Hello, We know that achromatic refractors have less chromatic aberation when using long focal ratio's like f/10 to f/15 or even longer. Today large aparture...
Hi Wouter, I'm no optical expert, but I believe the longer focal length increases the tolerance for focusing, the so-called "focusing critical zone". This...
I'm ready to upgrade from my FS102 to at least 5" aperture refractor. I'd prefer an apo but there is a small issue of $$$ !!! Now, I'm considering a 5" D&G,...
As an alternative, Rob, have you considered a used FS-128? It will be easier to handle and require a smaller mount and will be more portable.......... Sorry I...
... My understanding is that the increased chromatic aberration with short FL refractors comes because of the steeper curves on the objective. If that is the...
Hi all, I'm fairly new to refractors and am considering the Orion 80mm ED for wide field photography...it's f/7.5 and I was wondering if you can use a focal...
Here is what I found after some more research on the subject: The linear size of chromatic aberration blur circle varies with aperture, but remains constant at...
Hi Rob Yep, there is additional cost. But, a 5 inch refractor is usually a keeper for many, many years, and the extra time and "work" to get the APO will be...
My apologies to all. Looks like I may've been wrong, once again \-) Roland Christen e-mailed me to say that a barlow magnifies the size of the airy disk *and*...
Hi Rob: Handling a 5" f/12 is a great deal more difficult that working with a 5" f/8. I used to have a D & G 5" f/12 and lugging it around was a real chore. ...
The sketches are very nice, thanks Eric. I have a 2" IDAS filter http://www.sciencecenter.net/hutech/idas/nbn.htm Any experience or tips with this? All the...
Thanks for the inputs. I may just do that. In fact, I may just save a bit and move up to a 6" apo. Rob ... with a 5" ... real chore. ... FS 128 it, ... money...
Hi Rob, Didn't you have a TEC 140 or am I confusing you with another group member? Another possibility would be a 7" Teleport. Yes, I know this is the ...
Steve, Yes, that was me. I sold off my 140/g11 rig and now I really regret that. I miss the 140 ... sweet apo. I really want a refractor ... 5-6". ... member?...
Hi Rob, I know that feeling when I was deciding on going on going on the waiting list for the Teleport 10" or the TEC 140. It was a very tough decision! In the...
I am looking for info on an Atco scope that I picked up at a local swap meet. The label on the focuser reads "Atco astronomical-terrestrial" and indicates that...
Hi Steve, My budget is tight so I have to be creative here. I will use it on my homemade altaz mount for awhile. I can't afford a nice gem just yet, and...
Hi Nick: Thanks, and glad you enjoyed the sketches. I haven't tried the IDAS filters but in general I try to keep them clean between observing sessions by ...
... *my deep-sky filters* ... *light* ... And a couple of mispelled words as I haven't had my caffine this morning yet ;-). Eric ... diagonal ... hood ... ...
Can anyone tell me which 2" extension tube should I purchase to allows straight-through viewing with 2" or 1.25" eyepieces for the FS102 scope. My scope is a...
Hi Tim No, ron didn't forget the "1". Richard Baum does indeed observe with a classic 4.5" (114mm) refractor. I guess we all need a bit more workout with...
Rob: I own a 6" f/12 AP triplet apo, the one known as "Superplanetary". It performs superbly though it was made in the middle 80´s. Maybe you can get a used...
Hi Eric, I was thinking along similar lines .... maybe the AP152 f/9 or the 6" f/12. Either way, they'd be a lot more than a D&G but .... less than a modern...
Greetings (and please forgive the cross-postings!), I love my TV-85. It gives excellent wide-field and planetary views. I am satisfied with its color...
Hi Mark, I've seen some very good planetary views through several Celestron C8s. Several, meaning maybe 4 different OTAs over a couple of years. A C8 OTA on...
rnapo
rnapo@...
Jul 6, 2004 6:59 am
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I am very pleased with my TEC 140 APO on a GIRO-2 Deluxe mount with JMI mounted DSCs. Portable, easy to set up, and fun to use. And, it meets your...
... you ... if my memory serves me right, I heard it was tele Vue Nagler Zoom :-) ... Markus; "Hearing " that a Nagler Zoom showed astigmatism at the Winter...
Hi Steve and Markus, I am seriously looking at buying a Televue Nagler 3-6 mm Zoom for a TEC 140. Having just read this makes me stop and think. Has anyone out...
Hi, I use this eyepiece with my NP101 and find it to be a superb performer. jeff ... a TEC 140. ... planning on ... astigmatism ? ... if ... Zoom :-) ... Star ...
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