Show Posts

This section allows you to view all posts made by this member. Note that you can only see posts made in areas you currently have access to.


Topics - Jon Beckner

Pages: [1]
1
Well,

this is meant to be a beginner thread from a beginner to a beginner as I am pretty sure that everyone else already knows about these. I thought I would just share with new people what I found on my journey of just picking a telescope good for my own needs (still on-going at the time of writing).

3 main types of telescopes:

1.) Refractors: These are lense-based telescopes. Depending on quality of the telescope these contain anything between 2 and 6. Simple refractors suffer "purple-fringing" surround especially bright subjects (ak chromatic abberations) which are the result of different colors of the light spectrum being bent to different degrees. To fight this symptom, higher quality lenses were developed. Telescopes that have these lenses are called achromatic telescopes. More sophisticated setups contain various concave and convex lenses to focus different colors into one focal point again. These sorts of telescopes are called apochromatic telescopes. Because these telescopes contain many lenses with many surfaces, that each have to be finely crafted, they are the most expensive. Prices increase quickly...and for these telescopes it is not too uncommon to see prices as high as 10K for a moderately sized siystem (5-6").

To get started though, one does not need to pay exorbitant amounts. Here are a few (mostly achromatic) telescopes:

- 102mm Achromatic Refractor: 4" telescope with good wide field of vision. I have seen sale prices as low as $399 for the OTA only.
- 127mm Achromatic Refractor: 5" telescope with better light capture then the model above. Normal prices are around $599.

I have read many good reviews. Good price for quality achieved. Of course, at these prices you are not going to fully eliminate purple-finging, but it should not be very noticeable with these achromats. Bigger sizes are also available, but they, in my opinion start getting unwieldly large. Smaller sizes are going to be cheaper of course, but for those you will be limited to brighter objects (such as planets, and the really brightest and biggest nebulas and DSOs)

2.) Reflectors: These are "mirror-based" telescopes. Instead of lenses, mirrors are used to bundle the light. They are MUCH cheaper because, instead of polishing 4-12 surfaces, one only needs to do a good job on the primary mirror (1 surface). It's common wisdom that in terms of bang for the bug, this is where you will likely find it. I personally have been exploring 5" newtonians on a Go-To mount, and found that basically, the OTA is the same piece of equipment in each of them. Examples below:

- Celestron Skyprodigy 130:
- Celstron 130 SLT: The link to this is actually a review meaning to show that despite the concerns below, people can be happy with these sorts of systems.
- Orion Starseeker IV 130:

People on these forums will quickly point out that there are several issues with these scopes. Despite great optics of the mirror, these scopes come on very undermounted tripods - at least the Skyprodigy and SLT system. I can attest to that as I looked at the tripods for the first 2 models. I have yet to see the Starseeker IV tripod. It appears to be more solid and might be acceptable actually. The other piece I WAS able to confirm though is that the Celestron telescopes mentioned above have a plasticy looking focuser piece.
People on the forum say that these focusers will prevent great accuracy at higher (~200x) magnifications. Again, I have not been able to confirm this for the Orion model.

When I was in 2 different stores, I found it kind of interesting: Newtonians below 6" were made in the cheapest possible way. Most were afflicted by the above type problem. I could not find well-built telescopes below 6". If the community or searcher did find Newtonians of this sort do point it out! What I found instead was that 6" somehow represents the magic boundary for for well-built Newtonians with solid tripods (of course, one buy tripod/mount and ota separately but somehow this is less cost effective). I don't know why that is, but one outstanding example I think is the below:

- Celestron Advanced VX 6" Newtonian: Comes with the well-built Celestron VX GoTo EQ mount (by itself this costs $799 when not on sale), and Celestron's 6" Newtonian (by itself $299). You will save $100 when you buy the bundle as the bundle cost is $899 when not onsale.
- Celestron XLT 150 OTA: This is the telescope only. Great optics. Great mechanics, too! You will notice 150mm = 6" roughly.

3.) Catadioptric telescopes use both (a corrector) lense and a mirror. In terms of pricing, it is common wisdom that these are between reflectors and refractors in terms of price. This is also where it gets a bit more complicated. There are 2 common types of catadioptric telescopes. The so-called "Cassagrain" design uses a corrector lense in the front, a primary mirror in the back, and a secondary mirror in the front where the corrector is to reflect the light back to the back of the telescope. This light-folding pattern leads to very compact OTAs.The 2 flavors are Schmidt-Cassegrain and Maksutov-Cassegrain. The main difference between these 2 scopes are that in the case of the mak telescope, the corrector is a meniscus type lense, and the secondary mirror is just the silvered central part of the meniscus lense. It is said that the smaller obstruction in mak telescopes leads to better contrast at the cost of more magnication/but smaller fields of view. Walking into a telescope store, and online, the potential buyer will quickly come across the Celestron NexStar or Evolution Series. These are the models I looked at from a very beginnery point of view. Obviously, the more money you have the larger you would want to go (up to 8" in my opinion). I will only list the Nexstar versions here as they are more cost-effective. But if you like very techie products with things such as local wifi, phone and tablet control features etc, look to the Evolution series. Be aware though these features will likely cost you at least $200 more compared to an equivalently sized Nextstar model.

Celestron Series (below are the models I was mostly considering for costs and portability):
- Celestron Nexstar 4SE
- Celestron Nexstar 5SE
- Celestron Nexstar 6SE

Orion sells Maks:
- Orion Starseeker IV 127mm

There is some discussion going on as to the FoVs of these telescopes. Fact: The FoVs will be narrower than comparable Newtonains or refractors. This is the reason why all these systems mostly come on computerized mounts: with narrow FoVs, a new beginner would quickly lose patience finding objects without computer help. The open question is: With computer aid, are narrow fields of visions a drawback. There is a different thread for this discussion. In this thread, I am just raising this as a point the potential buyer should be aware of.

In my search what I found most surprising was that there are other variants as well, things like: Maksutov-Newtonian, or Schmidt-Newtonian. You will guess from the name that these scopes are essentially newtonian telescopes with either the Schmidt or Mak version of a corrector. Their main advantages are that these plates can correct for "aspherical abberations" very well - something standard, larger Newtonians are prone to. An example of that sort of scope can be found below:

- 152 Comet Hunter Maksutov-Newtonian: 6" OTA. Cost when not on sale $699. You will need to buy a solid tripod/mount to go with this OTA. Since I want a GoTo mount, I would have to consider the VX mount which runs another $799. For a beginner, I feel that this is pushing the outer boundaries of initial costs. The upside is that this scope + proper mount would last a long time.

I will end this post by pointing out that in addition to the scope, one should plan in a budget to buy at least 1-2 additional good quality eye pieces and a barlow lense. This last statemen in itself could be a whole new chapter of discussion. But since this post is already pretty long, I will keep it short and end it here.

Anyway, this is not the end-all, be-all guide, but perhaps this sharing of what I have found so far will be useful to other new community members also on the hunt for the holy scope :-)

Cheers!

3
Beginners Forum / New Zhumell Z8 mirror smudges
« on: December 29, 2017, 09:54:22 AM »
This is my first post, and hope I am posting in the correct place & also that this is not a duplicate question/concern. I am the prod owner now of a Zhumell Z8 (mostly due to this site ), which I am upgrading or better adding to a Celestron 114slt. First off I have got to say the Z8 is a beautiful piece of machinery. Everything looks great and went together without a hitch. I know it is not advised to look t a primary mirror with a flashlight, but since it was new I thought it should be one time I could. What I noticed when peeking is what appears to be 1/2" smudges next to the mirror mounts like it had been rotated the 1/2" after it was mounted. I'm not sure if this is common, or any need for concern. The mirror looks centered & seemed to collimate correctly. I am wondering if anyone thinks this requires further investigation or just let it be? I have taken apart my 114slt many times, so I am not squeamish about taking the primary mirror off, but was not expecting to have to on day one. If I do take it off and everything looks OK, should I clean the small smudges, or let them be. Any thoughts would be greatly appreciated. Thanks!!

Attaching an image where you can make out one of the smudges, all 3 are the same.

4
Beginners Forum / Resolution Vs Magnification?
« on: December 29, 2017, 04:11:27 AM »
I have recently (last couple of months) started observing the skies again after I bought the GSO 8" Dob.
From my location (Balcony of an apartment building with limited views of the sky), I have been observing mostly the south, south -west and central part of the sky - resulting in observations of the Orion constellation, Cancer, Taurus, Jupiter, Venus as well as the big dipper and Cassiopeia, this time of the year.
I got 25 mm and 9 mm SPs with the scope.
My main concern is that while the 25mm shows remarkable views of Jupiter, with the bands clearly visible along with the four moons, I am yearning for a large size of the image, because I really need to strain the eyes to see the details; after using the 9mm eyepiece, the size does increase a little and it shows up slightly more features of the planet., but then it is not very easy to view it using the 9mm vs the 25 mm
I am assuming that a Barlow would help to increase the image size ( I am quite ok with the details (resolving power) the eyepieces are able to generate).If so, are there any particular specifications for the Barlow lenses that I should consider? Will the same Barlow also be helpful in viewing DSOs?

Thanks!

5
Reflectors Telescopes Forum / Lightbridge 16 trusses
« on: December 28, 2017, 09:36:01 AM »
So, I was lookin for a telescope for my daughter, who's taking an astronomy class at the local  collage. And I figure 8, 10" dobsonian would be great. I'm on craigslist when I find a mystery  telescope, I call and find out it's a 16 lightbridge! But it has been beat up and abused, second and spider we're chipped and bent, no finder scope, no eyepieces and I'm missing a knob or 3. But the tubes are in good shape and the primary is decent. I can get a finder scope, eyepieces and a secondary mirror. My only obstacles is I have no trusses. I have a backyard machine shop and am making the mounts and tubes out of aluminum but my largest obstacle is focal lenth. How long between  the tubes. If there is any lightbridge  16 owners out there that could give me the masurments between the tubes, I would be forever grateful. I know it could be calculated but since it's a know distance it sure would make life easier. Cheers tim

6
General Astronomy & Observing / Enough with the clouds/rain already...
« on: December 28, 2017, 01:16:10 AM »
Any of my Ohio brethren ready to give up?

From November 19, 2016 though January 19, 2017, there have been 57 days classified as cloudy/overcast out of a total 62 days in central Ohio. Of that, 48 have also seen precipitation which for the majority has been nothing but rain. I drove to work this morning once again in rain. This is the 11th consecutive day with rain.I know we tend to get a little over zealous when it comes to complaining, but I seriously don't remember a more depressing/insufferable winter. My yard is quickly becoming swampland and rain is in the forecast EVERY day through next Thursday.

7
Reflectors Telescopes Forum / Keep my Dob in the car?
« on: December 28, 2017, 12:26:02 AM »
I'm in a condo/apartment, 19th floor in a big city. My 12.5" Dob sits in the spare bedroom with its poles, wheelbarrow handles, stalk and UTA.  It is a major pain in the fundamental region to load it in the car for observing. The ramps are in the storage locker in the building's garage. I do want to use it as much as possible this observing season but the time/effort to get it all in the car and back upstairs makes me weak in the knees and reluctant to 'commit' to the effort except for week-long events like Star Parties....

So........

What if I kept the Rocker/base, poles, stalk, handles, UTA (in its case) etc. in the van all spring, summer and fall. I would take the mirror out, though. I'm getting a case made for it.... So a trip to observe would be that much easier. A couple of elevator trips with the auxiliary stuff, eyepiece case, and so on.

I'm lazy.

But I want to observe as much as possible......

Dave

8
Light Pollution Topics / The New DarkSiteFinder.com
« on: December 27, 2017, 11:40:35 PM »
Hi everyone

I just finished updating my website: DarkSiteFinder.com
The light pollution mapis now based off of the newer 2006 data instead of 2001. The entire website should now load faster and be more mobile-friendly. I also added a few other new features to the site. Let me know what you think and if you have any ideas to make it better.

Special thanks to DaveL for his help with creating the map.


9
Beginners Forum / How do I know cooldown is done? What is the view?
« on: December 27, 2017, 01:54:53 PM »
Hi! I have been observing only eight months. I have enjoyed the rapid learning process that comes with a brand new hobby, but I am stuck figuring out cool-down.

TL;DR: How can I confirm, visually, when my scope is correctly cooled down? What will the view look like when it is insufficiently cooled?

I think my challenge is that thermal effects are minor where I live, so I maybe the effect is minor? I have never learned to spot thermal effects, or to discriminate it from other visual imperfections. Now that it is winter, I wonder if I should learn this better. I want to get the best views I can, of course.

I presume the view looks "bad" or "fuzzy"? But I've learned that different things look "bad" in different ways: haze looks different from dew, which looks different from poor seeing, which looks different from astigmatism. (Sometimes I forget to wear glasses in a wide exit pupil. What can I say? I'm having too much fun!)

So what should I look out for?

For reference, I live in a tropical climate. My 5" Mak is stored in the front room closet. I estimate it is perhaps 28°C (82°F) in the closet. Outside is 24°C (75°F) in the evening. In winter, the lows go down to 18°C (64°F). So my maximum differential is 10°C (18°F) if I decide to observe at midnight.

Before, there was no temperature difference, now that it's winter ("cool season," technically) I am guessing there could be a subtle effect. What should I look for? Should I look at a wide field, or a high zoom? Should I look at a star, the Moon, or an extended object? Since the effect could be subtle, what is the best way I can "bring out" the problem, if only to learn the proper technique. Thank you very much!

10
Light Pollution Topics / Has anyone taken the "green" approach?
« on: December 24, 2017, 08:21:35 PM »
I have been wondering about that a couple of days ago and have been meaning to post the question here.  Has anyone written to a "offensive" business concerning their lights and said how much money they're wasting by departing floodlights on all night when nobody reaches the business?For case have you ever written to a company and stated "I have noticed that in the middle of night you've got every light in the building on and floodlights in the parking lot.  I am not planning to cover your inflated prices knowing that my bucks at are being spent to pay your electric bill.  I'd rather the money go to the product instead.  If you are worried about security install motion lights and cameras rather than leave pricey floodlights on 24x7. "I'm wondering whether anyone has attempted this with auto dealerships, recreational centers, plazas, furniture stores, and other common offenders?  It may just work.  At least offering to tell them to turn half the lights off or only those in front of the building may work.I am also tempted to contact government institutions such as airports, libraries (that "close" after dark anyways), and other facilities in which there's nobody there all night but we pay their electric bill.  It seems the "cut wasteful spending" approach might function there.obin

11
Beginners Forum / 10" Dob, Coma Question
« on: December 24, 2017, 02:44:13 AM »
Being new to dobs, I've read about a coma corrector for Advantage of Area focus, during first light I Had Been using 1.25 ES 82?? eyepieces, Can Not remember if the Border of Area was dim or Marginally Outside of focus,
I have obtained the Skywatcher truss 10, but a corrector wasn't discussed during buy.
Most of what I read has been roughly AP with a dob but some mentioned the usage of a CC for greater visual.

Is your 10" aperture boarder lineup for needing field correction in reflectors?
I really do want to up grade to a dual speed focuser, could I simply buy an ES coma corrector or how about the new ES AP acro focuser, could this work?

12
Hey I introduced myself but it's yet to gain much traction.  I was wondering about a Barlow Lense and perhaps 1 eyepiece around the 4-6 mm area.  There is way to many Barlow's to pick from.  Is 1 greater than another?  I have only take out my scope 3 times now.  Yesterday I brought it to a party and set it up on the deck.  Terrible idea as every step caused the image to shake.  I did get a couple of good moon viewpoints and when I moved to look for Jupiter the angle was really hard to get so I packed it up.
Celestron Astromaster 130Eq
Filters: Moon, Red, & Blue
Eyepieces: 20mm, 15mm, 10mm, & 9mm
Finder: StarPointer Finders Scope (useless?)

Pages: [1]