114mm Mirror Advice /damage repair

[Mr TamiyaCowboy]

i own the skywatcher 1141 catadioptric short tube newton. 

i know it is not the best of telescopes having a spherical mirror, but it had been doing the job.

The telescope has been used around FIVE times in two years of ownership from new. 

scope has been moved twice, and not been bashed around, scope has been dust free

and looked after. HAS NOT BEEN USED OUTSIDE !!!

So there i am making a focus mask. i had to measure up the scopes tube end.

while doing this, i notice my secondary mirror has a white/fuzzy like appearance around the edge.

a bit like when superglue hits plastic it turns it that off white hazy look. iam seeing this on my secondary mirror

and i mean a lot of it. 

so i thought hey maybe this is a reflection of the main mirror, so face in the end of scope time to check main mirror. and GUESS

WHAT, the exact same fuzzy white haze is also around the edge of my main mirror to. i have also noticed a very unusual

rainbow color hue over my mirror ( akin to heavy fuel oil ontop of water ).

so the scope is what you could still call brand new, its never been outside in damp cold weather.

been dust covered and kept clean and dust free. my views via eyepiece are not crisp and clear,

more a dirty hazy fog like view. 

IS my scope mirror knackered, if so how do i send it back to skywatcher as faulty 

the coating should not be harmed so why is it showing damage after minimal use and dry storage,

why have i got this superglue like substance creaping over my mirrors.

I am now left without a scope and stuck with just my camera lenses. and am coming to the point, where

i should just take a hammer to the darn thing in anger, its cost me £120 for the scope, i have seen jupiter once

taken around 16 solar images ( using correct filtering and safety reqs) in the space of two years,

yet the mirror has aged around 200 years.

so any ideas what is going on, and how i RMA this whole scope back to skywatcher as unfit for purpose. ?

(ps, am unsure how i can photograph said mirrors to show the damage and problem i have)

[ronin]

After 2 years there is probably nothing you can do.

Sending it to Skywatcher (China) is pointless, OVL will just point out it is 2 years old and out of warrenty, similar with the retailer.

As you may well have to pick up any postage charge it is most likely not really worth doing.

The mirror will I expect be moulded and glued into a support backing, so the white stuff round the edges could be glue as you describe. Equally the protective coating will I doubt go round the edge of the mirrir so it may be oxidisation off  the edge of the mirror coating. Aluminium is very reactive, so would be expected I suppose.

The rainbow effect, again the mirror is coated with a protective layer which may well be acting the same as an oil layer and you are seeing interference colours caused by the reflected light from the different thicknesses of the protective layer and the main reflective surface.

[Mr TamiyaCowboy]

if this is the case Ronin. 

i have researched the scope, took a long time, but it uses a 114mm spherical mirror.

and inside the focuser tube itself is a third correcting/barlow lens.

the focal length of the tube is the same size of a skyhawk 114mm F500.

yet my scope with the corrector gives a f1000 focal length.

heres my idea.... dump the main mirror, and replace this with a skyhawk 114mm @ f500

parabolic , cut out/off he corrector/barlow in the focuser tube. and the scope is converted to what it really should have been

a short focal length fast newton ( not a slow f8 long FAKED 1000mm focal length monster) 

problem is i made the biggest mistake buying this first telescope , but dont want to make any more mistakes and extra costs

converting it to a decent scope, ( cant sell it on knowing its not any good for anything/one)

[Peter Drew]

Harsh as it sounds, I would dump the complete OTA and replace it with a complete normal 114mm Skyhawk OTA. Replacing the spherical mirror with the parabolic version might involve difficulties with focus positions. 

[ronin]

I cannot see you getting a mirror for less then £50-60.

Also unless you get the figures for a replacement parabolic then it may not match the focal length of a spherical, the diameter may be a possible indication but not a match. If the parabolic is 25mm longer focal length it will never go in your tube and work. You would not have the adjustment to wind the mirror far enough back.

Had you had a long focal length mirror (1.2 meters or more) in the present scope then I would have used to mirror to build a transportable one along the lines of the Sumarian items. But being short it is not sensible, if possible.

The bird Jones design is actually fairly good but it needs good optics, both barlow and mirror. It should really be at least 2 achro doublets whose focal lengths are f1 and f2 where f2 = 2 times f1, f1 being the lens closest to the secondary/primary. Then it would be a better final image. But instead of 2 achromats in a holder you get what is likely 1 cheap negative lens dropped in the focusing tube.

Personally I wish they did not sell those 114's with the barlow built in, they are simply a lot of trouble. A short fast spherical mirror will not produce a good image, so immaterial of the barlow design it is being presented with a poor image to make bigger.

If you try to get it to do anything then consider it simply as spending money for the hell of it. I wouldn't consider spending money on the scope, I would, had the items on it been suitable, turned it into something different. As in use the components fron it but purchase nothing additional.

Thinking about it the scope is "wrong". They should have used a long focal length spherical and a reducer, possibly fractionally cheaper to produce but the combination would have worked better.

Save the money and get an Evostar 90 refractor, or a 150PL dobsonian.

[NGC 1502]

Before you give up on this scope, and "take a hammer" to it, maybe give the mirrors a careful wash, using luke warm soapy water, soft

cotton wool, no pressure, frequent change of cotton wool, rinse with distilled water, allow to dry.

Of course you'd have to dismantle, reassemble and recollimate, not quite so easy with the corrector lens in the focuser, so maybe you're not up for that.

It's really tough to tell what's on the mirrors, maybe it's beyond cleaning, but worth a try perhaps ?

Regards, Ed.

Edited March 3, 2014 by NGC 1502

[Mr TamiyaCowboy]

well my choice is narrowed down. 

either a ST80 or a Orion 80. both around the same price as each other.

one a clone of the other it looks like. 

it is a massive drop in apeture for me, i must be stupid or something, people want

bigger light buckets and im going for smaller.

short tube and light weight is my requirement, i cannot be lugging around large scopes

doctors orders. and the above two are the only ones i could see that have a £100 price tag.

either way They HAVE to be better than the scope i have now ( hey they dont have a fake corrector plate )

i have an EQ-1 with single ra drive motor, but i also own a fully working Goto merlin mount unit to.

my imaging gear consist of a canon 350D for prime and a lifecam modded for planetary work.

main targets of interest , Clusters , nebula , DSO, comets and large impacters.

any ideas for a suitable'ish scope would be greatfully taken in and wrote on my beermat

ideas pad

[Piero]

Sorry to hear this sad story and for commenting a bit late. 

I don't know whether my comment may help you, but, unless planets are important for you, have you ever considered a pair of 15x70 binoculars? 

They are very light and can be easily mounted on a relative cheap light tripod. Using them is extremely easy and you can take them around basically everywhere. 

What can you see with them? The beauty of a wide field sky! There are plenty of large-medium DSOs that can be seen with them. 

Sometimes I just enjoy looking at the sky without a specific target in mind and admiring star colours and the milky way. 

Sometimes you may see a little cloud in the eyepieces and then, through a starmaps, you can recognise you saw a globular cluster or a medium size galaxy.

Will you see details on such DSOs? Nope, but you won't see details even with your Newton 114mm.

Is this relevant? well.. I think the real pleasure is to think, while watching, that you are actually seeing a tiny bit of light coming from thousands (or even millions) light years and how many things there are out there that we don't even imagine!

Of course Aperture is important for DSO, possibly for many people it is the only parameter, but I think that is an endless story to justify that you need to go bigger and bigger for seeing something of interest.

What's the point of having a big telescope if you cannot move it around easily or if you know little about the sky or if you have to wait for 2h for cooling the scope before using it or if you spend ages trying to find an object as your FOV is very small. 

Clearly, if you are happy with these aspects and this is what you want, that's great and you should buy one. 

But I suspect that most of us actually buy them without even considering these aspects and then they end up reselling and loosing a lot of money.. 

How little they would spend and how much observation they would do if they had something smaller! And they could just focus on what they are seeing through those eyepieces, instead of looking at those eyepieces+telescope!

This of course is my opinion, and you might receive completely opposite comments. 

Anyway, quick and well tested options by many people are: 

- revelation 15x70 (~£50, acceptable quality. 1.4kg). 

- helios apollo 15x70 (~£250, good quality. 2.5kg)

Tripod: 

- Horizon 8115 2-way heavy duty tripod (~£80, good quality.  4kg)

Between the two binoculars, I suggest you the helios as they are great, robust and they last ages.

If price is a concern, you can consider the other one. In any case, you can will walk with max 6.5kg and you won't be tired.

If you prefer a telescope instead, the Evostar 90 refractor as previously suggested, is a good choice to me.

Piero

[Stu]

I hate to ask silly questions...but here goes. Have you tried taking it outdoors, letting it cool properly and looking at some stars with it? Does it work or look terrible?

Just a thought :-)

Cheers,

Stu

Sent from my iPhone using Tapatalk

[tank20101955]

if it was me I would cut the back end off of the tube after figuring your focal length of new mirror, then mount new mirror in original mirror mount and reinstall on back of tube and them align.

[tank20101955]

sorry guys I answered before I saw the date of post.