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 >> ATM, Optics and DIY Forum

Pages: 1 | 2 | 3 | 4 | 5 | 6 | (show all)
wh48gs
Carpal Tunnel
*****

Reged: 03/02/07

Re: 17 inch spotplots new [Re: kfrederick]
      #4993655 - 12/31/11 09:58 AM

Kevin,

Quote:

The good glass only costs less than a eyepiece more.




A glass is only as good as the correction it delivers. Spots in Ed's modification are tighter than in the original Mike's design, even if the corrector is "only" BK7. In fact, Ohara glasses would not qualify for the technical definition of an apo, because the error in the violet g-line is larger than 1/2 wave (0.65 wave). On the other hand, this same system with the Schott analogs satisfies the apo definition. The respective photopic polychromatic Strehl at best focus is 0.957 and 0.964, which would make both apo-corrected, if the criteria is (more reliable) 0.95 Strehl minimum.

Oddly enough, the best polychromatic Strehl - 0.967 - has the BK7/BASF64A combination, despite having g-line error somewhat larger than Ohara glasses. This is compensated by a tighter focusing of the other wavelengths.

Vla


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

Reged: 02/01/08

Re: 17 inch spotplots new [Re: wh48gs]
      #4993722 - 12/31/11 10:41 AM

Eds design is f9.5 And has a secondary that would be imposible to get 1/20th wave cheaply! The CONVEX edge has to be turned up alot .I am folowing Mike Jones design .No complated to .get 1/20 wave optics All sherical secondary optics .Glad you are looking at this and your work! Via Mike had not goten your numbers to work in Zemax as of yesterday .not sure why. good fun

Edited by kfrederick (12/31/11 11:41 AM)


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

Reged: 04/06/04

Loc: Sin-sin-atti
Re: 17 inch spotplots new [Re: kfrederick]
      #4993925 - 12/31/11 12:08 PM Attachment (33 downloads)

Quote:

will yours work with a f8 -1.4 conic primary?


This primary is F/8.19 and could probably be scaled to work except the conic is -2 and would require refiguring.
Quote:

The CONVEX edge has to be turned up alot



Hardly, if you read my post I said the secondary aspheric deformation is only 0.36 microns. One fringe of HeNe light is 0.315 microns, so it's similar to a typical Cass secondary. No this isn't an easy design but anyone familiar with making a Cass secondary could make this one.
Color is good over the whole visible range:


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

Reged: 02/01/08

Re: 17 inch spotplots new [Re: Ed Jones]
      #4994172 - 12/31/11 01:59 PM

Ed I read it as 36 micron looks like it was .36 micron .My mistake .How big is your secondary? And the overall length of the telescope .The primary is in polish and could be corrected more.

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

Reged: 02/01/08

Re: 17 inch spotplots new [Re: kfrederick]
      #5003935 - 01/06/12 09:27 AM

Looking at EDs design I would have little chance geting it to work .Mikes design will give me the best chance. As for saving a a fiew dollars on bk7 lens NO.If Zemax says s-lah53 and s-phm53 works best that is what will be used .This is alot of work to do away with the obstruction but I know it is worth it for me to try. kevin

Edited by kfrederick (01/06/12 07:36 PM)


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

Reged: 02/01/08

Re: 17 inch spotplots new [Re: kfrederick]
      #5006478 - 01/07/12 11:30 PM

http://photonics.com/BuyersGuide.aspx lots of lens makers listed here

Post Extras: Print Post   Remind Me!   Notify Moderator  
wh48gs
Carpal Tunnel
*****

Reged: 03/02/07

Re: 17 inch spotplots new [Re: kfrederick]
      #5008488 - 01/09/12 07:56 AM

Kevin,

Quote:

Via Mike had not goten your numbers to work in Zemax as of yesterday .not sure why.




Judging on Mike saying that he needed help to convert Zemax coordinates to OSLO, the two programs use different conventions and/or interface. So, proper conversion from OSLO to Zemax is also needed.

If a system works in OSLO, there is no reason it wouldn't work in any other raytracing program.

Vla


Post Extras: Print Post   Remind Me!   Notify Moderator  
Mike I. Jones
Post Laureate
*****

Reged: 07/02/06

Loc: Fort Worth TX
Re: 17 inch spotplots new [Re: wh48gs]
      #5008551 - 01/09/12 09:11 AM

Right - software implementation of tilts and decenters is THE most poorly standardized aspect of every optical code I've ever used. You just have to keep practicing with a particular code's method until you more or less master its own way of doing it. CODE-V, SYNOPSIS, ACCOS, SIGMA, ZEMAX, and OSLO all do it differently. Of the lot, and I've used them all, I actually prefer CODE-V's.

What all modern optical codes need is (1) a standardization of translation and rotation sign and order conventions, and (2) a graphical method using a pop-up GUI screen that shows users in advance what will happen to the surface, element or group if certain orders of tilts and decenters are applied. The GUI would show the before/after position and orientation of the selected surfaces, with exaggeration in the case of small angles or shifts that are hard to see.

If for any optical design, its tilts and decenters are entered properly for any different code, then you are right, they should and actually do give essentially identical analysis results. But getting there can be quite a learning experience.

Mike


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

Reged: 02/01/08

Re: 17 inch spotplots new [Re: Mike I. Jones]
      #5009236 - 01/09/12 04:10 PM

Via you can see why I am so excited in this type of telescope , Hope many will try one !As more are built and improved. it only gets better .Mike what does the chiefocular look like? Kevin

Post Extras: Print Post   Remind Me!   Notify Moderator  
wh48gs
Carpal Tunnel
*****

Reged: 03/02/07

Re: 17 inch spotplots new [Re: Mike I. Jones]
      #5012512 - 01/11/12 04:27 PM

Quote:

What all modern optical codes need is (1) a standardization of translation and rotation sign and order conventions...




It would be very practical to have a standardized "simple" option - and that would be easier to implement - without all the bells and whistles attached to their different conventions, that can make conversion from one program to another a nightmare. But doesn't seem as if it will be happening any time soon.

Vla


Post Extras: Print Post   Remind Me!   Notify Moderator  
wh48gs
Carpal Tunnel
*****

Reged: 03/02/07

Re: 17 inch spotplots new [Re: kfrederick]
      #5012517 - 01/11/12 04:30 PM

Go for it, Kevin - it is always more of a trill to try something different, even if it is more challenging (or maybe because of that).

Vla


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

Reged: 02/01/08

Re: 17 inch spotplots new [Re: wh48gs]
      #5012607 - 01/11/12 05:47 PM

Only the primary will need moved .Up and down to set the focus the correct distance .Side to side to line up the laser on the center of the primary then tilt so the laser reflection off the center of the primary and hits the laser target mounted on the top .Get the top set correct[ Laser target secondary mirror, two lens and a focuser the only thing to move is the primary .As easy as a newt if the top is set .

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

Reged: 02/01/08

Re: 17 inch spotplots new [Re: kfrederick]
      #5042137 - 01/28/12 08:51 AM

Can any one post the spot plots fot a 17 inch f4 and f8 newtonian to the same scale as Mikes .Got some finished lens prices not too bad. Hope more will try one .Bet a 14 inch f8 would be nice size

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

Reged: 02/01/08

Re: 17 inch spotplots new [Re: kfrederick]
      #5074268 - 02/15/12 06:29 PM

http://apod.nasa.gov/apod/astropix.html no spikes with this telescope

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

Reged: 02/01/08

Re: 17 inch spotplots new [Re: kfrederick]
      #5100692 - 03/02/12 09:40 AM

The primary is done . Carl Z nailed the RC 272.06and the hyberolic curve is very close .The lens need to be done next think I will buy them .If any one wants to go together now is the time to say so as there are 4 test plates to be made includes the secondary.17 INCH APO for two little lens . This telescope should be able to see some of jupiters smaller moons.

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

Reged: 02/01/08

Re: 17 inch spotplots new [Re: kfrederick]
      #5100886 - 03/02/12 11:31 AM

The mounting of two lens and a secondary mirror in a box is easer to hold correct and block stray light.In many ways a Chief is easer to make than a newt just the newt has been perfected .The primary needs to be perfect or just make a newt.

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

Reged: 02/01/08

Re: 17 inch spotplots new [Re: kfrederick]
      #5224699 - 05/16/12 07:41 AM

A update on the 17inch unobstructed WB chief .The primary is done .The design has changed, the lens glass has changed as the secondary . The lens are being finished and coated by a top lens maker .Mikes new design is even better .Dave O has been helping me make a top end for a friends 10inch chief This has shown me sone cool ideas .That I will use on the 17 inch W B CHief . The 10 inch chief is nice as it uses off the shelf lens and a standard long f newtonian primary and a flat secondary.Mike tweeked the design for the 10inch chief.I will post a pic of the top end . Thanks for the help it is needed Kevin

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

Reged: 02/01/08

Re: 17 inch spotplots new [Re: kfrederick]
      #5286389 - 06/24/12 08:30 AM

The lens are finished and Mike gave me the RC for the secondary .The design is better than the first spotplots posted .Very excited to work on this .

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

Reged: 02/01/08

Re: 17 inch spotplots new [Re: kfrederick]
      #5315498 - 07/13/12 07:04 AM

All the optics are done for the W-B CHief . The 17 inch f8 hyperbolic primary was done by Carl Zambuto . The spherical secondary optics were finished by Cumberland Optical . Thanks to Mike Jones for all the help on this great design . Hope more will try a chief .

Edited by kfrederick (07/13/12 07:06 AM)


Post Extras: Print Post   Remind Me!   Notify Moderator  
mark cowan
Vendor (Veritas Optics)
*****

Reged: 06/03/05

Loc: salem, OR
Re: 17 inch spotplots [Re: kfrederick]
      #5316787 - 07/13/12 11:27 PM

How long will it before it rolls out under the stars???

Best,
Mark


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


Extra information
11 registered and 15 anonymous users are browsing this forum.

Moderator:  ausastronomer, richard7, Starman81 

Print Thread

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


Thread views: 7606

Jump to

CN Forums Home


Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics