Jump to content

  •  

CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.

Photo

2020 Eyepieces Buyer's Guide

  • Please log in to reply
63 replies to this topic

#26 Eliserpens

Eliserpens

    Mariner 2

  • -----
  • Posts: 296
  • Joined: 30 Jan 2020
  • Loc: Corwhin, Ontario (13km SE of Guelph)

Posted 10 April 2020 - 09:20 AM

Terrific chart - thanks. 

 

For the record, I also had the line spacing issue and I had to use Bob's method to fix it. 

Just to expand for those of us that are not very proficient 'Excel'ers:

'Unhide' columns S and T.  Select both (at top, or do one at a time), right click on column, select 'Format cells', select 'Alignment', uncheck 'Wrap text'.


  • BFaucett and Jay6821 like this

#27 Starman1

Starman1

    Vendor (EyepiecesEtc.com)

  • *****
  • Vendors
  • topic starter
  • Posts: 46,210
  • Joined: 23 Jun 2003
  • Loc: Los Angeles

Posted 10 April 2020 - 12:17 PM

Thanks!

Also, the latest version of OpenOffice is available, now called Apache Open Office.

It will allow you to do all that Microsoft Office allows you to do, but it's a free program:

https://www.openoffice.org


  • markb and Eliserpens like this

#28 Starman1

Starman1

    Vendor (EyepiecesEtc.com)

  • *****
  • Vendors
  • topic starter
  • Posts: 46,210
  • Joined: 23 Jun 2003
  • Loc: Los Angeles

Posted 10 April 2020 - 12:23 PM

Terrific chart - thanks. 

 

For the record, I also had the line spacing issue and I had to use Bob's method to fix it. 

Just to expand for those of us that are not very proficient 'Excel'ers:

'Unhide' columns S and T.  Select both (at top, or do one at a time), right click on column, select 'Format cells', select 'Alignment', uncheck 'Wrap text'.

Thanks.

Here is the re-formatted version of the spreadsheet:

I've also cleaned up a few typos.

Attached Files


  • John Rogers, BFaucett, Second Time Around and 1 other like this

#29 Eliserpens

Eliserpens

    Mariner 2

  • -----
  • Posts: 296
  • Joined: 30 Jan 2020
  • Loc: Corwhin, Ontario (13km SE of Guelph)

Posted 10 April 2020 - 01:49 PM

Can I ask why anyone would make an eyepiece with a 25mm exit pupil?  I can barely managed 5.  Are octopi using telescopes now? :D

[If this is not the place please ignore...]



#30 Starman1

Starman1

    Vendor (EyepiecesEtc.com)

  • *****
  • Vendors
  • topic starter
  • Posts: 46,210
  • Joined: 23 Jun 2003
  • Loc: Los Angeles

Posted 10 April 2020 - 02:02 PM

Can I ask why anyone would make an eyepiece with a 25mm exit pupil?  I can barely managed 5.  Are octopi using telescopes now? laugh.gif

[If this is not the place please ignore...]

No one makes an eyepiece with a 25mm exit pupil.

An eyepiece could have an exit pupil of 25mm if, say, a 75mm eyepiece were used in an f/3 scope.

But the exit pupil is a function of the focal length of the eyepiece in relation to the f/ratio of the scope.

Eyepieces do not, inherently, have exit pupils.

In a reflector, such an eyepiece would transmit no visible light because the shadow of the secondary mirror would cover your pupil.

What prompts the question?


  • happylimpet and 25585 like this

#31 Eliserpens

Eliserpens

    Mariner 2

  • -----
  • Posts: 296
  • Joined: 30 Jan 2020
  • Loc: Corwhin, Ontario (13km SE of Guelph)

Posted 10 April 2020 - 03:30 PM

Ah, those numbers were filled in by the excel calculations (I thought they were fixed): I was trying to find a good wide field EP for my Stellarvue 9X50 finder scope which has a FL of 200 but that generated some absurd Exit Ps!  I still get a lot of EPs with exit pupuls over 10mm based on my 1000mm F/5.3 scope. 

 

The EP that came with it is 23 mm (~50 AFOV?) and all the stars on towards the edges are comma shaped.  Obviously, it has to be 1.25 inch,  I don't want to break the bank on this and was looking at the Explore Scientific 68° 24mm - with a calculated exit pupil of 6 mm. Maybe a bit too high for my eyes now.

 

I hope this isn't too naive, a bit new at this!



#32 Starman1

Starman1

    Vendor (EyepiecesEtc.com)

  • *****
  • Vendors
  • topic starter
  • Posts: 46,210
  • Joined: 23 Jun 2003
  • Loc: Los Angeles

Posted 10 April 2020 - 05:45 PM

On average, the pupil diameter of the eye decreases with age, but the range is huge, say, <2mm to >8mm, depending on whether or not the outliers are excluded..

