Eye Piece advice/Laymen’s terms

[Sunnydays]

My first time on this  forum and thanks to all who help many of us who are just starting out!

Just got a Nexstar 6se and as many of you know it comes with a 25mm? If one wants to view  the planets , would i start with the 25mm to get the planet in focus and  then move to another EP to get greater detail of a planet? I find most people seem to comment on doing that? So if i wanted to view  for example Saturn... what would be a good step by step method, with the eyepieces?  So without getting into the very specifics of eyepieces, I would hope someone could as best as possible relay their viewing method in simple laymen’s terms? And if it a matter of switching out between two EP’s will they work for most  scenarios when viewing planets? Thanks so much! 

[Kyle Allen]

It is normally recommended to start with your lowest power eyepiece because this shows you a wider field of view, making it easier to find and centre your target. I normally work my way up through to higher powers gradually because some nights won’t support high magnification. Increasing magnification in this way let’s you easily see whether the view through the eyepiece  is an improvement or not.

If you are viewing the planets though, you could just start with a high power eyepiece because there isn’t much to see at low power. However, if your GoTo accuracy isn’t great, it might not be in the field of view. 

[Ruud]

The 6SE has a focal length of 1500 mm.

With your 25mm eyepiece you get a magnification of 1500 / 25 = 60 times.
The calculation also works the other way around:
if you want 100 times magnification, you need  an eyepiece with a focal length of 1500 / 100 = 15 mm.

For planets on a good night you can go up to 200 times (it depends on if the atmosphere is stable enough).

An 8mm eyepiece magnifies 1500 / 8 = 187.5 times. (FLO has the the BST StarGuider 60º 8mm ED Eyepiece for £47, a good choice if you're on a budget.)

 

 

[RT65CB-SWL]

Hi @Sunnydays and welcome to SGL. 

Another thing to bear in mind is you don't have to 'stick with' the brand name of your 'scope/OTA. Some brands are better than others for a similar specification e/p or accessory. As long as it says 1.25" or 2" you should be fine as this is now accepted as the default.  

I was going to include 0.965". These are included and bundled with the cheap & nasty telescope brands for sale on various auction sites and online warehouses or old/secondhand telescopes. That said there are a few 'good ones' out there and are rarely seen now days either new or secondhand. If you do find a 'good one' you will also need a 0.965"-1.25" adapter. 

 

My 0.965"/6mm Ortho e/p and 1.25" adapter. 

[Sunnydays]

Thanks so much!! Would going in 5-10mm increments , lets starting at 25mm, 15mm, 10mm be a good start, to get more clarity? I was trying to look at Saturn yesterday with the 25mm but, was not clear and focusing did not do much?

[John]

4 minutes ago, Sunnydays said:

Thanks so much!! Would going in 5-10mm increments , lets starting at 25mm, 15mm, 10mm be a good start, to get more clarity? I was trying to look at Saturn yesterday with the 25mm but, was not clear and focusing did not do much?

If you can add a 7mm for high power observing, those 4 focal lengths would give you a good range. Later you might also want to add a 32mm for lower power observing as well.

4-5 eyepieces of focal lengths at or around these focal lengths will give you a versatile set.

 

[RT65CB-SWL]

As Saturn, Jupiter & Mars are low down in the early morning skies for us northern hemisphere observers; (at time writing); those light photons have to get through layers of our 'dirty' atmosphere. 

[Sunnydays]

I spoke with a very nice man with Highpoint scientific and asked about the zoom lens... Highpoint Scientific Apertura 9mm - 27mm Zoom Eyepiece - ZOOM927?? This may be a good starting point for me. It allows one to focus(no pun intended) on the basics of astronomy, the scope etc.. at first, without having to deal with removing eyepieces, and will do the job. Starting out this way may give me what i need and i can move to single eyepieces as I begin to learn the finer points??

[Cosmic Geoff]

I have a zoom eyepiece - a 8-24mm Starguider. Like many zoom eyepieces, it has a small apparent field of view at 25mm and a large apparent field of view at 8mm.   A slight re-focusing is required when changing the zoom.  And the zoom action is quite stiff, so I gave to take it off the telescope and hold it under a light to see what I am doing with it.  So a useful device for some tasks, but not  a substitute for a set of fixed eyepieces.

[Mr niall]

Just to be 100% clear - longer focal length eyepieces don't exist purely as stepping stones to the higher focal length eyepieces.

Each eyepiece serves a different function and has its place - while it is true that the larger eyepieces with longer focal lengths have lower magnification and a wider field of view that doesn't mean that their job is purely to centre stuff in the eyepieces so you can get to the "good high power eyepieces". I'm sure you know that already I just thought I would reinforce the point based on some previous comments.

