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

[JonnyAlpha]

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

Sorry double post and I cannot get rid of the quote box?

[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.

Can any admin help me out everytime I go to reply I keep getting the quote above already inserted??

Anyway following the advice on here I went ahead and ordered 8mm, 15mm and 25mm BST Explorer EP's from 365 Astronomy (the 8mm is out of stock so I guess it will be on a back order?).

I'll get some filters and then a Barlow next.

Thanks for all the advice.

[Ricochet]

On 29/04/2016 at 16:07, Space Beagle said:

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

No problem. I think about half of my posts have linked to those eyepieces. They're a great buy and I've never regretted ordering mine.

On 29/04/2016 at 17:49, JonnyAlpha said:

Can any admin help me out everytime I go to reply I keep getting the quote above already inserted??

Anyway following the advice on here I went ahead and ordered 8mm, 15mm and 25mm BST Explorer EP's from 365 Astronomy (the 8mm is out of stock so I guess it will be on a back order?).

I'll get some filters and then a Barlow next.

Thanks for all the advice.

The forum saves any drafts you write so if you change your mind you need to delete it. Either place your cursor at the bottom of the post and hold backspace until it's all gone or highlight the text and press delete if it happens in future. Congratulations on the new eyepieces.

[JonnyAlpha]

Received my the EPs yesterday (great service from 365) 

Question: 

There doesn't seem to be a rubber eyeguard / shroud on these similar to my old stock Celestine ones ? There is a rubber shroud that pulls of hough, is that supposed to be raised upwards to give the desire eye relief?  

 

[Ricochet]

The eye cup should twist up and down to allow you to set the desired height. It shouldn't pull completely off if that's what you've finding. 

A picture is worth a thousand words so eye cup down on the left and up on the right. 

 

[Louis D]

Yea, these are twist-up style eyeguards pioneered by the Pentax XLs back in the 90s.

[BISHWO370]

Hi, I own device celestron ultima 80mm 45 deg angled monocular device. It included 8mm to 24mm zoom eyepiece.

Is this eyepiece same as the one in Ultima 80 monocular and with barrel dimensions same ?
Becoz I am planning to purchase another telescope nexstar 5se and I want to use my Ultima eyepiece in nexstar 5se is it possible. Just concerned about the sizes of barrel. Currently I am not concerned about the quality of the image coz till now I m using ultima as landscape views only and for watching moon some time.

Thanks in advance.

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https://www.highpointscientific.com/celestron-8-24-mm-1-25-zoom-eyepiece-93230?utm_source=bing&utm_medium=cse&utm_term=CEL-93230
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item code written 93230
https://www.bhphotovideo.com/c/product/370331-REG/Celestron_93230_8_24mm_Zoom_Wide_Angle.html
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https://www.telescopesplus.com/products/celestron-zoom-telescope-eyepiece-8-24mm-1-25-inch-format
---------------------------------------
item code written 93230
https://www.amazon.com/Celestron-93230-24mm-1-25-Eyepiece/dp/B0007UQNV8
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[BISHWO370]

Hi, I own device celestron ultima 80mm 45 deg angled monocular device. It included 8mm to 24mm zoom eyepiece.

Is this eyepiece same as the one in Ultima 80 monocular and with barrel dimensions same ?
Becoz I am planning to purchase another telescope nexstar 5se and I want to use my Ultima eyepiece in nexstar 5se. I found the measurement of barrel dia of ultima eyepiece is only 27mm(1.06in) which is less than 31.75mm(1.25in) and it become loose into eyepiece holder in telescope.

eyepiece body
eyepiece locking thread 41mm(1.614 inch)
eyepiece barrel 27.16mm(1.07 inch)

telescopy body
eyepiece holder 31mm(1.22 inch)
eyepiece holder smaller thread 34.8(1.37 inch)
eyepiece holder bigger 41.04mm(1.6 inch)

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https://www.highpointscientific.com/celestron-8-24-mm-1-25-zoom-eyepiece-93230?utm_source=bing&utm_medium=cse&utm_term=CEL-93230
---------------------------------------
item code written 93230
https://www.bhphotovideo.com/c/product/370331-REG/Celestron_93230_8_24mm_Zoom_Wide_Angle.html
---------------------------------------
https://www.telescopesplus.com/products/celestron-zoom-telescope-eyepiece-8-24mm-1-25-inch-format
---------------------------------------
item code written 93230
https://www.amazon.com/Celestron-93230-24mm-1-25-Eyepiece/dp/B0007UQNV8
---------------------------------------

[Ricochet]

The internal lens elements might be the same but the Ultima zoom has a non standard screw fitting. You would need to find an adaptor to convert it to an astronomical 1.25" barrel. 

[Alfian]

On 4/21/2016 at 04:17, Louis D said:

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.

Found this zoom available at a very good price.  (see link) I keep dabbling with the idea of a zoom and was tempted, but I really don't need one.

https://www.amazon.co.uk/Celestron-Regal-Eyepiece-Spotting-Scope/dp/B00P67XVF8/ref=sr_1_2?s=electronics&ie=UTF8&qid=1522174528&sr=1-2&keywords=Celestron+Regal+Zoom+M2

[Alfian]

A good thread with some good stuff from Louis, thanks.

[Louis D]

1 hour ago, Alfian said:

Found this zoom available at a very good price.  (see link) I keep dabbling with the idea of a zoom and was tempted, but I really don't need one.

https://www.amazon.co.uk/Celestron-Regal-Eyepiece-Spotting-Scope/dp/B00P67XVF8/ref=sr_1_2?s=electronics&ie=UTF8&qid=1522174528&sr=1-2&keywords=Celestron+Regal+Zoom+M2

If you ever need to pack light, a good zoom is a great addition.  I took my Celestron Regal zoom with me to Nebraska along with a 32mm GSO plossl, a 1.25" diagonal, and an 80mm f/5 achromat refractor with white light solar filter on a fluid video head on a camera tripod to observe the total solar eclipse last summer.  That combo covered pretty much all my observing needs.  I was concerned with my car getting broken into while parked in a motel parking lot along the major interstates.  I didn't want to be out too much monetarily.

[Cosmic Geoff]

I'd just like to mention here that a lot of the cheaper 8-24 mm zooms appear to be basically the same apart from the branding - this includes the Seben and others that look like it.  I have the 'BST Starguider' 8-24mm zoom in this range and it works okay.  Subject to some issues you should note, which may be common to other zooms but rather take the shine off if you were expecting a perfect replacement for 3 eyepieces:  Too small field of view at 24mm, action stiff so that it is easiest to take the zoom out of the telescope to adjust it, slight refocus required after adjusting zoom.

[Louis D]

2 hours ago, Cosmic Geoff said:

I'd just like to mention here that a lot of the cheaper 8-24 mm zooms appear to be basically the same apart from the branding - this includes the Seben and others that look like it.  I have the 'BST Starguider' 8-24mm zoom in this range and it works okay.  Subject to some issues you should note, which may be common to other zooms but rather take the shine off if you were expecting a perfect replacement for 3 eyepieces:  Too small field of view at 24mm, action stiff so that it is easiest to take the zoom out of the telescope to adjust it, slight refocus required after adjusting zoom.

The Celestron Regal zoom referenced has a very smooth and light zoom action with very good edge correction at f/6 (but certainly not perfect).  It does require slight refocussing during zooming.  It's AFOV varies from 44 degrees at 24mm to 63 degrees at 8mm.  The change in AFOV is very linear.  I can't detect any stalls or jumps in size while zooming.  Usable eye relief with the eyecup screwed off is about 14mm throughout the range.  I have no trouble taking in the entire view with eyeglasses.  The top does not rotate during zooming, unlike the Baader Hyperion zoom, so winged eyecups can be used when binoviewing with them.

[SpaceBass]

On 3/28/2018 at 16:33, Louis D said:

The Celestron Regal zoom referenced has a very smooth and light zoom action with very good edge correction at f/6 (but certainly not perfect).  It does require slight refocussing during zooming.  It's AFOV varies from 44 degrees at 24mm to 63 degrees at 8mm.  The change in AFOV is very linear.  I can't detect any stalls or jumps in size while zooming.  Usable eye relief with the eyecup screwed off is about 14mm throughout the range.  I have no trouble taking in the entire view with eyeglasses.  The top does not rotate during zooming, unlike the Baader Hyperion zoom, so winged eyecups can be used when binoviewing with them.

Can it be used with a barlow at all Louis?  Mine is the Q-Barlow 2.25

[Louis D]

1 minute ago, SpaceBass said:

Can it be used with a barlow at all Louis?  Mine is the Q-Barlow 2.25

If it is a barlow with a 1.25" eyepiece receiver, then I don't see a problem.  Since it has no filter threads, the Celestron Regal zoom can't use any barlows that require them to be threaded on.

Technically, when I use it in my binoviewer with the nosepiece from a Meade 140 2x barlow on the front of the binoviewer, I'm using it with a barlow, just at about 3x.  Under those conditions, it's nearly sharp to the edge, and I haven't noticed any exit pupil issues like blackouts with it.

[SpaceBass]

20 minutes ago, Louis D said:

If it is a barlow with a 1.25" eyepiece receiver

Yeah it does.  Anyhow I just snapped up the last Regal at £54, so will see how it fares in a few days.  Thanks!

[Louis D]

59 minutes ago, SpaceBass said:

Yeah it does.  Anyhow I just snapped up the last Regal at £54, so will see how it fares in a few days.  Thanks!

I think you'll be pleasantly surprised with it.  It feels quite a bit more sophisticated in build quality than its price would suggest.