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8" Flex Dob Eyepeiece recommendations - APM 30mm UFF + Super Zoom?

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#1 astrogastro

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Posted 16 June 2024 - 11:13 PM

Hi All,

 

I have an 8" Skywatcher flex dob with the provided 10mm and 25mm plossl eyepieces. They aren't great and I am looking at something better. Current magnification provided by the eyepieces is 48x and 120x.

 

mirror size=200mm
focal length=1200mm
f stop= 6

 

I have gone down the eyepiece rabbit hole and want to sanity check my eyepiece selection before I make the purchase.... as together these will cost more than the telescope itself...

 

So far, I have settled on the following:

Sky Rover 30mm UFF 2" (Re-brand of APM 30mm UFF). [This seems like a given]

Sky Rover HFM 7.7-15.4mm Zoom (Re-brand of APM Super Zoom).

 

I have kids so I wanted a zoom to make it easier for them and reduce swapping out eyepieces all the time. 

 

I have looked for used items (for both APM and super zoon) but can't find any in my country. There is no stock of the APMs where I live - hence purchasing the "Sky Rover" instead.

 

In addition to the above, I am looking to either:

(1) barlow the zoom - but not sure what to get yet.... open to suggestions; or

(2) Buy a higher power fixed eyepeiece, maybe 5/6mm??

 

Open to your recommendations - thanks in advance.

 

In terms of budget, I am very much "value" focused - i.e. willing to spend money to get to 80% of the performance for 60% of the price and weight compared to the very top eyepieces. I don't want to be left wanting by cheaper eyepeices and end up buying again later. 

 

EDIT: Myself and one of the kids use glassess... so eye relief is a priority.


Edited by astrogastro, 16 June 2024 - 11:51 PM.


#2 ShaulaB

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Posted 16 June 2024 - 11:36 PM

The Baader Mark IV 8-24mm zoom is really nice. Ours gets used on our "good" telescope. We use it with a barlow when looking at planets. Our Celestron 8-24mm zoom is used frequently for outreach on Dobsonians.

 

A 5 to 6mm eyepiece usually has a really short eye relief. Eyelashes will caress the top lens. I do not find short eye relief eyepieces to be comfortable to use.  Kids might not enjoy using such an eyepiece.

 

1200mm telescope focal length / 5mm eyepiece focal length gives 240X magnification. Where I live, atmospheric seeing rarely allows good viewing above 200X. it might be a good idea to spend a lot of observing time at 150X at most for some months before pumping up magnification. Many Summer Milky Way objects in the Northern Hemisphere can be enjoyed at 50X actually.


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#3 astrogastro

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Posted 16 June 2024 - 11:49 PM

Thanks - I was thinking of holding off higher power for now anyway. 7.7mm of the APM zoom gives me 155x so that is probably enough for now?


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#4 ShaulaB

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Posted 17 June 2024 - 02:01 AM

I have no experience with APM gear, so if it looks good to you, give it a try.



#5 Alex.C

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Posted 17 June 2024 - 03:25 AM

I also have a 200/1200, glasses, and a kid I observe with!

Our UFF30 is amazing, but only gets used on very large targets like M31, the Pleiades and the double cluster in Perseus, or to simply "glide" around the night sky.

We went for the Baader 8-24 zoom, but we do find the view at the long focal end very tight and mostly use it around 8-12mm these days.

I also have a SVbony 3-8mm zoom that I exclusively use on planets when the seeing is right. I even use them with my glasses because of heavy astigmatism; no, I can't see the entire field, but I CAN see the planet, and man is it sharp.

Curiously, I found that we originally spent a lot of time with the Baader Zoom at around 20mm, despite actively disliking the cramped view. I ended up getting a Founder Optics Marvel 20mm 80° for a wider view at the same exit pupil, and it's become our most heavily used eyepiece.

By the by, Sky Rover isn't a shady rebrand of APM, it's the house brand of United Optics, the actual manufacturer of these eyepieces.
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#6 25585

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Posted 17 June 2024 - 04:35 AM

I wear glasses and can recommend the 30 UFF. No idea about the superzoom, but I think you will need a focal length between 30 & 17, say a wide field 20mm like the Pentax XW.


Edited by 25585, 17 June 2024 - 04:36 AM.


#7 pregulla

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Posted 17 June 2024 - 05:24 AM

I would add a barlow for the zoom first, IMO zoom works better than fixed length at higher magnifications for Moon and planets when you are trying to get the maximum magnification for given seeing. I am using Celestron Xcell barlow + Hyperflex Zoom (8-24mm) for the Moon and planets with my 8" Flextube. I am able to push above or close to 200x most of the time, and on some occasions of good seeing closer to 300X.

 

I also have short fixed focal length eyepieces because I like larger FOV for DSO, but it's more of a luxury that a necessity.

