Jump to content

Welcome to Stargazers Lounge
Register now to gain access to all of our features. Once registered and logged in, you will be able to create topics, post replies to existing threads, give reputation to your fellow members, get your own private messenger, post status updates, manage your profile and so much more. If you already have an account, login here - otherwise create an account for free today!
Photo

Skylux F=700 D=70 Refractor Telescope Maximum Magnification?

- - - - -

  • Please log in to reply
16 replies to this topic

#1
Bas009

Bas009

    Vacuum

  • New Members
  • 3 posts
  • Location: London
First post :)

Recently came across my step fathers telescope which has not been used for a while. It is a Skylux telescope and here is a picture of it: Posted Image

Skylux F=700 D=70 Refractor Telescope Art.-Nr.:96-18800 RK=20mm

I Have been using it for about a week now looking at the moon and stars with the RK=20mm piece, I am seeing the surface of the Moon clearly but i was wondering if i could get a closer magnification. I only have the one piece and was wondering what magnification it is, also what is the maximum magnification i can reach with the telescope with different kinds of eye pieces.

#2
knobby

knobby

    Red Dwarf

  • Advanced Members
  • 4,630 posts
  • Location: bottom right of the U.K.
Hi Bas
mag is calculated by F divided by EP size
so you are 700 / 20 = 36x mag
Maximum mag is debatable but people say things like 25-30 time per inch apeture ...
you have 70mm (nearly 3 inches)
so possibly 90x mag for your scope
That would be a 8mm eyepiece


Good luck

Skyliner 250px Dob with modded mount
Celestron Excel LX s and the odd plossl, Celestron C8 edge / advanced vx mount (grab & go...ish)

William Optics Zenithstar 71 ED ----- Lots of clouds

Co. founder of the Essex cloud dodgers social group
Nikon D300 & 7100 , ASI 120 MC


#3
Bas009

Bas009

    Vacuum

  • New Members
  • 3 posts
  • Location: London

Hi Bas
mag is calculated by F divided by EP size
so you are 700 / 20 = 36x mag
Maximum mag is debatable but people say things like 25-30 time per inch apeture ...
you have 70mm (nearly 3 inches)
so possibly 90x mag for your scope
That would be a 8mm eyepiece


Good luck


Thank you for the fast response:) Do you know where I am able to buy a 8MM piece? regards.

#4
knobby

knobby

    Red Dwarf

  • Advanced Members
  • 4,630 posts
  • Location: bottom right of the U.K.
Dont jump in on my advice, wait for a few more answers :cool: I'm still a newbie myself !
How much do you want to spend ... best bet would be to check some prices - First light optics - who sponsor this site , or try uk astro buy and sell, probabaly get a decent second hand one.
They range from £10 used to £400 new !

Skyliner 250px Dob with modded mount
Celestron Excel LX s and the odd plossl, Celestron C8 edge / advanced vx mount (grab & go...ish)

William Optics Zenithstar 71 ED ----- Lots of clouds

Co. founder of the Essex cloud dodgers social group
Nikon D300 & 7100 , ASI 120 MC


#5
ronin

ronin

    Main Sequence

  • Advanced Members
  • Pip
  • 5,501 posts
  • Location: Cambridge
Just check first that it is a 1.25" eyepiece.
Assuming it is then most retailers sell several brands that will fit your scope.
For 8mm a standrd plossl will be OK, if you want more magnification then the eye relief reduces with the shorter focal length plossl eyepieces. So you may then want an eyepiece with more eyerelief. Basically how close you have to get to the eyepiece to have an optimum view.

Around £30 will get you one, the GSO brand and the Vixens are said to be good.

That looks a decently built scope.
Have fun with it, try Saturn at 90x might be enough for a good view.

Scope will probably be fine for 70x with a 10mm EP and you may get to 100x with a 7mm.
The 8mm is a good compromise.

#6
knobby

knobby

    Red Dwarf

  • Advanced Members
  • 4,630 posts
  • Location: bottom right of the U.K.
Not exactly the same scope as yours but this might be of interest

Skyliner 250px Dob with modded mount
Celestron Excel LX s and the odd plossl, Celestron C8 edge / advanced vx mount (grab & go...ish)

William Optics Zenithstar 71 ED ----- Lots of clouds

Co. founder of the Essex cloud dodgers social group
Nikon D300 & 7100 , ASI 120 MC


#7
umadog

umadog

    Brown Dwarf

  • Advanced Members
  • 2,675 posts
  • Location: Basel, Switzerland
This is worth reading: http://www.cloudynig...php?item_id=547
9" DIY job, Sumerian 10", Webster 18", Lunt LS60/PT
M:109/109, C:72/109, H400:154/400, Mercury->Pluto

#8
JamesF

JamesF

    Supernova

  • Advanced Members
  • PipPipPipPip
  • 21,593 posts
  • Location: Wiveliscombe-ish, Somerset
As a generally rule, it's usually considered that the maximum reasonable magnification is twice the aperture size in millimetres, so the above "25x per inch" is in line with that. Given a good scope and good seeing you can push it further than that sometimes, though even with a large aperture scope the seeing in the UK is not often good enough to push beyond 250x magnification.

