Celestron Nexstar 4se- general accessories questions

[papak]

hey guys i've had a Nexstar 4se for a little while now and I have a few questions. Before i knew a telescopes magnification was determined by DIVIDING the telescope focal length by the eyepiece focal length, I thought eyepieces with larger focal lengths would give me more magnification. so, as one can imagine, I convinced my dad to get me a 40mm plossl eyepiece thinking it would offer almost twice the magnification. so now 3 years later, I have some extra christmas money, and I was thinking about getting some new accessories. I found the sweet spot for my scope is around 12mm. I belong to an astronomy club, and the guys there also told me i could push my scope to a 12mm. so my question is, for my my type of viewing (no astrophotography) does it matter what type of 12mm eyepiece i get? I usually like sticking to celestron, (nostalgia, i guess) and the question is whether to get a 12mm omni (23 dollars) or a 12mm X-cel LX (72 dollars). i have 150 dollars, so price is not an issue. any suggestions? Also, after reading about planetary filters, I started getting interested in solar filters. Celestron also sells a solar telescope for 70 dollars, but after looking on amazon, i found a few solar filters (good internet reviews of course) for 4 inch scopes such as mine. look, I know i'm a little late for the venus transit, but still, i think it would be interesting to observe our home star for a change, especially during its activity peak. anyways, the question is whether to simply buy a safe filter (another question: are they 100% safe?...) off amazon or ebay, or just go ahead and buy a whole new scope. suggestions would be appreciated. my final question is about barlow lenses. I know a barlow will give me a huge image of m42, but is that at the cost of horrible resolution? in other words, barlow lenses will give you a larger image, but is the cost of that larger image a more blurry view?

Thanks a lot, papak

p.s. please respond with detailed answers.

[swamp thing]

Hi

As far as Barlows degrading the view is concerned, here is an extract from the Televue site concerning this.

Barlows

Concept: I originally designed the Tele Vue Barlow line to complement the high performance of our eyepieces. Only 2 elements of high index glass were required to reduce all aberrations to well below the airy disc in an f/4 system. It has taken a good 15 years, but I think we're finally laying to rest the popular myth of the "degrading Barlow." In a 1997 Sky & Telescope review, Terrence Dickenson wrote "...Technology has erased the old objections. A modern Barlow will not degrade your telescope's optics. Anyone telling you otherwise is using outdated information. Moreover, the highly regarded Nagler eyepieces and their clones have built-in Barlows - ample evidence that the lens is not some detrimental intruder." Thanks Terry, I couldn't agree more. — Al Nagler

[Pig]

Very interesting, So using a Barlow is not too bad an issue after all

Mind you, it is a Televue Barlow they are discussing in the caption above, I guess that makes all the difference.

[Brinders]

A barlow won't give yo a larger view, but a magnified view by effectively doubling the focal length. Unfortunately, the trade off for increasing the focal length is a reduction in the light gathered and a narrower field of view. A telescope of say f10 with a focal length of 2000 mm becomes a f20 telescope with a focal length of 4000 mm if using a 2x barlow. If you want a wider view, you need to use an eyepiece with long focal length, say 32 mm. If you want a narrower but increased magnification then either a barlow or an eyepiece of shorter focal length (say 12 mm).

The advantage of a barlow is that it will effectively double your eyepiece collection. So, if you have two eyepieces of say 32 mm & 12 mm focal length, by employing a barlow of say 2x magnification, you effectively have eyepieces of 16 mm & 6mm with the advantage (particularly if, like me, you wear glasses) of greater eye relief than using a shorter focal length eyepiece would offer.

Brinders

[RikM]

Either the 12mm Omni or the 12mm X-cel LX will work fine in your 4se. The extra cash for the LX will give you a larger field of view for the same magnification, and longer eyerelief, which means you wont need to get your eyeball quite so close to the lens, so it should be more comfortable to use.

A full aperture front filter made of Baader Astrosolar safety film is perfectly safe for solar observing, so long as the film is undamaged. It is quite robust but should of course be checked for pinholes or tears before every use! I use one of these with a 70 or 80mm refractor to view the sun almost every clear day. Baader film gives the best quality of white light solar view short of a Hershel wedge. Much better than any of the full aperture glass filters I have looked through. One word of caution though, you should stay well away from the screw-in 'Sun' eyepiece filters. These have to block the full + magnified light and heat from the sun and are quite prone to cracking from the heat. If you happen to be looking through the eyepiece when this happens you are almost certain to loose your sight!

[papak]

Thanks so much guys, this really helps a lot. So in other words, RikM, only buy a solar filter for my actual telescope lens, to avoid permanent damage to my eyes, as well as over heating of the scope? also, my telescope will be ok for viewing the sun?

[RikM]

Your 4se will be fine for solar viewing with an appropriate solar filter fitted in front of the main lens and something like a 20mm Plossl eyepiece. If you can, try and find something like this: http://www.firstlightoptics.com/solar-filters/astrozap-baader-solar-filter.html If you cant find a specific 4se one, an EXT105 one should fit.

[papak]

Thanks again. Greatly appreciated.

[Pig]

Sherwoods photographic do the filters for around £20

Sent from my GT-P7510

[glowjet]

If you are interested in Planetary eye pieces there are some good quality TMB Optical Planetary type 11 at present on offer in Astronomics on your side of the pond. The well known author Terrance Dickinson has also remarked that Barlows supplied with some basic outfits are more useful as door stops, so if you are going to consider investing in one, then get one with a good pedigree, enjoy your Astronomy

John