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 >> Classic Telescopes

Pages: 1 | 2 | 3 | 4 | 5 | 6 | 7 | (show all)
Jon Isaacs
Postmaster
*****

Reged: 06/16/04

Loc: San Diego and Boulevard, CA
Re: Is bigger better? new [Re: SpooPoker]
      #6352132 - 02/02/14 09:55 PM

Quote:

Quote:


It is excellent, even out of focus. But it's not really a 4 inch F/5.4, or at least the objective is not. It's a bit of a simplification but it's basically a long focal length apo double with a fancy ED focal reducer/field flattener at the rear of the scope. NP stands for Nagler-Petzval.

You could do a similar thing with a 6 inch apo but then you could do a similar thing with with a Newtonian but neither makes much sense.

Jon




Cool sounds like an awesome scope.

Is the FOV just like a f/7 or f/8 frac or does the design get around that? I am seriously considering getting one of these for a big FOV, but if it has the same FOV as a regular 4" ED doublet, then I may sit tight on my money




The TeleVue NP-101 is a 4 inch apochromatic with a focal length of 540mm and functions as 4 inch F/5.4. But the actual objective is not F/5.4.

Jon


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

Reged: 07/09/13

Loc: The Deep South, USA
Re: Is bigger better? new [Re: SpooPoker]
      #6354326 - 02/03/14 09:11 PM

I'll summarize my post from another forum: A city's heat dome will affect seeing, which will affect viewing options, and consequently the scope I use on a given night.

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

Reged: 06/16/04

Loc: San Diego and Boulevard, CA
Re: Is bigger better? new [Re: Bomber Bob]
      #6354380 - 02/03/14 09:28 PM

Quote:

I'll summarize my post from another forum: A city's heat dome will affect seeing, which will affect viewing options, and consequently the scope I use on a given night.




In my experience, the "heat dome" is localized so that if the object is at a reasonable altitude, it does not affect the overall seeing. But the localized heating effects are very important, viewing over trees and building, viewing on concrete or asphalt, these can make a big difference.

Jon


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

Reged: 07/09/13

Loc: The Deep South, USA
Re: Is bigger better? new [Re: Jon Isaacs]
      #6354389 - 02/03/14 09:33 PM

"In my experience, the "heat dome" is localized..."

What I've found in my current location (the city is in a Bowl) is that winds from the north make the dome much more unstable than the warm muggy air from the Gulf of Mexico. But, just 10 miles away, it's not a factor at all.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Pages: 1 | 2 | 3 | 4 | 5 | 6 | 7 | (show all)


Extra information
7 registered and 30 anonymous users are browsing this forum.

Moderator:  Rich (RLTYS), Brian Risley 

Print Thread

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


Thread views: 2345

Jump to

CN Forums Home


Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics