John
-
Posts
53,544 -
Joined
-
Last visited
-
Days Won
453
Content Type
Profiles
Forums
Gallery
Events
Blogs
Posts posted by John
-
-
.Any recommendations on makes/models of reasonably priced quality EPs would be appreciated.
Thanks
You get what you pay for with eyepieces but, for your scope, the TAL, Skywatcher, Meade or Celestron plossls will work pretty well.
First Light Optics have a good deal on Skywatcher Plossl's at the moment:
Skywatcher - Skywatcher SP Plossl eyepieces
John
-
This was so helpful for me. Reading through my user manual was pretty basic but this thread really cleared some things up.
My Scope is a F/8.6 and came with a 9mm, 25mm and 2x Barlow lens. So from what was posted above it appears that I have the standard high power and low power eye pieces.
Would you all recommened any other sizes?
You might want to post this question in the beginners section as well to get some other views but I'd suggest a 32mm Plossl which will give you nice low power views. With the barlow lens you would have quite a comprehensive range of powers then.
John
-
1
-
-
Portability won't be a big issue i could do what many of you have done and add wheels but it's not that big of a problem for me.
In which case you might as well go for the 12" and then you won't always be wondering about "what might have been"
John
-
1
-
-
I used the 8-inch for 9 years and could have happily have gone longer as there were still so many things I hadn't seen with it, but figured if I was ever going to get into the heavy-duty league then I ought to do it before I was too old.
This is exactly the stage that I am at as well. I sold my 8" F/6 Skywatcher dobsonian and got a 12" Meade Lightbridge dob. I don't regret doing this but I have not been able to use the larger scope as much as I did the 8" because the latter was practically a "grab and go" scope. At F/6 the 8" was easier to keep in collimation as well.
That said I think the 12" scope is the first I've had that really starts to show the brighter DSO's like they look in pictures - globular clusters in particular are stunning with a foot of aperture
John
-
1
-
-
These look really good.
Add somme velcro and thats one awesome light shield.
Thanks for all the suggestions folks
I think the adapted camping mat approach looks very promising - I must make sure that I don't get a self-inflating one by mistake though - could be rather awkward !.
John
-
I have quite a lot of lateral lighting to contend with until around midnight and my neighbours go to bed and switch their lights off.
This light has a tendancy to find it's way into the top of the OTA of my Meade Lightbridge 12" dobsonian and causes a noticable drop in contrast when the scope is pointing at certain angles.
I'd like to get or make a light shield (similar to a dew shield) to put on the top end of the scope to reduce / remove this issue. I'm guessing that I will need one around 18" tall to be really effective in shielding the secondary - does that sound about the right height ?.
I'm also going to need something that goes right around the OTA (rather than the partial one that Astro Engineering make) because my unwanted light comes from a number of directions (including my own house when my family are still awake
).Has anyone made anthing like this and, if so, could you share the details. I'd prefer something a light as possible because the Lightbridge is already rather "top heavy" especially with a 2" Nagler eyepiece in the drawtube !.
Would commercially available dew shields be appropriate ? - I saw one of these being used at the SGL4 Star Party but that was on a SW Flextube 12" and I wonder what it's (the dew shields) weight was.
All suggestions and further ideas welcomed
Thanks,
John
-
Hi John, I use to own the mak that my brother now owns and don't recall having to turn the focus that much when I change eyepieces or with any other Telescope that I owned. I tried the comparision with my present telescope WO80 at x18. With the mak it would be around x41 and I wonder with the mak longer focal length would the difference be less or even noticeable.
I think it's only the 35mm Ultima that needs the additional inward focus travel - the others in the range all seem to focus at a relatively "normal" position. Focus travel is rarely an issue with Mak's and SCT's though.
John
-
It's funny you should say that Darren ...... I've often read that the Ultima 30mm is a superb eyepiece (the other Ultimas are not too shabby either) but I've not had the pleasure of actually trying one. I have owned a couple of Ultima 35mm's though which were excellent but (unlike the rest of the Ultima range) do need a lot of additional inward focusser movement which means they have trouble coming to focus in some scopes - that would not be a problem in a Mak though.
John
-
Sounds like my next upgrade from my standard eye pieves.
What is a Televue EP? Is it the make of one or a style?
Tele Vue are a small company based near New York. They market quality refractors, eyepieces and other astro optical gear. Their stuff is top notch but does cost more than many other brands. They have been around since the early 1980's and one of their most famous products is an eyepiece design called a Nagler after the company founder Al Nagler. They also market an excellent range of eyepieces of the plossl design, including the 32mm.
John
-
Good report Jarvo
I've been a fan of Tele Vue products for years now. Even though I've now got Naglers and an Ethos I still feel tempted to add a TV 32mm Plossl to the collection - a classic !.
John
-
Debates about the pros and cons of lens designs and glass types are interesting but only part of the story IHMO.
Personally I feel that the quality of the figuring, polishing, coatings and mounting of the lens elements are not always given enough weight. Poor attention to any of these factors can produce a poor objective regardless of the glass type used.
John
-
1
-
-
Dave,
I've also heard rumours of the fragility of true flourite lenses - when the Vixen Flourite doublets came out in the early 1980's there was a debate about whether the FL element would deteriorate over time - they don't seem to have so it was probably just sour grapes from the non-flourite scope makers !.
One factor that has affected lens production are new environmentally-driven laws on lead and other content of glass. My Vixen ED102SS had a comparatively short production life (approx 1999 to 2001 I think) because the unspecified ED glass element did not comply with the new legislation. After a short gap in production Vixen came out with the ED103 which used different (compliant presumably) ED glass although it's focal length had also grown a bit.
John
-
My 1st view of Saturn was though a 60mm refractor about 28 years ago ! - I simply could not believe what I was seeing - so beautiful even through that small scope.
I showed my neighbours the planet with a 6 inch scope a few years back and they thought I had stuck a picture of Saturn on the front of the scope !.
It's a wonderful sight, even with the rings almost edge on. Titan is quite easy to spot even with small scopes. With my 4 inch refractor I can make out 4 moons on a good night.
John
-
- Popular Post
- Popular Post
I've recently come across this piece on the web written by Alan MacRobert from the well known and respected astronomy magazine Sky & Telescope. It is well worth a read if you are thinking of getting into the hobby - ideally before you leap in and buy a telescope
:
https://www2.wwnorton.com/college/astronomy/astro21/sandt/startright.html
As someone who has been in the hobby for many years now I found that many of the hints, tips and pointers in this article are right "on the button".
John
As the link keeps breaking, here is the text of the article:
HOW TO START RIGHT IN ASTRONOMY
By Alan MacRobert Adapted from Sky & Telescope "DEAR SKY & TELESCOPE," the letter began. "I am 20 years old and new to astronomy. I have always been fascinated with the stars and universe. What would you suggest my first step be to get into the hobby, so that I might get the most enjoyment out of it?"
It's a good question, one that deserves better answers than most beginners find. Many newcomers to astronomy call us in exasperation after blundering down some wrong trail that leaves them lost and frustrated. Such experiences, widely shared, create a general public impression that astronomy is a tough hobby to get into. But this impression is altogether wrong and unnecessary.
Many other hobbies that have magazines, conventions, and vigorous club scenes have developed effective ways to welcome and orient beginners. Why can't we? For starters, novice astronomers would have more success if a few simple, well-chosen direction signs were posted for them at the beginning of the trail.
What advice would help beginners the most? Sky & Telescope editors brainstormed this question. Pooling thoughts from more than 200 years of collective experience answering the phone and mail, we came up with a number of pointers to help newcomers past the pitfalls and onto the straightest route to success.
1. Ransack your public library. Astronomy is a learning hobby. Its joys come from intellectual discovery and knowledge of the cryptic night sky. But unless you live near an especially large and active astronomy club, you have to make these discoveries, and gain this knowledge, by yourself. In other words, you need to become self-taught.
The public library is the beginner's most important astronomical tool. Maybe you found Sky & Telescope there. Comb through the astronomy shelf for beginner's guides. Look for aids to learning the stars you see in the evening sky. One of the best is the big two-page sky map that appears near the center of every month's Sky & Telescope, which the library should have. When a topic interests you, follow it up in further books.
Many people's first impulse, judging from the phone calls, is to look for someone else to handle their education -- an evening course offering, a planetarium, or some other third party. These can be stimulating and helpful. But almost never do they present what you need to know right now, and you waste an enormous amount of time commuting when you should be observing. Self-education is something you do yourself, with books, using the library.
2. Learn the sky with the naked eye. Astronomy is an outdoor nature hobby. Go into the night and learn the starry names and patterns overhead. Sky & Telescope will always have its big, round all-sky map for evening star-finding. Other books and materials will fill in the lore and mythology of the constellations the map shows, and how the stars change through the night and the seasons. Even if you go no further, the ability to look up and say "There's Arcturus!" will provide pleasure, and perhaps a sense of place in the cosmos, for the rest of your life.
3. Don't rush to buy a telescope. Many hobbies require a big cash outlay up front. But astronomy, being a learning hobby, has no such entrance fee. Conversely, paying a fee will not buy your way in.
Thinking otherwise is the most common beginner's mistake. Half the people who call for help ask, "How do I see anything with this %@&*# telescope?!" They assumed that making a big purchase was the essential first step.
It doesn't work that way. To put a telescope to rewarding use, you first need to know the constellations as seen with the naked eye, be able to find things among them with sky charts, know something of what a telescope will and will not do, and know enough about the objects you're seeking to recognize and appreciate them.
The most successful, lifelong amateur astronomers are often the ones who began with the least equipment. What they lacked in gear they had to make up for in study, sky knowledge, map use, and fine-tuning their observing eyes. These skills stood them in good stead when the gear came later.
Is there a shortcut? In recent years computerized, robotic scopes have come on the market that point at astronomical objects automatically. They represent an enormous change. No longer do you need to know the sky.
Once fully set up, a computerized scope is a lot faster than the old way of learning the sky and using a map -- assuming you know what's worth telling the computer to point at. But they're expensive, and opinions about them are divided. For beginners, at least, there's some consensus that a computerized scope can be a crutch that prevents you from learning to get around by yourself and will leave you helpless if anything goes wrong. Moreover, you miss out on the pleasures of making your own journeys through the heavens.
At star parties beneath gorgeous black, star-sprinkled skies, we have seen beginners struggling for hours with electronics when they should have been sweeping the heavens overhead. Is this just the carping of old fogeys? The jury is still out.
4. Start with binoculars. A pair of binoculars is the ideal "first telescope," for several reasons. Binoculars show you a wide field, making it easy to find your way around; a higher-power telescope magnifies only a tiny, hard-to-locate spot of sky. Binoculars give you a view that's right-side up and straight in front of you, making it easy to see where you're pointing. An astronomical telescope's view is upside down, sometimes mirror-imaged, and usually presented at right angles to the line of sight. Binoculars are also fairly inexpensive, widely available, and a breeze to carry and store.
And their performance is surprisingly respectable. Ordinary 7- to 10-power binoculars improve on the naked-eye view about as much as a good amateur telescope improves on the binoculars. In other words they get you halfway there for something like a tenth to a quarter of the price -- an excellent cost-benefit ratio.
For astronomy, the larger the front lenses are the better. High optical quality is important too. But any binocular that's already knocking around the back of your closet is enough to launch an amateur-astronomy career.
5. Get serious about maps and guidebooks. Once you have the binoculars, what do you do with them? You can have fun looking at the Moon and sweeping the star fields of the Milky Way, but that will wear thin after a while. However, if you've learned the constellations and obtained detailed sky maps, binoculars can keep you busy for a lifetime.
They'll reveal most of the 109 "M objects," the star clusters, galaxies, and nebulae cataloged by Charles Messier in the late 18th century. Binoculars will show the ever-changing positions of Jupiter's satellites and the crescent phase of Venus. On the Moon you can learn dozens of craters, plains, and mountain ranges by name. You can split scores of colorful double stars and spend years following the fadings and brightenings of variable stars. If you know what to look for.
A sailor of the seas needs top-notch charts, and so does a sailor of the stars. Fine maps bring the fascination of hunting out faint secrets in hidden sky realms. Many reference books describe what's to be hunted and the nature of the objects you find. Moreover, the skills you'll develop using maps and reference books with binoculars are exactly the skills you'll need to put a telescope to good use.
6. Find other amateurs. Self-education is fine as far as it goes, but there's nothing like sharing an interest with others. There are more than 400 astronomy clubs in North America alone; see the directory on Sky & Telescope's Web site. Call the clubs near you. Maybe you'll get invited to monthly meetings or nighttime star parties and make a lot of new friends. Clubs range from tiny to huge, from moribund to vital. But none would have published a phone number unless they hoped you would call.
Computer networks offer another way to contact other amateurs. CompuServe, America Online, and the Internet all have active astronomy areas. These present a constant flow of interesting news and chatter by amateurs who are quick to offer help, opinions, and advice.
7. When it's time for a telescope, plunge in deep. Eventually you'll know you're ready. You'll have spent hours poring over books and ad brochures. You'll know the different kinds of telescopes, what you can expect of them, and what you'll do with the one you pick.
This is no time to scrimp on quality; shun the flimsy, semi-toy "department store" scopes that may have caught your eye. The telescope you want has two essentials. One is a solid, steady, smoothly working mount. The other is high-quality optics -- "diffraction-limited" or better. You may also want large aperture (size), but don't forget portability and convenience. The telescope shouldn't be so heavy that you can't tote it outdoors, set it up, and take it down reasonably easily. The old saying is true: "The best telescope for you is the one you'll use the most.
Can't afford it? Save up until you can. Another year of using binoculars while building a savings account will be time you'll never regret. It's foolish to blow half-accumulated telescope money on something second rate that will disappoint. Or consider building the scope yourself, an activity that many clubs support.
8. Lose your ego. Astronomy teaches patience and humility -- and you'd better be prepared to learn them. There's nothing you can do about the clouds blocking your view, the extreme distance and faintness of the objects you desire most, or the timing of the long-anticipated event for which you got all set up one minute late. The universe will not bend to your wishes; you must take it on its own terms.
Most of the objects within reach of any telescope, no matter how large or small it is, are barely within its reach. Most of the time you'll be hunting for things that appear very dim, small, or both. If flashy visuals are what you're after, go watch TV.
"Worthiness" is the term entering the amateur language for the humble perseverance that brings the rewards in this hobby. The term was coined by Ken Fulton, author of The Light-Hearted Astronomer(1984) -- a book describing the hobby as a jungle full of snares, quicksand, and wild beasts that only those with the spiritual skills of a martial artist can traverse unmauled. It's really not that bad -- but there are definitely times when a Zen calmness will help you through.
9. Relax and have fun. Part of losing your ego is not getting upset at your telescope because it's less than perfect. Perfection doesn't exist, no matter what you paid. Don't be compulsive about things like cleaning lenses and mirrors or the organization of your observing notebook.
And don't feel compelled to do "useful work" right away. Ultimately, the most rewarding branches of amateur astronomy involve scientific data collecting -- venturing into the nightly wilderness to bring home a few bits of data that will advance humanity's knowledge of the universe in some tiny but real way. Such a project often marks the transformation from "beginner" to "advanced amateur," from casual sightseer to cosmic fanatic. But it only works for some people, and only when they're good and ready.
Amateur astronomy should be calming and fun. If you find yourself getting wound up over your eyepiece's aberrations or Pluto's invisibility, take a deep breath and remember that you're doing this because you enjoy it. Take it only as fast or as slow, as intense or as easy, as is right for you.
Alan MacRobert is an associate editor of Sky & Telescope magazine and an avid backyard astronomer.
-
78
-
8
-
A very useful addition to the guidance on SGL Andrew - it's almost impossible to get the level of detail "right" on these things but I think your primer stikes a good balance.
Thanks for putting it together
John
-
Hi Andrew,
I've not tried one of these but Pentax EP's generally have a great reputation and a few years ago the .965 inch Pentax ortho's were highly sought after as planetary eyepieces. My guess would be that it would be a fine performer. At £80 used it is not cheap though and it might be worth having a look at other options in that niche as well - Burgess / TMB Planetaries, and the new William Optics SPL's for a start - both are cheaper new than this Pentax and might offer benefits such as better eye relief.
John.
-
1
-
-
Well I'm new to C8 ownership and mine is a 1994 model but, apart from the 3 screws holding the focusser knob in place I can't see any other screws / nuts on the rear cell of the OTA at all. Maybe it's an error in the instructions or they apply to a different model of SCT
Incidentally I had the same fun with collimation - mine was way out at 1st light and it took about 30mins of fiddling to get it to an acceptable state. I don't have Bob's Knobs fitted yet but will soon !. I found the scope needed at least 45 mins to reach ambient temperature and during that time the out of focus star image that I was using for collimation showed a distinct heat plume. Once I'd finished fiddling though the views of Saturn were very satisfying though so it was well worth the effort and I think I can improve on the collimation further in due course. From now on I'm also going to allow an hour for cool down as well.
John
-
My 1960's Tasco 60mm f13 Alt-Az refractor in it's wooden trunk. My first scope which I purchased 2nd hand around 1981. It's mount and tripod are not good and the 2 eyepieces that came with it frankly awful. The breakthrough came when I started using the eyepiece from a discarded pair of 8x30 binoculars in the scope - it was a kellner design with a focal length of about 16mm - with no field stop - hardly ideal but a big step up from the Huygenian EP's that came with the scope - I now found some of the brighter Messier objects and felt very proud !!. This scope also showed me my first telecsopic view of Saturn, which, as with many folk, got me hooked on astronomy.
I reckon that these older Tasco scopes generally have good optics - they just need half decent eyepieces (ie: not those supplied with the scopes) to show it. One day I'll mount the OTA on a good mount and see what it can do with my Tele Vue plossls.
Can't see me parting with this somehow - definately for sentimental reasons.
John,
North Somerset
-
1
-
-
Sorry I did not chip in earlier on the formula but Gaz's post a few back sets it out well. The Tele Vue web site (www.televue.com) has lots of useful info and fomulas regarding eyepieces (inclding general stuff - not just their own products).
The issue has also been confused over the years by some eyepiece manufacturers claiming fields of view for their eyepieces which they did not deliver in reality. An example of this is the Celestron 32mm Erfle (31.7mm fitting) which was marketed in the 1980's as having a 65 degree apparent field. I finally got to own one of these a few years back and found that it's field was the same (slightly less actually) as my Taiwanese 32mm Plossl - around 50 degrees. Even when I removed the field stop from the inside of the chrome barrel the Erfle's field was only about 52 degrees - the same as the Meade 32mm 4000 series plossl as it happens - another illusion shattered - I had wanted one of those Erfles for about 10 years !.
John,
North Somerset
-
My understanding is that the field of view of any eyepiece is ultimately limited by the internal diameter of it's barrel. In the 31.7mm format this is about 29mm. Because of this limitation, as the focal length of the eyepiece increases the maximum apparent field (AF) that can be achieved decreases - in 31.7mm format at 40mm, 44 degrees AF is possible, at 32mm, 52 degrees at 25mm, 70 degrees is possible and so on. I used to own a 10mm ultra wide field modified plossl design that offered 84 degrees and I think you can get a Nagler in 13mm in 31.7mm format which offers 82 degrees. If someone offers an 80 degree, 32mm eyepiece in the 31.7mm fitting I'd love to know how they do it !.
John,
North Somerset
-
I was following an e.bay ad for a 32mm Konig last week and actually bid for it - I got beaten by about 10 pence with 0.5 secs to go - hmmmm....
The only thing is that this was a 1.25 inch eyepiece and UK based although it looks like a 2 inch - the body is over 2 inches wide and the eyelens is about 45mm across. They offer the widest field available in 1.25 inch format but need 0.8 inch inward focusser travel compared with a standard plossl because the field stop is placed in the body of the eyepiece rather than in the chrome barrel as per most eyepieces.
I believe the field is around 52 degrees.
I wonder if this was the same eyepiece ?.
John,
North Somerset
-
On the Bresser vs Celestron issue, having looked at the specs of both instruments both are made in China, although probably by different manufacturers. The Celestron looks like a Synta clone and the Bresser looks like it's out of the same factory as the 127mm refractors sold by Skys the Limit via e.bay. Interestingly the latter factory is also supposed to make the Meade AR55 5 inch refractors as well. In the past Bresser has been a brand name that does well in continental Europe while Celestron tends to be preferred in the USA and the UK. In the past virtually identical models have been sold under both brand names. Sometimes the accessories supplied with the scopes vary so it is worth checking exactly what you get.
Having owned 2 types of 4 inch refractors in the past - a Bresser 102mm (then made in Japan by Vixen) and more recently a TAL 100R (russian) I can vouch that they make good beginners scopes and provide great views of planets, double stars and the moon. Views of deep sky objects (ie: Messiers etc) are nice but ultimately 4 inches of apeture will limit the detail that can be seen. All the instruments talked about so far have a focal ratio of f10. Shorter focal ratio 4 inch refractors (in this budget range) will not be so good on the planets and double stars. One warning I would give to a prospective owner of an f10 4 inch refrator is to get one with a tall tripod. When looking at objects overhead it's not uncommon for the eyepiece to be only a couple of feet above the ground which can mean some gymnastics to get a decent view !. Also a 4 inch f10 refractor in an equatorial mount is still quite a heavy telescope.
It is for these last reasons (having back problems I can't manage the gymnastics) that I have recently sold my refractor and moved on to a 5 inch Schmidt Cassegrain on a fork mounting - in my case the Celestron Nexstar 5. I have been delighted with this scope as i) it's very portable ii) it provides noticably better images than my 4 inch refactors did on both planets and deep sky objects and iii) the eyepiece height is always convenient. All in all I can highly recommend these - it cost me £300 in excellent used condition - this was a particularly good deal though. Schmidt Cassegrains do need collimation (adjusting mirror alignment) from time to time as well like other mirror-based designs.
John,
North Somerset.
Show me your eyepiece/accessories case, please.
in DIY Astronomer
Posted · Edited by John
This pic is a bit out of date now but it shows the Maplins case off - it's the one with cubed foam which I've pressed the eyepieces into: