Eyepiece Advice needed please.

[ukskies]

Hi everyone,

as some of you know I have just bought a Skywatcher 300p synscan dob, now called R2-D2 by swmbo, it came with a few extras but but I got it without any eyepieces. This suited me tbh as now I can buy some really good ones and start my eyepiece collection off.

I would like to keep eye relief at 12mm min wherever possible as I do sometimes wear spectacles when viewing.

First question, do any particular eyepieces work well with this telescope please, from your experience?

I did get a Skywatcher 2" coma corrector with the scope and would appreciate your thoughts on this too please, purely for visual, at least at the moment.

I have owned previously a Teleview 3-6 zoom and tho the eye relief was tough to get on with i did like the ability to match power to seeing and also to warp up into close lunar orbit from some distance away.

With this in mind I have become interested in a Baader hyperion mk 4 zoom with matching 2.25 barlow. Looks good value for what it can do,does the collective have any thoughts on this? 

I also fancy a nice 2" eyepiece, maybe more than one, would you recommend this as a good choice?

I don't mind buying good quality eyepieces but if you know of a mid priced one that works really well then I'm all ears.

And finally I'm hoping, later this year, to be the proud owner of a Takahashi refractor. Obviously there are different focal lengths between the two scopes but I would like to be able to use my eyepieces in both scopes as wherever possible so please bear this in mind or advise if you can

[John]

Congratulations on your Skywatcher 300P - very nice scope with so much potantial

Do you have a budget in mind for eyepieces ?

As you know they range from around £50 apiece to £800+ apiece so having some idea of a guide price does help narrow things down !

The minimum 12mm eye relief guide line is useful. The Nagler zooms have 10mm so I'm not surprised they are marginal for you.

My scopes range from a 100mm Takahashi to a 12 inch dob as well (with other fracs in between) so I've had a similar issue. I've ended up with an eyepiece set for the dob and another one for the refractors but that is a bit extreme I grant you

 

[Timebandit]

 

 

Hi ,sounds like you have a nice reflector already and going to get a quality refractor also. I personally use my Pentax XW range 3.5xw up to the 10XW in my 14" dob reflector and my 120mm frac and they work great in both these scopes. Also there is the TV delos which I am sure would also be worthy of considering. These eyepieces are not the cheapest, but once purchased will be able to be used in a variety of scopes over many years.

I hope the above helps.

 

 

[ukskies]

1 hour ago, John said:

Congratulations on your Skywatcher 300P - very nice scope with so much potantial

Do you have a budget in mind for eyepieces ?

As you know they range from around £50 apiece to £800+ apiece so having some idea of a guide price does help narrow things down !

The minimum 12mm eye relief guide line is useful. The Nagler zooms have 10mm so I'm not surprised they are marginal for you.

My scopes range from a 100mm Takahashi to a 12 inch dob as well (with other fracs in between) so I've had a similar issue. I've ended up with an eyepiece set for the dob and another one for the refractors but that is a bit extreme I grant you

 

Thanks John, Im hoping the scope will be a keeper.

Well the budget is quite tight this month after the scope purchase so probably £600ish? But then I don't have to buy them all at once. so any and all suggestions will be appreciated.

To begin with I'd like to get two different focal lengths this month so split the budget 300 ish each or if I went for a Baader zoom combo say I'd poss have 400 ish for the second choice.

I am aware that buying cheap eyepieces is a waste of money so will avoid that road.

Anybody recommend the Baader zoom or is there more preferred choices?

[ukskies]

1 hour ago, Timebandit said:

 

 

Hi ,sounds like you have a nice reflector already and going to get a quality refractor also. I personally use my Pentax XW range 3.5xw up to the 10XW in my 14" dob reflector and my 120mm frac and they work great in both these scopes. Also there is the TV delos which I am sure would also be worthy of considering. These eyepieces are not the cheapest, but once purchased will be able to be used in a variety of scopes over many years.

I hope the above helps.

 

 

Thank you, yes, I like TV eyepieces and from what I have read the XW's are also highly regarded.

[John]

I've owned a couple of the Baader zooms and found them pretty good eyepieces, for a zoom. They are better than the sub £100 8-24 zooms but not as good as things like the Pentax XW's, TV Delos in my view. A useful tool to have no doubt but personally I would not want to be 100% reliant on the zoom as the only eyepiece I had in the range that it covers.

It's very hard to beat the TV Delos or Pentax XW ranges in my view and I have a mix of them in my 1.25 in set.

I've built up a 5 eyepiece ultra / hyper wide set for my 12 inch dob which comprises of the Nagler 31 and Ethos in 21, 13, 8 and 6mm focal lengths but those would break your budget by quite a bit !

There are lower cost options around from Explore Scientific which are still very good and some of the APM (Germany) eyepieces get very good feedback as well.

I'm sure you will get lots of other suggestions - we all have our favourites

[Geoff Barnes]

I have the same 12 inch Dob as you and I find that just about any decent eyepieces seem to work very well with it.

I too like generous eye relief and a big eye lens for comfortable, relaxed viewing.

I find I use my Baader Mk 1V zoom an awful lot of the time, it works so well with the scope. Also highly recommend the Baader Morpheus ep's, superb quality for the price, sharp, bright images with nice natural colour rendition.

I'm on a fairly tight budget myself but find the Skywatcher Planetary ep's also work superbly well with the scope for high power viewing of the moon and planets for very little cost.

[Ruud]

The telescope has 1500 mm focal length and the focal ratio is f4.9

If you are young and have very dark skies you may want an exit of up to 7mm. In that case you should not get eyepieces longer than 4.9*7 = 34.3mm

Maybe you aren't that young any more and your pupil maxes out at 6 or 5 mm.
Light pollution is also a reason not to use too large an exit pupil.

To keep the exit pupil under 6mm, you should only get eyepieces with focal lengths up to 4.9*6 = 27.6mm
If you want to keep the exit pupil under 5mm, you should limit your eyepieces to focal lengths up to 4.9*5 = 24.5mm

Due to atmospheric seeing, magnifications over 300x are rarely useful.
But if you use an off-axis aperture mask you will occasionally  be able to use 300x.
To get 300x you should use an eyepieces of 1500/300 = 5mm. That would be nice for Moon and planets.

Magnifications of around 200x can be used on more nights.
For 200x you would need an eyepiece of 1500/200 = 7.5mm
Again, an off-axis aperture mask will probably benefit the Moon and  brighter planets, as reducing the aperture tends to improve the seeing.

For deep sky a 2.5 to 3 mm exit pupils are often recommended. Corresponding eyepiece focal lengths are 2.5*4.9 = 12.25mm and 3*4.9 = 14.7mm.

 

For your telescope I would want a set ranging from 5 to 28mm. 

 

 

 

[ukskies]

10 hours ago, John said:

I've owned a couple of the Baader zooms and found them pretty good eyepieces, for a zoom. They are better than the sub £100 8-24 zooms but not as good as things like the Pentax XW's, TV Delos in my view. A useful tool to have no doubt but personally I would not want to be 100% reliant on the zoom as the only eyepiece I had in the range that it covers.

It's very hard to beat the TV Delos or Pentax XW ranges in my view and I have a mix of them in my 1.25 in set.

I've built up a 5 eyepiece ultra / hyper wide set for my 12 inch dob which comprises of the Nagler 31 and Ethos in 21, 13, 8 and 6mm focal lengths but those would break your budget by quite a bit !

There are lower cost options around from Explore Scientific which are still very good and some of the APM (Germany) eyepieces get very good feedback as well.

I'm sure you will get lots of other suggestions - we all have our favourites

You have some lovely quality eyepieces in your collection John no doubt. I would like to get some ultra wide eyepieces myself sometime in the future so thanks for sharing your thoughts.

For the moment at least I am thinking I should be looking at TV delites and Panoptics or Pentax XW's as they fit more within the current budget.

[ukskies]

10 hours ago, Geoff Barnes said:

I have the same 12 inch Dob as you and I find that just about any decent eyepieces seem to work very well with it.

I too like generous eye relief and a big eye lens for comfortable, relaxed viewing.

I find I use my Baader Mk 1V zoom an awful lot of the time, it works so well with the scope. Also highly recommend the Baader Morpheus ep's, superb quality for the price, sharp, bright images with nice natural colour rendition.

I'm on a fairly tight budget myself but find the Skywatcher Planetary ep's also work superbly well with the scope for high power viewing of the moon and planets for very little cost.

Thank you Geoff, I'm very tempted by the mk4 zoom I admit. It's nice to have a zoom in the collection and everyone seems to speak well of this one.

[ukskies]

9 hours ago, Ruud said:

The telescope has 1500 mm focal length and the focal ratio is f4.9

If you are young and have very dark skies you may want an exit of up to 7mm. In that case you should not get eyepieces longer than 4.9*7 = 34.3mm

Maybe you aren't that young any more and your pupil maxes out at 6 or 5 mm.
Light pollution is also a reason not to use too large an exit pupil.

To keep the exit pupil under 6mm, you should only get eyepieces with focal lengths up to 4.9*6 = 27.6mm
If you want to keep the exit pupil under 5mm, you should limit your eyepieces to focal lengths up to 4.9*5 = 24.5mm

Due to atmospheric seeing, magnifications over 300x are rarely useful.
But if you use an off-axis aperture mask you will occasionally  be able to use 300x.
To get 300x you should use an eyepieces of 1500/300 = 5mm. That would be nice for Moon and planets.

Magnifications of around 200x can be used on more nights.
For 200x you would need an eyepiece of 1500/200 = 7.5mm
Again, an off-axis aperture mask will probably benefit the Moon and  brighter planets, as reducing the aperture tends to improve the seeing.

For deep sky a 2.5 to 3 mm exit pupils are often recommended. Corresponding eyepiece focal lengths are 2.5*4.9 = 12.25mm and 3*4.9 = 14.7mm.

 

For your telescope I would want a set ranging from 5 to 28mm. 

 

 

 

Thank you Ruud for your interesting post, I'll take that into consideration. This has given me something to think about.

A question though if i may. Does going to the smallest exit pupil not affect the ease of viewing afforded by a slightly larger one. I get what you are saying that some of the light is wasted if your exit pupil is larger than your eye can accommodate but doesn't that allow a bit of latitude with eye position?

Maybe it depends on the target too? Would I be right in thinking that on brighter targets that have too much brightness, a large exit pupil would be less of a problem than on a dim and distant target or am I barking up the wrong tree?

[Ruud]

4 hours ago, ukskies said:

A question though if i may. Does going to the smallest exit pupil not affect the ease of viewing afforded by a slightly larger one. I get what you are saying that some of the light is wasted if your exit pupil is larger than your eye can accommodate but doesn't that allow a bit of latitude with eye position?

With a smaller exit pupil, blackouts will happen less frequently, but very suddenly. Small exit pupils give you more space available to mover your head around without causing any loss of light, though if you do get a blackout with a small exit pupil, it kind of comes without warning.

4 hours ago, ukskies said:

Maybe it depends on the target too? Would I be right in thinking that on brighter targets that have too much brightness, a large exit pupil would be less of a problem than on a dim and distant target or am I barking up the wrong tree?

Yes, for the Moon and brighter planets smaller exit pupils (XPs) are fine (unless the exit pupil gets smaller than 0.5 mm - then the blur from diffraction effects becomes so big than the any advantage of higher magnifications is lost).
Deep sky benefits most from mid-sized XPs.
For observing in light polluted areas XPs of 5mm or less are recommended. Contrast is better when background isn't too bright.
Because of the shadow of the secondary mirror, for reflectors exit pupils ideally should not be bigger than the observer's pupil. (You don't want the secondary's shadow to fill your pupil.)
The main advantage of larger XPs is that they come with lower magnification, allowing larger targets to fit in the view.
Refractors have no secondary: with a refractor, even when the exit pupil exceeds your own, the image will not dim form that. It just stops getting brighter. But the view gets wider.

 

Edited February 9, 2020 by Ruud

[ukskies]

2 hours ago, Ruud said:

With a smaller exit pupil, blackouts will happen less frequently, but very suddenly. Small exit pupils give you more space available to mover your head around without causing any loss of light, though if you do get a blackout with a small exit pupil, it kind of comes without warning.

Yes, for the Moon and brighter planets smaller exit pupils (XPs) are fine (unless the exit pupil gets smaller than 0.5 mm - then the blur from diffraction effects becomes so big than the any advantage of higher magnifications is lost).
Deep sky benefits most from mid-sized XPs.
For observing in light polluted areas XPs of 5mm or less are recommended. Contrast is better when background isn't too bright.
Because of the shadow of the secondary mirror, for reflectors exit pupils ideally should not be bigger than the observer's pupil. (You don't want the secondary's shadow to fill your pupil.)
The main advantage of larger XPs is that they come with lower magnification, allowing larger targets to fit in the view.
Refractors have no secondary: with a refractor, even when the exit pupil exceeds your own, the image will not dim form that. It just stops getting brighter. But the view gets wider.

 

Ruud, thank you very much for the explanation. I am able to understand now after reading that.

[ukskies]

Right, most of the day doing internet research has led me to believe that there is little to chose between the TV Delos and the Pentax XW's.

Would this be a reasonable assumption? The Delos is much more expensive and I'm on a budget so if this is the case then the Pentax XW's appear to be terrific value.

I'm going to not order a Baader zoom for the time being and would prefer to order a couple of XW's instead.

Would this be a wise thing to do? Any thoughts on this would be greatly appreciated.

Is there a problem with field curvature in the longer fl Xw's?

Edited February 9, 2020 by ukskies

[Louis D]

2 hours ago, ukskies said:

The Delos is much more expensive and I'm on a budget so if this is the case then the Pentax XW's appear to be terrific value.

Only a $50 difference in the US.  Perhaps more in the UK then.

2 hours ago, ukskies said:

Is there a problem with field curvature in the longer fl Xw's?

The 14mm and 20mm do have some, but if you're young, your eye may be able to accommodate the difference when gazing from the center to edge.  I used the 14mm Pentax XL for years without noticing field curvature.  Then during my mid-late 40s, presbyopia set in and I could clearly tell that center and edge focused at two different distances.  Once refocused, the edge is pin sharp.  I ended up replacing it with a 14mm Morpheus despite its edge astigmatism and slight field curvature.  That larger apparent FOV is just so much more immersive than the XL's 65 degrees.

The 7mm Pentax XW is nice, but it has some edge issues.  The 3.5mm XW is pretty much flawless.

I'd look into the 6.5mm and 9mm Morpheus as well.  I have the latter, and it pretty much the equal of my 10mm Delos.  The 6.5mm is supposed to be similar.

For a 2", check out the 30mm APM Ultra Flat Field.  I really like how immersive, flat of field, and well corrected to the edge it is.  It also has really comfortable eye relief.  I ended up retiring my venerable 27mm Panoptic in favor of it.

For a mid-range, the 17.5mm Morpheus is supposed to be pretty nice.  Personally, I really like the 17mm ES-92, but it is huge and heavy.

[Ricochet]

2 hours ago, ukskies said:

Is there a problem with field curvature in the longer fl Xw's?

Your current dob has a large radius of curvature so the combined fc might be acceptable. I've got a 14XW and 8" dob that are ok together, but focusing slightly off centre does help. However, if the Tak you are possibly getting is a doublet then it will have a very small radius of curvature and the combined fc will be higher. I would estimate that approximately 99% of the people who complain about fc in the 14/20mm XWs are trying to use them in doublet fracs. 

[ukskies]

2 minutes ago, Ricochet said:

Your current dob has a large radius of curvature so the combined fc might be acceptable. I've got a 14XW and 8" dob that are ok together, but focusing slightly off centre does help. However, if the Tak you are possibly getting is a doublet then it will have a very small radius of curvature and the combined fc will be higher. I would estimate that approximately 99% of the people who complain about fc in the 14/20mm XWs are trying to use them in doublet fracs. 

Thanks, that's really good to know.

tbh there are so many eyepieces available that I'm having trouble deciding which to go for. I figure the Pentax XW's are good sharp eyepieces and excellent quality. Everyone seems to like them from all the reviews so they seem to be a good choice.

[Louis D]

7 hours ago, Ricochet said:

I would estimate that approximately 99% of the people who complain about fc in the 14/20mm XWs are trying to use them in doublet fracs. 

Actually, many of them are older with presbyopia and can no longer accommodate field curvature.  I used to be able to accommodate it, but no longer.  That's why it's important to understand each observer's situation.  Not only what telescope was the eyepiece used in, but what condition are the observer's eyes in (presbyopia, astigmatism, distance vision, etc.) and type of correction or lack of any.

[rwilkey]

Hi Gary, congratulations on your new 300P, a great choice.  Talking about eyepieces, if I was only allowed two eyepieces on a desert island they would be:

TV Panoptic 24mm
TV Nagler (T6) 13mm

I, inherently, don't like zooms and prefer fixed focal lengths.

[ukskies]

22 hours ago, Louis D said:

Only a $50 difference in the US.  Perhaps more in the UK then.

The 14mm and 20mm do have some, but if you're young, your eye may be able to accommodate the difference when gazing from the center to edge.  I used the 14mm Pentax XL for years without noticing field curvature.  Then during my mid-late 40s, presbyopia set in and I could clearly tell that center and edge focused at two different distances.  Once refocused, the edge is pin sharp.  I ended up replacing it with a 14mm Morpheus despite its edge astigmatism and slight field curvature.  That larger apparent FOV is just so much more immersive than the XL's 65 degrees.

The 7mm Pentax XW is nice, but it has some edge issues.  The 3.5mm XW is pretty much flawless.

I'd look into the 6.5mm and 9mm Morpheus as well.  I have the latter, and it pretty much the equal of my 10mm Delos.  The 6.5mm is supposed to be similar.

For a 2", check out the 30mm APM Ultra Flat Field.  I really like how immersive, flat of field, and well corrected to the edge it is.  It also has really comfortable eye relief.  I ended up retiring my venerable 27mm Panoptic in favor of it.

For a mid-range, the 17.5mm Morpheus is supposed to be pretty nice.  Personally, I really like the 17mm ES-92, but it is huge and heavy.

Hi Louis, thanks for your post.

Unfortunately I am no longer young and my eyes ,tho pretty good still, have aged.

Your comments about the Morpheus are interesting, I did look at those before the XW's. How do you think they would compare? Everybody speaks well of the XW's.

Edited February 10, 2020 by ukskies

[ukskies]

6 hours ago, rwilkey said:

Hi Gary, congratulations on your new 300P, a great choice.  Talking about eyepieces, if I was only allowed two eyepieces on a desert island they would be:

TV Panoptic 24mm
TV Nagler (T6) 13mm

I, inherently, don't like zooms and prefer fixed focal lengths.

Thank you Robin, I always liked the TV's, they are superbly sharp.

I'm just thinking that I might get more eyepieces for my budget with something of comparable quality with a different manufacturer. I won't rule out having some TV's in my collection in the future though.

I'm actually thinking that it might be a good idea to use different manufacturers.

Looking at your signature I see you have several manufacturers listed in you collection.

Edited February 10, 2020 by ukskies

[John]

For my 1.25 inch set I went for:

24mm Panoptic

17.3 and 14mm Delos

10mm, 7mm, 5, and 3.5mm Pentax XW's.

I also have a 2-4mm Nagler zoom but that won't get much used in a 12 inch F/5 scope.

I opted for the 17.3 and 14 Delos over the Pentax XW 20 and 14mm because of the field curvature. The 17.3 and 14 Delos have focal points close to the XW's whereas the other Delos reach focus around 8mm further outwards.

Optically and for viewing comfort the Delos and XW's are very similar indeed.

 

[ukskies]

2 minutes ago, John said:

For my 1.25 inch set I went for:

24mm Panoptic

17.3 and 14mm Delos

10mm, 7mm, 5, and 3.5mm Pentax XW's.

I also have a 2-4mm Nagler zoom but that won't get much used in a 12 inch F/5 scope.

I opted for the 17.3 and 14 Delos over the Pentax XW 20 and 14mm because of the field curvature. The 17.3 and 14 Delos have focal points close to the XW's whereas the other Delos reach focus around 8mm further outwards.

Optically and for viewing comfort the Delos and XW's are very similar indeed.

 

Thank you John, That looks just like a shopping list! 😀

I'm going to avoid zooms for the time being but I was already thinking the shorter XW's up to 10mm would be worth a try. The Delos is a nice recommendation tho, I'll give that some attention, thanks.

[Timebandit]

9 minutes ago, John said:

For my 1.25 inch set I went for:

24mm Panoptic

17.3 and 14mm Delos

10mm, 7mm, 5, and 3.5mm Pentax XW's.

I also have a 2-4mm Nagler zoom but that won't get much used in a 12 inch F/5 scope.

I opted for the 17.3 and 14 Delos over the Pentax XW 20 and 14mm because of the field curvature. The 17.3 and 14 Delos have focal points close to the XW's whereas the other Delos reach focus around 8mm further outwards.

Optically and for viewing comfort the Delos and XW's are very similar indeed.

 

 

 

 

Nice eyepiece choice there John. I think many newbies or more experienced alike who are looking for a set of quality eyepieces will not go far wrong with your suggestions 👍

 

 

 

[Louis D]

58 minutes ago, ukskies said:

Hi Louis, thanks for your post.

Unfortunately I am no longer young and my eyes ,tho pretty good still, have aged.

Your comments about the Morpheus are interesting, I did look at those before the XW's. How do you think they would compare? Everybody speaks well of the XW's.

I have the 9mm Morpheus and 10mm Delos, and they are very close.  Both are very sharp and contrasty center to edge.  The Morpheus is noticeably wider.  Here's a comparison of images shot through my various 9mm/10mm eyepieces using my AstroTech 72ED refractor.  The full view is shot with a lower resolution, wider field of view phone camera and resized upward to match resolution, so don't pay too much attention to it for sharpness.  It's mostly there to give you a better idea of its apparent field of view.