Is 44x Low Enough?

[Sunshine]

My 18mm APM eyepiece yields 44x in my 115mm Eon refractor, I am aware this is purely subjective but, should I bother buying a 24mm or 30mm lets say?. How often do you use powers in the 25x range? and, what would I be missing out on at such low magnifications?

Edited March 15, 2020 by Sunshine

[Stu]

2 hours ago, Sunshine said:

My 18mm APM eyepiece yields 44x in my 115mm Eon refractor, I am aware this is purely subjective but, should I bother buying a 24mm or 30mm lets say?. How often do you use powers in the 25x range? and, what would I be missing out on at such low magnifications?

It's less about power and more about field of view, so you can fit in some of the larger open clusters and nebulae if these interest you.

Your 18mm gives 1.5 degrees, a 30mm 82 degree eyepiece would give 3 degrees which can frame larger objects well. M45 set within a wider context is lovely in a scope for example. With an OIII filter, the Veil and NAN can be amazing under a dark sky. The two blue circles on these images are 1.5 and 3 degrees.

[John]

Large true fields are nice for observing extended objects as Stu says. To get that you either go to lower magnifications or to wider apparent field of view, or a combination of both.

With my ED120 refractor I use a 40mm SWA eyepiece (2 inch format) which shows 3 degrees of sky at 22.5x and is great for the sort of targets that Stu illustrates. Your current 1.5 degrees from your 18mm eyepiece will show lots of deep sky objects as well of course but wont fit the larger ones into a single field.

 

[joe aguiar]

Both explained it well

I too would agree I sometimes go as low as 20x, besides what both said about the fov, if you star hop low power will also help

I only use a rigel or telrad then my 1st ep depending on my scope I'm using is either the meade 56mm  2 inch ep or the 32mm meade swa  2 inch ep. 

It's kinda like a large  finderscope view almost once I find the item I then bump to the meade 4k 24.5  swa ep etc the highter

So yes get a lower power ep or wider fov one

Joejaguar 

Edited March 15, 2020 by joe aguiar

[Don Pensack]

On 14/03/2020 at 21:53, Sunshine said:

My 18mm APM eyepiece yields 44x in my 115mm Eon refractor, I am aware this is purely subjective but, should I bother buying a 24mm or 30mm lets say?. How often do you use powers in the 25x range? and, what would I be missing out on at such low magnifications?

For me, yes, 44x is low enough as a low power.  I don't need for my refractor to duplicate a binoculars power or field size.

IF you seek a really wide field and really low power, then perhaps it makes sense, but I really see very little reason even then to have a magnification below about 5X/inch (5mm exit pupil)

That would be a 23mm eyepiece.  Yes, the image is brighter at low power, but star clusters will be poorly resolved, and galaxies really small so unless you really enjoy the "context" view,  I wouldn't bother.

The largest eyepiece I use with my 4" refractor is an 18.2mm yielding 39x.  My most-used eyepiece is an 11mm (65x) or a 7mm (102x).

 

Edited March 18, 2020 by Don Pensack

[Mr Spock]

A low power opens up many star fields to observe. The wider you can get the more immersive the experience. What kind of budget do you have?

[Merlin66]

Isn’t that the definition of a Rich field telescope????

 

[NGC 1502]

I really enjoy very low power wide field.  My TV Pronto with 35 Panoptic produces 14x and a 5 degree true field.  At my club’s dark site it’s totally relaxing to pan starfields.   It’s amazing just how much can be seen with a small aperture.  If I add in my 2” Ultrablock some large nebulae pop into view.   Back in 2012 the only scope I took to Kelling star party was the above kit.  I didn’t regret leaving my much larger Dob at home......

YMMV of course.........🙂.......Ed.

[John]

1 hour ago, Merlin66 said:

Isn’t that the definition of a Rich field telescope????

 

You don't see that term used much these days !

 

[John]

5 hours ago, Don Pensack said:

For me, yes, 44x is low enough as a low power.  I don't need for my refractor to duplicate a binoculars power or field size.

IF you seek a really wide field and really low power, then perhaps it makes sense, but I really see very little reason even then to have a magnification below about 5X/inch (5mm exit pupil)

That would be a 23mm eyepiece.  Yes, the image is brighter at low power, but star clusters will be poorly resolved, and galaxies really small so unless you really enjoy the "context" view,  I wouldn't bother.

The largest eyepiece I use with my 4" refractor is an 18.2mm yielding 39x.  My most-used eyepiece is an 11mm (65x) or a 7mm (102x).

 

I tend to prefer more magnification than 40x as well - hence the value of my Ethos 21. 43x and 2.3 degrees of true field with my ED120.

Sometimes it is nice to go lower though and I do enjoy the "context" views

 

[joe aguiar]

On 15/03/2020 at 18:42, joe aguiar said:

Both explained it well

I too would agree I sometimes go as low as 20x, besides what both said about the fov, if you star hop low power will also help

I only use a rigel or telrad then my 1st ep depending on my scope I'm using is either the meade 56mm  2 inch ep or the 32mm meade swa  2 inch ep. 

It's kinda like a large  finderscope view almost once I find the item I then bump to the meade 4k 24.5  swa ep etc the highter

So yes get a lower power ep or wider fov one

Joejaguar 

Um quoting myself I know weird am I the only one that did this?

Just wanted to add I dont use regular finderscope at all my 56 or 32mm 2 inch ep is my finder. 

Most people use a 6x to 9x finder which doesnt do much in white zone cities anyway maybe in country skies it's more useful. 

Maybe thay y for me going as low as 20 or 30x makes sence since I dont use finderscope and I'm in a white zone 

Joejaguar 

[Mr niall]

Have you considered exit pupil as well?

I would say no eyepiece collection is complete without at least something in the 5-6mm range. I use a 40mm Vixen NPL in my 90/900 - this gives 22.5x but importantly a nice 4mm exit pupil (which is about the most I can physically get). There is a whopping difference in contrast between that and my 25mm (36x but a 2.5mm exit pupil).

The 25mm gives much more contrast (which is good for helping cut through light polluted skies) but does dim the image a fair bit compared to the 40mm as a result. Sometimes really faint stuff is just undetectable for me at 36x unless I've already dialled it in at 22.5x and know what I'm looking at! 

When fuzzy hunting I normally start with the 40mm - then if I find what I am looking for, move to the 25mm - then if it improves try again with the 15mm. 

Both the 40 and the 25mm have a wider TFOV than my scope can support so I get vignetting with either - which is why I went all the way to 40 rather than 30 - because of the increased exit pupil.

But on a more subjective note - nice big exit pupils are a dream when it comes to eye positioning and flexibility at the eyepiece you just get so much more wiggle room.

[jetstream]

2 hours ago, Mr niall said:

Have you considered exit pupil as well?

I would say no eyepiece collection is complete without at least something in the 5-6mm range

[Don Pensack]

8 hours ago, John said:

I tend to prefer more magnification than 40x as well - hence the value of my Ethos 21. 43x and 2.3 degrees of true field with my ED120.

Sometimes it is nice to go lower though and I do enjoy the "context" views

 

Since you can have an exit pupil larger than your pupil in a refractor (it only sacrifices some light, but the magnification is really low), I've tried a 55mm Plössl in my 4" refractor and got to 13x and a field of 3.7°.

It's not quite large enough a field for using the scope itself as a finder (my finder is 8x and a 6° field), and the magnification is barely more than my finder, albeit with a significant jump in aperture.

"Context" views for objects like the Pleiades or M31 do require massive fields of view.  My best view of those objects with context is something that yields ~10-20x and a 4.5° field, like a 31mm Nagler in a TeleVue NP101 refractor.

I've regretted selling mine for several years.

[Stu]

48 minutes ago, Don Pensack said:

Since you can have an exit pupil larger than your pupil in a refractor (it only sacrifices some light, but the magnification is really low), I've tried a 55mm Plössl in my 4" refractor and got to 13x and a field of 3.7°.

It's not quite large enough a field for using the scope itself as a finder (my finder is 8x and a 6° field), and the magnification is barely more than my finder, albeit with a significant jump in aperture.

"Context" views for objects like the Pleiades or M31 do require massive fields of view.  My best view of those objects with context is something that yields ~10-20x and a 4.5° field, like a 31mm Nagler in a TeleVue NP101 refractor.

I've regretted selling mine for several years.

That’s what I love about my Genesis at 500mm focal length, easy enough to get to a 5 degree field with a 31mm Nagler. Lovely on the Veil and NAN plus these other large objects.

[Sunshine]

13 hours ago, Mr Spock said:

A low power opens up many star fields to observe. The wider you can get the more immersive the experience. What kind of budget do you have?

Well, about 250 CAD i guess, i think my next eyepiece will need to have better eye relief, i am tired of touching eyeball to glass as i do with my ES 14mm 82 degree.

[Louis D]

5 hours ago, Sunshine said:

Well, about 250 CAD i guess, i think my next eyepiece will need to have better eye relief, i am tired of touching eyeball to glass as i do with my ES 14mm 82 degree.

More questions for you:

1. Do you have a 2" diagonal for the refractor?
2. What are you using for low power in the Starmaster Dob?

I have a large range of low power eyepieces that I've tried and used over the years, and I guess it depends on your preferences for eye relief, edge correction, apparent field of view, and true field of view which one I would recommend to you.

[Sunshine]

54 minutes ago, Louis D said:

More questions for you:

1. Do you have a 2" diagonal for the refractor?
2. What are you using for low power in the Starmaster Dob?

I have a large range of low power eyepieces that I've tried and used over the years, and I guess it depends on your preferences for eye relief, edge correction, apparent field of view, and true field of view which one I would recommend to you.

My refractor is a 115mm Eon, 805mm FL, the lowest power eyepiece I have is the 18mm APM ultra flat field. My diagonal is 1.25, not sure if there is much benefit to a 2" diagonal to accommodate maybe a single 2"eyepiece in ones collection. Maybe I am wrong, you can enlighten me on why I may want a 2" diagonal for mostly 1.25 eyepieces, I would love to hear from experienced refractor users. They are quite a bit heavier i'm guessing, adding more weight to the optical train I would like to avoid unless i'm really missing out. For certain my 14mm ES 82 is getting sold, I would like more eye relief, maybe ill replace it with a comparable FL Morpheus or, a particular line you might suggest. As for the low end, I think something in the 70-80 degree 25-30mm FL with half decent eye relief would be great. OH, I forgot to mention, I have a 2.5x TeleVue powermate also.

My 3 eyepieces as of now: ES 14mm 82, APM 18mm, Baader Morpheus 9mm and a 2.5x powermate.

Thanks for your recommendations!

[Stu]

I nearly always use 2" diagonal in my refractors, even the 72mm. I only have 1 1.25" and that is a Tak prism. Perhaps a T2 diagonal might be a good compromise depending on what focal length you end up using.

With 1.25" eyepieces there is a theoretical benefit as you are using the centre part of a larger mirror, avoiding any edge inaccuracies. I say theoretical because it may or may not be a real factor. Having extra weight on the back of a normally front heavy refractor is often a benefit as it means you can mount the scope further forward in the rings and have the eyepiece higher when viewing towards the zenith.

It all depends on what you end up enjoying. For me personally I wouldn't ever be without at least one or two 2" eyepieces for those wider field of view.

[joe aguiar]

I too have a 2 inch diagonal on most scopes cept the solarmax of course

Joejaguar 

 

Edited March 19, 2020 by joe aguiar

[John]

5 hours ago, Stu said:

I nearly always use 2" diagonal in my refractors, even the 72mm. I only have 1 1.25" and that is a Tak prism....

Same here.

 

[Stu]

I meant to also add that a 2” diagonal just feels more secure, and more resistant to rotating in the focused due to the larger clamped area, something I prefer.

[Louis D]

I use 2" diagonals in my 72mm and 90mm refractors because I have many 2" eyepieces that I love to use in them.  Balance could be an issue, but I just use a long dovetail that projects back toward the focuser to achieve balance.  Most 1.25" diagonals I've had experience with have been fairly flimsy or have unnecessary stops in them to limit clear aperture.  My GSO 2" diagonals experience none of these issues.  I even use a 2" diagonal on my 127mm Mak despite the small rear baffle because it vastly opens up the views without noticeable vignetting.  Bright stars do produce funky oval distortions from a reflection somewhere.

Two inch eyepieces that I use on a regular basis in my refractors (and Dob):

• 40mm Meade 5000 SWA
• 35mm Baader Scopos
• 30mm ES-82
• 30mm APM UFF
• 22mm Nagler T4
• 17mm ES-92
• 12mm ES-92

In the past, I've also use the following 2 inch eyepieces in my scopes:

• 42mm Rini Erfle
• 40mm Meade 5000 Plossl
• 38mm Rini MPL
• 35mm OVL Aero ED
• 30mm 80 Degree Widescan III clone
• 29mm Rini MPL
• 27mm Panoptic
• 22mm AT AF70
• 17mm Nagler T4
• 12mm Nagler T4 in 2" mode

I love panning about rich star fields at lower powers discovering star clusters that are not at all obvious at higher powers.  It's sort of like going out for a drive on an empty road and just enjoying the scenery instead of heading for a destination.  It's just relaxing to have no particular observing plan which allows me to unwind after a stressful day.

[Sunshine]

Considering what i read here, maybe a 2" diagonal will be my next purchase. The idea of offsetting the extra weight by moving the OTA forward a bit is great, raising the viewing position a bit for observing near zenith.

I hope all you SGL friends are doing well, wish you all the best and keep healthy.

Edited March 19, 2020 by Sunshine

[michael.h.f.wilkinson]

I love using low magnification. The views of the Pleiades in my 6" F/5 Schmidt-Newton with the Nagler 31T5 at 24.6x and 3.34° FOV are just breathtaking. Likewise, I use the same EP in my APM 80 mm F/6 triplet at 15.5x, which gives stunning views of wide-field objects