catadioptric telescopes

[Mr TamiyaCowboy]

i have been searching for something a little bigger than my Mini 76mm dob tabletop. it is nice but lacks the beef to hold my dslr safely and lets me down with its small mirror and short focal length. my camera lens is a 300mm focal. but using a webcam with the dobson gives me same view as if i was using my 300mm cam lens. trying to find a nebula with the dob and webcam is impossible. i am stuck to jupiter and the moon, these are bright enough to see.

so i have been looking around at the sub £100 mark scopes and found the skywatcher skyhawk 114. a catadioptric scope. as always i did a couple hours googling to find very mixed reviews. mostly saying stay away from scope. but for £99 it does sound a bargain. reviews are few and far between aka very little. most saying find something better, i have looked and do not see anything for under £100 with a 4.5 inch mirror.

so Why are catadioptric telescopes so bad ? surely it has to be better than my mini dobson and allow for better astro imaging, but i am worried about purchasing one then finding out it was a big bad mistake.

[kniclander]

I thought the skyhawk was a small newtonian scope? it will be a pretty major step up form the 76mm mini-dob and for £99 I'd say it was a pretty good deal.

[Cornelius Varley]

Cats such as MCT and SCT etc are great telescopes. Cats such as the Skywatcher 114/1000 and other similar Bird-Jones designs (corrector lens in the focuser, think Seben 150/1400) aren't that good.

Peter

[Chris H]

If you want to take photos of the night sky this scope s not going to work. It comes on an EQ1 mount which is undriven and is not going to hold the scope steady enough to enable photos to be taken. I'm afraid that if astro photography is want you want to do you are going to have to up your budget considerably.

[kniclander]

I don't think the skyhawk has a f/l of 1000 - the spec is f4.4. as far as i can see it's just a regular little newtonian ... http://www.opticalvision.co.uk/documents/61.pdf

[Chris H]

It's f8.7 so it must have a corrector plate or a built in barlow.

[E621Keith]

CAT aren't bad. SCT, Mak-cas and Mak-Newt are good designs. However, the Skyhawk is not really a CAT. It's a bad Newtonian with a barlow fitted in the focuser to hide defective optics. It's cheap, but it ain't a bargain as it's a waste of money.

You mentioned you wanted to use your webcam to find nebula with your dob. It won't work. Nebula are dim, so it will require long exposure. A standard webcam won't do it, but a DSLR will. You will still need a good equatorial mount for tracking (e.g. HEQ5). There are some good options for under £1000, but none for £100.

Your 300mm lens should be sufficient, assuming it's one of the fixed focal length 300f4 or 300f2.8.

[Mr TamiyaCowboy]

Skywatcher have two models in this 4.5" range.

skyhawk 1145p, the 5 denotes a 500mm focal

skyhawk 114 catadioptric , this is a 1000mm focal.

i wish i could up the game on the cash front, but am limited to bang on £100. around couple month after xmas i should have enough for a large 6" (£250).

now others here have said they are not a good idea, i will keep away from this idea and try find something else to bridge the 2 month wait i have for a bigger scope.

my lens is a 90-300mm F4.5-5.6 very finicky on focus. even mak's and likes will be beyond my means, i have priced around 250 for a large dobson, nothing with a heavy duty eq mount. best would be a EQ3-2

[Chris H]

I'd stick with what you already have, use it to learn your way round the sky and save the money till you can afford some thing much better.

[E621Keith]

What eyepiece are you using. The kit eyepiece that came with the 76p are rather poor. You may get a big improvement by using a better set of eyepieces such as Vixen or GSO plossl.

I'd forget about imaging for now

[Gottzi]

I have a Skywatcher Skyhawk 114mm and I love it.

It is plety good enough for visual but I agree not too good for photogaphic work.

Quick and easy to use and holds collimation well.

Clear skies

David.

[Mr TamiyaCowboy]

what about a small refractor / mak

have seen the skywatcher small refractors they look nice , 3.1" f400

also seen a couple of those celestron mini mak's very nice looking scope.

both the above would be ideal for the windowsil, but are smaller than the dob.

one thing i cannot do is stop imaging. it is the first thing into mind when darkness falls. and once darkness arrives i have camera all ready on windowsill.

[Tinker1947]

Maybe a better idea to just a driven mount with your camera attached using its own lens, although i can't recommend a mount that's not going to cost 4 or 5 times more than you want to pay, something like this....

First Light Optics - Skywatcher EQ3 PRO Synscan GOTO

[Mr TamiyaCowboy]

i like recording with camera, but those dso realy need a scope. you become bored shooting the moon every night, and the struggle to get focus bang on. i end up spending a nice time shooting to find all shots out of focus. then dss throws a fit because the stars are out of focus or trailing.

A nice mount would just make me want a scope even more, you can only do so much with a camera lens

hence the idea of a bigger scope and using my webcam to find new objects. see M42 alot bigger than what my 90-300mm lens or even the mini dob could,

have made up my mind not to buy a new scope, feel deflated after finding the 114 is like flogging a dead donkey, and the rest of the scope choice is beyond my means. so i am back to watching the moon and wishing the canon lens was a huge 200mm mirror

[E621Keith]

Don't be disappointed, even camera lenses can produce good results.

Here is a review comparing Televue's TV60is against a Canon 400mm f5.6L

TV-60is

A big reflector is not useful in beginner astrophotography, because it demands a lot from the mount. If the mount cannot track correctly, it will not produce good images regardless of scope.