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Eyepiece progression

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#1 Luca B.

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Posted 18 December 2018 - 06:20 AM

Hi!

 

I've been a lurker on this forum but finally i decided to jumop in :) I'm Luca and i come from Italy.

 

My first post here is a question for you, i'm planning my eyepiece progression for my Dobsonian 10" scope.

 

At the moment i have:

 

-30mm erfle (low quality but good as spotting EP) 

-10mm Pentax XW

-6.7mm ES82

 

I'm looking for a factotum eyepiece in the medium range of focal lenght..i first tought about the ES18/82 but i need more ER as a glasses wearer, so i'm considering the Baader Morpheus 17.5..

 

The progression would be:

 

-30mm 41x 1.7°

-17.5mm 71x 1.07°

-10mm 125x 0.56°

-6.7mm 186x 0.44°

 

Do you think the Baader will be good as a factotum eyepiece or the TFOV is too narrow? I want the XW10 to be the best for medium/high magnification and the baader to be the best for medium/low..

 

Sorry for my bad eng. :D



#2 DLuders

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Posted 18 December 2018 - 09:13 AM

Welcome to Cloudy Nights!  smile.gif   You should download the free "2018 Buyer's Guide to Eyepieces" spreadsheet (linked from  https://www.cloudyni...e-buyers-guide/ ), enter your telescope's parameters, and see which eyepieces meet your needs for

 

Magnification

Eye Relief

Apparent Field of View (AFOV)

Exit Pupil size



#3 epee

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Posted 18 December 2018 - 10:14 AM

I think you'll be quite happy with the Morpheus 17.5mm; I know I am. You will find it far superior to your 30mm Erfle. It's AFOV will fall between your Pentax and your ES82 with many knowledgeable users saying it will fall closer to the ES82 than paper specs would indicate. I can't vouch for this as I don't own the Pentax or the 1.25" ES82.


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#4 MitchAlsup

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Posted 18 December 2018 - 12:00 PM

Hi!

 

I've been a lurker on this forum but finally i decided to jumop in smile.gif I'm Luca and i come from Italy.

 

My first post here is a question for you, i'm planning my eyepiece progression for my Dobsonian 10" scope.

 

At the moment i have:

 

-30mm erfle (low quality but good as spotting EP) 

-10mm Pentax XW

-6.7mm ES82

From a 30mm Erfle to a 10mm XW is a big jump.

There is a rule conjecture of thumb that says a nice spacing between EPs is a 50% increase in magnification.

 

So 50% more power than a 30mm is about 20mm.

Then 50% more power than a 20mm is about 14mm.

And 50% more power than a 14mm is about 10mm.

 

So, I suggest you think about putting 2 EPs between your 30mm and your 10mm.

And if you decide this is a good conjecture to follow,

.....something in the 20-22mm range and

.....something in the 13-15mm range.


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#5 rowdy388

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Posted 18 December 2018 - 12:23 PM

I think the 17.5 Morpheus would make a great fit in your collection.

I don't think the field will be too narrow at all. I think you will love the 

view with or without your eyeglasses. The field will be twice as wide 

and just as easy to take in as your 10mm Pentax XW.


Edited by rowdy388, 18 December 2018 - 12:31 PM.


#6 sickfish

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Posted 18 December 2018 - 12:43 PM

You could maybe squeeze a ES 24mm 68* between the 30 and 17.5

Just saying 



#7 epee

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Posted 18 December 2018 - 01:10 PM

Heh, I "squeezed" a 30mm & 24mm ES beneath my Morpheus 17.5mm. But I like small jumps in magnification; gotta have just the right "framing" ya'know?


Edited by epee, 18 December 2018 - 01:14 PM.

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#8 Jeff Morgan

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Posted 18 December 2018 - 02:13 PM

Many ways to skin the cat. Meaning, many progression schemes. As a general rule, most people accept gaps on the low power end and increase the spacing towards the high power end.

 

The Leica Zoom has 19mm eye relief covers 8.9 to 17.8mm, zero gaps. And it barlows well. Just add a couple of eyepieces for the low power roles and you are done. It really simplified my astronomy. Looks expensive, but selling off all of my primes more than paid for it.

 

Speaking of which - the eyepiece game gets very expensive. It may only be $250 here, $300 there, but it never seems to end. It really adds up over the years, easy to end up with more money tied up in eyepieces than in telescopes.

 

Before the Leica I primarily had the shorter Pentax XW's and the longer Delos. I'm partial to the 70 degree class of eyepieces and those are excellent (if not the best in class). That being said, I never did meet a Nagler I did not like either.

 

All good choices. And while "the chase" does get expensive, it is also a lot of fun. 


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#9 havasman

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Posted 18 December 2018 - 02:35 PM

Hi!

 

The progression would be:

 

-30mm 41x 1.7°

-17.5mm 71x 1.07°

-10mm 125x 0.56°

-6.7mm 186x 0.44°

 

Do you think the Baader will be good as a factotum eyepiece or the TFOV is too narrow? I want the XW10 to be the best for medium/high magnification and the baader to be the best for medium/low..

 

Sorry for my bad eng. laugh.gif

Hi Luca and welcome to the forums!

 

Your English is nothing to be concerned about. Few Americans speak the language any better. wink.gif

 

I think the progression you list is quite good. And you are right about the ES82 18mm. I think it's a great eyepiece but if you enjoy having long eye relief or observe wearing glasses then it will be awful. The Morpheus should be great. Be aware that the ES82 6.7mm is not much more generous in eye relief than the 18mm. There's a 6.5mm Morpheus also as well as 7mm XW and 6mm Delos that all have sparkling performance reputations and all would be excellent choices. Good luck with your selections. You seem to have a good handle on how to put your kit together.



#10 earlyriser

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Posted 18 December 2018 - 02:42 PM

The 17.5 is almost an exact split between the 30mm and 10mm, geometrically speaking, so I think that is an excellent choice. Eventually, you might want to fill the gaps between the 30 and 17.5 and 17.5 and the 10mm, but there needn't be any rush. I have a gap between my 17.3 and 10mm Delos, but I don't really feel the need to fill it.


Edited by earlyriser, 18 December 2018 - 02:43 PM.


#11 Luca B.

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Posted 18 December 2018 - 03:44 PM

Wow so many replies!! thanks you all for the help and the welcome:)
I think i'll go for the morpheus 17.5, a question to those who use it..i've read that some find this eyepiece to suffer from blackouts or kidney bean due to long ER..do you find this true?
@havasman, i don't know why but with the 6.7 my astigmatism doesn't show most of his effect so i don't really need to use eyeglasses, maybe due to small exit pupil?
@earlyriser @sickfish..have to admit that knowing myself i already know those "squeezing" will be sometime in the next future, also because i find the es24/68 a real gem for it's price and it's been on my wishlist for quite some time
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#12 RAKing

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Posted 18 December 2018 - 04:37 PM

I jump from a 26T5 to a 13mm eyepiece in my refractor -- going from 40x to 75x.  I jumped from a 30mm to a 17.3 mm Delos and now I jump from a 40mm to that same 17.3mm eyepiece in my Mak.  The jump is from 45x to 104x.  I added a 24mm, but didn't really need it.  Anything I could see at 75x, I could see a little better at 104x, so I left the 24mm at home and don't worry about it.  Why carry an eyepiece I won't use?

 

The Baader 17.5mm Morpheus is my favorite in that series and I think it will work well in your scope.  I also think you will eventually sort things out for yourself as you get familiar with your gear and the things you like to observe.

 

Cheers,

 

Ron



#13 sjc327

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Posted 18 December 2018 - 04:47 PM

Wow so many replies!! thanks you all for the help and the welcome:)
I think i'll go for the morpheus 17.5, a question to those who use it..i've read that some find this eyepiece to suffer from blackouts or kidney bean due to long ER..do you find this true?
@havasman, i don't know why but with the 6.7 my astigmatism doesn't show most of his effect so i don't really need to use eyeglasses, maybe due to small exit pupil?
@earlyriser @sickfish..have to admit that knowing myself i already know those "squeezing" will be sometime in the next future, also because i find the es24/68 a real gem for it's price and it's been on my wishlist for quite some time

I find the the 17.5 Morpheus very comfortable with no blackouts, but you have to get the correct eye placement height due to the long eye relief.

 

You have 4 adjustment heights:

 

1) Supplied M43 Extension off and Eyecup rolled down

2) Supplied M43 Extension off and Eyecup extended

3) Supplied M43 Extension on and Eyecup rolled down

4) Supplied M43 Extension on and Eyecup extended


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#14 25585

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Posted 18 December 2018 - 06:05 PM

I think you'll be quite happy with the Morpheus 17.5mm; I know I am. You will find it far superior to your 30mm Erfle. It's AFOV will fall between your Pentax and your ES82 with many knowledgeable users saying it will fall closer to the ES82 than paper specs would indicate. I can't vouch for this as I don't own the Pentax or the 1.25" ES82.

+1 



#15 25585

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Posted 18 December 2018 - 06:13 PM

I find the the 17.5 Morpheus very comfortable with no blackouts, but you have to get the correct eye placement height due to the long eye relief.

 

You have 4 adjustment heights:

 

1) Supplied M43 Extension off and Eyecup rolled down

2) Supplied M43 Extension off and Eyecup extended

3) Supplied M43 Extension on and Eyecup rolled down

4) Supplied M43 Extension on and Eyecup extended

There is also the screw on eyecup which can be used without the M43 extension, so 6 choices;

 

1 & 2) Eyecup on barrel up or down

3 & 4) Screw on eyecup instead up or down

5 & 6) M43 extension and screw on eyecup up or down



#16 Aleko

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Posted 18 December 2018 - 06:47 PM

I speak only from my personal experiences with my 8-inch and 15-inch dobs...

 

I almost always went from a 31 or 35 straight to a 13 or 14mm.  For those scopes I never found much of a use for a 17-20mm eyepiece. My 20 Nagler felt like an orphan. 

 

Go with a high quality 13-14mm eyepiece. It will be your most used. Consider anything else in that gap only after you've used a 13-14 for a while. 

 

YMMV. 

 

Alex


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#17 astro744

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Posted 18 December 2018 - 08:53 PM

When talking eyepiece progressions one should also consider true field of view which is related to eyepiece field stop diameter and apparent field of view.

 

If you select eyepiece with the same apparent field then your magnification and true fields progress in the same ratio.  You can also create a progression based on exit pupil, e.g. 0.5, 0.7, 1.0, 1.4, 2, 2.8, 4.  If you select eyepieces that have the same apparent field to give you these exit pupils then your magnification and true field progress in the same ratio.  Nice but not essential, just pick a series of eyepiece you like for comfortable and enjoyable viewing.  At the higher power end magnification and to some extent exit pupil (too small and floaters and a dim image apply) is more important than true field so any progression there is not necessarily linear.

 

At the high power end it depends too if you are viewing planets or double stars for example with the latter allowing for a smaller exit pupil more often than not.

 

 

 

 

 


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#18 CeleNoptic

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Posted 18 December 2018 - 11:25 PM

IMO, most important for f/5 scope owner to have an eyepiece providing exit pupil of ~2.5-2.9mm for observing faint extended DSOs. Whatever you have now doesn't matter since you may want to overhaul you EP collection many times what most of us here actually do  grin.gif . So, I'm with those who suggested you an eyepiece of 13-14mm FL. IMO, building your EP collection on the basis of exit pupils (or magnifications per a unit of aperture) rather than based on  just general magnifications or progression would be more important in the long run.


Edited by CeleNoptic, 18 December 2018 - 11:26 PM.


#19 Luca B.

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Posted 19 December 2018 - 06:10 AM

Thanks for your suggestions, my only concern going for a 14 is for my XW10.

 

I already owned a 13mm (baader hyperion) and it felt like the XW10 wasn't needed as they gave similar view (in term of magnification and tfov); i decided to sell the hyperion because the xw10 is too nice to give away. I'm afraid that a good 14mm will fall in the same range of the Pentax giving the same problem.

 

I know that i'll overhaul my collection many times in future, but having a limited budget for the moment i'd prefer to invest in something different from what i already have. Maybe the idea that the 14 will replace the 10 is not really true.



#20 earlyriser

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Posted 19 December 2018 - 07:28 AM

Thanks for your suggestions, my only concern going for a 14 is for my XW10.

 

I already owned a 13mm (baader hyperion) and it felt like the XW10 wasn't needed as they gave similar view (in term of magnification and tfov); i decided to sell the hyperion because the xw10 is too nice to give away. I'm afraid that a good 14mm will fall in the same range of the Pentax giving the same problem.

 

I know that i'll overhaul my collection many times in future, but having a limited budget for the moment i'd prefer to invest in something different from what i already have. Maybe the idea that the 14 will replace the 10 is not really true.

Someday down the road you might want to add a 13-14mm to span the gap between your 17mm and 10mm eyepieces. If you do, I would buy another Pentax XW or maybe a Nagler. If you have have 10mm and 17.5mm eyepieces you really like, and you fill in the gap with a lower quality eyepiece, you will almost always skip over that eyepiece. So if you do buy a gap-filler eyepiece, my advice is to buy one that is of similar (or higher) quality to the other eyepieces you have.



#21 25585

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Posted 19 December 2018 - 10:55 AM

The constant question of FL spacing.... 

 

If you can find a Vixen LVW 22mm, that is an excellent eyepiece. I recommend that, or a Baader Morpheus 17.5mm. Not much between TFOV for both, exit pupil and magnification more. The Vixen has a smaller eye lens.



#22 Aleko

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Posted 19 December 2018 - 11:43 AM

Thanks for your suggestions, my only concern going for a 14 is for my XW10.

 

.... Maybe the idea that the 14 will replace the 10 is not really true.

Yes, what you just said.  You will still use the 10.  And if you ever barlow for planets or double stars, it will be great for that.  

 

13-14 (Delos?) first, 17 later if you still feel you'll need it. But you won't. smile.gif



#23 rowdy388

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Posted 19 December 2018 - 11:52 AM

Thanks for your suggestions, my only concern going for a 14 is for my XW10.

 

I already owned a 13mm (baader hyperion) and it felt like the XW10 wasn't needed as they gave similar view (in term of magnification and tfov); i decided to sell the hyperion because the xw10 is too nice to give away. I'm afraid that a good 14mm will fall in the same range of the Pentax giving the same problem.

 

I know that i'll overhaul my collection many times in future, but having a limited budget for the moment i'd prefer to invest in something different from what i already have. Maybe the idea that the 14 will replace the 10 is not really true.

I agree with you that a 13-14mm is a little too close to your 10 XW. I see that others here disagree. The 

17.5 is a better spacing IMO. I have eyepieces in 5, 6, 7, 8, 9, 10, 11,12, 13, 14, 17 and beyond and can

chose whatever focal length I feel like using.

 

I use them all but space them out when I observe. For instance if using the 17, one of my favorites, I go

next to a 10 or 9.



#24 blamkin86

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Posted 19 December 2018 - 03:54 PM

Started observing this year with a SW 100ED. So,

 

SW 5mm

SW 20mm.

 

I bought a ES 6.7/82, which I liked just fine.

I also bought a Baader 8-24 - that one I didn't care for the changing AFOV.

I also bought a 2" ES 30mm, I love that thing and use it all the time.

 

I traded the 6.7/82 for a 5.5/100 and some cash.

I sold the Baader outright.

 

Because I loved the 5.5, I bought a matching 9/100 when it came up for sale this year. I've hovered over the "add to cart" button on the 14mm many times.

 

So I wound up with

SW 5mm

SW 20mm.

ES 5.5/100

ES 9/100

ES 30/82

 

I plan on adding a Mak in 2019, so I'll have to fill in the gaps there. For those, I'm going to try some thing different, since I clearly don't need the SWA eyepieces. 


Edited by blamkin86, 19 December 2018 - 03:55 PM.


#25 CeleNoptic

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Posted 19 December 2018 - 10:03 PM


I know that i'll overhaul my collection many times in future, but having a limited budget for the moment i'd prefer to invest in something different from what i already have.  Maybe the idea that the 14 will replace the 10 is not really true.

 

Eyepieces are a really subjective thing. Here or somewhere else you can get just general recommendations and many of them if not all are not necessary what will work for you. Nobody knows what exactly your sky quality is, what your scope quality is, what your vision is, what your observing preferences are etc. Only you decide. Many of us are budget observers and frequently ask questions like you do because not everybody can/want to take easy errors when planning budget for a hobby. Even though we still do errors, I do. So all these advises should be taken with a grain of salt. Some join astro clubs and try before buying, others like me before spending money on a premium eyepiece once in a while do homework and experimenting with cheap eyepieces and a Barlow to figure out what combination/exit pupil provide most pleasing views. I understand that your 10mm XWA is a nice premium EP giving you a very useful exit pupil of 2mm, but you don't know maybe a 9mm Baader Morpheus will show you what you'll like better. I'm personally sure that the 1.8mm exit pupil might be preferable, so the spread e.g. 14mm Delos-9mm Morpheus would be nicer, but YMMV. So, if you can/wish join your local astro community, maybe visit some Star parties, try to use various eyepieces. Or buy an inexpensive Zoom and try various magnifications on various objects and you'll get better idea what exactly you need. Find a kind of *anchor* focal length/magnification (exit pupil) you like best and it'll be easier for you by stepping up/down 1.4-1.5x to make a nice EP collection without wasting a lot of extra money. IMO, all useful advises you've got here is a good food for thought and further experiments, they definitely would make steeper your learning curve.


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