 

Having something between 30mm and 15mm is nice, but not a must IMO. When I had ES82/11, ES68/16, ES68/24, Aero ED 35mm, I almost never used 16mm or 24mm, eventually replaced both with ES82/18. If you are looking for best value to close the gap than probably SkyWatcher SWA70 22mm (or under one of many other brands, whichever is cheaper) will be it - it's reportedly very good optically, eyeglasses friendly and relatively cheap.



#8 TheChosen

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Posted 17 June 2024 - 05:39 AM

The 30mm SkyRover is amazing. I very much doubt you will easily find a used one. Excellent eyepieces tend to not get re-sold much. Just get it on AliExpress if you can when there is some sale going on with coupons etc.. It can be purchased for about 150$.

 

Be careful with the Zooms .. they are not as good as it may seem. I just sold my Hyperion Zoom which I bought used 2 weeks ago with a 20$ loss. Maybe check the on-going discussions first before putting a lot of money into a Zoom:

https://www.cloudyni...eview-f5-wo-cc/

 

To be honest , with the 8" .. I would just go with the SVBony 'red line' 15mm. It will offer you plenty nice views at f/6 for every little money. Once you get some experience you can always get something better. I observed the entire messier in my 8" using a 32mm Kellner and a 15mm SVBony 'red line'. The 9mm 'red line' is also nice. The advantage of the 8" at f/6 is that these budget options are still working pretty well.

 

A Barlow 2x like the Celestron Omni 2x is a very good addition which I still use in my 12" with premium eyepieces.

 

If you really want a Zoom , get the SV191 or the SVBony lighter 7-21mm. A lot better price for all the inherent downsides a Zoom gives. I would never buy a new Hyperion Zoom unless you have tested it extensively and are absolutely sure it is the right thing for you.



#9 astrogastro

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Posted 17 June 2024 - 05:58 AM

Thanks for the replies so far. There is actually a sale on today at aliexpress (as always) so I picked up the Sky rover 30mm uff and super zoom.

Now… how do I know what Barlow to get? On the apm website they offer kits with the super zoom and a “comacorrecting” 2.7x Barlow that apparently acts like a 1.89x magnification? How do I know what Barlow is best for the zoom? Do I need coma correcting?

Edited by astrogastro, 17 June 2024 - 05:59 AM.


#10 pregulla

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Posted 17 June 2024 - 06:10 AM

You don't need a specific barlow. I believe GSO 2.5x is considered good value. I personally didn't try it. Some people prefer telecentric barlows, but I didn't like the larger size and weight (I had ES 2X focal extender).

Check how much focuser travel the zoom requires in 1.25" format and how much and in which direction the Barlow shifts the focus to make sure the combo can come to focus, maybe you'll need a lower profile 2" to 1.25" adapter or an extension tube.



#11 astrophile

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Posted 17 June 2024 - 06:27 AM

At f/6 I’d skip the coma corrector for now and see how you like the views without it. It’s the 30mm where you’d notice coma the most anyway—so if you decide you need a coma corrector, it’d be a full time one like Paracorr or GSO, not part of a Barlow for the zoom.

As for a Barlow itself, I’m not directly familiar with the APM zoom so recommend searching through some of the threads on that ep for peoples’ experiences/recommendations about a good Barlow for it. Unless you live under consistently poor seeing, you will likely want more than 155x available for planets; with that scope I’d want a Barlow that got the zoom down to 5mm for 240x at least; 4mm for 300x better, for the good nights.
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#12 pregulla

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Posted 17 June 2024 - 06:41 AM

 

I don't think you need a 30mm ep on an f6 scope, imho.

30mm UFF has 48% larger filed compared to 25mm X-Cel LX. Worth having in my book. I still keep my 35mm because sometimes the 30mm UFF just that little bit too narrow, even in my F/5 120mm achromat. Larger exit pupils are also useful for use with narrowband filters if OP decides to get one in the future.


Edited by pregulla, 17 June 2024 - 06:42 AM.

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#13 Starman1

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Posted 17 June 2024 - 09:03 AM

Hi All,

 

I have an 8" Skywatcher flex dob with the provided 10mm and 25mm plossl eyepieces. They aren't great and I am looking at something better. Current magnification provided by the eyepieces is 48x and 120x.

 

mirror size=200mm
focal length=1200mm
f stop= 6

 

I have gone down the eyepiece rabbit hole and want to sanity check my eyepiece selection before I make the purchase.... as together these will cost more than the telescope itself...

 

So far, I have settled on the following:

Sky Rover 30mm UFF 2" (Re-brand of APM 30mm UFF). [This seems like a given]

Sky Rover HFM 7.7-15.4mm Zoom (Re-brand of APM Super Zoom).

 

I have kids so I wanted a zoom to make it easier for them and reduce swapping out eyepieces all the time. 

 

I have looked for used items (for both APM and super zoon) but can't find any in my country. There is no stock of the APMs where I live - hence purchasing the "Sky Rover" instead.

 

In addition to the above, I am looking to either:

(1) barlow the zoom - but not sure what to get yet.... open to suggestions; or

(2) Buy a higher power fixed eyepiece, maybe 5/6mm??

 

Open to your recommendations - thanks in advance.

 

In terms of budget, I am very much "value" focused - i.e. willing to spend money to get to 80% of the performance for 60% of the price and weight compared to the very top eyepieces. I don't want to be left wanting by cheaper eyepeices and end up buying again later. 

 

EDIT: Myself and one of the kids use glasses.. so eye relief is a priority.

With the 8" dob, the 30mm and the Super Zoom is a great combination.

Use the Zoom in the 2" mode to make its focus come close to the 30mm.

 

You will be able to use glasses with both.  Just fold the rubber eyecups down.

 

As for a Barlow for the Zoom, a very cost effective Barlow is the 2" 2X GSO ED Barlow.

It comes with a nice 1.25" adapter as well.  It can be found on AliExpress, too.

And IF (I don't think you will need it) you find you want an eyepiece in between the 30mm and 15.4mm setting on the Zoom, the lens cell of the GSO 2" 2X ED unscrews from the Barlow's tube and threads directly to the 30mm

eyepiece, turning it into a 20mm (It becomes a 1.5x Barlow if used that way.


Edited by Starman1, 17 June 2024 - 09:04 AM.

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#14 peter k

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Posted 17 June 2024 - 09:12 AM

Thanks for the replies so far. There is actually a sale on today at aliexpress (as always) so I picked up the Sky rover 30mm uff and super zoom.
 

Good move. 



#15 SeattleScott

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Posted 17 June 2024 - 09:17 AM

I would want something higher power. The Superzoom is already heavy. I don’t know that I would want to add a 2” barlow to that. It’s a lot of weight to balance on an 8” Dob. I would probably just get a 5mm and call it good. Some good long ER options are Delite, Nikon SW, Pentax XW and Morpheus (the 4.5 is actually 4.8). On the cheaper side is the 5SLV but it is narrow AFOV so it would require more manual tracking.
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#16 astrogastro

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Posted 17 June 2024 - 10:57 AM

Thanks - never really considered the weight balance.. I guess because all I know is the small 10mm and 25mm plossl lenses. 

 

I really like the dual functionality of the 2" 2X barlow with removable lens per the previous suggestion, this will give me:

 

Zoom + barlow: 3.8mm - 7.7mm

Zoom only: 7.7mm - 15.5mm

30mm + barlow (1.5x) - 20mm

30mm only... 30mm

 

For me, that is a complete set with decent quality, practicality and ease-of-use. 

 

Looking at the weights (from the data sheets):

Zoom: 522g (wow.. heavy... I didn't check that)

2x GSO 2" Barlow: 388g  

 

So total weight would be 910g

 

Without any reference point I don't know if that is acceptable or not give my scope. The scope is a 3-truss design and seem pretty solid, but adding almost 1kg on top - will this need some kind of counterweight on the bottom? then you are adding maybe 1.5kg to balance on the other end? would this then affect the bearings?



#17 Starman1

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Posted 17 June 2024 - 11:12 AM

Thanks - never really considered the weight balance.. I guess because all I know is the small 10mm and 25mm plossl lenses. 

 

I really like the dual functionality of the 2" 2X barlow with removable lens per the previous suggestion, this will give me:

 

Zoom + barlow: 3.8mm - 7.7mm

Zoom only: 7.7mm - 15.5mm

30mm + barlow (1.5x) - 20mm

30mm only... 30mm

 

For me, that is a complete set with decent quality, practicality and ease-of-use. 

 

Looking at the weights (from the data sheets):

Zoom: 522g (wow.. heavy... I didn't check that)

2x GSO 2" Barlow: 388g  

 

So total weight would be 910g

 

Without any reference point I don't know if that is acceptable or not give my scope. The scope is a 3-truss design and seem pretty solid, but adding almost 1kg on top - will this need some kind of counterweight on the bottom? then you are adding maybe 1.5kg to balance on the other end? would this then affect the bearings?

It won't affect how the scope moves, but it will likely require a counterweight when the scope is pointed low.

This can be easily accomplished with magnetic weights you can put on and take off (some even have handles!).

Or, it can be accomplished with a "virtual" counterweight.

 

To wit: on my own scope, heavy eyepieces cause the top to fall when the scope points low.

I attach a mini bungee cord (or two for very heavy eyepieces) between the rocker box and the mirror box so that when the scope points high, there is no tension on the bungee cord,

and it starts to stretch at about the 45° point and gets tighter the lower the scope points.

I can get the scope to have equal force needed to move the scope up or down at a 20° altitude, so it neither dives nor rises.

I leave one cord always attached and I rarely notice it's there.

 

With really lightweight eyepieces, I remove the bungee cord as the upward force on the UTA is not necessary.

 

Like any counterweight, though, if the scope is pointed low and you remove the eyepiece, the scope will rise.

Since the motion is only in one axis it's usually pretty easy to just pull it back down to the same object after a new eyepiece is inserted.

It helps to have a finder on the scope so you don't shoot past the object or stop short.



#18 SeattleScott

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Posted 17 June 2024 - 11:24 AM

I wouldn’t worry about the 1.5x deal. You have ~18mm with 65 AFOV. The 1.5x gives you 20mm with 70 AFOV. Screwing the barlow nose on and off isn’t likely to be worth the hassle for a touch lower magnification and a touch more AFOV. Once in a great while you might come across a target that really needs that 15% or so wider view and maybe it is worth it to get optimal framing. But this would be once in a blue Moon, and even then you may decide it isn’t worth the effort.
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#19 Simoes Pedro

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Posted 17 June 2024 - 11:45 AM

Decide first whether you are going to build a 2" or 1.25" system. Balancing 2" eyepieces on your scope maybe a challenge.

 

On the other hand, what is it you dislike about those 10 and 25 mm eyepieces you already have?


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#20 pregulla

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Posted 17 June 2024 - 12:34 PM

I have tried using ES82/30 + 2" GSO barlow (1.4kg monstrosity :D) in 8" Flextube, just to see if the scope can handle it. It did fine, but did require a counterweight. IIRC it was 700g counterweight, and altitude clutches somewhat tightened. Get some magnets from AliExpress while you are shopping and you can easily fabricoble few counterweights.



#21 sevenofnine

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Posted 17 June 2024 - 02:53 PM

Agreed, the 30mm & Zoom is a great start! I would hold off on the 2" barlow for now. Too much weight is a frequent complaint about these. Instead, see if you really need one or just buy a planetary eyepiece in the future. I recommend the AT 4/82 UWA from our sponsor waytogo.gif

 

https://www.astronom...5-eyepiece.html.


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#22 SeattleScott

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Posted 17 June 2024 - 03:25 PM

Agreed, the 30mm & Zoom is a great start! I would hold off on the 2" barlow for now. Too much weight is a frequent complaint about these. Instead, see if you really need one or just buy a planetary eyepiece in the future. I recommend the AT 4/82 UWA from our sponsor waytogo.gif

https://www.astronom...5-eyepiece.html.

7.7 to 4 is too big of a step for high power viewing. 5 to 5.5 would be more appropriate, then add a 4mm once collimation skills warrant it. There is some logic to being able to hit 300x but 240x will be useful more often, and doesn’t require as precise of collimation, hence it should be the higher priority. But eventually yes, a 4mm would be reasonable. On a budget, a used 3.8mm Ultrascopic or Parks Gold is very sharp, although the eye relief and AFOV aren’t on par with the 4mm UWA.

#23 astrogastro

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Posted 17 June 2024 - 09:04 PM

What about nagler 3-6mm? Looks expensive but if it replaces 3-4 lenses then might be worth it?



#24 Starman1

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Posted 17 June 2024 - 09:23 PM

What about Nagler 3-6mm? Looks expensive but if it replaces 3-4 lenses then might be worth it?

In an undriven dob at really high powers, the amount of pushing of the scope that would be required by a 50° eyepiece is excessive.

The OP also says he and one of his kids needs to wear glasses at the eyepiece, which rules out the Nagler 3-6mm Zoom, anyway.

 

However, the APM/Sky Rover Super Zoom is 66-67° over its entire range and compatible with glasses, as it would be when Barlowed.

That gives him a 3.85-15.4mm continuous range plus a 30mm glasses compatible 70°.

Magnifications available would be 40x and 78-312x.

The 40x to 78x jump is not large for an 8" scope, so it really doesn't need a magnification in between, but if he did, the GSO Barlow could yield 60x.

I would bet he would never feel the need for it.



#25 astrogastro

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Posted 17 June 2024 - 11:23 PM

Thanks, what about a 1.25" barlow? That *might* keep the weight down but obviously not as flexible as the 2"

 

bit more fiddly though:

2" -1.25" adapter > 1.25" barlow > zoom

 

vs. 

2" extender > 2" barlow > Zoom?

 

probably not going to save a lot of weight?

 

Maybe it's just easier to buy the 2" barlow, a counter weight and be done with it. 


Edited by astrogastro, 17 June 2024 - 11:25 PM.



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