If you haven't already I would recommend reading the following:

 

[Louis D]

20 hours ago, Sunnydays said:

Thanks so much!! Would going in 5-10mm increments , lets starting at 25mm, 15mm, 10mm be a good start, to get more clarity? I was trying to look at Saturn yesterday with the 25mm but, was not clear and focusing did not do much?

Generally, power progressions are in square root of 2 or 1.4x increments.  Thus, 35mm, 25mm, 18mm, 13mm, 9mm, 6.5mm, 4.5mm, 3.2mm would be one power progression.  Often, folks skip by powers of 2 and go 35mm, 18mm, 9mm, 4.5mm.  However, at high powers, the jump from 9mm (or 8mm or 10mm) to 4.5mm (or 5mm) may be too much for the seeing conditions, so they my try 6.5mm (or 7mm).  That's because power rises rapidly with decreasing eyepiece focal length.  At long focal lengths, many folks will skip directly from 35mm (or higher) straight to 13mm or so, depending on the object.

[Louis D]

19 hours ago, Sunnydays said:

I spoke with a very nice man with Highpoint scientific and asked about the zoom lens... Highpoint Scientific Apertura 9mm - 27mm Zoom Eyepiece - ZOOM927?? This may be a good starting point for me. It allows one to focus(no pun intended) on the basics of astronomy, the scope etc.. at first, without having to deal with removing eyepieces, and will do the job. Starting out this way may give me what i need and i can move to single eyepieces as I begin to learn the finer points??

I'm not a big fan of this style of zoom eyepiece due to the very limited eye relief.  If you did want to get one, I would order it from FLO and have it cross imported to the US for at least $30 less than High Point.  There's no import tariffs into the US for personal purchases below $800/day, no VAT because you're outside the EU/UK, and no sales tax since FLO has no nexus of business in any US state.  That, and it supports our sponsor.

The zoom most recommended on here is the Baader Hyperion Zoom Mark IV 8-24 mm.  Again, you'd be saving over $80 cross importing it from FLO to the US.  For some reason, Baader products are much cheaper in Europe than in the US.

If that's out of your budget, then the Meade/Celestron/Agena 8-24mm zoom is usually the next best choice.  The work fine and are well priced.

My personal favorite is the Celestron/Olivon Regal 8-24mm zoom originally sold with spotting scopes.  It lacks a filter thread, but has better eye relief, eye cup, field correction, wider field of view, and smoother zoom motion than the cheaper Celestron zoom above.  Also, the top doesn't rotate during zooming, unlike the BHZ above, so winged eye guards can be used with it.  Sometimes, you can find it on Cloudy Nights classifieds or ebay local to the US.

[RT65CB-SWL]

+1 for the Baader Zoom as mentioned above by @Louis D.

I do not know of any other 2" zoom e/p's but the Baader has the option to be used in 1.25" and 2" drawtube, visual back, star diagonal, etc.

I borrowed one at the end of February [2020] in my 're-modded' ETX105 & C6/SCT from a member of my local astro society/club, and found it was quite good and not as heavy as I thought. If I decide to purchase a zoom in the 8-24mm range, then it will it will be the Baader. I already use 7-21mm; (image below);  which is OK for public outreach/star party or grab & go if travelling light.

 

The other zoom I use is the TeleVue Nagler 3-6mm and about the theoretical maximum my 'scopes and eyes can handle.
The only down side is the price... it is almost twice the price of the Baader.

[Sunnydays]

 Thanks so much for the input. I have reads many reviews on the zooms and have found that for the most part they have received no less then 4 out of 5 stars, with ease of use, being able to not have to refocus as much and the clarity has been praised as being on par or at times better then single eye pieces? It seems as though as i have quickly learned that most items come down to user preference and not so much that a single eye piece is going to give anyone 50% better viewing then a zoom. From what i have been told that for most eye pieces from mid to expensive, one might achieve Maybe 5-8% better viewing in general? Don’t expect a drastic change just because something is really expensive? When using my 25mm piece that i got with my 6se i was thrilled at the FOV, so if the zoom that i am looking at goes from 40*-60* which is in line with what the 25mm (60*)gives me, i would be happy? If i want to look at nebulae then I could just get a 32mm? Am I off base with my thinking???

[Sunnydays]

Isn’t 18mm eye relief pretty good? That’s what the zoom i was looking at listed it as? (Apertura 9mm - 27mm Zoom Eyepiece - ZOOM927), The Baader is 12-15mm which is still really good right?

[John]

17 minutes ago, Sunnydays said:

Isn’t 18mm eye relief pretty good? That’s what the zoom i was looking at listed it as? (Apertura 9mm - 27mm Zoom Eyepiece - ZOOM927), The Baader is 12-15mm which is still really good right?

If the eyepiece actually has that, 18mm is generous eye relief.

Often the actual usable eye relief is rather less though. The eye cup design and eye lens recess can eat into the eye relief.

 

[RT65CB-SWL]

39 minutes ago, Sunnydays said:

Isn’t 18mm eye relief pretty good? That’s what the zoom i was looking at listed it as? (Apertura 9mm - 27mm Zoom Eyepiece - ZOOM927), The Baader is 12-15mm which is still really good right?

18mm is generous; if it remains constant throughout the 9-27mm range.

You may find these articles an interesting read... 
https://www.chuckhawks.com/comparison_zoom_eyepieces.htm  
https://www.chuckhawks.com/common_eyepiece_designs.htm 
...if you have not already done so.

FWIW - I have just read the review of the zoom e/p you are thinking of purchasing too and
the reviewer seems to be happy/pleased with it.
Even the price seems respectable and maybe worth a punt/gamble if your budget funding
is tight/limited and not unlimited. 

[Sunnydays]

White Dwarf- thanks for the articles, great reviews. The Zoom review, basically said that really the Celestron zoom ( bargain) worked just as well as the higher cost zooms reviewed and that they were “a hair better”?   I believe the click zooms are better at not having to focus again after changing magnifications?? For me I believe that if with a single eye piece i am only going to improve the view by lets say 5-8% over the use of a zoom its not that big of difference to justify $65.00 on average for each individual eye piece from 8mm on up? Now as I get more experience and want to see the finer points of a planet etc.. then yes. But starting out, it may be best focusing on getting the object in focus, learning to see which mag works best for you and practicing on skills??? am I wrong?

[Louis D]

2 hours ago, Sunnydays said:

Isn’t 18mm eye relief pretty good? That’s what the zoom i was looking at listed it as? (Apertura 9mm - 27mm Zoom Eyepiece - ZOOM927), The Baader is 12-15mm which is still really good right?

I have a version of the 7.2-21.5mm zoom from that same manufacturer, and though they claim 15mm of design eye relief, it only has 9mm to 11mm of measured usable eye relief, depending on the focal length.  It also claims to have a 40 to 60 degree AFOV, but I measured it as 33 to 49 degrees which is significantly less.  As such, it's a very claustrophobic and difficult to use eyepiece with eyeglasses.  That, and the zooming action is incredibly stiff.  It takes two hands to zoom mine.  I will grant it is very sharp across its limited field, but so would wider AFOV zoom eyepieces be if stopped down by 10 degrees at each end.

Granted, the 9-27mm version has a slightly larger eye lens that seems no less recessed than the 7.2-21.5mm version, so if it claims 18mm of design eye relief, it probably has 12mm to 14mm of usable eye relief by extension from above.  This would make it fairly comfortable to use without eyeglasses, but still nearly impossible to use with eyeglasses.

[Louis D]

2 hours ago, Sunnydays said:

 Thanks so much for the input. I have reads many reviews on the zooms and have found that for the most part they have received no less then 4 out of 5 stars, with ease of use, being able to not have to refocus as much and the clarity has been praised as being on par or at times better then single eye pieces? It seems as though as i have quickly learned that most items come down to user preference and not so much that a single eye piece is going to give anyone 50% better viewing then a zoom. From what i have been told that for most eye pieces from mid to expensive, one might achieve Maybe 5-8% better viewing in general? Don’t expect a drastic change just because something is really expensive? When using my 25mm piece that i got with my 6se i was thrilled at the FOV, so if the zoom that i am looking at goes from 40*-60* which is in line with what the 25mm (60*)gives me, i would be happy? If i want to look at nebulae then I could just get a 32mm? Am I off base with my thinking???

Since your telescope is an f/10 system, it will be fairly gentle on eyepieces and indeed, the differences between lower cost, mid range, and premium eyepieces will be somewhat more subtle than if it was an f/4 system, for instance.  In that case, the differences are not subtle at all once you get away from the central 30% of the FOV.  Budget eyepieces become a blur, mid range eyepieces lose sharpness, while premium eyepieces keep on putting out sharp images at small focal ratios as the edge is approached.  Just about any 7+ element zoom will provide very good views in your telescope.

[Chaz2b]

As much as the the telescope has been carefully designed to give it best performance, the eyepiece generally gets taken for granted.

So far I have owned and used over at least 30 different eyepieces, four zooms, TV Nagler, Baader mk3, TV 8-24...I think. and a Orion, which I’m pretty sure is generic to a lot of brands.
My current crop is TV plossls,  Siberian Erfle 50mm. 
I frequently done comparisons between brands, just to see what the rave was all about, I wasn’t always impressed! Largely because the seeing wasn’t upto much, also, my eyes became tired. Now I have a TV binoviewer and it’s been a revelation, particularly on the planets, my eyes don’t feel so stressed out after an hours viewing!
The point is, that eyepieces are particular to you, your own eyes will verify that when you do comparisons to what others are saying about their experiences with the same eyepiece you are using.

some people can be very critical about their experience, whilst others can be generally happy with their choice.

The best way to find out what works for you, go to a star party, take along your eyepiece collection and get some comparisons.

If you’re hooked on astronomy, then buying the eyepiece that gets you the best result will last you your lifetime, be that singular or zoom, or both!

I do regret selling that TV Nagler zoom...oh! Well.

chaz

 

[MimasDeathStar]

On 26/06/2020 at 18:38, Sunnydays said:

 Thanks so much for the input. I have reads many reviews on the zooms and have found that for the most part they have received no less then 4 out of 5 stars, with ease of use, being able to not have to refocus as much and the clarity has been praised as being on par or at times better then single eye pieces? It seems as though as i have quickly learned that most items come down to user preference and not so much that a single eye piece is going to give anyone 50% better viewing then a zoom. From what i have been told that for most eye pieces from mid to expensive, one might achieve Maybe 5-8% better viewing in general? Don’t expect a drastic change just because something is really expensive? When using my 25mm piece that i got with my 6se i was thrilled at the FOV, so if the zoom that i am looking at goes from 40*-60* which is in line with what the 25mm (60*)gives me, i would be happy? If i want to look at nebulae then I could just get a 32mm? Am I off base with my thinking???

 Where did you get the "5-8%" figure from, I've never heard of eyepieces being quantified on any sort of ranking scale before, short of using a ronchi test I have no idea how it would be possible to make such a statement? Its not really possible to say eyepiece X is 43.7% or whatever better than Y. Like you say, its all subjective. Its only through trial and error that you can make a decision yourself what is an appropriate amount of money to spend on eyepieces.

Just a word of warning though - as I'm sure you will find out in due course - nearly all astronomy items always (and I mean always!) get at least 4 out of 5 stars!

And zooms field of view goes backwards - so it would be 40 degrees at 24mm and then 60 at 8mm (it might not sound it but it is a whopping difference between 40 and 60% at 24mm). Most zooms do need refocussing ever so slightly. The largest drawback with zoom eyepieces is their narrow field of view.

But like you say - there is no eyepiece (zoom or otherwise) that will either A: completely transform your experience at the telescope or B: show you much more or create a transformational experience in terms of sharpness or definition, its worth keeping that in mind if you are feeling overwhelmed.

If Saturn is not completely sharp at 60x in your scope already with your 25mm eyepiece it is almost definitely one of two things - atmospheric conditions (Its really hot, and Saturn is really low, so it'll wobble about in the haze no matter what) OR your scope is out of adjustment. Of the two it is 99% more likely its just the current atmospheric conditions. A £50,000 eyepiece couldn't make it any sharper. But either way, a zoom is a reasonable choice and very versatile.

Edited June 27, 2020 by MimasDeathStar

[Sunnydays]

I had a rep from a company tell me the 5-8% ? He said that for the approx 5-8% better view that one would get from getting very expensive eye pieces or single eye pieces rather then using a zoom, for most people if wouldn’t be worth it? As the difference  would not amount to anything significant?  

[MimasDeathStar]

1 hour ago, Sunnydays said:

I had a rep from a company tell me the 5-8% ? He said that for the approx 5-8% better view that one would get from getting very expensive eye pieces or single eye pieces rather then using a zoom, for most people if wouldn’t be worth it? As the difference  would not amount to anything significant?  

I see. I suppose a rep may be trying to rationalise a nebulous concept so I can see where they are coming from. But I don't agree.

Imagine a scenario where you could get every major eyepiece on the market and test them against these known standards, and then plot them on a chart using a quotient of some sort. Well in that scenario - picking your eyepiece would take 10 seconds and require almost no thought at all. It would be easier for eyepiece manufacturers, and consumers.

But you have to factor in the subjectivity of eyepiece selection - which is based on many more things than just cost:

•  It depends a fair amount on the telescope type, the aperture, the focal length.
• It depends on your favoured targets.
• It depends on your preferred field of view, and then it depends on how happy you are sacrificing edge sharpness for field of view
•  It depends on your own eyes, your own hands, and how comfortable you are getting close to the eyepiece or whether you wear glasses

Only then can you really compare eyepieces, and then it is so so subjective. I've got a 17mm Plossl that cost me about £20 - and I've got a 13mm Baader Hyperion that shows almost the exact same area of sky, but cost £100. In my scope there is very little difference between them. Certainly not a "5-8%" difference. But the hyperion has a wide field of view, slightly better edge sharpness, slightly less light fall off on the edge, a much nicer exit pupil. But it is much heavier. But its also 5x more expensive.

Zoom's are great eyepieces and many people own one (me too), but its not as if they are some well-kept secret. If what the rep was saying were true then very few people would own anything but zoom eyepieces and that's just not the case.