Return to the Cloudy Nights Telescope Reviews home pageAstronomics discounts for Cloudy Nights members
· Get a Cloudy Nights T-Shirt · Submit a Review / Article

Click here if you are having trouble logging into the forums

Privacy Policy | Please read our Terms of Service | Signup and Troubleshooting FAQ | Problems? PM a Red or a Green Gu… uh, User

Equipment Discussions >> Equipment

Pages: 1 | 2 | (show all)
cpsTN
Carpal Tunnel
****

Reged: 04/26/07

Loc: Rutherford Co, TN
Refractor vs. Mak?
      #4593033 - 05/20/11 04:41 PM

Almost all of my observing experience in the last 25 years has been with Newts. I have briefly owned a 90mm Mak and was wondering if you would choose between a long focus achro refractor or a Mak of the same aperture as far as Lunar and Planetary observing is concerned. What I have in mind is between getting a 90mm f/10-11 achro refractor or a 90mm f/13.9 Mak. Price, mounting, and photography are not concerns here, only quality of Lunar and Planetary views.

Post Extras: Print Post   Remind Me!   Notify Moderator  
BobinKy
Post Laureate
*****

Reged: 04/27/07

Re: Refractor vs. Mak? new [Re: cpsTN]
      #4593096 - 05/20/11 05:22 PM

Charles...

Do you have any models in mind?


Post Extras: Print Post   Remind Me!   Notify Moderator  
cpsTN
Carpal Tunnel
****

Reged: 04/26/07

Loc: Rutherford Co, TN
Re: Refractor vs. Mak? new [Re: BobinKy]
      #4593155 - 05/20/11 05:57 PM

I was speaking generally but we can talk about Orion's 90mm f/10 achro and Orion's Apex 90mm f/13.9 Mak, or we can compare Sky Watchers or whatever. It is really just general question of similiar quality instruments.

Post Extras: Print Post   Remind Me!   Notify Moderator  
KWB
Postmaster
*****

Reged: 09/30/06

Loc: Westminster,Co Elev.5400 feet
Re: Refractor vs. Mak? new [Re: cpsTN]
      #4593232 - 05/20/11 06:48 PM

For only planetary,Lunar and double star splitting,make mine the 90mm Mak. No CA to deal with but when using a 90mm F/10 acro,there is.

A handier setup for me than using a long focal length refractor. Take it outside and let it set for about an hour before using.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Gene7
scholastic sledgehammer


Reged: 06/10/10

Loc: Mid Ohio, USA
Re: Refractor vs. Mak? new [Re: KWB]
      #4593245 - 05/20/11 06:55 PM

My experience is that you get "junk" views from folded mirror scopes unless you kick in a few extra thousand for a premium brand. No so with other scopes. Gene

Post Extras: Print Post   Remind Me!   Notify Moderator  
MtnGoat
Carpal Tunnel
*****

Reged: 02/18/07

Loc: Columbia Gorge, WA
Re: Refractor vs. Mak? new [Re: KWB]
      #4593252 - 05/20/11 07:01 PM Attachment (87 downloads)

Mak...simply an amazing scope usually. No CA, long FL, and a short package which is solid on any mount. I was shocked how crisp the Meade DSX90 i picked up on CList is, and I love that little thing. It's my favorite small scope.

Just let it cool down and it is simply amazing. I've run it side by side with F15 90mm achromats which are identical FL or close, and the central obstruction issue doesn't appear to have any visual impact and what does is the perfect color correction and razor sharp focus. Sure, it's smallish aperture at 90mm...but then so is the same sized refractor.

Now what I want is a bigger one! Someday I want one of the 7" F15 bad boys...2700mm of planetary power!

Here's what the lil mak90 can do on a cheapo mount with a cheapo DSI. The limb is pretty crisp for the large pixels of the DSI's sensor and there is no filter of any kind, and zero CA.

Edited by MtnGoat (05/20/11 07:06 PM)


Post Extras: Print Post   Remind Me!   Notify Moderator  
KWB
Postmaster
*****

Reged: 09/30/06

Loc: Westminster,Co Elev.5400 feet
Re: Refractor vs. Mak? new [Re: Gene7]
      #4593256 - 05/20/11 07:01 PM

Quote:

My experience is that you get "junk" views from folded mirror scopes unless you kick in a few extra thousand for a premium brand. No so with other scopes. Gene



I've owned a couple 90mm Maks and even though they were aperture limited,when the scopes cooled down,the views were far from "junk". The Moon is a pretty bright target and the CO of these scopes is a non-factor. Jupiter is another good target for this compound design.

Whatever floats your boat.


Post Extras: Print Post   Remind Me!   Notify Moderator  
cpsTN
Carpal Tunnel
****

Reged: 04/26/07

Loc: Rutherford Co, TN
Re: Refractor vs. Mak? new [Re: KWB]
      #4593297 - 05/20/11 07:27 PM

Thanks everyone. For a short time, I owned an Orion Apex 90 but did not have the mount for it so I went away from it. I would like to get the 102mm f/12.7!!! I will be building a tabletop or similar mount when I get whichever it is. Aside from the good things about these scopes that MtnGoat mentioned, they use interchangable diagonals. I will be getting a correct-image diagonal for terristral viewing too. We'll see after I do some thinking.

Edited by cpsTN (05/20/11 07:33 PM)


Post Extras: Print Post   Remind Me!   Notify Moderator  
pubquiz
scholastic sledgehammer


Reged: 10/07/04

Loc: Lancashire England
Re: Refractor vs. Mak? new [Re: cpsTN]
      #4593326 - 05/20/11 07:50 PM

The 'junk' and 'folded mirror' comment above is just plain daft!

You don't have to spend 'thousands' to get a good Mak.

I have had an ETX 90 a 105 and a 125 and all are great OTA's ..the mounts are a different story:)

Also my C8 'folded mirror' gives excellent planetary views.

The views of the ETX OTA's is very crisp and refractor like and I am sure there are even better Mak's out there for reasonable money

On bright objects the CA of an achro is a definate disadvantage compared to a Mak ...and an equivalent APO (and yes I love my C100) is dearer.

Tom


Post Extras: Print Post   Remind Me!   Notify Moderator  
Darren Drake
Carpal Tunnel
*****

Reged: 10/09/02

Loc: Chicagoland
Re: Refractor vs. Mak? new [Re: cpsTN]
      #4593327 - 05/20/11 07:52 PM

There is a lot of variation in the quality of the achromats. I have the Meade 395 (which I am trying to sell) and my 80mm WO apo definately beats it on lunar planetary. I would think a 90mm mak would about match the WO and beat out my achromat. But the Meade does have some spherical aberration so there is room for improvement there As long as the maks are collimated and since they involve spherical optical elements they are more reliably well made. So I would recommend the mak as your best bet.

Edited by Darren Drake (05/20/11 07:53 PM)


Post Extras: Print Post   Remind Me!   Notify Moderator  
andromeda59
sage


Reged: 04/06/10

Re: Refractor vs. Mak? new [Re: Darren Drake]
      #4593362 - 05/20/11 08:21 PM

My 125mm ETX puts up razor sharp images. No junk here...

Post Extras: Print Post   Remind Me!   Notify Moderator  
Gene7
scholastic sledgehammer


Reged: 06/10/10

Loc: Mid Ohio, USA
Re: Refractor vs. Mak? new [Re: andromeda59]
      #4593540 - 05/20/11 10:39 PM

Yes, I know folks, there ARE good Cats and Maks, and I read the reviews and checked the posted Lunar photos before I bought my 127Omni and my AT6RC, it is just that I do not have any good ones. I am advising anyone who gets one to check it out well before they decide to keep it. I am not happy to read good reviews of an item and not be able to get an acceptable unit. Gene

Post Extras: Print Post   Remind Me!   Notify Moderator  
j3ffr0
Pooh-Bah
*****

Reged: 07/06/08

Loc: Virginia
Re: Refractor vs. Mak? new [Re: Gene7]
      #4593644 - 05/21/11 12:14 AM

You could also consider a 127mm Mak which puts up very nice planetary views. That's getting a little bit big for a table top mount, but the resolution is better and it's worth considering.

In the 90mm range I would rather have the long focus achromat assuming it was a good sample. Longer than f10 would be better, but I'd still take the F10 over the 90mm Mak.


Post Extras: Print Post   Remind Me!   Notify Moderator  
KWB
Postmaster
*****

Reged: 09/30/06

Loc: Westminster,Co Elev.5400 feet
Re: Refractor vs. Mak? new [Re: j3ffr0]
      #4593657 - 05/21/11 12:27 AM

Quote:


In the 90mm range I would rather have the long focus achromat assuming it was a good sample. Longer than f10 would be better, but I'd still take the F10 over the 90mm Mak.



Hello

I'm curious as to why you recommend the long acro over the Mak for mainly planetary and lunar viewing? I still own a 90mm F/10 acro. It gets used almost never.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Jon Isaacs
Postmaster
*****

Reged: 06/16/04

Loc: San Diego and Boulevard, CA
Re: Refractor vs. Mak? new [Re: KWB]
      #4593930 - 05/21/11 08:47 AM

Quote:

Hello

I'm curious as to why you recommend the long acro over the Mak for mainly planetary and lunar viewing? I still own a 90mm F/10 acro. It gets used almost never.




The advantages of the long focal length achromat are it's lack of a central obstruction and thermal stability. There is no getting around the effect of the CO and the need to set the scope out an hour or so early to get the good views make it less practical than the refractor. The refractor's brighter views are also helpful in these small apertures.

The ideal small achromat would be closer to F/15 than F/10 which makes for a large tube to deal with.

Given the cost of used 80mm apo's, I think they make the most sense. Relatively compact, thermally stable, no CO and no color fringing. I see used ED-80s on Astromart for under $300.

Jon


Post Extras: Print Post   Remind Me!   Notify Moderator  
94bamf
Carpal Tunnel
*****

Reged: 12/15/08

Loc: Kansas City,Mo
Re: Refractor vs. Mak? new [Re: Jon Isaacs]
      #4593952 - 05/21/11 09:06 AM

Quote:

Quote:

Hello

I'm curious as to why you recommend the long acro over the Mak for mainly planetary and lunar viewing? I still own a 90mm F/10 acro. It gets used almost never.





Given the cost of used 80mm apo's, I think they make the most sense. Relatively compact, thermally stable, no CO and no color fringing. I see used ED-80s on Astromart for under $300.

Jon




I agree completely. Suprised it took so long for somebody to say it in this thread!

Ken


Post Extras: Print Post   Remind Me!   Notify Moderator  
Midnight Dan
Postmaster
*****

Reged: 01/23/08

Loc: Hilton, NY, Yellow Zone (Bortl...
Re: Refractor vs. Mak? new [Re: 94bamf]
      #4593978 - 05/21/11 09:28 AM

Quote:

In the 90mm range I would rather have the long focus achromat assuming it was a good sample. Longer than f10 would be better, but I'd still take the F10 over the 90mm Mak.




I'd have to disagree here. For the OP's stated goal of lunar and planetary viewing, hi magnification is in order. The chromatic aberration seen in achromats will just look worse at higher mags.

Now, as Jon says, an 80mm APO or ED-semiapo would be a good contender if the price was right. But between a Mak 90 or an achromat for planetary, I'd go with the Mak.

-Dan


Post Extras: Print Post   Remind Me!   Notify Moderator  
j3ffr0
Pooh-Bah
*****

Reged: 07/06/08

Loc: Virginia
Re: Refractor vs. Mak? new [Re: KWB]
      #4594075 - 05/21/11 10:41 AM

Kenny,
Exactly what John said. The slower the scope the less CA - f12 would be better than f10. I think a decent sample of a 90mm Achro refractor will have better contrast than a 90mm Mak.

I'm glad someone mentioned the 80mm ED. Let's think of a few other possibilities. If I was going to spend the neighborhood $500 or less on a planetary scope, here's how I'd rank the choices (ymmv):

1) Used Orion/Skywatcher 100ED at F9 (These can be had for around $450 and really can't be beat for the price)
2) 127mm Mak (although it will take a long time to cool)
3) 80ED
4) Tie 90mm Achro or 102mm Mak
5) 90mm Mak


Post Extras: Print Post   Remind Me!   Notify Moderator  
helpwanted
Post Laureate
*****

Reged: 07/04/07

Loc: Phoenix, AZ
Re: Refractor vs. Mak? new [Re: j3ffr0]
      #4594418 - 05/21/11 01:46 PM

i'm glad to see someone mention the 100ED from Orion (j3ffr0 = Jeffro?).
this scope is not reviewed very ofter, but when it is, it gets great reviews. it must be a sleeper!


Post Extras: Print Post   Remind Me!   Notify Moderator  
KWB
Postmaster
*****

Reged: 09/30/06

Loc: Westminster,Co Elev.5400 feet
Re: Refractor vs. Mak? new [Re: Midnight Dan]
      #4594883 - 05/21/11 07:11 PM

Quote:

Quote:

In the 90mm range I would rather have the long focus achromat assuming it was a good sample. Longer than f10 would be better, but I'd still take the F10 over the 90mm Mak.




I'd have to disagree here. For the OP's stated goal of lunar and planetary viewing, hi magnification is in order. The chromatic aberration seen in achromats will just look worse at higher mags.

Now, as Jon says, an 80mm APO or ED-semiapo would be a good contender if the price was right. But between a Mak 90 or an achromat for planetary, I'd go with the Mak.

-Dan



We are on the same sheet of music,Dan. My opinion was based on just those 2 scopes. No doubt in my mind about the ED80 being the superior alternative.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Pages: 1 | 2 | (show all)


Extra information
12 registered and 21 anonymous users are browsing this forum.

Moderator:  zjc26138, tecmage, rflinn68 

Print Thread

Forum Permissions
      You cannot start new topics
      You cannot reply to topics
      HTML is disabled
      UBBCode is enabled


Thread views: 2584

Jump to

CN Forums Home


Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics