Posts Made By: William Paolini

Dennis Freeman said:

Sometime this year I plan on replacing my 35mm Pan and 27mm Pan with a 26mm T6. Probably after tax time. I also have a 17mm T4.

Let's suppose that having gaining some experience with the 26mm, I feel that I want an EP bewteen the 26 and the 17. What would you recommend, a 20mm T5 or a 22mm T4? Why?

I have a 10" Xti (f/4.7) and a C6 SE (f/10.

Dennis,

Excellent plan IMO replacing the 35+27Pan with the 26 Nagler. The 35 Pan in the 10XT has a 7.4mm exit pupil so you are probably getting some light loss - not good if you plan to use your wide fields for DSO hunting. For this reason the 40 Paragon should not be considered either since exit pupil would be over 8mm. The 26 Nagler gives you a good exit of 5.5mm so darker background and only losing 0.12deg TFOV over the 35 Pan.

As for your question, when you look at the magnification increase and TFOV decrease when you go from 26mm to 17mm, there should really be no need for an intermediate eyepiece. Going from 26mm to 17mm is a 50% (or traditional 1/2 step) increase in power and your TFOV is reduced by a little more than a 1/3. This is about perfect. If we were talking about higher magnifications (i.e., if you had a much longer focal length scope) then stepping up in magnification less than 50% would make sense since the atmosphere comes into play. At these lower powers though it does not. So I'd save the cash and not get something in between the 26 and 17, and instead opt to use the money saved to enhance the short FL range of your EPs....or go the other way and opt for the 31Nagler instead of something in between the 17 and 26 as the 31 Nagler would give you .35deg more TFOV and still keeps the exit pupil at only 6.55mm so you'll get full light.

Good luck!
-Bill

Giuseppe,

Hello and welcome! Since you are new, I would really recommend finding a local club 1st. $1500 is a lot of money to buy something that ends up not working for you. And this is the point to remember, besides the obvious with optics and capability of the scope, it's "what works for you" that may end up being the most important factor.

Me for instance, I absolutely hate equatorial mounts. And polar aligning one....for get it. My "habit" is to make a last minute decision to take the scope out. It never wonders outside of my back yard...so I'm not a traveler. All that being the case, once I get outside I don't care to spend more than a few moments getting it set up and ready to rock and roll. So usually I put it outside before dinner, then after dinner start observing (allows for needed cool down).

With a dobsonian, you just plunk it out there pointed in any old which way direction, then find two stars, tell the hand computer whcih stars they are, and done! The automated system is now ready and you just choose an object to look at in the electronic handset, then it tells you which way to "push" the scope to get on target. Very easy and precise. And the non-equatorial alt-azimuth setup of a Dob is very intuitive to point at an object in the sky. With equatorial it sometimes is difficult to navigate itself to a spot you want by hand or ends up putting the eyepiece pointed in a strange direction. It's silly I know, but ergomically for me, equatorials are just not worth the added effort. And since I don't want to do photography, not an issue not having one.

Anyway, just wanted to say all that to give you an idea that sometimes it's the little things outside of optics that might be most important.

If you go with a Dob, around $600 gets you a great 8" scope (Orion XT8i) with the Inteliscope option (the push to automation). Nice convenient size plus plenty of cash left for eyepieces (and you'll need some cash for these).

Gook luck!
-Bill

David,

Every EP (or design) seems to have a niche where it really excels. The RKEs fall into this IMO. They only have a 1/4 wave MgF2 coating instead of full multi coatings, so they don't transmit as much light as multicoated ones. But this is an advantage in some situations. Plus there is a school of thought which says that multicoatings, although great for thruput and seeing faintest stars and nebula, is a disadvantage for subtle details on planetary atmospheres.

For sure, on-axis my RKEs show as good...sometimes better, subtle details on both planets and moon even when pitted against premium EPs. This is in both slow and fast scopes (my fast one is f/4.7).

Also, the 21.5mm with 2X Ultima showed me the best rendition of Trapezium E & F than even highly touted Premium EPs have. So depending on the target and scope and conditions, sometimes these little EPs beat them all. For what it's worth, while overall they are not the "best" eyepiece, for some applications they are and they are a line I won't part with in my case.

-Bill

Joe Moskowitz said:
Right now my lowest power eyepiece is a 26mm plosel, I have pairs of Stratus 21's and Nagler 13's for use in a Denk. My scopes are an 80mm W/O refractor and an Orion 11" SCT. I do about 70% observation, and 30% imaging with the Orion and about 90% imaging with the refractor. I seem to want to get a 30-36mm wide angle eyepiece,(Meade qx or W/O SWA, but I'm not really sure if I have a need for one. Any thoughts.
Thanks,
Joe

I think you definitely need a longer FL eyepiece, particularly for the 11" SCT! Right now your 26mm Plossl only lets you see about .48deg TFOV. If you popped a 2" 40mm Paragon in that scope you'll almost double the TFOV to just shy of 1 full degree (.94). I'd say that would be worth it alone!

In the 80mm, not sure which one you have, but if it's the Zenithstar at f/6.8-6.9, then the 26mm Plossl gives you about 2.45 deg TFOV and the 40mm Paragon would give you 4.77 deg TFOV while still keeping your exit pupil at only 5.8mm!!!

So if you like star cruising, I think a good 35mm or 40mm 2" would be eye opening for you

-Bill

I don't know Ivan...I've seen that look in his eye before. I can just imagine you waking up one morning and come out to see him playfully carrying in his mounth....what....Nagler...he somehow opened the eyepiece case ?!@ Hey...come back here...and where in the yard did you bury the others!! :-o

Hello all. Never participated in this forum before.

Anyway, regarding Iran and the question on the table. I wouldn't say they are out of control, just barking for some respect. The larger nuclear community, afterall, does like to "parent" other soveign nations around. So I'm sure any teenager can empathize with how Iran might feel.

All I can think of over this situation is to recall the Pueblo incident which happened while I was in H.S. If diplomacy doesn't work, then a quick covert extraction with minimal force would be best, and I think the other Arab nations would turn their heads. But if there is some overt show of force by Brits or allies, then I think we'll force the other Arab nations with having to get involved on Iran's side, then the whole thing will explode in our faces. Plus any land war in Iran would be complicated by how they could potentially initially respond since they are also in possession of a bit of a naval presence including at least 6 subs. Yes, not much, but it only takes one to do some fairly complete damage to a surface fleet, especially if they by chance have any nuclear torpedo capability. If it were me at the helm, if any ground action were to occur, it would have to be with a simultaneous destruction of the subs and missile boats they have 1st. Complicated...messy...other nations will get involved...regional war...everyone loses. Diplomacy or covert extraction are the only two sane options I see.

During my piloting days in USAF, medical examiners told us not to use red lights in cockpit for night flights as it was more detrimental to night vision than was dim white light. So all our gear for maps had dimmers on them and white lights...worked very well and felt comfortable transitioning between the low white and back out the cockpit into the darkness. Never asked the why, but perhaps has something to do with the eye's color cones requiring higher intensity light to fire and actually see colors. B&W receptors need less intensity to see.

Astro-Tech also has a 2” Astro-Tech first-surface mirror star diagonal has state-of-the-art 46-layer dielectric mirror coatings for a full 99% reflectivity.

It uses brass compression rings. The mirror housing is precision-machined from solid aluminum and a rigid U-shaped die-cast metal backplate with stainless steel hardware holds the mirror in optical alignment in the machined body.

The interior of the body is lined with light absorbing materials, in addition to being anodized an antireflective matte black. The 2” focuser-side barrel is also anodized antireflective matte black, and is internally antireflection threaded for even higher contrast. The barrel is threaded to accept standard 2” filters.

Fit and finish is great. It weights 17 oz and costs about $120.

...looks like the WO diagonal...probably same OEM.

Mike Alexander said:

...ANY filter CAN and DOES absorb different amounts of light at any given wavelength,(nm).

...Furthermore, although all galaxies visually appear white - due to our insensitivity to color in the dark - there are hundreds of Hubble telescope pictures which show that galaxies are not only colored, but multi-colored with different intensities of colors.
...

This being the case...although probably completely unprofitable, given that each Galaxy probably has its own unique emmission spectrum, wouldn't it be cool to have a filter customized for the major DSO! Maybe for the top 10 brightests, then a handful for the really popular, but difficult ones.

I live in suburb of city. My typical limiting magnitude is 3.0-3.5, with 4.5 being super exceptional evening (handful of times a year). I can't really practically seperate between PN,DN,Glx given the light pollution so they are all just faint fuzzies so I lump them into DSO. Chart attached.