One study on PubMed saw:

N=Two-hundred sixty-three individuals. 

18 to 19 years (n=6), the mean dark-adapted pupil diameter was 6.85 mm (range: 5.6 to 7.5 mm);

20 to 29 years (n=66), 7.33 mm (range: 5.7 to 8.8 mm);

30 to 39 years (n=50), 6.64 mm (range: 5.3 to 8.7 mm);

40 to 49 years (n=51), 6.15 mm (range: 4.5 to 8.2 mm);

50 to 59 years (n=50), 5.77 mm (range: 4.4 to 7.2 mm);

60 to 69 years (n=30), 5.58 mm (range: 3.5 to 7.5 mm);

70 to 79 years (n=6), 5.17 mm (range: 4.6 to 6.0 mm); and

80 years (n=4), 4.85 mm (range: 4.1 to 5.3 mm).

These values were consistent with studies using infrared photography. The standard deviation was >0.1 mm in 10 (3.8%) participants, all of whom were younger than 55 years.

 

If you don't know what your pupil diameter is, it's fairly safe to use this chart:

 

Attached Thumbnails

  • Pupil size.jpg

  • danielguo and Second Time Around like this

#33 Starman1

Starman1

    Vendor (EyepiecesEtc.com)

  • *****
  • Vendors
  • topic starter
  • Posts: 46,210
  • Joined: 23 Jun 2003
  • Loc: Los Angeles

Posted 10 April 2020 - 06:06 PM

Ah, those numbers were filled in by the excel calculations (I thought they were fixed): I was trying to find a good wide field EP for my Stellarvue 9X50 finder scope which has a FL of 200 but that generated some absurd Exit Ps!  I still get a lot of EPs with exit pupuls over 10mm based on my 1000mm F/5.3 scope. 

 

The EP that came with it is 23 mm (~50 AFOV?) and all the stars on towards the edges are comma shaped.  Obviously, it has to be 1.25 inch,  I don't want to break the bank on this and was looking at the Explore Scientific 68° 24mm - with a calculated exit pupil of 6 mm. Maybe a bit too high for my eyes now.

 

I hope this isn't too naive, a bit new at this!

At f/5.3, it's fairly safe for individuals of any age to use a 5mm exit pupil, or a 26-27mm eyepiece.

If your pupil is larger, you won't lose any light, but the image could be a bit brighter at lower power and larger exit pupil.

If your pupil is smaller, you lose a bit of light, but since the magnification is low, the image will be bright anyway.

Regardless of what exit pupil results, I see little reason for scopes to go below:

30x on a 4"

40x on a 6"

50x on an 8"

60x on a 10"

70x on a 12.5"

90x on a 16"

100x on a 20"

Yes, going lower means a brighter image, and a smaller image scale, and that could be useful for an object here and there.

But matching magnification to aperture means that, as I see it, there is little value in magnifications below about 5-6x/inch of aperture.

I'm certain some will disagree, but though the images at lower powers are bright, the magnifications are too low to see the objects with a decent scale.

 

On the other end, those of us above a certain age tend to have a lot of floaters in the eye that can interfere with the image when the image is bright, like the moon or planets.

It's usually quite safe to use 1mm as your smallest exit pupil for eyepieces, which means magnification = diameter of the telescope in mm.

Higher powers can be useful for double stars or the Moon at times, but it's cost effective to create such powers with a Barlow because those magnifications won't be used as often.

 

A 1000mm focal length f/5.3 implies a 190mm scope, or about 7.4". A 27mm eyepiece yields 37x.  You might find that a bit low in magnification as a low power.

I think you'd be happier with 40-50x as alow power (25 to 20mm range)

 

P.S., your finder has significant aberrations because it is very short in f/ratio--f/4, which is incredibly fast for a lens.  The eyepieces that work well in that finder will not be inexpensive, alas.

I think the eyepiece in question might be a Kellner, so the ES you contemplate for the finder might be a step forward.  But that assumes the lens is good, which is a big IF.


Edited by Starman1, 10 April 2020 - 06:09 PM.

  • Eliserpens likes this

#34 sanbai

sanbai

    Messenger

  • *****
  • Posts: 452
  • Joined: 18 May 2019
  • Loc: Baton Rouge, LA

Posted 11 April 2020 - 10:05 PM

The eye relief for the Baader Morpheus eyepieces are different to the official ones. Differences for some is negligible, for others up to 1mm.

 

EP    excel     manufacturer

4.5     16.7       17.5
6.5     17.5       18.5
9         21.4      21
12.5    19.8      20
14       18.3     18.5
17.5     24.0    23(.4)

 

Thanks for the list, this great job.

 

I wonder how many of those eyepieces don't offer any advantage at all to consumers, not even in price. I also wonder how so many offerings can provide a revenue in such small market.


  • Eliserpens likes this

#35 daslolo

daslolo

    Ranger 4

  • -----
  • Posts: 364
  • Joined: 18 Jan 2020
  • Loc: Camano Island, WA

Posted 14 April 2020 - 04:43 AM

here is the online version where you can set your too low and too high price at the top
https://docs.google....dit?usp=sharing

#36 Starman1

Starman1

    Vendor (EyepiecesEtc.com)

  • *****
  • Vendors
  • topic starter
  • Posts: 46,210
  • Joined: 23 Jun 2003
  • Loc: Los Angeles

Posted 14 April 2020 - 08:49 AM

Thanks, but it looks like you used the 2019 version according to the label.

Is it a labeling issue, or do you need to redo it with the 2020 version?



#37 sanbai

sanbai

    Messenger

  • *****
  • Posts: 452
  • Joined: 18 May 2019
  • Loc: Baton Rouge, LA

Posted 14 April 2020 - 09:10 AM

On average, the pupil diameter of the eye decreases with age, but the range is huge, say, <2mm to >8mm, depending on whether or not the outliers are excluded..

One study on PubMed saw:

N=Two-hundred sixty-three individuals. 

18 to 19 years (n=6), the mean dark-adapted pupil diameter was 6.85 mm (range: 5.6 to 7.5 mm);

20 to 29 years (n=66), 7.33 mm (range: 5.7 to 8.8 mm);

30 to 39 years (n=50), 6.64 mm (range: 5.3 to 8.7 mm);

40 to 49 years (n=51), 6.15 mm (range: 4.5 to 8.2 mm);

50 to 59 years (n=50), 5.77 mm (range: 4.4 to 7.2 mm);

60 to 69 years (n=30), 5.58 mm (range: 3.5 to 7.5 mm);

70 to 79 years (n=6), 5.17 mm (range: 4.6 to 6.0 mm); and

80 years (n=4), 4.85 mm (range: 4.1 to 5.3 mm).

These values were consistent with studies using infrared photography. The standard deviation was >0.1 mm in 10 (3.8%) participants, all of whom were younger than 55 years.

 

If you don't know what your pupil diameter is, it's fairly safe to use this chart:

 

Given the presumed distribution of actual, active observers and the state of the pollution for most of them, I think the classical 7 mm goal is chimera.

 

If I'm only allowed to few words, I'll generically recommend a max 6 mm from now one (or 5 for city observers). If I have more words, then I'll add and "but if you are young and/or at a dark site, it can go up to 7.5 mm"

Add astigmatism to the reasons of lowering the generic recommendation.


  • Eliserpens likes this

#38 daslolo

daslolo

    Ranger 4

  • -----
  • Posts: 364
  • Joined: 18 Jan 2020
  • Loc: Camano Island, WA

Posted 14 April 2020 - 12:52 PM

Thanks, but it looks like you used the 2019 version according to the label.

Is it a labeling issue, or do you need to redo it with the 2020 version?

There are 4 tabs at the bottom: the leftmost is 2020.

I see the title is still 2019 which is confusing so I changed it.



#39 Second Time Around

Second Time Around

    Mariner 2

  • -----
  • Posts: 260
  • Joined: 08 Oct 2019

Posted 15 April 2020 - 11:08 AM

On average, the pupil diameter of the eye decreases with age, but the range is huge, say, <2mm to >8mm, depending on whether or not the outliers are excluded..

One study on PubMed saw:

N=Two-hundred sixty-three individuals. 

18 to 19 years (n=6), the mean dark-adapted pupil diameter was 6.85 mm (range: 5.6 to 7.5 mm);

20 to 29 years (n=66), 7.33 mm (range: 5.7 to 8.8 mm);

30 to 39 years (n=50), 6.64 mm (range: 5.3 to 8.7 mm);

40 to 49 years (n=51), 6.15 mm (range: 4.5 to 8.2 mm);

50 to 59 years (n=50), 5.77 mm (range: 4.4 to 7.2 mm);

60 to 69 years (n=30), 5.58 mm (range: 3.5 to 7.5 mm);

70 to 79 years (n=6), 5.17 mm (range: 4.6 to 6.0 mm); and

80 years (n=4), 4.85 mm (range: 4.1 to 5.3 mm).

These values were consistent with studies using infrared photography. The standard deviation was >0.1 mm in 10 (3.8%) participants, all of whom were younger than 55 years.

 

If you don't know what your pupil diameter is, it's fairly safe to use this chart:

Don, where's this interesting chart from please? I've never seen it before.

 

I've always advocated measuring the pupil diameter of one's eye to determine the best focal length for a low power eyepiece.  As this topic shows there's a huge variation from person to person.  It's certainly unwise to assume it's the "standard" 7mm, especially as we get older!

 

Of course, getting an even lower focal length eyepiece can also be useful as, although one may lose a bit of light, the field of view is likely to be wider.



#40 Starman1

Starman1

    Vendor (EyepiecesEtc.com)

  • *****
  • Vendors
  • topic starter
  • Posts: 46,210
  • Joined: 23 Jun 2003
  • Loc: Los Angeles

Posted 15 April 2020 - 12:20 PM

Don, where's this interesting chart from please? I've never seen it before.

I've always advocated measuring the pupil diameter of one's eye to determine the best focal length for a low power eyepiece. As this topic shows there's a huge variation from person to person. It's certainly unwise to assume it's the "standard" 7mm, especially as we get older!

Of course, getting an even lower focal length eyepiece can also be useful as, although one may lose a bit of light, the field of view is likely to be wider.

As I said, it was on PubMed.

#41 Starman1

Starman1

    Vendor (EyepiecesEtc.com)

  • *****
  • Vendors
  • topic starter
  • Posts: 46,210
  • Joined: 23 Jun 2003
  • Loc: Los Angeles

Posted 15 April 2020 - 12:20 PM

Don, where's this interesting chart from please? I've never seen it before.

I've always advocated measuring the pupil diameter of one's eye to determine the best focal length for a low power eyepiece. As this topic shows there's a huge variation from person to person. It's certainly unwise to assume it's the "standard" 7mm, especially as we get older!

Of course, getting an even lower focal length eyepiece can also be useful as, although one may lose a bit of light, the field of view is likely to be wider.

As I said, it was on PubMed.
Or do you mean the graph?

#42 Second Time Around

Second Time Around

    Mariner 2

  • -----
  • Posts: 260
  • Joined: 08 Oct 2019

Posted 15 April 2020 - 12:42 PM

I meant the graph, Don.

BTW, I'd to take the opportunity to thank you publicly for the Eyepiece Buyer's Guide. It's been a huge help to me, and I imagine a great many others.

#43 Starman1

Starman1

    Vendor (EyepiecesEtc.com)

  • *****
  • Vendors
  • topic starter
  • Posts: 46,210
  • Joined: 23 Jun 2003
  • Loc: Los Angeles

Posted 15 April 2020 - 12:48 PM

I meant the graph, Don.

https://stargazerslo...pil-size-v-age/


  • Second Time Around likes this

#44 Second Time Around

Second Time Around

    Mariner 2

  • -----
  • Posts: 260
  • Joined: 08 Oct 2019

Posted 15 April 2020 - 01:07 PM

Many thanks, Don.

#45 Cpear004

Cpear004

    Lift Off

  • -----
  • Posts: 1
  • Joined: 17 Apr 2020
  • Loc: Gaithersburg, MD

Posted 17 April 2020 - 09:43 PM

Thanks so much Don for this wonderful Excel tool!

 

This is my first post here on CN as I'm a new member, and wanted to make it count. Will be reading up on all the message boards regarding telescopes, equipment, etc. to help me sort through the best option for me and my family as we embark on this new journey of amateur astronomy. Cheers!



#46 daslolo

daslolo

    Ranger 4

  • -----
  • Posts: 364
  • Joined: 18 Jan 2020
  • Loc: Camano Island, WA

Posted 17 April 2020 - 09:57 PM

On the online version of Don's 2020 eyepiece list there is now a filter by fl, diameter, min afov, price range, min exit pupil, field stop range

 

Annotation 2020-04-17 195700.jpg



#47 beacco

beacco

    Lift Off

  • -----
  • Posts: 5
  • Joined: 08 Aug 2016

Posted 19 April 2020 - 07:33 PM

Allow me to add a thank you for you efforts as well.

 



#48 attaran

attaran

    Lift Off

  • -----
  • Posts: 1
  • Joined: 11 Oct 2016

Posted 13 May 2020 - 04:13 PM

Thank you very much for the Buyer's Guide, Don.



#49 Starman1

Starman1

    Vendor (EyepiecesEtc.com)

  • *****
  • Vendors
  • topic starter
  • Posts: 46,210
  • Joined: 23 Jun 2003
  • Loc: Los Angeles

Posted 13 May 2020 - 06:04 PM

Be sure to get the latest version in post #28.


  • 25585 likes this

#50 25585

25585

    Cosmos

  • *****
  • Posts: 8,959
  • Joined: 29 Aug 2017
  • Loc: In a valley, in the UK.

Posted 14 May 2020 - 04:34 AM

On the online version of Don's 2020 eyepiece list there is now a filter by fl, diameter, min afov, price range, min exit pupil, field stop range

 

attachicon.gifAnnotation 2020-04-17 195700.jpg

Is there a filter for eye relief as well? 




CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.


Recent Topics






Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics