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 >> Refractors

Pages: 1 | 2 | 3 | 4 | 5 | 6 | (show all)
coutleef
Post Laureate
*****

Reged: 02/21/08

Loc: Saint-Donat, Québec, Canada
Re: Apochromatic or Achromatic does it really matter? new [Re: ken hubal]
      #5214198 - 05/09/12 05:26 PM

Quote:

Having owned a large number of apo's and achros, a well corrected long focus achro is well suited for serious visual planetary observing. For visual work, an apo is overkill.




i like using a fast apo for visual as it allows me to have large FOV and wide views a long achro could not give as well as nice high power views.


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

Reged: 06/24/09

Re: Apochromatic or Achromatic does it really matter? new [Re: coutleef]
      #5214200 - 05/09/12 05:30 PM

Incidentally the choice is not either-or. The intermediate state between apo and achro is ED doublet. These exist in various formulations, including the FS tak series (FS102, FS128, FS152).

I definitely think that the color correction of an ED doublet is worth the price. In fact, am thinking about getting ED binoculars, but sometimes I just wait for the feeling to go away.

Greg N


Post Extras: Print Post   Remind Me!   Notify Moderator  
Refractor6
Post Laureate
*****

Reged: 10/20/04

Loc: Vancouver B.C. , Canada
Re: Apochromatic or Achromatic does it really matter? new [Re: coutleef]
      #5214206 - 05/09/12 05:36 PM

Quote:

Quote:

Having owned a large number of apo's and achros, a well corrected long focus achro is well suited for serious visual planetary observing. For visual work, an apo is overkill.




i like using a fast apo for visual as it allows me to have large FOV and wide views a long achro could not give as well as nice high power views.





Bingo!...we have a winner!

Due to light pollution conditions around my place having a 120 f/7.5 apo for viewing the "brighter" targets at high powers at night or for going down to low powers for daytime use on a shorter tube easy to view through rock solid package has been a real pleasure.


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

Reged: 01/13/07

Loc: Carmel, NY
Re: Apochromatic or Achromatic does it really matter? new [Re: ken hubal]
      #5214245 - 05/09/12 06:04 PM

Agree a 6" F12 achro like the D&G would be real nice but I jjust dont have the mount for that scope as of yet, I went threw a few F8 and under achros to finally find one that had what I would consider decent optics, the current scope seems to hit it and its an F5.9, slighly better correction than the CR150 I had back 10 years ago and the CA is way better controlled. I still want the 6" F12 but maybe someday but have been more than pleased with the AT152, even on lunar the amount of CA on the limb is not all that bad, craters and mountain shadows are black and white, no blueish haylows and thats without any filters in line plus saturn has looked real well. It takes a slight back seat to my 7" mac but not by allot and on deep sky wide feilds its stunning. I have had a few apo's and ED doublets up to 5" but the 6" class is just a different veiw IMO.
Jim


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

Reged: 05/01/07

Re: Apochromatic or Achromatic does it really matter? new [Re: skyjim]
      #5214315 - 05/09/12 06:56 PM

I've found that deep sky objects appear with better contrast in a long achro than in the much overhyped apo! The ONLY reason for an apo is to help keep the tube length manageable while maintaining decent color correction. Depth of focus which is important for close binary and planetary observation is sorely lacking in the fast apos.

Post Extras: Print Post   Remind Me!   Notify Moderator  
Refractor6
Post Laureate
*****

Reged: 10/20/04

Loc: Vancouver B.C. , Canada
Re: Apochromatic or Achromatic does it really matter? new [Re: ken hubal]
      #5214333 - 05/09/12 07:08 PM

Not so sure about that Ken? I've already had some truly wonderful views of tight doubles right up to 450 power combined with some stunning planetary/lunar/sunspot views with an ED doublet f/7.5 120mm scope.

And yes I too have owned LOTS of scopes including some fine long f/ratio achros in the past for comparison in regards to the views at the ep.


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

Reged: 05/01/07

Re: Apochromatic or Achromatic does it really matter? new [Re: Refractor6]
      #5214377 - 05/09/12 07:33 PM

I'm sure!! I have yet to see one apo that can perform admirably as a "do everything scope"! The arguement now becomes one of personal subjectivity. As for your observation through a 120mm ED doublet, I too have had the same type of refractor and have since returned to classic long focus achros because they simply perform better, espescially for splitting close binaries. They also don't require the use of exotic eyepiece designs with six or more elements of contrast-reducing air to glass surfaces. The much overhyped apos are good for astrophotography, which I've spent much time with but, as I said previously, are overkill for visual. I'll go with a larger reflector for serious A.P. anytime over the smaller apos. I have yet to view through any apo that did anything better than my long focus achros! I've owned apos from Takahashi, A.P., William Optics and others and was simply unimpressed by their performance to cost ratio! The continued market hype behind apos is total, complete and utter nonsense!
CHEEERS!


Post Extras: Print Post   Remind Me!   Notify Moderator  
Refractor6
Post Laureate
*****

Reged: 10/20/04

Loc: Vancouver B.C. , Canada
Re: Apochromatic or Achromatic does it really matter? new [Re: ken hubal]
      #5214387 - 05/09/12 07:38 PM

Well as a pure visual observer too using nothing more complex than a well coated and well figured ED doublet we'll have to agree to disagree then on this matter Ken

Post Extras: Print Post   Remind Me!   Notify Moderator  
mikey cee
Postmaster
*****

Reged: 01/18/07

Loc: bellevue ne.
Re: Apochromatic or Achromatic does it really matter? new [Re: ken hubal]
      #5214794 - 05/10/12 12:54 AM Attachment (51 downloads)

Ken I agree with you! It's all hogwash. Mars tonight thru my Istar 10" f/11 R30 at 815x looks exactly like Mars did in 2003 thru all those f/6 apos. Mike

Post Extras: Print Post   Remind Me!   Notify Moderator  
jmiele
Patron Saint?
*****

Reged: 12/04/10

Re: Apochromatic or Achromatic does it really matter? new [Re: mikey cee]
      #5215207 - 05/10/12 10:37 AM

815x! I'll be over tonight.
Joe


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

Reged: 07/07/10

Loc: Davison, Michigan
Re: Apochromatic or Achromatic does it really matter? new [Re: jmiele]
      #5215361 - 05/10/12 11:58 AM

cool joe, you can put your cot next to mine in his observatory. I am moving in. haha

Post Extras: Print Post   Remind Me!   Notify Moderator  
ValeryD
Vendor (Aries)
*****

Reged: 11/26/05

Loc: Kherson, Ukraine.
Re: Apochromatic or Achromatic does it really matter? new [Re: ken hubal]
      #5215380 - 05/10/12 12:03 PM

Quote:


1. I have yet to view through any apo that did anything better than my long focus achros!

2. I've owned apos from Takahashi, A.P., William Optics and others and was simply unimpressed by their performance to cost ratio!

3. The continued market hype behind apos is total, complete and utter nonsense!
CHEEERS!




1. Any well executed 7" F/8 fluorite doublet will do any astro-work much better than any your achromat of the same aperture.

2. The key words are "performance to cost ratio". The same can be said about Chevy vs BMW vs Ferrari. You get what you pay for. Nothing new under the moon.

3. Just only your personal opinion on this question + opinions of thouse, who split your opinion on 2.


Valery.


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

Reged: 10/11/05

Loc: Piedmont, California, U.S.
Re: Apochromatic or Achromatic does it really matter? new [Re: ken hubal]
      #5215568 - 05/10/12 01:46 PM

Quote:

I've found that deep sky objects appear with better contrast in a long achro than in the much overhyped apo! The ONLY reason for an apo is to help keep the tube length manageable while maintaining decent color correction. Depth of focus which is important for close binary and planetary observation is sorely lacking in the fast apos.



I agree that there is no perfect scope, but a shorter tube is hardly the ONLY reason for an apochromat. In addition to a shorter tube, you get a scope that is usable for deep sky astrophotography, especially wide field astrophotography, as well as a scope that provides wonderful wide field views visually. At most apertures, you also get better color correction than is achievable with a reasonable focal ratio achromat. As far as depth of focus goes, I believe a two speed focuser pretty much eliminates that advantage. I know there are many that feel slower scopes have more stable views--don't want to open that can of worms. Suffice it to say that there is legitimate disagreement on that score.

Do long focus scopes (achromats or apochromats) have advantages? Certainly. Optical aberrations are minimized, fields are flatter, longer eye relief eyepieces can be used for planetary viewing, and, at the very least, the longer tube length gets the aperture above some of the ground-level seeing "muck". Do short focus apochromats have advantages beyond a shorter, more manageable tube? Again, I would say certainly. I listed several above. If you prefer the slower scope, more power to you, but there is more to an apochromat than just a short tube.


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

Reged: 01/13/07

Loc: Carmel, NY
Re: Apochromatic or Achromatic does it really matter? new [Re: ValeryD]
      #5215837 - 05/10/12 04:09 PM

Oh no here we go again, I thought pushing your products is for the Venders forum Valery!

Post Extras: Print Post   Remind Me!   Notify Moderator  
Jan Owen
Pooh-Bah


Reged: 02/12/06

Loc: Sun City West, Arizona
Re: Apochromatic or Achromatic does it really matter? new [Re: skyjim]
      #5215851 - 05/10/12 04:18 PM

...on the other hand, Valery's right...

Post Extras: Print Post   Remind Me!   Notify Moderator  
jrbarnett
Eyepiece Hooligan
*****

Reged: 02/28/06

Loc: Petaluma, CA
Re: Apochromatic or Achromatic does it really matter? new [Re: ValeryD]
      #5215853 - 05/10/12 04:20 PM

Bah! What do you know, Valery? You're only a respected optical designer with dozens of game-changing innovations under your belt!


- Jim

Edited by LLEEGE (05/11/12 12:52 PM)


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

Reged: 01/13/07

Loc: Carmel, NY
Re: Apochromatic or Achromatic does it really matter? new [Re: jrbarnett]
      #5216059 - 05/10/12 06:36 PM

This is really funny, I was only stating that he is pushing his refractor in a post, that was it, nothing to do with his optical expertice at all.

Post Extras: Print Post   Remind Me!   Notify Moderator  
PJ Anway
Double-Star Observer
*****

Reged: 06/04/03

Loc: North Coast
Re: Apochromatic or Achromatic does it really matter? new [Re: Dubliner]
      #5216112 - 05/10/12 07:12 PM Attachment (31 downloads)

I had a Zeiss AS100 refractor for many years and thought it delivered outstanding images. Several years ago I got an offer to buy a Showa SD100 apo refractor. I decided to go ahead, purchase and compare the two. Both are 100mm f/10's.

Though the Zeiss AS is considered to be somewhat better than a normal achromat, using a leading "short-flint" element; compared to the Showa, it showed noticeable color; at least more than I had ever noticed before. I still have the Showa. Sometimes you have to compare to really see the difference.


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

Reged: 11/21/07

Loc: St. Louis, MO
Re: Apochromatic or Achromatic does it really matter? new [Re: PJ Anway]
      #5216208 - 05/10/12 08:24 PM

Quote:

I had a Zeiss AS100 refractor for many years and thought it delivered outstanding images. Several years ago I got an offer to buy a Showa SD100 apo refractor. I decided to go ahead, purchase and compare the two. Both are 100mm f/10's.

Though the Zeiss AS is considered to be somewhat better than a normal achromat, using a leading "short-flint" element; compared to the Showa, it showed noticeable color; at least more than I had ever noticed before. I still have the Showa. Sometimes you have to compare to really see the difference.




Patient says to the doctor: "Doc it hurts when I do this." Doctor says to the patient: " Don't do that!"


Post Extras: Print Post   Remind Me!   Notify Moderator  
PJ Anway
Double-Star Observer
*****

Reged: 06/04/03

Loc: North Coast
Re: Apochromatic or Achromatic does it really matter? new [Re: watcher]
      #5216287 - 05/10/12 09:07 PM

Good one Joe!

Post Extras: Print Post   Remind Me!   Notify Moderator  
Pages: 1 | 2 | 3 | 4 | 5 | 6 | (show all)


Extra information
35 registered and 32 anonymous users are browsing this forum.

Moderator:  Scott in NC, FirstSight, panhard, star drop 

Print Thread

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


Thread views: 8891

Jump to

CN Forums Home


Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics