beka

17 minutes ago, sonicninja said:

Thanks so much for your replies. There's a lot of information for me to go through here, especially on eye pieces. For the time being I'll look into some different eye pieces for my current set and forget about the GOTO mount. I may look into the SkyWatcher Skymax 127 as an addition to my set-up at a later date. I'll have a look on the classifieds and see what I can find, hopefully with the right conditions and equipment I can start getting the views of the bright planets I was hoping for.

Hi sonicninja,

My twopence, I used a 114mm f8 reflector (Celestron FirstScope 114) on a manual mount for a long time with inexpensive eyepieces from an eyepiece and filter kit. I used these eyepieces later for another length of time with my CPC 1100 (11 inch SCT) before getting some Baader Hyperions. I will just say that on the CPC 1100 I am still not sure if the more expensive eyepieces actually showed me more detail on the planets. They are on the other hand more comfortable to use (with a higher exit pupil) and have a more satisfying build quality. Just saying that the differences between eyepieces - near the center of the field of view on planets, will be very subtle. I think you can go a long time with just the eyepieces you have and the 2X Barlow. The 3X Barlow is probably not useful.

Best!

Hi All,

Was just wondering about SVBONY eyepieces. Browsing their site, they don't seem to have specific lines of eyepiece products like other companies. They also seem to use designs like Plossl freely without regard to the actual design. For example here they have 4, 5 and 6 element different arrangement eyepieces all called "Plossl". Then some SVBONY eyepieces on Amazon like here don't seem to exist on their own web site. Finally all the eyepieces are very inexpensive and generally are seen favorably by users on this forum. So are they actual manufacturers or are they scavenging  surplus eyepieces from elsewhere and reselling? Do the likes of Stellarvue and Baader have to be worried?

Best!

On 25/10/2021 at 23:50, ChevyFan said:

I am trying to figure out what would be the best eye piece and lens to get for my wife's telescope, (Celestron 130 SLT) and I have was thinking about getting the following....

"SVBONY Telescope Eyepieces 4mm 10mm 23mm 62 Degree Wide Angle Aspheric Eyepiece for 1.25 inches Astronomic Telescopes "

https://www.amazon.ca/gp/product/B01LZ6DDC2/ref=ox_sc_act_title_2?smid=A1QUQZI6UT4117&th=1

 

and pairing it with a 2X Barlow Lens...

 

 

Would these two together exceed this telescopes capabilities?

Thank you!

Hi ChevyFan,

Checking the link, the eyepiece specifications are a little strange. Specified as Kelner aspheric with 62 degrees field of view - conventional Kelner eyepieces or even Plossls which are considered better, don't have such a wide field. Aspheric elements are found in more expensive eyepieces so three different eyepieces as this price needs further looking into (strangely could not find these items on the Svbony site). If you and your wife are just beginning astronomy it would really be better if you just use the eyepieces that came with the scope for a while. The difference in the views between these and more expensive eyepieces is quite subtle near the center of the field of view. An inexpensive 2X Barlow will allow you to expand the range of magnification. Once you know what types of objects your wife is interested in you can plan the next items you purchase accordingly.

Cheers!

1 hour ago, rl said:

The idea of maximum magnification is to extract all the detail in the image without over-magnifying which makes it dimmer and fuzzy. 

The image at the prime focus contains a finite amount of detail. the bigger the aperture, the more detail. It's like a mosaic...the bigger the aperture, the smaller the pieces in the mosaic. The resolution (mosaic piece size) depends on the wavelength of the light and the scope aperture. Resolution in arcseconds = 138mm divided by the scope aperture in millimetres, so a 60mm scope will resolve just over 2 arcseconds of angle. A 6" will resolve to about 0.9 arcseconds which is finer detail

The maximum magnification will match the scope's resolution to that of the eye. Now, people's eyes are all a bit different so there is no cast-in-stone rule for this, but on average most people's eyes can resolve between 1 and 4 arcminutes of angle depending on the brightness of the object and its contrast. This is between 60 and 240 arcseconds. Thus, for your 60mm scope resolving 2 arcseconds, you need to multiply by 60/2 to 240/2 or 30 to 120 times.  For a 6" scope, you get 60/0.9 to 240/0.9 or 66 to 267 times. The 50 times per inch figure is just a generalisation of this principle assumimg your eye resolves just over 4 arcminutes. 

A lot of caveats apply. Astigmatism in your eye favours higher magnification. Floaters favour dropping the magnification down a bit since the very narrow exit pupil is more easily scattered.

This is the kind of calculation I attempted - I assumed the eye to have a resolution of about 0.2mm for near objects and came up with numbers closer to the lower end of the ranges you mentioned.

Thanks

Hi All,

It has been suggested that the maximum useful magnification of a telescope is about 50X for every inch of aperture. So for a 4 inch for example it would be 200X.  I was wondering what the basis for this is? On Celestron's site, the magnifications they give for their scopes seem to be higher. For the NexStar 130 SLT it is 307X but it should be about 250X (5" X 50) from the rule above. I tried some calculation based on the image scale of the telescope and the resolution of the human eye but did not really get numbers close to these. Does anyone know how these numbers are arrived at?

Best

13 hours ago, ChevyFan said:

I just recently purchased a Celestron NexStar® 130 SLT Telescope for my wife, and I want to get the most out of it for her...I was thinking I should buy a 3X Barlow Eye Piece for it (mind you I am TOTALLY new to this) My wife and I have never even owned a Telescope before.

I was reading online that for a particular Telescope.. the "AstroMaster 130EQ" to get the best magnification possible a person should get  a Omni 4mm eyepiece  and a 2X Barlow Lens....

 

https://www.celestron.com/blogs/knowledgebase/how-to-determine-which-eyepieces-to-use-with-your-telescope

 

I was thinking about getting a 3X Barlow Lens, and pairing it with a really good eye piece, but as I don't know much about Telescopes, I don't even know if it would be compatible with a Omni 4mm eyepiece, or I would just get this., and call it a day...

Could someone please tell me what would be THE best combination possible for the Celestron NexStar 130 SLT Telescope?

 

I would appreciate ANY feedback you guys can give me!

 

Thank you!

 

 

 

Hi ChevyFan,

I have been using this scope over the last few months. If I recall the scope comes with 9mm and 25mm eyepieces. If you are completely new to astronomy I would not buy any more eyepieces just yet. You should get an inexpensive 2X Barlow for a maximum of 144X magnification. In times of good seeing this will show quite a bit of detail on the big planets. Jupiter's red spot and the Cassini division on Saturn are possible. The 25mm will give you excellent wide field views and many star clusters will be nice. Like has been stated by others, magnifications much higher than above will be hard to use because the mount's instability will make focusing and tracking difficult. You will also need to learn how to collimate the scope. I have found this important  to get decent views. 

Have Fun!

I managed to borrow this scope from a friend. Initially I was interested in using it for DSLR astrophotography, thinking it would be better than the 102 SLT refractor I had because it would be free of chromatic aberration. However I learned that DSLRs would not come to focus even before I tried - without modifying the OTA or using a barlow. I then wondered if it might be good on planets. On Jupiter using a 8mm to 24mm Celestron zoom eyepiece and 2X barlow (162.5 time magnification) the view was quite good. I could see details in the bands and it was free of CA. However I could tell from the moons that collimation was not prefect. I had tried some time back but was never fully satisfied with the result. Saturn was more disappointing. I could barely make out the Cassini division and some banding. I didn’t try to see its moons but I think I would have noticed them if they were obvious. I did not try any deep sky objects on this night but some months back I had tried to view the Orion Nebula and the stars of the Trapezium. Four stars were crisp but I could see no sign or the E and F stars. I will continue to check this scope for deep sky but I already reached some conclusions.

Visually on planets my old FirstScope 114 900mm FL f8 is better. The longer focal length makes it easier to get higher magnifications and I guess the f8 focal ratio makes it easier to collimate. The 130 SLT scope does track but for me the manual FirstScope slow motion controls were better at high magnification.

Visual deep sky - of course my CPC 1100 is vastly superior except for wide fields. Star fields in Orion and Southern Cross were very pleasant in the 130 SLT. So for wide field low magnification visual, this scope is better than the either of these two.

Casual astrophotography I can do with the 102 SLT refractor without any modification. CA is prominent but it can be reduced in processing. The 130 SLT has the potential to be better but I would need to buy a dedicated astro camera (but somewhere I read that mirrorless cameras can come to focus without modification).

My final thought is that it is a decent scope to have - if you have other scopes! Good for grab and go for quick wide field views. I would not recommend it as a good all rounder for a beginner. For that my opinion would be a 4.5 inch f8 reflector on a good manual mount – I don’t know how well a dob will track at 200x mag, but why does no one make these on a good equatorial or alt-az mount?

Thanks for reading!

Exciting yes, and also some serious nail biting and restless nights for all that have been looking forward to this! 

14 hours ago, drivera said:

Hi there,

So my... fiancé broke my Redcat. 🤣

Considerations: William Optics 2019 Gran Turismo GT71 APO Triplet Refractor; William Optics New Super Zenithstar 81 f/6.9 I'm looking at purchasing a new scope. I currently have (had) a Redcat 51 and looking at a new purchase, while also upgrading from DSLR to the ASI533MC.  What would people recommend for this setup? I'm limited by weight with my Sky Guider Pro at this stage.

The WO GT71 is a tiny bit cheaper than the WO 81.

I'm looking at a closer FOV for DSO objects than the Redcat but unsure of the 533MC impact.

OR any scopes like these out of the WO would be worthwile and/or better?!

Thanks!

Steve

Sure it was accidental - maybe jealous?😀

2 hours ago, Tiny Clanger said:

 

...Do remember before buying any eyepieces or filters, you need to establish that your eyepieces are 1.25" diameter barrels or they will not fit your telescope.

Heather

The Powerseeker 50AZ eyepieces are 0.96" so the usual 1.25" will not fit...

2 hours ago, Sweet dreams said:

Thanks you so much guys. As for the stars I am able to spot out a few bright stars. Yesterday, I looked up at procyon and was able to see the binary stars separated. I am planning to see Mizar in my next observation. I installed stellarium and finding it very useful. From where can I get much more information about the phases and positions of the planet?

Stellarium will help on the planets as well - use the search feature on the left of the screen. 

Cheers! 

3 hours ago, Sweet dreams said:

Thank you beka and Tiny clanged. As I am just a starter I do not know much about the sky. I hope that the stellarium will work and I am going to install it today. By the way, beka, tiny clanger and everyone else, can the light pollution in my city affect my observing of the planets. I am asking this as I am living in the highly polluted Indian city Chennai.

The light pollution will not affect your views of the planets. You should even be able to glimpse Uranus and Neptune as a tiny dots with no detail using this scope. You can also try some of the brighter deep sky objects like star clusters for example the Beehive Custer, and some people like observing double stars - you can try Mizar. 

Happy Observing!

9 minutes ago, Sweet dreams said:

Thanks for the information but what about venus??

Venus is close to the Sun now so you can't see it presently. You will be able to see it in the evening a few months from now - the scope will be able to show you the phases like the moon. Actually most other backyard scopes won't show much more. If you have not used it so far Stellarium is a very good planetarium program that will allow you to plan your observing sessions. I would suggest that you avoid the image erecting eyepiece and Barlow, and that you hold of buying any accessories (filters, eyepieces) for a while. You can decide later after using the scope for a while and you know more about what kind of observing you are more interested in.

All the best!

On 16/09/2011 at 19:19, Pogge said:

Guys, it wasn't the eyepiece, barlow, nor the moon being too bright. The problem was actually me not using the Focus Knob, haha. After using the Focus Knob, I could get the results I expected using what you said, onesmallstep (3x barlow with 20mm or just the 12.5mm). I could even see Jupiter with 4 moons? I don't know but 4 circles around that planet (Using google, it should be 4 moons ). So this means I don't/didn't need any filters or adapters, but what do you expect from beginners?

Thanks for all the help guys, great forum and sorry for my stupid mistake

It's of course not a stupid mistake but I imagine no one on Stargazers Lounge would have thought of that! It is a better scope than Galileo had when he changed humanities view of the cosmos - so have fun!

Best

Hi All,

In principle as the corrector plate is correcting spherical aberration, then some refraction is taking place at the surfaces and therefore there will be chromatic aberration (it effectively is a very weak over corrected lens). It must be that it is too little to significantly affect the final image.

Best

3 hours ago, Mike Read said:

Morning,

I currently have a Celestron 9.25" SCT and am in the process of upgrading the focuser to baader steeltrack. I have the f/6.3 FR on back order. My question is: where will the FR fit in the image train? Is it compatible?

Thanks Mike

Hi Mike, you have to fit the steeltrack focuser in place of the standard visual back adapter. You will then need a 2 inch to SCT adapter to fit the 6.3 flattener/reducer.

Best!

17 hours ago, NovaeSci said:

Regarding the mathematics in The Milky Way, did you get taught the maths need prior to, or along with, the course? Or do they expect you to teach yourself the suitable maths before you start studying? If so, is there any direction for this, or does it just come as a surprise? Regarding Energy, Matter and the Universe, does this course have all the physics and maths in the course notes, or did you find you had to look on the online library quite a lot?

Regarding grades, I believe in the UK, your final grade with the degree is only calculated from the Level 2 and Level 3 courses.

What would you say has been your favourite course as of yet? I'm excited to study Introduction to Cosmology.

The maths in the article we had to review was not covered anywhere in the course but in retrospect I think it is a rather specialized area that is probably not covered in general undergraduate courses. It was to do with Velocity Ellipsoids and digging into that takes you into deeper mathematics like Tensors also not covered in the course. But it is stated that for Level 5 modules some independent work will be needed - I personally don't think this should put you off. For the "Energy Matter and the Universe" course the maths and physics required is covered in the course materials.

My favorite course is tough to say. I liked "Introduction to Cosmology" and next probably "Energy Matter and the Universe". Even "Sun Earth and Climate" which I was initially lukewarm towards because I thought it was least astronomy related, I ended up enjoying. 

All the best.

11 hours ago, NovaeSci said:

In 'Energy, Matter and the Universe', how much physics and maths do you end up learning? Is it mainly A-Level level, or does it go in to University level? I also hear it feels more like a 30 credit course, rather than 20 credits, if there is any truth in that? I have the recommended books 'Engineering Mathematics' and 'Principles of Physics', and I wondered how much does the course refer you to these books, along with how much of the books do they cover? Is it just selective parts, or does the module cover a great deal of info from the book?

One I'm interested in is 'Investigations in Astronomy'. Would you say this provides the student with a good foundation in scientific writing and research skills? What did you get a choice of doing as well?

I plan on doing 3 modules each year and possibly maybe studying the Dissertation in a year by itself. But that's a bit of a way off yet.

Thanks again for the response

Well, regarding how much physics and math you end up getting from the 'Energy, Matter and the Universe' course, while I am unfamiliar with the A level I have seen some of the International Baccalaureate (IB) courses my daughter had been doing which I understand are of a similar level. So the physics will be at the same kind of level as the IB Higher Level (there is also standard level), The mathematics though I believe might be on a slightly lower level than the IB Higher Level mathematics. In the 'Milky Way' course we had to review some papers and the mathematics in some of them was beyond the levels I had encountered in any of the courses.

On the texts books I can't say much as I did not use them. I mostly used the course notes and resources on the Internet as it is not very strait forward accessing them or purchasing them where I am. In fact I ended up purchasing the recommended texts only for the first two courses. Some of the others were available online in the UCLAN library, otherwise I made do with the course notes and other Internet resources - though it might not be ideal. My own opinion would be that some mathematics beyond that covered by the above course would be a great advantage - for example differential equations, probability and statistics etc. 

Finally in 'Investigations in Astronomy' you choose one from five or six topics to write up. I would agree that it gives a good foundation in scientific writing and research skill, my reservation was that you learn what your mistakes were when you receive your graded feedback and there is no further chance to correct these in a subsequent assignment - which might be significant if you are concerned about getting good grades.

Three courses a year is okay I think if you are not in a demanding full time job.

I hope this information is helpful.

Best

9 hours ago, Newbiestargazer said:

Hi folks , I am a complete newbie to star gazing and a want to take up the challenge of  astro photography. I`m pretty good at normal photography and know my way round a camera. My total budget to get me going is 2.5k (holiday money, for the holiday i did`nt have last year)

So looking for advice on what is a good telescope to start in astro photography. Now with all i`ve read so far in need a good mount and this is where the money should be spent, budget is 1k. if i can get a good mount for less then whats left over can be spent on a telescope. My Budget is 1k for the telescope. 

My understanding is that i will require a guidescope to make sure the telescope stays on target. PHD2 is the software that seems to be what peeps are using.

Thanks in advance

 

Hi Newbiestargazer,

If you are completely new to astronomy I am not sure it is a good idea to dive strait into astro-photography. It might be better to do some visual astronomy even with a pair of medium binoculars to familiarize yourself with the night sky and the objects that will be of interest to you. The gear you use for astrophotography is different for planets and so called deep sky objects for example, or if you want to do wide field vs galaxies or globular clusters. Also if you already have a DSLR and all you want to do is wide field stuff you may not even need a telescope - you might be happy with a tracking mount like the Star Adventurer with a suitable lens.

Welcome to the hobby!

On 08/01/2021 at 23:43, NovaeSci said:

Hi Beka,

What courses have you completed/enrolled on, up to now? Just trying to get as much info; but, there doesn't seem to be many people to talk to about the course.

All the best,

Michael

I have completed 8 courses, currently on my ninth. Here is the list...

Introduction to Astronomy, Introduction to Cosmology, IT for Astronomy, Energy Matter and the Universe, Investigations in Astronomy, Sun Earth and Climate, Introduction to Astrobiology, The Milky Way and finally Ultraviolet, Optical and Infrared Astronomy. 

The last which I am currently doing. Some of them require the first two as a prerequisite. I have really enjoyed all them - the course materials are fantastic. The instructors when needed are responsive on the forums. I intend to go as far as I can to the extent my time and resources allow. 

Best

Hi Kadersin,

While I have no experience with the NexStar 6SE,  I have used the PowerSeeker 127 and I have no doubt that it would be a worthwhile upgrade. Just the stability and goto features of the mount will give a much improved observing experience. You will need to factor in getting better eyepieces though if all you have are those that came with the PowerSeeker. 

Cheers!

3 hours ago, Rusted said:

iStar make f/10 achromats specifically for H-alpha solar work.
These seem to work well on lunar imaging with a green filter too.

That is strange isn't it? H-alpha is red so they should work best at that wavelength. 

I was thinking, does an apo produce better images than an achromatic refractor for narrow band imaging? Chromatic aberration should not be an issue for NB but I read somewhere that for apo's spherical aberration is corrected for two wavelengths vs one for achromats.

Cheers!

Hi Celestron4,

I have not used it so far but I purchased this that Celestron says can be attached to any of their SCTs to "piggyback" your DSLR.

Cheers

1 hour ago, keora said:

Thank you for the information on eyepieces, I'll go ahead and buy some.

A final question - how do I know if the telescope needs collimating? When I've looked at the moon, or distant tv aerials, the image doesn't seem distorted.

Use your 4mm eyepiece on a brightish star, center it in the field of view and focus in or out slightly. The star will de-focus into a doughnut shape with a few bright rings which should be perfectly concentric when collimated. If the rings are asymmetric then you have to use the knobs at the back of the scope to align the mirror. You have to re-center the star after adjusting and checking again. There should be instructions on how to use the knobs in the scopes manual. There are screws that lock the mirror in position which should be loosened first. You then use the adjustment knobs and re-tighten the lock screws when you are done. It is not difficult after a little practice. You can also try in the daytime with a high contrast point like object in the distance.

Cheers!