Skywatcher skyhawk 114 / 1000mm conversion ?

[Mr TamiyaCowboy]

hello everyone. 

way back in 2011 i purchased an above mentioned telescope.

not the best being a catadioptric design. 

its now two years on , the scope sits mounted on a eq-1 the same mount it came with

covered in dust and used about 10 time maximum for a few mins. 

truth is i am sick to the sight of it, a £100 lump of alloy tube glass mirrors and plastic.

so i thought at the very least i could adjust the focuser to a smoother running,

remove the old sticky gunk grease and re-lube with some white lithium grease. 

so screwdriver in hand i went about my task. 

sliding the focuser tube out of the focuser body i cleaned away the gunk.

and then i noticed something, a glass/plastic lens shoved into the end of the focuser tube.

i am unsure how i tell what type of lens this is but it sits direct in the end of the focuser tube.

in the path of the light cone. now if this is a barlow lens that means the scopes original focal length should be

500mm , the barlow would boost it to 1000mm and hence a 114/1000 scope.

Now interweb searching has came up with a second scope exactly the same but is a 114/500

thats a big fast scope ideal for my needs ( digital dslr photography ).

Now my questions are. 

Has anyone ever heard of a person converting one of these scopes back to a shorter focal length, IE removing the

correcting lens/barlow ? 

if yes/no what risk do i run removing it ?

if i remove it, how do i make sure it is replaced exact to how it was installed in the first place ?

i cannot/do not want to sell the scope on and have some poor newbie struggling with these fairly worthless scopes

i have been unable to get ANY answer from skywatcher at all on the subject of this corrector lens

and the removal of it affecting scope, and i have had a scope for 2yrs and has more dust than the surface of mars.

it is not fitting for a scope to be left and not used.  so what do you think could i change this cheapy into something thats not so bad.

a shorter original focal length and a faster F stop , currently the scope has a f8.9 ( its slow, dog slow) but that barlow/correcter is affecting the f stop

without that the tube would be more closer to f4.4 - f5 a nice ball park speed for dslr not to fast not to slow.

i will grabs some images of the focuser tube assembly and the barlow/corrector unit shoved into the tube end.

[knobby]

I've looked and looked but can't find it... I remember a thread about collimating a Skyhawk and the fella removed the Barlow to do it.

so in theory it will come out :-)

Why not try it, it will probably move the focal point out a fair bit but you may be able to counter that by moving the mirror up the ota or by extending the focuser.

good luck

[Mr TamiyaCowboy]

I've looked and looked but can't find it... I remember a thread about collimating a Skyhawk and the fella removed the Barlow to do it.

so in theory it will come out :-)

Why not try it, it will probably move the focal point out a fair bit but you may be able to counter that by moving the mirror up the ota or by extending the focuser.

good luck

thank you knobby 

yes one thing i really dont want to be doing is hacking away at the mirror, even moving it forwards.

thats a bit to far for my toolbox to extend to ( dremal and a hammer, screwdriver n stick for measuring)

also i have no work area just a pc desk/bed. 

with the fuzzy white stuff in the sky it is hard to tell if focus will be gained when the scope is converted,

are there ways to work out if a scope is seeing correct ? without need to re-build and have fingers crossed in hope.

[Schorhr]

I have a 130/1000 catadioptre mirror and focuser here for my classes, but not tested it yet.

From what I've read so far there are several issues when you try to use it without the catadioptre/barlow lens.

It will reduce the focal length but due to the cheap quality mirrors, you probably end up with a spherical ~f4.4 mirror.

A spherical mirror is cheaper to produce, and with a type of barlow lens they try to reduce spherical aberration, coma and generally save money by mounting a short tube on a weak EQ mount.

I don't know about your telescope for sure, but it's probably the same way with that mirror...

114/500 if it's spherical, it has a theoretical 0.014 Strehl.

You'd have to cover it down to ~78mm diameter to get a usable 0.8 Strehl, yikes! ;-)

It's sad that so many companies sell these kind of telescope. While there is nothing wrong with them in theory, it's just causing more frustrated beginners to loose interest in this hobby.

Regarding the mount, I'd probably make a small dobsonian / table dobsonian out of the current catadioptre setup. Cost: 4gbp in wood and hardware store stuff.

[John]

If you remove that relay lens (as it's known) you will get a rather poor l scope I'm afraid because the main mirror has spherical rather than paraboidal figuring and it has a very short focal length. The relay lens corrects these things and extends the focal length to achieve a reasonable scope but without it the optical system just won't work well at all.

[ronin]

Sorry to change the subject entirely but you give your location as: N 52° 65' - E 1° 21'

Since there are only 60' in a degree then the 65' bit cannot be correct. :eek:

Curious as your signature says you have a goto.

[Mr TamiyaCowboy]

yes i have a goto mount. 

its a cheap skywatcher merlin mount, yes i have bolted the 114 to it and no its not very good.

scope does not balance with its short tube length and can hit mount, so i use it for panorama

and as a timelapse mount. was said it would carry telescopes upto 4kg the 1141 weights less but does not fit the mount. 

thats google maps for you about my location took it from googles map.

so basicly i did buy a dud scope, have left it sitting for two years returned to it and found its still the biggest

Fail skywatcher ever made for a telescope. and is why jupiter looks more like a blurred out ufo,

and you can never never get that sweet spot focus on the moon even with a 25mm ep and no barlow.

so this is where i stand now. i need something to shoot solar and space objects. 

i am looking at the skywatcher 80/400 shorttube refractor ( £104 )  i own a canon 90-300mm telephoto lens and canon 350d and a t-mount system) 

or the celestron 70mm 400 shorttube refractor ( 59.99 uk ) again i would be using the canon 350d and t-mount system

any advice on the above scopes to replace the 1141 ? ( was in hope to use tracking feature of the merlin mount with short tubes)

what do i do with a useless scope as the 114, i cannot sell it on knowing problems and how cheap and dirty this scope is ( even for a decent scope maker like skywatcher) ?

and the mount to, the eq-1 what do i do with this stuff now ?

[Schorhr]

It's not a complete dud, you should be able to get some nice views and perhaps shots when collimated.

I've seen a few pictures of Jupiter with such a telescope, though on more rigid mount, that wheren't half bad.

Don't get a short tube if it's a simple fh refractor. The color fringe will be horrid if you try to image or view the planets with a barlow or short focal length eyepiece!

As for deepsky imaging, a good camera lens (though zooms have some downsides) and a mount or barndoor can go a long way. A lot of objects don't need long focal lengths...

German site, but all done with camera + lens + barndoor mount:

http://www.j-baechli.ch/astrofotografie/Controller?action=GALLERY

The EQ1 should be fine for camera + short/medium lens. I don't have the small EQ mounts, but I've seen images done with it once in a while.

As for visual, and a budget around 110gbp, I'd go with a 130/650, such as the Heritage 130p for visual. There are full-tube EQ mounted sets, but the EQ-2 is not much more sturdy and can't carry such a telescope well especially with Camera (plus the 130/650 on EQ2 usualy don't reach focus with a DSLR, there is a more expensive imaging 5" newt though, The 150 PDS for example).

The Merlin is a AltAz mount, I looked at that option as well before getting my AltAz GoTo mount for video astronomy. Unfortunately it can't carry the 130/650 as far as I could find reviews.

The Skywatcher Synscan AltAz mount will and the cheaper NexStar SLT. They also cary a 4" or 5" mak and that combination would work for planets I suppose (and probably perform better then the 5"f/5 newtonians but sucks on DSO imaging), as a NEQ3 with motors or even GoTo would cost quite a bit more...

As allways, there is no such thing as a telescope ideal for visual, planetary imaging and DSO imaging.

There should be a few tutorials on how to collimate a Catadioptre newtonian like yours, but I have no links at hand nor did I try it myself yet. Too much other projects at hand right now :-)

You should be able to get it to focus with a 25mm eyepiece. Unless it's really off or the lens (or mirror) is REALLY dirty, though usualy even a lot of dust does not influence the performance as much as one might think. Cleaning is possible, though it has to be done careful, no rubbing what so ever... Lots of guides here on the forum, too. Usualy this is only necessary if you have pollen all over the surfaces or dropped a jar of Nutella down the tube ;-) ;-)

So either try getting your current telescope optimized as far as you can, or consider other options.

But with your camera and the mount there should be a few nice short exposure shots possible even though it's an altAz mount. The equipment you already own, is usually the best equipment!

But whatever you do, don't trade one mediocre telescope for another, stay clear of any catadioptre newtonians, non-parabolic newtonian mirrors, or short FH refractors, and weak mounts ;-)

The old "you get what you pay for" usually applies to telescopes, and some on-line stores and manufacturers really make an art of describing junk as something supposedly great...

[Mr TamiyaCowboy]

yes am fairly stuck then. i have a heart condition so no heavy lifting and carrying stuff.

the 114 is a struggle and even the eq-1 mount , so carrying it into the middle of a field 

is well out of the question, its just me and myself in this game. i dont drive and live in a road filled with street lights

the new lights them bright white lights.

the reasoning on short tube refractors, they more easy to carry weight less

and will fit the merlin when i am not learning timelapse.

views through the scope are no omg wow, jupiter is a dot, saturn a dot with a litte dusty ring if you call it that.

put the barlow in your struggling for focus its a constant touching of the focuser to keep it in focus ( no slipping), those dots become blurrished dots

with a hint of something like color using a 25mm eyepiece and a meade 17mm eyepiece.

and well shoving a dslr onto it just goes against the grain, that 1000mm with the 1.6 crop on my camera makes it into a

1600mm focal length scope. and so slow photons get lost trying to find the mirror. 

i really dont want to go near big scopes anymore the 114 has put me well off, that and the prices of anything remotely good

for photography of stars and dso's 

[Schorhr]

Sorry to hear that :-(

I have no heart condition but rely on light-weight, backpack-able equipment and found the Heritage as well as the SLT Goto (that can mount the heritage or a small mak) very neat. For video astronomy altAz will do anyway, or DSLR <30 seconds...

Same with light pollution here.

Jupiter will allways be a dot under most seeing conditions. Rarely 200-250x are possible, 300x+ only once or twice a year probably.

The EQ1 is weak. It will shake, make it hard to focus.

On a Dobsonian such as the Heritage the thing is rock-solid and focusing no issue.

The 114 belongs on a Astro3 or Neq3 IMHO!

If the mount is stable, observing objects is much easier, and even at the small size faint details become visible. Of course aperture helps.

Imaging the planets will result in many blurry pictures. Also the large DSLR chip is not ideal for planets!

A webcam or at least a DSLR video mode (where you pick the best frames later) are more suited, and only after selecting and stacking a few dozen pictures you'll get nice results...

Imaging can really be anoying, I settled on visual, only dabbling in imaging and video astronomy once in a while. 

5" is a good size to handle. Either mak with the focus on planets, or a f/5 newt for DSO...

As for DSO, you should try with camera + lens for a while, with lower focal length it'll be less frustrating, and the DSLR is more suited for it anyway then imaging planets.