Portable but powerful scopes

[swedonator]

But apochromatic refractors.. for example SkyWatcher Evostar ED80 80/600mm (link), would that be a better choice? it's just 80mm I can't understand how you may get so good images with so small instruments.

[E621Keith]

How come that such a small scope are able to create such great images?

But apochromatic refractors.. for example SkyWatcher Evostar ED80 80/600mm (link), would that be a better choice? it's just 80mm I can't understand how you may get so good images with so small instruments.

Long exposure astrophotography. Don't expect to see anything remotely similar with your eyes.

Those images are made by exposing the CCD to collect photons for a long period of time, so the total number of photons collected is equivalent to a much larger telescope exposed for a shorter period.

For visual observation, you eyes exposure time is limited to fraction of a second, so you need aperture to dump as much photons into your eye in that short period of time. As such a C6 or a 8" Newtonian will easily outclass a 80mm apo on DSO for visual observation.

Put it another way. Lets use the bucket analogy. The image your eye see or a camera can capture depends on the amount of signal received by the detector (water in bucket). Your telescope is the hose pipe to fill that bucket. A big telescope is like a big hose, a small telescope is a smaller one. The big hose is going to fill the bucket quicker than the small one. When you observe with your eyes, you are only allowed to turn on the tap for fraction of a second. A large scope will put more photons on your retina than the small one, so the image appears brighter. When you do long exposure imaging, it's like leaving the hose running for a long time. If you leave the small hose running long enough it will eventually put more water in the bucket than the big hose turned on for a fraction of a second. In fact it will put a lot more water in that bucket.

You can also leave the big hose running for a long time to fill that bucket, but without someone holding it tight, it will fly around and make a mess of everything. A small scope like the ED80 is lighter and easier to control, so the water only goes into the bucket, whereas a larger scope shakes and vibrates and put water into the adjacent buckets thus blurring the image

[E621Keith]

Does it require a expensive CCD-camera?

If I do not want to take photos, will the altair scope still be a good choice for just observing?

Not necessarily. You can also take long exposure astro photo with relatively cheap DSLR.

You will need a mount with good tracking accuracy, otherwise you will get star trail.

[swedonator]

Oh my.. I am getting sick on not having a scope, I have had clear skies several days now, and the birdwatcher scope is no good and the 8x48 binoculars do not reveal much.

When I think I found a good scope, I find someone who says it's bad :-P A list of candidates:

- Skymax 127

- Skymax 102

- Celestron C6-NGT

- Nexstar 6se

- Explorer 200PDS

- Meade ETX 125

- Celestron C8 (SGT XLT)

- Meade or SkyWatcher Dobson

- Evostar 120ED

- Omni XLT 120

What I want to do?:

* Observe the solar system

* Observe double/variable stars

* Image solar system

* Image double/variable stars

* Observe and image special happenings (transits, conjuctions, comets like Panstarrs)

[Mr Fiery Jack]

And don't let the Chromatic Aberration freak you out - I found out it was way less intrusive that I was led to believe - it's perfectly fine.

Indeed, CA is in my experience far worse using Newtonians' than it ever was using achromatic refractors (except short tubes) its not the mirror you understand, its the EPs' that add colour, and all my EPs' are decent TeleVues'.

[Mr Fiery Jack]

Oh my.. I am getting sick on not having a scope, I have had clear skies several days now, and the birdwatcher scope is no good and the 8x48 binoculars do not reveal much.

When I think I found a good scope, I find someone who says it's bad :-P A list of candidates:

- Skymax 127

- Skymax 102

- Celestron C6-NGT

- Nexstar 6se

- Explorer 200PDS

- Meade ETX 125

- Celestron C8 (SGT XLT)

- Meade or SkyWatcher Dobson

- Evostar 120ED

- Omni XLT 120

What I want to do?:

* Observe the solar system

* Observe double/variable stars

* Image solar system

* Image double/variable stars

* Observe and image special happenings (transits, conjuctions, comets like Panstarrs)

You are missing a TAL100RS from your list

[Mr Fiery Jack]

I need (need) to repeat, you are missing a TAL 100RS from your list.

[rowan46]

I think the problem is you want a scope and mount that does everything and you don't want to pay the price of a luxury car to get it. Unfortunately such a scope and cheap doesn't exist. The c8 combo comes closest at least you will be able to see most things and image planets and doubles. you will have an eq mount to maybe put a small refractor on at a later dater for dso imaging. not exactly portable but 3m isn't that far. A tal 100 is a nice scope by the way but a 200mm sct will show more

[swedonator]

Well.. I could trash the image-thing and get a dob, and do sketches of the planets and double systems and so on. Or I buy the C8 as you say. If I buy a dob I might also buy a small mak like skymax 102 or 127 to use a portable scope, because dobs are not so expensive :-) Then we have refractors, but I have realised by watching images that 120 refractors are HUGE

[LukeSkywatcher]

but I have realised by watching images that 120 refractors are HUGE

Not only are they HUGE but they are very expensive. The reason is because they use glass lens rather then mirrors. My 90mm Celestron refractor cost me about 400 euros about 5 yrs ago.

