Celestron 8 - 24mm Zoom Eyepiece - Should I buy it?

[JonnyAlpha]

Hi;

I asked on here a while ago about what lenses to get for my Celestron Astromaster 130EQ scope, here's the thread.

Due to time I never got around to getting them. I am now thinking of getting some lenses for this scope, the above post suggested an 8, 18 and 25mm and a 2 x Barlow however I just spotted one of these in my local camera shop.

Question:

What sort of usage will I get out of this lens on my scope. I am a beginner and would like to be able to look at something more that just dots of light in the sky, possibly a bit of colour when looking at stars and be able to make out some planets?

Would this lens be a better option than buying 3 lenses (8, 18 and 25mm)

If I get this lens should I also get a 2 x Barlow and a Moon filter?

I currently only have two lenses for my Celestron, the 20mm erecting eye piece and a 10mm lens.

 

Thanks for your advice :-)

 

  

 

 

 

[Louis D]

It's a passable zoom, just don't expect great things from it.  This zoom is head and shoulders better.  I use two in my binoviewer.

[JonnyAlpha]

You use this in a Bino viewer,  I want to use this in a Telescope as a main lens instead of using separate lenses will the standard one I linked or the regal one you linked work great in my Astro Master in place of individual lenses? 

[billyharris72]

Hi JonnyAlpha:

In general, a zoom eyepiece won't perform as well as those of a fixed focal length. You are likely to find the image is compromised by being less bright, having light scattered (glare) or being distorded away from the centre of the image. Also, the field of view tends to be narrow compared to fixed focal length eyepieces, especially at the longer focal lengths.

That's not to say zooms don't have a place - they are very convenient - but if you are after a better quality image I think you would be better off buying the separate eyepieces and a Barlow.

Billy.

[F15Rules]

It depends what your budget is and whether a zoom will focus on your scope. 

Assuming it will focus ok ( and maybe some reflector users can chip in here), I would either buy 3 fixed focal length EPs or a decent used Baader MKIII zoom..on the used market.

Expect to pay around £120 for 3 decent used fixed EPs or one Baader zoom. If you like your scope you will get more out of it this way.

UKAstrobuysell have lots of decent used gear every day..

Good luck:-)

Dave

[Grotemobile]

I have got one. I find it handy for getting the right magnification on something.

I start @ 24x & then work down. I think it is worth getting.  

[RobertI]

I think field of view is a big factor to consider. I have a Seben Zoom, which has the same FOV ranges as the the Celestron zoom in your link, ie: 60 degrees at 24mm reducing to 40 degrees at 8mm. I got my zoom to aid my grab and go astronomy with my small refractor by replacing my two Hyperion eyepieces which have a FOV of 68 degrees. Unfortunately 40 degrees is just too narrow for me compared to 68 degrees (the experience just isn't the same), so I have reverted to using two eyepieces again. I think even the 52 degrees of a more premium zoom such as the Baader Hyperion Zoom would not suit me. I suspect your existing eyepieces are not very wide field so you may not notice such a difference, but I would personally now go for a couple of decent wide field eyepieces instead of a zoom.

But if your objective is to save money by not buying three eyepieces, then that is a different matter!!

[JonnyAlpha]

Money is not really a major issue up to £200 would be OK and if by spending a little more I will get a much better experience then that's the way to go. Basically I want to be able to make out some features of stars such as colour and see planets a little better than just a small white dot. 

So to replace my current stock EP should I get an 8mm 18mm and 24mm, is it worth also getting a 2 x Barlow? What make of lenses Celestron (Omni Plossyl) ? 

[JonnyAlpha]

This for instance This sorry did this on my smart phone :-) 

[Louis D]

Eyepiece kits usually come with less than stellar eyepieces and filters you'll rarely use.  Consider the BST Explorer line for starters instead.  They come in a range of lengths, have 60 degree AFOV, and decent eye relief.

[F15Rules]

I 

 

1 hour ago, Louis D said:

Eyepiece kits usually come with less than stellar eyepieces and filters you'll rarely use.  Consider the BST Explorer line for starters instead.  They come in a range of lengths, have 60 degree AFOV, and decent eye relief.

Agree with this 100%. Try the eyepieces first, a Barlow can wait til you're sure you need one:-)

Dave

[JonnyAlpha]

9 hours ago, Louis D said:

Eyepiece kits usually come with less than stellar eyepieces and filters you'll rarely use.  Consider the BST Explorer line for starters instead.  They come in a range of lengths, have 60 degree AFOV, and decent eye relief.

Any good sellers in to UK looking at the reviews is confusing someone rates SWL as sharper? 

[JonnyAlpha]

OK so having read Robin Wilkey's guide here  I am considering 3 lenses (32mm, 15mm, 9mm and 6mm) and a 2 x Barlow Lens, either Celestron or BST Explorer.

Couple of questions :

1. I have a Celestron Astromaster 130EQ and from previous research I seem to recall something about the maximum magnification affecting lens choice, so will my scope work with a 6mm lens?

2. The 15mm will Barlow down to 7.5mm and the 9mm down to 4.5mm so if these are beyond my maximum magnification maybe I should not bother with the Barlow?

3. I wear glasses for close up work and also for distance - which are the better lenses for this.

4. As highlighted below I cannot find the sizes recommend by Robin in the BST Explorer range so have opted for a 25mm, 15mm, and 8mm would this range be good? 

5. Can anyone recommend some filters to add to this list?

Anyway price comparisons and options:  

Celestron Omin Plossyl:

First Light Optics (cheaper than Amazon), Celestron Omni Plossyl 32mm, 15mm, 9mm, 6mm (As recommended in the link) and a Celestron 2 x Universal Barlow = £122.55

BST Explorer: (Don't seem to sell above 25mm (are they available?)), BST Explorer 25mm, 15mm and 8mm (No Barlow) = £139.20

According to the guide I linked he also thoroughly recommends the BST Explorer range but they don't do a 32mm?

 

  

[Louis D]

Let me answer your questions one point at a time:

1. Technically, you should be able to go up to 50X your aperture in inches in power, thus 5*50=250X.  Realistically, I've found 30X more reasonable for Newts, so 5*30=150X for a maximum magnification.  Given the focal length, you can work backward to find your minimum eyepiece focal length: 650mm/150X=4.3mm.  That would yield an exit pupil of 130mm/150x=0.86mm (aperture/power=exit pupil at the eye lens).  That is still usable.  Go much below 0.7mm, and floaters in your eye become a big issue.  Your eyepiece and barlow choices are all above this lower limit, so you should be good.  You can always experiment with a short eyepiece in a barlow to see if it is usable for you.  There's no harm in trying.

2. A good barlow lens can clean up the edges in longer focal length eyepieces and yield longer eye relief at shorter focal lengths by using longer focal length eyepieces at higher powers.  The downside is that they are one more thing to swap in and out of the optical train.  When using one, I tend to just leave it in the focuser for all eyepieces when looking for the best high power view.

3. There are only two reasons to wear eyeglasses at the eyepiece: 1) You have strong astigmatism (cylinder correction and axis on your prescription) that will distort stars into crosses even at best focus, or 2) You are constantly looking back at star charts or up at the naked-eye sky.  You'll need 16mm to 20mm of eye relief to see the entire field with glasses on.  It depends on how the manufacturer measures the eye relief, how deeply set your eyes are, and how close your eyeglasses are to your eyes.  The BSTs are known for good eye relief as are the Celestron X-Cel LX and Meade HD-60 lines.  All three get good reviews.  It comes down to price and availability.

4. Because the apparent field of view is 60 degrees, those would be good choices.  If you are looking at 50 degrees, then get a 32mm plossl for your lowest power eyepiece.  If you had a 2 inch focuser, you would have more low power options.  Those eyepiece lines I listed above max out at 25mm because at 60 degrees, you get about the same field of view as a 32mm 50 degree eyepiece.  It's the 1.25 inch barrel that limits the maximum true field of view.  That's where the 2 inch focuser comes into play.

5. Everyone finds an 80A light blue filter to be universally helpful with Jupiter.  A medium red or orange filter can help with Mars.  Avoid the dark ones, it's hard to make out anything at all through them.  An OIII filter helps immensely with nebula like the Orion or Veil nebulae.  Many people like the Baader Moon & Skyglow filter not just for cutting through light pollution, but also for improving contrast on planets like Jupiter.  Lastly, there's the UHC class of nebula filters that have a wider notch than the OIII ones to also let some H-Beta (and even a little B-Alpha) emissions through as well.

You'll probably hate the 8mm plossl due to an eye relief of around 6mm, so don't even consider it.  Pretty much no one likes plossls that short in focal length.

The BSTs (and X-Cel LX/HD60) all have a consistent 16mm or so of eye relief.  They also have 60 degree AFOVs rather than 50 degree AFOVs like plossls.  You'll notice the difference.  They are also better corrected across the inner 50 degrees than are the plossls.  If you want to try plossls sometime in the future, you can always pick they up for cheap used.  They do work well in binoviewers, I've found.

Again, the lack of a 32mm BST is  a non-issue.  The true field of view will be just about the same for a 25mm BST as for a 32mm plossl, only at a higher power which will yield a darker sky background (a good thing).  You can always add a used 32mm plossl later if you want to ensure you're getting the maximum TFOV.

[Highburymark]

Some excellent advice from Louis.

When you're starting out the temptation is to try and cover every option, and all too often that means buying a high magnification eyepiece - which in practice overpowers the telescope and will rarely be used unless you're looking at the moon. 

You have a telescope with excellent optics - particularly for the price - but ramp up the power too much and you'll find the mount gets increasingly jittery. So the best advice is to get EPs that you will USE - you can always make additions in the future.

Another small point - a lot of zoom eyepieces used by astronomers were originally designed for spotting scopes. They are just as effective for stargazing as for any other task. But I agree with others' advice that you'd be better off with 3 fixed focal length EPs - and the BSTs are constantly recommended on this website for unbeatable value and quality.

[Louis D]

Zooms are handy when binoviewing because it's a royal pain to swap out a pair of eyepieces, make sure the new ones are fully seated to avoid tilting due to their undercuts, and then try to reacquire the target in a non-tracking telescope.  The only problem is getting your nose between two wide zooms.  Thus, you need to make sure the top tapers enough for your nose to fit.  That's why I like this zoom as mentioned above because the entire eyeguard mechanism can be screwed off, leaving a fairly narrow eye lens region.  With the effective 3X OCA ahead of them to reach focus, they are sharp to the edge at all focal lengths.

[JonnyAlpha]

2 hours ago, Louis D said:

Let me answer your questions one point at a time:

1. Technically, you should be able to go up to 50X your aperture in inches in power, thus 5*50=250X.  Realistically, I've found 30X more reasonable for Newts, so 5*30=150X for a maximum magnification.  Given the focal length, you can work backward to find your minimum eyepiece focal length: 650mm/150X=4.3mm.  That would yield an exit pupil of 130mm/150x=0.86mm (aperture/power=exit pupil at the eye lens).  That is still usable.  Go much below 0.7mm, and floaters in your eye become a big issue.  Your eyepiece and barlow choices are all above this lower limit, so you should be good.  You can always experiment with a short eyepiece in a barlow to see if it is usable for you.  There's no harm in trying.

2. A good barlow lens can clean up the edges in longer focal length eyepieces and yield longer eye relief at shorter focal lengths by using longer focal length eyepieces at higher powers.  The downside is that they are one more thing to swap in and out of the optical train.  When using one, I tend to just leave it in the focuser for all eyepieces when looking for the best high power view.

3. There are only two reasons to wear eyeglasses at the eyepiece: 1) You have strong astigmatism (cylinder correction and axis on your prescription) that will distort stars into crosses even at best focus, or 2) You are constantly looking back at star charts or up at the naked-eye sky.  You'll need 16mm to 20mm of eye relief to see the entire field with glasses on.  It depends on how the manufacturer measures the eye relief, how deeply set your eyes are, and how close your eyeglasses are to your eyes.  The BSTs are known for good eye relief as are the Celestron X-Cel LX and Meade HD-60 lines.  All three get good reviews.  It comes down to price and availability.

4. Because the apparent field of view is 60 degrees, those would be good choices.  If you are looking at 50 degrees, then get a 32mm plossl for your lowest power eyepiece.  If you had a 2 inch focuser, you would have more low power options.  Those eyepiece lines I listed above max out at 25mm because at 60 degrees, you get about the same field of view as a 32mm 50 degree eyepiece.  It's the 1.25 inch barrel that limits the maximum true field of view.  That's where the 2 inch focuser comes into play.

5. Everyone finds an 80A light blue filter to be universally helpful with Jupiter.  A medium red or orange filter can help with Mars.  Avoid the dark ones, it's hard to make out anything at all through them.  An OIII filter helps immensely with nebula like the Orion or Veil nebulae.  Many people like the Baader Moon & Skyglow filter not just for cutting through light pollution, but also for improving contrast on planets like Jupiter.  Lastly, there's the UHC class of nebula filters that have a wider notch than the OIII ones to also let some H-Beta (and even a little B-Alpha) emissions through as well.

You'll probably hate the 8mm plossl due to an eye relief of around 6mm, so don't even consider it.  Pretty much no one likes plossls that short in focal length.

The BSTs (and X-Cel LX/HD60) all have a consistent 16mm or so of eye relief.  They also have 60 degree AFOVs rather than 50 degree AFOVs like plossls.  You'll notice the difference.  They are also better corrected across the inner 50 degrees than are the plossls.  If you want to try plossls sometime in the future, you can always pick they up for cheap used.  They do work well in binoviewers, I've found.

Again, the lack of a 32mm BST is  a non-issue.  The true field of view will be just about the same for a 25mm BST as for a 32mm plossl, only at a higher power which will yield a darker sky background (a good thing).  You can always add a used 32mm plossl later if you want to ensure you're getting the maximum TFOV.

Many thanks for the comprehensive answer which I think I understand.

Based on your comments I should get a BST Explorer 25mm, 15mm and 8mm (No Barlow) = £139.20 

Which Barlow should I get to compliment these BST eyepieces and what would be the minimum recommended filters to get? Do you need an adapter for the filters or do the screw on any eyepiece?  

[Louis D]

I'll let others answer about which modern barlow to buy.  I'm partial to my ancient Meade 140 APO 2X even over my Televue 2X.  My advice, avoid shorty barlows.  I have one from China, and it is awful.  Apparently, the higher end ones can be good, but the entry level ones are not good in my estimation.  Try to find a medium to long barlow made in Japan or Taiwan.  I have a 2 inch GSO ED 2X which is excellent, so GSO (rebadged under various house brands) would seem like a good one to look for.

Start with an 80A filter, a light orange or red filter, and a neutral density moon filter because they'll be under $15 each.  The others I listed are much more expensive.  And no, you don't need an adapter to screw them into the bottom of an eyepiece.  Just make sure to buy the 1.25" version.  The only exception to this are Brandon eyepieces which have a different thread and do require an adapter.  It's a historical thing with them.  Check the classifieds to see if anyone is selling theirs.  Well cared for, age is unimportant for them.  You could even put out a want ad.  I'm sure someone is itching to unload a few filters not seeing regular use.

Oh, and that zoom I recommended?  It doesn't have filter threads at all to shorten the barrel to make it come to focus in spotting scopes.  Not a big deal for binoviewers since any filters would be placed before the binoviewer.

[Louis D]

I just got back inside from viewing Jupiter.  I tried the Meade blue filter I have that's part of an astrophotography set, and it definitely made the GRS stand out better.  My Zhumell Urban Sky Filter (similar to the Baader M&SG) also improved contrast on Jupiter somewhat.  My red and green filters did nothing for Jupiter.  My Lumicon UHC did help a little on Jupiter.  Mainly, it gave it funky green outlines around pinkish belts.  Using my binoviewer reduced eye strain immensely over monoviewing, but didn't really reveal much more detail.  My GSO coma corrector definitely flattens the field and sharpens up wide field images.  Once again, I absolutely love my vintage Meade 140 2X barlow.  Very sharp with no aberrations like blooming or blurring on Jupiter.

[RobertI]

14 hours ago, Louis D said:

Let me answer your questions one point at a time:

1. Technically, you should be able to go up to 50X your aperture in inches in power, thus 5*50=250X.  Realistically, I've found 30X more reasonable for Newts, so 5*30=150X for a maximum magnification.  Given the focal length, you can work backward to find your minimum eyepiece focal length: 650mm/150X=4.3mm.  That would yield an exit pupil of 130mm/150x=0.86mm (aperture/power=exit pupil at the eye lens).  That is still usable.  Go much below 0.7mm, and floaters in your eye become a big issue.  Your eyepiece and barlow choices are all above this lower limit, so you should be good.  You can always experiment with a short eyepiece in a barlow to see if it is usable for you.  There's no harm in trying.

2. A good barlow lens can clean up the edges in longer focal length eyepieces and yield longer eye relief at shorter focal lengths by using longer focal length eyepieces at higher powers.  The downside is that they are one more thing to swap in and out of the optical train.  When using one, I tend to just leave it in the focuser for all eyepieces when looking for the best high power view.

3. There are only two reasons to wear eyeglasses at the eyepiece: 1) You have strong astigmatism (cylinder correction and axis on your prescription) that will distort stars into crosses even at best focus, or 2) You are constantly looking back at star charts or up at the naked-eye sky.  You'll need 16mm to 20mm of eye relief to see the entire field with glasses on.  It depends on how the manufacturer measures the eye relief, how deeply set your eyes are, and how close your eyeglasses are to your eyes.  The BSTs are known for good eye relief as are the Celestron X-Cel LX and Meade HD-60 lines.  All three get good reviews.  It comes down to price and availability.

4. Because the apparent field of view is 60 degrees, those would be good choices.  If you are looking at 50 degrees, then get a 32mm plossl for your lowest power eyepiece.  If you had a 2 inch focuser, you would have more low power options.  Those eyepiece lines I listed above max out at 25mm because at 60 degrees, you get about the same field of view as a 32mm 50 degree eyepiece.  It's the 1.25 inch barrel that limits the maximum true field of view.  That's where the 2 inch focuser comes into play.

5. Everyone finds an 80A light blue filter to be universally helpful with Jupiter.  A medium red or orange filter can help with Mars.  Avoid the dark ones, it's hard to make out anything at all through them.  An OIII filter helps immensely with nebula like the Orion or Veil nebulae.  Many people like the Baader Moon & Skyglow filter not just for cutting through light pollution, but also for improving contrast on planets like Jupiter.  Lastly, there's the UHC class of nebula filters that have a wider notch than the OIII ones to also let some H-Beta (and even a little B-Alpha) emissions through as well.

You'll probably hate the 8mm plossl due to an eye relief of around 6mm, so don't even consider it.  Pretty much no one likes plossls that short in focal length.

The BSTs (and X-Cel LX/HD60) all have a consistent 16mm or so of eye relief.  They also have 60 degree AFOVs rather than 50 degree AFOVs like plossls.  You'll notice the difference.  They are also better corrected across the inner 50 degrees than are the plossls.  If you want to try plossls sometime in the future, you can always pick they up for cheap used.  They do work well in binoviewers, I've found.

Again, the lack of a 32mm BST is  a non-issue.  The true field of view will be just about the same for a 25mm BST as for a 32mm plossl, only at a higher power which will yield a darker sky background (a good thing).  You can always add a used 32mm plossl later if you want to ensure you're getting the maximum TFOV.

Some great advice, a nice summary of some complicated issues. 

[Mark at Beaufort]

That is an excellent thread by Louis D with some very useful advice. I have tried several zooms over the years - Baader Hyperion, Pentax 6.5-19.5 and currently a TeleVue 8-24mm. They are very useful in their own way but I would agree that a small set of fixed eyepieces would serve you better. One of the main disadvantages of zooms is the small FOV at the lower end and many people buy a fixed 24mm EP to overcome that problem.

[Ricochet]

Bresser still have 16 mm and 24 mm ES 68 degree eyepieces in their sale (does it ever end?) which I would recommend over the 15mm and 25mm BST's. Usually they would be double the price of a BST and blow your budget but at about £60 each at the current exchange rate they might be affordable. The BST's are still very good eyepieces that you might never feel the need to upgrade, but the ES68's give you a slightly wider field of view (the 24 is the same as a 32mm Plossl and the max for your scope) and I think a slightly better corrected image.

[LukeSkywatcher]

Zooms can be very handy. Not quite up to the quality views of individual eyepieces, but very close. EP kits are OK, but you do get a lot of stuff in it that is there just to fill the case and you will not use often if ever. The basic EP collection everyone should have should include a low,medium and high powered EP (so something like 30mm,15mm and 9mm). With these 3 EP's you wont have much need for a 2x Barlow. 

 

[JonnyAlpha]

On 4/22/2016 at 16:53, Louis D said:

Let me answer your questions one point at a time:

1. Technically, you should be able to go up to 50X your aperture in inches in power, thus 5*50=250X.  Realistically, I've found 30X more reasonable for Newts, so 5*30=150X for a maximum magnification.  Given the focal length, you can work backward to find your minimum eyepiece focal length: 650mm/150X=4.3mm.  That would yield an exit pupil of 130mm/150x=0.86mm (aperture/power=exit pupil at the eye lens).  That is still usable.  Go much below 0.7mm, and floaters in your eye become a big issue.  Your eyepiece and barlow choices are all above this lower limit, so you should be good.  You can always experiment with a short eyepiece in a barlow to see if it is usable for you.  There's no harm in trying.

2. A good barlow lens can clean up the edges in longer focal length eyepieces and yield longer eye relief at shorter focal lengths by using longer focal length eyepieces at higher powers.  The downside is that they are one more thing to swap in and out of the optical train.  When using one, I tend to just leave it in the focuser for all eyepieces when looking for the best high power view.

3. There are only two reasons to wear eyeglasses at the eyepiece: 1) You have strong astigmatism (cylinder correction and axis on your prescription) that will distort stars into crosses even at best focus, or 2) You are constantly looking back at star charts or up at the naked-eye sky.  You'll need 16mm to 20mm of eye relief to see the entire field with glasses on.  It depends on how the manufacturer measures the eye relief, how deeply set your eyes are, and how close your eyeglasses are to your eyes.  The BSTs are known for good eye relief as are the Celestron X-Cel LX and Meade HD-60 lines.  All three get good reviews.  It comes down to price and availability.

4. Because the apparent field of view is 60 degrees, those would be good choices.  If you are looking at 50 degrees, then get a 32mm plossl for your lowest power eyepiece.  If you had a 2 inch focuser, you would have more low power options.  Those eyepiece lines I listed above max out at 25mm because at 60 degrees, you get about the same field of view as a 32mm 50 degree eyepiece.  It's the 1.25 inch barrel that limits the maximum true field of view.  That's where the 2 inch focuser comes into play.

5. Everyone finds an 80A light blue filter to be universally helpful with Jupiter.  A medium red or orange filter can help with Mars.  Avoid the dark ones, it's hard to make out anything at all through them.  An OIII filter helps immensely with nebula like the Orion or Veil nebulae.  Many people like the Baader Moon & Skyglow filter not just for cutting through light pollution, but also for improving contrast on planets like Jupiter.  Lastly, there's the UHC class of nebula filters that have a wider notch than the OIII ones to also let some H-Beta (and even a little B-Alpha) emissions through as well.

You'll probably hate the 8mm plossl due to an eye relief of around 6mm, so don't even consider it.  Pretty much no one likes plossls that short in focal length.

The BSTs (and X-Cel LX/HD60) all have a consistent 16mm or so of eye relief.  They also have 60 degree AFOVs rather than 50 degree AFOVs like plossls.  You'll notice the difference.  They are also better corrected across the inner 50 degrees than are the plossls.  If you want to try plossls sometime in the future, you can always pick they up for cheap used.  They do work well in binoviewers, I've found.

Again, the lack of a 32mm BST is  a non-issue.  The true field of view will be just about the same for a 25mm BST as for a 32mm plossl, only at a higher power which will yield a darker sky background (a good thing).  You can always add a used 32mm plossl later if you want to ensure you're getting the maximum TFOV.

Many thanks for the comprehensive answer which I think I understand.

Based on your comments I should get a BST Explorer 25mm, 15mm and 8mm (No Barlow) = £139.20 

If I get a Barlow which should I get  to compliment these BST eyepieces and what would be the minimum recommended filters to get? Do you need an adapter for the filters or do the screw on any eyepiece?  

[Space Beagle]

Just a quick thanks to 'Ricochet', who pointed out, in this thread, that Bresser were selling the ES68's (ex display items) on their site, as I have just bought a 24mm and a 16mm for a grand total of £136.00 delivered!

Another vote for the BST's for you 'JonnyAlpha', I have had most of them over the last few years and they are very good value for the cost, you will be very pleased with them!

Doc