Advice on first Telescope

[Camelopardalis (Dunk)]

Depends on the mount...some mounts, like the SLT and SE series from Celestron have no clutches to release, so moving it manually can (and likely will) damage the motor gears.

Many of the goto Dobs are built to allow manual pushing without loss of sense of direction, so the computer knows where it is, and tracking continues once you let go.

[Meru (Michael)]

Hi Dave,

Welcome to IIS! As Allan has pointed out the link, have a read. It's quite good to read. I would very much recommend you purchase a 8" dob. I owned both a 10" & 8" dob and have to say, unless you got dark skies the extra weight and hassle of moving a 10" is definitely not worth it (for me anyways ).

I believe Dobs are the best type for visuals and especially for beginners. The money goes towards good optics and simplicity of use - something you definitely need whilst in the dark learning for the first time. Anything with computers will probably make you spend more time reading the manual than gazing! Plus they have better resale value than the SLTs. I personally think the SLTs are just a good marketing strategy for making money of those who haven't done their research which you clearly are

Try joining an astronomy club or see when the next public viewing night is (Bintel can probably help you there).

[raymo]

On the SLTs you can slacken nuts on both axes so they can be moved by hand without damaging anything. Most modern day GoTo EQ mounts
don't have any manual slow motion controls, but the motor controls can be operated to point the scope where you want using the finderscope
without going through the GoTo setup procedure, and you can set it to
track your target.
raymo

[Allan_L (Allan)]

Originally Posted by OzStarGazer

Can a GOTO also be used in normal mode with a finderscope?

Not sure about other DOBs, but a Skywatcher GoTo DOB definitely can.
You can use it manually, without even switching the control system on.
You can use it switched on and star aligned, but still manually push it to objects (the system still knows where it is pointed).
You can use it switched on but not aligned. This will be for manual pointing, but you can use the motion buttons to slew manually to an object.
You can use it switched on, and just levelled, pointing North, for manual pointing to an object, and it will Track it in sidereal mode.

It has a slip clutch system that allows any combination of manual pushing the scope fully or partially to objects.
I like to use the finder to push the scope to the near vicinity of an object quickly, then hit the slew button for the system to fine tune to the object. (its is quicker, and saves battery power)

Celestron Nexstar SE series definitely NOT.

Celestron CPC series has torsion nuts on both axis, these can be slackened to allow manual movement of the scope, but doing this will throw out the star alignment.

[julianh72 (Julian)]

Originally Posted by raymo

On the SLTs you can slacken nuts on both axes so they can be moved by hand without damaging anything. Most modern day GoTo EQ mounts
don't have any manual slow motion controls, but the motor controls can be operated to point the scope where you want using the finderscope
without going through the GoTo setup procedure, and you can set it to
track your target.
raymo

I have a 130 SLT (Newtonian) which I bought second-hand. You can move it easily by hand in Altitude (up and down), and you can adjust the tension in the Altitude bolt so that it doesn't slip. However, it seems to be absolutely locked in Azimuth (side to side), and I have seen numerous forum posts from owners of SLT schools which confirm the same thing. I'm not game to push it any harder to see if it can be manually slewed.

So an SLT is really only suitable as a powered scope. It can chew through the 8 x AAA batteries pretty quickly (perhaps 4 to 6 hours use), so I strongly suggest having two sets of 8 x AAA NiMH rechargeable batteries, and just swap and recharge after each night's viewing. On a long night's viewing, you might even need to swap out part way through the night. (Or do what I have done, and get an external rechargeable 12 volt battery pack - I have a 7 amp-hour SLA (Sealed Lead-Acid) which is quite compact, and good for several night's viewing.)

As for the tube vibrations mentioned by Raymo in an earlier post - they're noticeable, but not excessively so. Make sure all tripod bolts are nice and tight, and make sure the dovetail is also properly tightened, and the Mount is perfectly fine for visual use. I have actually put my SLT mount onto a heavier EQ-2 aluminium tripod, and it's actually very stable indeed for a low-cost GoTo telescope.

[Pinwheel (Doug)]

Originally Posted by raymo

Doug, if you're good with D.I.Y. you could move the primary mirror up the tube the required amount, or look for a new or used low profile focuser if your scope nearly comes to focus. raymo

Thank's Raymo I am aware of the mod to remove around 2" of tube length. I just don't want to hack my 3 month old Dob just yet!

http://www.iceinspace.com.au/63-441-0-0-1-0.html

[raymo]

I used to hang a small car battery under the tripod which made it much
more stable.
raymo

[OzStarGazer]

Thanks for the replies re using GOTO in normal mode!

[AstralTraveller (David)]

Originally Posted by Meru

Hi Dave,

Welcome to IIS! As Allan has pointed out the link, have a read. It's quite good to read. I would very much recommend you purchase a 8" dob. I owned both a 10" & 8" dob and have to say, unless you got dark skies the extra weight and hassle of moving a 10" is definitely not worth it (for me anyways ).

Well, there you go - I'd say the exact opposite. A 10" gathers 100/64 = 1.5 times the light of an 8" for about 1.4 time the cost. But, more important (and after you have forgotten the cost), the tube lengths are basically the same so anywhere you can fit or carry an 8 you can also fit or carry a 10. I put a carry handle on my 10 and that helps a lot. No more cradling the tube. Just carry it in one hand like a large, odd shaped, suitcase. My first scope was a 10" f/8 (that was a beast to move!) and I've always found eights to be under-powered.

[Pinwheel (Doug)]

Originally Posted by AstralTraveller

Well, there you go - I'd say the exact opposite. A 10" gathers 100/64 = 1.5 times the light of an 8" for about 1.4 time the cost. But, more important (and after you have forgotten the cost), the tube lengths are basically the same so anywhere you can fit or carry an 8 you can also fit or carry a 10. I put a carry handle on my 10 and that helps a lot. No more cradling the tube. Just carry it in one hand like a large, odd shaped, suitcase. My first scope was a 10" f/8 (that was a beast to move!) and I've always found eights to be under-powered.

Before I bought my 12" F=5 dob I had an 8" F=4 on an EQ mount, both are timely & heavy to move from house to my viewing area. However the views from the 12" are so much more superior to the 8", there really is no comparison.

[raymo]

Hi Doug, I have to agree that the 12 is much better than the 8, but we
need to remember that we were comparing the 10 to the 8, and the difference is nothing like as great. The view through my 10 Dob is better
than my 8, but not greatly so. The only time that the difference is really
noticeable is when scanning starfields, when many more stars are
visible.
raymo

[Pinwheel (Doug)]

Originally Posted by raymo

Hi Doug, I have to agree that the 12 is much better than the 8, but we
need to remember that we were comparing the 10 to the 8, and the difference is nothing like as great. The view through my 10 Dob is better
than my 8, but not greatly so. The only time that the difference is really
noticeable is when scanning starfields, when many more stars are
visible.
raymo

Agreed, My point is these day's you can buy an 8",10" or 12" for pretty much the same money plus or minus a hundred here or there.
All input is important to a newbie thinking of taking the plunge.

[aganod (David)]

I picked up a second hand Saxon 90 Maksutov-Cassegrain to try out why I am deciding what to do. Will there be much difference between the 90 and the 127 in viewing? What are the main differences between the other types of scopes and the Cassegrain?

David

[raymo]

There are many basic types of scopes, and even more hybrid scopes that use features from two or more designs. You could write pages describing them, so I suggest googling " astronomical telescopes".
raymo

[noeyedeer (Matt)]

don't discount that dobs with an app like skeye (it's free on droid) can be used as a push-to if you Velcro your phone to the scope n do a star alignment (the more the merrier), have it level .. etc.

even just scanning the sky through the eyepiece is an experience and then stopping on some fuzzies and chucking in a higher power eyepiece reveals something totally astounding.

if I were you I'd get the dob .. learn the sky manually it makes it more of an experience .. instead of pressing a button, and possibly getting frustrated ..
matt

[julianh72 (Julian)]

Originally Posted by noeyedeer

don't discount that dobs with an app like skeye (it's free on droid) can be used as a push-to if you Velcro your phone to the scope n do a star alignment (the more the merrier), have it level .. etc.

even just scanning the sky through the eyepiece is an experience and then stopping on some fuzzies and chucking in a higher power eyepiece reveals something totally astounding.

if I were you I'd get the dob .. learn the sky manually it makes it more of an experience .. instead of pressing a button, and possibly getting frustrated ..
matt

Matt,
I have no problem with your argument that a Dob is a good way to get lots of light gathering power for a low purchase price, and I agree that using something like SkEye is a great way to add "PushTo" to your Dob ...

But I'm intrigued why you think strapping a smartphone onto a Dob and using SkEye to turn it into a "PushTo" is somehow philosophically different to using a GoTo powered mount (with or without an interface to a planetarium app on your computer / phone / tablet)?

• Both require that you align your scope - and the procedure is pretty similar for both.
• Once aligned, both allow you to check and refine your alignment by targeting a visual target in the area of your ultimate target. (And this can be a huge aid to track down the "faint fuzzies" that are on the limit of your telescope's capabilities - it is good to know that what you are seeking is indeed in the field of view, rather than just HOPING that it is in view after a bit of star-hopping!)
• Both allow you to point to your target reliably, but one drives the scope and stops on target, whereas the other requires you to push the scope and will tell you how far off you are.
• Both could be used with no almost knowledge of the night sky - which is "a good thing" in my book - the easiest way to learn the night sky is to ask your telescope to go to Jupiter (or Orion, or Acrux, or ...), get it in view, then look up and see it in the sky.

"Horses for courses" and all that.

[noeyedeer (Matt)]

Originally Posted by julianh72

Matt,
I have no problem with your argument that a Dob is a good way to get lots of light gathering power for a low purchase price, and I agree that using something like SkEye is a great way to add "PushTo" to your Dob ...

But I'm intrigued why you think strapping a smartphone onto a Dob and using SkEye to turn it into a "PushTo" is somehow philosophically different to using a GoTo powered mount (with or without an interface to a planetarium app on your computer / phone / tablet)?

• Both require that you align your scope - and the procedure is pretty similar for both.
• Once aligned, both allow you to check and refine your alignment by targeting a visual target in the area of your ultimate target. (And this can be a huge aid to track down the "faint fuzzies" that are on the limit of your telescope's capabilities - it is good to know that what you are seeking is indeed in the field of view, rather than just HOPING that it is in view after a bit of star-hopping!)
• Both allow you to point to your target reliably, but one drives the scope and stops on target, whereas the other requires you to push the scope and will tell you how far off you are.
• Both could be used with no almost knowledge of the night sky - which is "a good thing" in my book - the easiest way to learn the night sky is to ask your telescope to go to Jupiter (or Orion, or Acrux, or ...), get it in view, then look up and see it in the sky.

"Horses for courses" and all that.

hi Julian,
I was just putting it out there that a dob can be used as a push to.

it's nothing philosophical, the OP asked a question and I was adding some info that hasn't been stated about considering the dob.


matt

[aganod (David)]

Wow tried out the scope I got for the first time tonight and got some great views of the moon. It sure is great when you see it for yourself rather than in photos. Discovered the Saxon I bought has no finder scope so it was not easy to find anything else, the moon was easy to find.
David

[Amaranthus (Barry)]

Get a low-cost red dot sight - effective and easy to fit/use

[opensea64 (Chris)]

I Highly recommend a Telrad finderscope. Although very simple in design its very easy to use and collimate. I found it better than red dot finders as the one I had (sold since) needed allen keys to collimate where the Telrad has adjustable knobs.