For a 120mm refractor i would think they cost almost the same as a small family car.

Personally at the moment, i'd forget about imaging and buy the best you can for observing. Imaging and observing really are two very different fields of astronomy. Imaging being the more expensive way to go.

If I buy a dob I might also buy a small mak like skymax 102 or 127 to use a portable scope, because dobs are not so expensive :-)

That really would be the best of both worlds, if your budget allows.

[swedonator]

No, a 120mm cost around 5000 sek (500£ ?). That is not so expensive. But you are maybe talking about ED?

[LukeSkywatcher]

No, a 120mm cost around 5000 sek (500£ ?). That is not so expensive. But you are maybe talking about ED?

Not quite sure what i was thinking of but i've seen very large refractors sell for a high price.

[steve_bham]

You can get 120mm refractors for a few hundred quid. It depends on the type of refractor you want.

[swedonator]

With big refractors the mount is important, I think?

[swedonator]

Now astrosweden.se have a Meade 8" f/10 ACF OTA, anyone know anything about it? it seems to be a good scope for photo also, they say.

[rowan46]

Now astrosweden.se have a Meade 8" f/10 ACF OTA, anyone know anything about it? it seems to be a good scope for photo also, they say.

They would say that and no doubt if you put it on a £5000 mount it would be. But at f10 it's too slow and at 2m focal length you are looking at an neq6 guided to get anything out of it. by all accounts these acf scopes by meade and edge scopes by celestron have great optics but the sct isn't an inherently good design for imaging with cheap mounts. you need a substantial mount to make quality images with an sct

[swedonator]

Yes, that's what I thought. It weigh 9kg

[E621Keith]

Not quite sure what i was thinking of but i've seen very large refractors sell for a high price.

May be you were thing about that 12" APM APO rather than the 120mm achromat

[swedonator]

I have decided to go Celestron. Advanced C8-SGT XLT or the C9, 15 S-GT XLT. The price is about 4000 SEK higher on the bigger one, but maybe it's worth it? Which of them should I go for? which one would you choose and why?

[baggywrinkle]

I'll throw in my penny worth; Celestron 6SE. Good tripod, decent Go To azimuth mount. Can come aprt in two sections, 'scope and mount, easy to get into the boot.

I get some reasonable dark skies and I am very please with what I see.

[E621Keith]

I have decided to go Celestron. Advanced C8-SGT XLT or the C9, 15 S-GT XLT. The price is about 4000 SEK higher on the bigger one, but maybe it's worth it? Which of them should I go for? which one would you choose and why?

I'd go for C8. It's more stable in the CG5-GT mount.

C925 is a lot bigger than the C8 and should be paired with a bigger mount.

[michael.h.f.wilkinson]

I'd go for C8. It's more stable in the CG5-GT mount.

C925 is a lot bigger than the C8 and should be paired with a bigger mount.

Seconded. A CG5-GT mount is mechanically very similar to my Vixen GP mount. That holds the C8 without difficulties, but I would not put the C9.25 onto it. The C9.25 OTA is rather heavier, and with cameras or guide scopes or larger finders (great investment) added, the C8 is just about the limit of that mount.

Celestron makes good scopes, but they have a tendency to sell under-mounted scopes (as do many other manufacturers, BTW).

[swedonator]

C8 it is. Any recommendations for accessories? like finders, guidescopes, barlow, ep's and so on?

[E621Keith]

C8 it is. Any recommendations for accessories? like finders, guidescopes, barlow, ep's and so on?

To start

1. 12V Power lead for the CG5 GT mount. I don't know if this comes as standard or an optional extra. My Nexstar SE didn't have one.

2. 2" visual back for SCT

3. 2" dielectric diagonal

4. Terlard finder / Rigel quickfinder

5. Baader 8-24mm Hyperion zoom eyepiece (84x-254x, 0.5-0.3deg true field)

6. Skywatcher 35mm Aero ED eyepiece (58x, 1.2deg true field)

[michael.h.f.wilkinson]

Good suggestions by Keith, I would opt for the 40mm Aero however (1.34 deg true FOV). I used the TMB Paragon 40mm until I got my Nagler 31T5, and the Aero is a clone of the Paragon. The 40mm worked very well in the SCT and is very comfortable to use.