Improving my Eyepiece Options (102mm F10 refractor)

[MercianDabbler]

I've been reading up on eyepieces recently and trying to work out a shopping list myself but there are so many variables that I think I'm just going around in circles.

My scope is a late 1980s Vixen SP102 (1000mm F10) with a 1.25 inch eyepiece fitting.

I currently have two decent eyepieces - both Meade 4000 Super Plossls - 6.4mm and 26mm. I gather that 'Meade 4000 series' covers a bunch of different generations of varying reputation. Mine are late 1980s and made in Japan.

The 26mm is nice to use. The 6mm less so - not enough eye relief and tricky to get my eye lined up correctly to see through it.

I also have the bundled eyepieces that came with my Skywatcher ST80 (10 and 25mm) but I'm not really counting these in the equation. I also have a 2x Barlow from the same bundle.

When I've used the ST80 as a grab and go I've always used the Meade EPs on it.

I look at all sorts of things but my favourites are galaxies and nebulae... but when planets are favourable then I look at those too. I'm more of a sightseer than a dedicated observer.

So, what is missing?

1. Can I get a wider field than I have with the 26mm? Probably not much? I think this has a 23.9mm stop and 1.37 degrees TFOV on a 1000mm scope (and 3.42 degrees on the ST80)
2. Something in between like 10, 12 or 14mm ish. Another Meade 4000 or avoid like the plague?
3. Is there a better option for the high magnification EP that provides more eye relief?
4. Is there any point thinking about a better Barlow or better to save the money for EPs?

Budget-wise I'm thinking that I don't want to shell out for top grade eyepieces for my ageing mid range scope. It's unscientific but EPs that are well into 3 figure prices feel like too much. New or used are both options.

I don't think that fitting a 2 inch focusser is justified in terms of cost or effort and have no plans to change scopes.

Meade 4000s seem to be very numerous on a certain auction site compared to other types. Is that because they just sold more in the first place or because owners are keen to get rid?

Thanks in advance.

[Don Pensack]

3 hours ago, MercianDabbler said:

I've been reading up on eyepieces recently and trying to work out a shopping list myself but there are so many variables that I think I'm just going around in circles.

My scope is a late 1980s Vixen SP102 (1000mm F10) with a 1.25 inch eyepiece fitting.

I currently have two decent eyepieces - both Meade 4000 Super Plossls - 6.4mm and 26mm. I gather that 'Meade 4000 series' covers a bunch of different generations of varying reputation. Mine are late 1980s and made in Japan.

THOSE ARE 5 ELEMENT EYEPIECES MADE BY KOWA IN JAPAN.  IF THEY'RE THE ONES WITHOUT RUBBER EYECUPS, THEY'RE COLLECTOR'S ITEMS NOW.

The 26mm is nice to use. The 6mm less so - not enough eye relief and tricky to get my eye lined up correctly to see through it.

EYE RELIEF ON THE DESIGN IS FOCAL LENGTH X 0.75.

I also have the bundled eyepieces that came with my Skywatcher ST80 (10 and 25mm) but I'm not really counting these in the equation. I also have a 2x Barlow from the same bundle.

When I've used the ST80 as a grab and go I've always used the Meade EPs on it.

I look at all sorts of things but my favourites are galaxies and nebulae... but when planets are favourable then I look at those too. I'm more of a sightseer than a dedicated observer.

So, what is missing?

1. Can I get a wider field than I have with the 26mm? Probably not much? I think this has a 23.9mm stop and 1.37 degrees TFOV on a 1000mm scope (and 3.42 degrees on the ST80)

YES. THE BAADER HYPERION 24MM HAS A 28.5MM FIELD STOP, AND MOST 32 MM PLOSSLS HAVE 27.0MM FIELD STOPS.  A USED 35MM BAADER EUDIASCOPIC HAD A 29MM FIELD STOP IF YOU CAN FIND ONE.
2. Something in between like 10, 12 or 14mm ish. Another Meade 4000 or avoid like the plague?

THE 14MM S4000 WOULD HAVE BEEN THE SHORTEST FOCAL LENGTH WITH A REASONABLE EYE RELIEF.  
3. Is there a better option for the high magnification EP that provides more eye relief?

YES, BAADER HYPERION (OK IN YOUR F/RATIO), BAADER MORPHEUS (TRULY A HIGH-END EYEPIECE IN ALL BUT PRICE), TELE VUE DELITES (ALL), DELOS (ALL), PENTAX XW (ALL), APM ULTRA FLAT FIELD DOWN TO 15MM,

ALTAIR ASTRO ULTRAFLAT (DITTO), ETC.

AND THERE ARE HUNDREDS MORE IF 14-15MM OF EYE RELIEF IS COMFORTABLE ENOUGH
4. Is there any point thinking about a better Barlow or better to save the money for EPs?

Budget-wise I'm thinking that I don't want to shell out for top grade eyepieces for my ageing mid range scope. It's unscientific but EPs that are well into 3 figure prices feel like too much. New or used are both options.

YOUR SCOPE WAS A GOOD ONE.  DON'T CHEAP OUT WITH EYEPIECES UNDER £100 UNLESS YOU STICK TO 50° FIELDS.  THERE ARE A NUMBER OF SUB £100 58-60° FIELDS THAT ARE DECENT EYEPIECES, BUT IF YOU PREFER

65° OR MORE, I'D ADVISE SPENDING A BIT MORE.

I don't think that fitting a 2 inch focusser is justified in terms of cost or effort and have no plans to change scopes.

YOU CAN GET A 1.5° FIELD WITH 1.25", SO NO REAL REASON TO CHANGE FOCUSERS.

Meade 4000s seem to be very numerous on a certain auction site compared to other types. Is that because they just sold more in the first place or because owners are keen to get rid?

MEADE SOLD GOBS OF THESE, BUT BE CAUTIOUS: THE 5 ELEMENT JAPANESE ONE FROM KOWA WAS ONLY MADE UP TO THE START OF 1994.  ANYTHING MADE MID 1994 ON IS 4 ELEMENT AND NO BETTER THAN MANY MODERN PLOSSLS THAT SELL FOR MUCH LESS.

Thanks in advance.

 

[MercianDabbler]

1 hour ago, Don Pensack said:

 

Thanks for your input Don. I must admit that I have not yet understood what apparent FOV is all about... and therefore (I guess) what the value proposition of wide angle eyepieces is - clearly I need to do some more reading on that point before committing to spend money.

I did find a used M4000 26mm of similar vintage to mine on the net this afternoon and was a bit surprised at the price tag. Collectable eyepieces eh? - news to me! Anyway I'm not planning to sell mine on because it's still doing the job that I bought it for. Sounds like I shall steer clear of the later model M4000s.

Most of the TeleVues seem to come with a fairly hefty price tag. I won't say never but I'm not convinced at the moment that I want to go there.

The Vixen SLVs seem well regarded on here and their price tag is only just into three figures (GBP). Anyone care to comment whether one of those would be a good match for my scope in the middle focal length range? (probably 9, 12 or 15mm).

[John]

I was quite impressed with the Vixen SLV's when I reviewed them for the forum. They don't offer a wider view than plossls though.

 

[Paul73]

39 minutes ago, John said:

I was quite impressed with the Vixen SLV's when I reviewed them for the forum. They don't offer a wider view than plossls though.

They are a lot more comfortable to use than the Plossls. I was very impressed with the 5 and 6mm SLVs (haven’t tried any of the longer variants).

Paul

[MercianDabbler]

Hmm... I've been reading up on apparent FoV. I now understand how it is calculated/measured and what it means... but I don't think that's really what I want to know.

I have less understanding on what is good and what is not good in terms of apparent FoV.

I get the feeling from the previous replies that 'more is better'... always??

My current eyepieces (or rather their current equivalents from Meade) both state 52 degrees apparent FoV. Is this good or bad?

I'm somewhat puzzled by the idea that both the 6.4mm and 26mm Meades have the same apparent FoV because they are so different to look through... but me being puzzled by astro kit specs is not really news.

The Baader Hyperions state 68 degrees and say this is 'regarded as ideal' (they would say that, wouldn't they?)... other (higher priced) eyepieces have more... so is more than 68 really 'not ideal'?

The Vixen SLVs state 50 degrees and 45 for the shorter focal lengths, so less than the quoted numbers for my M4000s. Would I notice a difference at 50?... at 45?

I hadn't looked at the Hyperions before. They do look interesting, particularly the ability to attach a camera.

With my engineering head on I can't help wondering if hanging a Canon DSLR onto an eyepiece held by a single clamping screw on the focusser tube would be wise though.

Am I understanding the Hyperion blurb correctly? - would I need 2 inch filters or could I use 1.25 inch filters?

Sorry for the scattergun questions

[John]

Nothing wrong with 30, 40, 50 or more degrees of apparent field. Most plossl eyepieces have an apparent field of 50 or 52 degrees. Most orthoscopics have 40-42 degrees. Wide field designs offer 60-70 degrees, ultra-wides 80 / 82 degrees, hyper-wides 90+ degrees.

It all depends on the view you want and how much you want to spend. Preferences have a lot to do with it. Budgets play a part in narrowing down what is available as well.

The Hyperion eyepieces are 1.25" eyepieces with a 2 inch barrel section. You would use 1.25" filters with them.

Many people find 60-70 degree eyepieces comfortable to observe with both in respect of the eye relief they, offer and the field of view being accessible. Some folks (like myself) also like ultra and hyper wide fields. Some are quite happy with 40-50 degrees but want it very sharp and well corrected.

There are some decent quality zoom eyepieces available today as well - more options !

The market for eyepieces is even more complex than scopes these days - there are so many choices !

Sorry for the "scatter gun" answers !

 

 

 

Edited October 24, 2020 by John

[gilesco]

3 minutes ago, John said:

 

There are some decent quality zoom eyepieces available today as well  more options !

 

This is exactly what crossed my mind when I saw this thread, before getting into imaging I was contemplating eyepiece sets all over, then saw some advice - just get a quality click-step zoom, you can go through most of the sizes very easily, no fumbling around in the dark.

I eventually opted for the Baader Hyperion Zoom, and the Baader 2.25x Barlow to fit it, so it takes me through from 3.5mm - 10mm and 8mm - 24mm, in most cases without really needing to mess about in the dark.

Since I've got into imaging I've not really used it that much, but it isn't something I plan on letting go of. The Pentax zoom is the other one I hear about.

[Louis D]

4 hours ago, MercianDabbler said:

I must admit that I have not yet understood what apparent FOV is all about... and therefore (I guess) what the value proposition of wide angle eyepieces is - clearly I need to do some more reading on that point before committing to spend money.

Wide field eyepieces tend to be addictive.  You may find yourself wanting to go wider and wider until your wallet is empty.

2 hours ago, MercianDabbler said:

Hmm... I've been reading up on apparent FoV. I now understand how it is calculated/measured and what it means... but I don't think that's really what I want to know.

Think of looking through a paper towel tube versus a toilet paper tube versus a one inch long section of the latter.  The field magnification remains the same, but the field of view increases at each step.

2 hours ago, MercianDabbler said:

I'm somewhat puzzled by the idea that both the 6.4mm and 26mm Meades have the same apparent FoV because they are so different to look through... but me being puzzled by astro kit specs is not really news.

You're confused by the two usages of field of view (FOV).  One is true FOV (TFOV) and the other is apparent FOV (AFOV).  TFOV is how much of the actual sky is visible and AFOV is how big of an angle does it subtend across your eye's field of vision as I was alluding to above with the various tubes.

As an extreme example, the original ten or so 9mm ES120 eyepieces came without field stops and had a TFOV just about the same as a 32mm Plossl.  This is because both had about a 27mm field stop (or effective field stop) which is what determines how much of the telescope's image circle (camera speak) is magnified by the eyepiece.  The AFOV though went from 140 degrees (ES-120) down to about 50 degrees (Plossl).  Magnification also more than tripled.  Thus, the experiential difference between the two is enormous.

[MercianDabbler]

13 hours ago, Louis D said:

Wide field eyepieces tend to be addictive.  You may find yourself wanting to go wider and wider until your wallet is empty.

As an extreme example, the original ten or so 9mm ES120 eyepieces came without field stops and had a TFOV just about the same as a 32mm Plossl.  This is because both had about a 27mm field stop (or effective field stop) which is what determines how much of the telescope's image circle (camera speak) is magnified by the eyepiece.  The AFOV though went from 140 degrees (ES-120) down to about 50 degrees (Plossl).  Magnification also more than tripled.  Thus, the experiential difference between the two is enormous.

Yes that is an extreme (but still useful) example... thanks.

I'm familiar with the wallet emptying potential of my hobbies ( I have others ) so I shall try to keep myself under control. My local light pollution also acts as a natural brake on my desire to sink a lot of time and money into astronomy but at the moment I'm feeling that I've blown the dust off the scope this Autumn and refreshed my knowledge of how to use it so some further investment would be a good thing.

To come back to one of my original questions, the Hyperion 24mm would give me 1.63 degrees TFOV vs 1.37 for the Meade 26mm (correct??). Somewhat counter intuitive - my simple logic had suggested that 24mm would be a small step backwards from 26mm and I should be seeking a longer focal length but it seems that my simple logic was wrong.

I can't see the field stop size quoted for the zoom so I'm not sure how that option would measure up against the TFOV question at 24mm.

The Hyperion with its wider field of view and slightly lower price is looking like a better option than the Vixen SLV just now but am I missing someting? - Does the SLV have selling points that the Hyperion lacks?

At the moment I'm tending towards individual eyepieces rather than a zoom - my immediate plan would be to buy just one to fit in between the two Meades that I already have. Going down the zoom route with FLO immediately suggests going for their zoom + Barlow bundle... which puts the price up to 235. This price might not sit so well on the Xmas list. I get the point about the reduced need to swap things in the dark but to swap between, say 6mm and 24mm would still need the Barlow to be added or removed in the dark.

[Louis D]

The Hyperion would yield a significantly wider apparent and true FOV relative to the Meade Plossl.  It might even perform fairly well in your f/10 scope.  Unlike the rest of the Hyperion line, though, it does not perform very well in faster scopes below f/8 or so because it is basically an Erfle variation.  I would get a 24mm APM Ultra Flat Field or one of the other rebrandings (Altair, Meade, Celestron, Orion) out there instead.  It is well corrected even in faster scopes should you ever decide to buy one.

Zooms are very narrow at the long end of their range.  Most affordable zooms tend to have a 35 to 45 degree apparent FOV, so actually less than an equivalent Plossl at that focal length.  They do get decently wide (50 to 70 degrees) at the short end of their range.

The Vixen SLVs are very sharp, well corrected, consistent long eye relief, and have excellent stray light control.  They tend to perform more like premium wide field eyepieces, minus the wide field.  I would only recommend that at 12mm and below because there are better options at longer focal lengths.

[MercianDabbler]

After much more reading, agonizing, indecision and changes of mind I have just pushed the button on a 15mm Vixen SLV.

After initially thinking that I would keep the Skywatcher EPs out of the calculation I decided that that the SWs are probably not the worst ever bundled EPs and an EP at a given focal length is better than no EP. This way I will have four EPs (of varying quality) with reasonably well spaced focal lengths. I was really torn over whether to go for a Hyperion and it was a close run thing but I think their size and weight counted against them with me... plus the 17mm Hyperion seemed to be overlapping very much in terms of TFOV with the 26mm Meade which is my best EP at the moment so I don't want a new EP that is going to persuade me to use my favourite one less often.

Convoluted logic and probably the wrong answer but we shall see how things go when I have some suitable weather after Xmas.

Naturally this exercise has given me quite a wish list of further upgrade options... but that's for another day.

Thank you again to everyone who offered advice.