Bresser do still sell a 700/70 Skylux scope. I'd not be at all certain that it shares anything in common parts-wise with yours though

James

Skywatcher ST80, ST102, ST120, ED80, Skymax 127, MN190, 200P, Celestron C9.25, Coronado PST, several pairs of binoculars, 10" dob
EQ1, EQ3-2, AZ3, HEQ5 Pro, NEQ6 Pro
Planets: Mercury, Venus, Mars, Jupiter, Saturn, Uranus, Neptune
Messier Objects: 110
Lunar 100: 41


#9
glowjet

glowjet

    Sub Giant

  • Moderators
  • 9,415 posts
  • Location: North Yorkshire
Looks like a nice well made scope for it`s period although I am quite surprised at the long extension tube from the diagonal to bring the scope to focus, also your objective will not have the modern day coatings to improve light transmission. Bearing this in mind I should be on the cautious side when choosing other EP`s,your present one sounds like a Kellner and probably the best bang for your buck is to treat yourself to a s/h Orthoscopic around 8mm or 9mm, although a narrow field of view you will really see a difference, for basic wider field work you should, without spending a lot, be able to pick up some s/h Meade 4000 super Plossls or other similar quality makes. Do however make sure that your eye piece holder is for the modern standard 1.25" types or it will be necessary for you to buy an adapter. whatever you do, enjoy you Astronomy and the experience :)

John.
John.

#10
todd8137

todd8137

    G3IV3-V -TAG

  • Advanced Members
  • Pip
  • 8,184 posts
  • Location: Derbyshire
Nice scope my uncle as the same one
16" Reflector Oldham Optics Mirror set 1/4 waveC 9.25' SCT C GEM Pier Mounted in obsycables,[color=#00ff00]Filters, yes to many to list all baader some astronomics<p>

#11
Bas009

Bas009

    Vacuum

  • New Members
  • 3 posts
  • Location: London
Thanks guys for the responses, It is a 1.25 Inch, so am i able to use any eye piece that is within suitable magnification range that is 1.25 inch?.

Just came across a 2x Barlow scope also, If i get a 8mm eye piece will I be able to use the Barlow scope or will the image be fuzzed?

#12
rwilkey

rwilkey

    Brown Dwarf

  • Advanced Members
  • 2,736 posts
  • Location: Swindon, UK
It will be too much magnification, also considering UK atmospheric conditions as well (max 200x, beyond the capability of the scope).

Robin
Sky Watcher Explorer 200P EQ5 f/5 with 32mm Skywatcher PanaView EP. Meade 5000 Series 28mm, Baader Hyperions & FTR's. Celestron C100ED-R f/9 (Moonlited) on a Vixen Porta II mount. Plossls, ortho's, SW LET EP's, William Optics SPL 12.5mm, 6mm. Axiom LX's, 13mm LVW. BST Explorers. ES 82 Series. Various visual filters
Member of Swindon Stargazers and Salisbury Plain Observing Group


#13
glowjet

glowjet

    Sub Giant

  • Moderators
  • 9,415 posts
  • Location: North Yorkshire
Even with your Barlow, except on nights of exceptional seeing ( atmosphere clarity ) it is advisable not to exceed the rule of 50X per inch, at all other times you may well only achieve 25 to 30X per inch. Previous threads have explained this point and how to calculate it, so this will give you some insight into what to expect from a range of various eye piece sizes, used with or without a Barlow. As I have said, an Orthoscopic, without a Barlow, will provide you with very nice clear crisp views of the Moon, Star Clusters, single and double Stars, and basic views of the larger Planets Jupiter and Saturn. lower power eye pieces, but with a wider field of view, FOV, may help you pick up some of the Messier objects, this would be enhanced if you could do this from a very dark sight. One final word of advice, if you intend to go ahead with a Barlow, then it is worth investing in a quality unit, such as a Tal as there are many inferior cheap products which should be avoided, I am sure there will be others which the members can recommend, as worth spending your money on :)

John.
John.

#14
Moonshane

Moonshane

    Have I ever mentioned that I like dobs?

  • Global Mods
  • 15,781 posts
you could potentially get a 15mm plossl and a 2x barlow. this would give you a better low power option (46x) and also 92x with the barlow which I suspect is about as much as you'll enjoy. the plossl will give decent views on it's on providing about 1 degree of field.

Don't think, feel! It is like a finger pointing a way to the moon.

Don't concentrate on the finger or you will miss all that heavenly glory. Do you understand?

(Bruce Lee in Enter the Dragon)

It applies to eyepieces too

 

Messier 94/110 NGC 186/7836 Caldwell 23/109 Herschel 91/400 (non NGC) IC 1/179 Collinder 93/471 Stock 3/24 Melotte 32/245 Trumpler 1/37 Best 700 183/700 Cambridge showcase double stars 42/111 (123) (133) Lunar 66/100 Comets 7 Planets Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune

 


#15
Neil_F

Neil_F

    Nebula

  • New Members
  • 49 posts
  • Location: Sleaford, Lincolnshire
I have just picked one of these up for £30 in a local charity shop!! I have to say, for a budget scope it perofrms pretty well. I had some great views of Saturn last night which was quite suprising. The 20mm E.P that came with it is ok, but using the 25mm from my TAL-1 improves the view no end. The EQ2 mount that it sits on is a decent quality one, I'm really pleased with it and well worth the money I paid for it. :grin:
TAL-1 Newtonian reflector, GEM, 25mm + 15mm + 9.7mm + 2x Barlow
Skywatcher 130P, RDF, EQ2, 20mm + 10mm
Prinz Concord 450 cat, 20mm + 12.5mm + 6mm + 2x Barlow
10x60 Nikon binoculars
Bresser Skylux 70x700 refractor/EQ2

#16
Schorhr

Schorhr

    Sub Dwarf

  • Advanced Members
  • 1,444 posts
  • Location: Germany
I have this scope and it's a fun beginner device, I use it as fun tele lens for my camera (3d printed a adapter, ef-to-1,25").
My reccomendation would be cheap 8-10gbp Seben/Orbinar Plössl. They are really not bad for the price, much better then some of the stuff they sell otherwise.
I have the 4mm and 30mm Plössl eyepiece, but everything under 6mm is hard to view through (you have to get so close your eye lashes touch the lens).
On Moon and planets you can sometimes even go over the maximum magnification as they are still bright enough. It does not give you any more *real* detail, but the spacewalk/apollo feeling is really nice.
A 6mm Plössl will give you about 117x, a 6.5mm Plössl 108, and even though you allready have to get close, the image is usualy better then a 15/20mm eyepiece and a cheap "toy" barlow for magnification.
http://www.ebay.co.u...=item2ebe46f0d1

If you are willing to invest in better beginner eyepieces, those will last for a while AND have a nice wide-angle view... You get spoiled by that very quickly ;-)
http://www.ebay.co.u...=item20c36a1577 (66 degree apparent view of filed)
or for higher magnification
HR Planetary eyepiece from 38gbp
http://www.ebay.co.u...=item417304c41f
http://www.ebay.de/i...=item1e7a1728fa
(as an example, those vendors have other focal length/magnifications too)

Those have a apparant field of view of 58 degree (so still better then the Plössl 50 degree, but less then those uwa 66 degree) but they are available from 2.5mm for high magnification (though the limit for your telescope is about 5mm/140x)

At least on moon, saturn and jupiter it is nice to have a nice high magnification eyepiece if the conditions are right.
Else it's a good idea to get a 9mm, 15mm or 20mm wide angle eyepiece as it's great to just browse through the milky way or look at larger deep sky objects such as Andromeda.


If you want to get a barlow, get an achromatic one (as they are not much more expensive then the cheap plastic ones, and start at12-15gbp), though a good one usually costs more then one or two good starter eyepieces.
So to wrap it up, those could work:

Cheap plössl, or
9mm/66deg afov eyepiece AND cheap barlow, or
5 or 6mm 58deg afov Planetary and a 15 or 20mm 66deg afov

With 70-80mm aperture you can easily spot the rings of saturn, under great conditions with a good scope the cassini division, ring nebula but probably just as disc, and some DSO as small spots :-)
-Marcus
~ Even a small telescope will show the most amazing things.
If everyone would be aware of this, perhaps light pollution wouldn't be an issue anymore. ~
10" Sumerianoptics travel dobson, Heritage 130p, 102mm Mak, 76mm newt & firstscope-clone, 70mm refractor on astro3, 60mm cardboard newt, 10x50 binoculars, Erfles, Planetaries, Plössl.

#17
LukeSkywatcher

LukeSkywatcher

    Super Giant

  • Advanced Members
  • PipPip
  • 13,163 posts
  • Location: Maynooth,County Kildare,Ireland.
I agree that a 15mm EP and a 2X barlow would be a good idea. That way, you get two EP's (7.5 and 15mm). This would give you a wider range to observe and observe with.

Paul
___________________________________________________
 

Celestron 8se (Mick),Sky Watcher Heritage 130P,Celestron 90EQ,Celestron 70 Travelscope,Horizon 8115 tripod,Hyperion 8-24mm zoom. UHC filter,OIII filter and shed load of other various EP's, Canon 450D, Strathspey 20x90, Bresser 10x50 bins.





0 user(s) are reading this topic

0 members, 0 guests, 0 anonymous users