights, I'm really loving it. The new has worn off of the three main planets just a bit, and wide field viewing with an eyepiece full of stars has become my new passion in astronomy. Although I do very much enjoy the high contrast features that the moon offers quite a bit. And one of these days I'll start getting out early for Venus.

 

Aside from the spectacular wide field views, the stability on the Unistar mount is fantastic. I can rack the focuser and bump or rest my eye against the eyepiece with nary a twitch.

 

But the downside is that I'm loving the widefield viewing in the ED80 so much, that I feel compelled to start planning for a bigger, brighter, farther reaching ST120 so I can fill the eyepiece with even more stars! I just hope that when I get around to getting one that it also is super stable on my Unistar mount.


Edited by Echolight, 14 October 2020 - 12:29 PM.

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#49 Shorty Barlow

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Posted 14 October 2020 - 12:40 PM

I think it's more a matter of which is the better, smaller, more portable telescope than just comparing everything to a 400mm Dob'. 
 
The Synta 127mm Maksutov and the 80ED DS Pro Evostar are popular choices of portable telescopes. I read somewhere that Synta sell more 127mm Mak's than any other Mak' aperture size. If this is in fact true, there must be a reason.
 
It's easy to recommend a 120mm or 150mm refractor or a 800mm Dobsonian if you live in an observatory or in some parallel dimension where the laws of gravity are different.
 
It's less easy to recommend a choice between the two to someone who is genuinely trying to make the choice. I have both these scopes and enjoy using both of them.
 
 
If I had to recommend one it would be the refractor, not just because of the sharpness and contrast advantage, but because it is a much more versatile scope as a whole. Probably best to have both.
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#50 ABQJeff

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Posted 14 October 2020 - 06:50 PM

Many thanks, Jeff. I guess I’m suffering from the conceit of trying to answer questions that have no substitute besides experience. What does it fee like to cruise the deep sky in a wide field? How much time do I want to spend on a clear night just zooming in on a lunar mountain range?
 
More fundamentally, I think I’m struggling most with two questions.
 
Does a 127/150mm Mak close too many doors to deep sky, or does it just see them differently? I really appreciated the OPs question about adding a wide view EP to his Mak to squeeze out more deep sky capability? Have you ever tried that with your Mak? Does it play well with a 2” diagonal?
 
And if you’re a snooty photographer who will probably drift into Astrophotography, is an ED refractor just *that* much better at working out details? What are the tradeoffs of better contrast etc at lower magnification versus having Jupiter filling more of your proverbial windshield?
 
I guess it’s probably time for me to stop trolling the forum and get in the field smile.gif
 
Many thanks again,
 
Don

Don,
 
Yes nothing beats actually getting out there and for the record I am not a snooty photographer (I don't even own a DSLR), my AP comment was meant to say I didn't know if I would want to get into AP, but wanted a scope that would let me grow into it, should I take that path (but I know what you meant, I address that question below).
 
In fact I was right where you are at three months ago.  I just got my gear a couple weeks ago (so I am more than TWICE as experienced as Echolight who stated  "After having an ED80(SW) for 6 nights..." wink.gif.)  But it has been an intense, grand, enjoyable 2.5 weeks.  I have averaged 4 hours a night, pulling almost all nighters when moon allows, so am up to 60+ hours working with the two scopes.  So read my inputs as a 'test drive', or 'first reaction'.  
 
WIth that in mind, to answer your questions:
 
What does it feel like to cruise the deep sky?  It is an awesome experience, makes you reverant as you see the majesty of nature and each telescope has its advantages in the Deep Sky (more on this in a bit).  But for that feeling I quote Echolight:  "wide field viewing with an eyepiece full of stars has become my new passion in astronomy".
 
 

After having an ED80(SW) for 6 nights, I'm really loving it. The new has worn off of the three main planets just a bit, and wide field viewing with an eyepiece full of stars has become my new passion in astronomy. Although I do very much enjoy the high contrast features that the moon offers quite a bit. And one of these days I'll start getting out early for Venus.
 
Aside from the spectacular wide field views, the stability on the Unistar mount is fantastic. I can rack the focuser and bump or rest my eye against the eyepiece with nary a twitch.
 
But the downside is that I'm loving the widefield viewing in the ED80 so much, that I feel compelled to start planning for a bigger, brighter, farther reaching ST120 so I can fill the eyepiece with even more stars! I just hope that when I get around to getting one that it also is super stable on my Unistar mount.

 
Questions continued: 
 
How much time do I want to spend on a clear night just zooming in on a lunar mountain range?  I know this was rhetorical, 'ol Luna is pretty amazing in itself, both an ED80 (or ED100 if you can afford it, nod to gnowellsct) and Mak will rock it.
 
"Does a 127/150mm Mak close too many doors to deep sky, or does it just see them differently?"  The Maks absolutely do NOT shut the doors on DSOs.  In fact they are needed for many of them.  The 5" and 6" Maks are in a class some call the Messier class because they can see all the smaller Messier objects.  Not ideally see them, that is where 8"-plus comes in, but they can be seen.  The 150mm Mak does about 0.9 degrees with a 40mm EP, and with 6mm-66 degree, 300x (general atmosphere limit) it is getting down to 0.2 degrees TFOV.  Why that is important is that many double stars and planetary nebula are measured in arcseconds, and the high mag and 6" resolution capability are critical.  I can see M57 ring nebula at 150X in the ED80, but it is a smaller aperture so details aren't as apparent and the object not as large.  While at 300x in the Mak I can definitely see the smoke ring that is M57.  Another one is the Trapezium in M42 (Orion Nebula), yes the ED80 at 150x will see it, but it will be twice as large and beautiful at 300x.  Globular Clusters are just dust bunnies in the ED80, even at high mag, because aperture is too small to resolve individual stars.  In the 6" Mak, it can start to resolve the individual stars (Note: globular clusters are one of the biggest arguments for more aperture, an 11" EdgeHD would do wonders with them as aperture provides resolution along with larger eye pupil at same mag level).    And as far as doubles, I did a double star marathon a couple days ago: with the Mak.  I needed that 300x for multiple pairs to get them to clearly separate, something the ED80 would not be able to do (ED80 could do about 80% of the hundred double pairs or so I observed).
 
So along these lines and regarding...
 
"adding a wide view EP to his Mak to squeeze out more deep sky capability? Have you ever tried that with your Mak? Does it play well with a 2” diagonal?"   Astronomers (now including myself smile.gif !) sometimes get sloppy when things like "ED80 is a great DSO scope" are said.  They mean things like M31 (Andromeda), Veil Nebula, North America Nebula, M45 (Pleiades), Hyades, Double Cluster in Perseus, the large Open Clusters, etc.  All these things are over 1 degree, some over 3 degrees.   Even with a 2" TV 55mm 50 degree or ES 40 68 degree EP, a Mak 150 won't get there (a 40x68 gets you 1.5 degrees, not enough for what I just listed).  So yes a Mak plays well with 2" EP, you get an extra 0.6 degrees, but then you have a more expensive diagonal, more expensive filters, more expensive EPs and note: you can 't do a focal reducer plus 2" EP very well (get vignetting, so have to choose 2" EP or FR)  I personally went the 1.25" route, and used some the money save to get the ED80 to give me the wide field (meaning >1 degree) objects while also giving me an all-around scope.
 
is an ED refractor just *that* much better at working out details? What are the tradeoffs of better contrast etc at lower magnification versus having Jupiter filling more of your proverbial windshield?  Actually the 150mm Mak gets better contrast visually and better details at the high mag because of aperture, along this line a 127 mm refractor vs a 150mm Mak would be a fairer comparison.  Between the ED80 and Mak150, at 150x the scopes images of Mars look pretty much the same, but only Mak150 can crank up to 300x (where I many times definitely have crosed what seeing can sustain).
 
It seems like you want the Mak, that is great.  A Mak 150 is a great instrument.  I started with that as well as my base decision. And if you go that route there are lots of DSOs to see, as indicated: double stars, planetary nebula, Globular Clusters (M13, M15, M92, etc.), small clusters (M37, Wild Duck which are both awesome) in addition to all the Solar System items. 
 
But for me, when I then looked at the big beautiful wide field items I would be missing bawling.gif and that I wanted a scope for solar as well (not ideal for any reflector bc of need fo big front objective mounted Energy Rejection Filter, ie $$$$), and with all the money I was already spending for the Mak150 kit, a tripod upgrade, filters, EPs, scope covers, dew shield, power supply, focal reducers, filter wheels, books, tarp for the ground, red lights, etc.  adding the ED80 and a mount only added ~10% to my total "new hobby" bill, so I went with both, instead of leaving some of the most beautiful objects in the sky behind (DSO family vote was thumbs up on Double in Perseus, M45, Christmas Tree and Beehive, Hyades, area around Mirfak/Mirphak...M1, M57 and M31 were lost on them ("what, that greyish blob?"))
 
That is why I recommended the ED80 (or a short FL 4" APO if affordable to you) if you were to pick one between the two, because it will do all classes (just not as well as a more specialized scope).
 
But ideally, to quote my personal favorite handle in all CN, THE one, THE only, Shorty Barlow*, "Probably best to have both." 
 
Long Live Mak and Frac!
 
ABQJeff
 
* - Shorty, I laugh myself silly everytime I pull out my Shorty Barlow to use, thinking "Hi, I'm Shorty, Shorty Barlow".
 

I think it's more a matter of which is the better, smaller, more portable telescope than just comparing everything to a 400mm Dob'. 
 
The Synta 127mm Maksutov and the 80ED DS Pro Evostar are popular choices of portable telescopes. I read somewhere that Synta sell more 127mm Mak's than any other Mak' aperture size. If this is in fact true, there must be a reason.
 
It's easy to recommend a 120mm or 150mm refractor or a 800mm Dobsonian if you live in an observatory or in some parallel dimension where the laws of gravity are different.
 
It's less easy to recommend a choice between the two to someone who is genuinely trying to make the choice. I have both these scopes and enjoy using both of them.
 
If I had to recommend one it would be the refractor, not just because of the sharpness and contrast advantage, but because it is a much more versatile scope as a whole. Probably best to have both.


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