newbie looking for gear advice

[Gary]

thanks gary, having some bad experience, i m not keen to buy sensitive optical instrument online, and expensive optical instrument at that.

A bad online experience, especially the first few, can indeed have a long lingering effect. I personally have not purchase a lot of astro gear online. But some of my friends do. I believe with proper research, especially checking the credibility, track record and return-policy of online sellers, these risks can be lowered.

not keen on buying online cause i m not that sure what i want also, best option is to drop inside a shop to get a feel of things first

A lot of information can be gathered online. My take is that the more you are unsure of what to buy, the more online research you should carry on doing before walking into a shop. Unless the shop is near enough (thus not wasting too much of your transportation time and money) and does not pressurize its customers to buy things, then this may be the exception.

An analogy is newcomers to lT trying to visit big IT Shows to buy laptops instead of doing their homework online first. Some of them will be at the mercy of incompetent sales people (some of them are last-minute recruited part-timers with little IT knowledge). Others will believe whatever the salesperson say. And in the buying mood of the event venue, may make an impulse buy that they may regret later - e.g. salespeople using bait-and-switch tactics and tell you your preference is not good and recommend something else which you have not much knowledge of and thus cannot verify quickly on the spot. And in trying to justify the time and effort spent going down, giving the benefit of the doubt to potentially unscrupulous salespeople who is trying to leverage on this very point.

The smarter buyers will do their homework online, reduce their options to a few candidates and then go to the IT show to confirm what they already know and make a final decision. And if they can't find what they want and find no suitable alternatives, have the courage and faith in their research to walk away and leave the event empty handed.

just checking my knowledge,
for an eq mount, you need an equal amount of counterwight as your scope? i.e 10lbs of weight for 10lbs of scope?

Yes. Plus the weight of accessories added onto the telescope. If you add or remove something of significant weight during the stargazing session, you may need to adjust the counterweight position and re-balance your setup again.

can stacking of lots of fast photo using alt-az be equal to long exposure using eq?

My *guess* is no or too much hassle (e.g. post editing) to achieve similar eq results. Fast photos may not capture not enough data in the first place. Stacking such photos does not improve them much. At high magnification, stars should trail even faster - something AZ non-tracking mount is not designed to do. I am not an expert in photography, the experts in this forum may want to comment on this.

is it important/recommended to oversize a mount? i.e 20lbs rate mount for 10lbs scope. or as long as scope is less than rated it's fine?

Yes. As long as portability and bulk is not an issue, no amateur astronomer will complain their mount is too stable, especially in windy places. My friends have mounted their DSLR on my cg5 before. The milky way photos turned out fine.

Always give some allowance from the stated load capacity, especially for astrophotography.

how much extra weight does accessories add to the scope? (lens, filters, camera, etc)

You can check the specifications for each of these accessories from online retailers, reviews or from its manufacturer's website.

[cloud_cover]

Hello! Welcome to the forum!
You have a dilemma which is common to most newcomers: Most will ask about a system that can do both visual and astrophotography (AP) well. Unfortunately, I think that such a system doesn't really exist, at least for a new user, because of the complexities that AP requires and the competing demands on the optical system, (aperture vs. f ratio, other factors)
I think that if you really want a system that can do both, then you will want to buy a sturdy Equatorial mount with a decent sized refractor on it: at least a 4". This will be fine for AP and good for beginning visuals although you may eventually wish to buy something bigger, visually. I don't recommend starting out with an 8" SCT: these are fine for visual use but when performing AP the combination of long focal length and high f ratio (f/10) ultimately results in the need for long, long exposures, which magnify any errors in the mount or polar alignment. Take note though that a tracking equatorial mount needs a bit of time to set up. I find that I need about 30mins to get my Vixen SXD fully deployed, balanced, levelled and pointed north (not yet polar aligned for photography, which takes at least another half-hour). In contrast, I need about 10-15mins to fully set up and collimate/align my 14" Dob (which has tracking) and less than 5 mins to set up a small scope on my Giro3, which is a completely manual tripod head. As you can see, an AP capable setup needs a large setup time. This is of course, irrelevant if you can do a permanent setup at home.
Regarding your questions:

for an eq mount, you need an equal amount of counterweight as your scope? i.e 10lbs of weight for 10lbs of scope?

No. (sorry, Gary) You need to have the same moment of force about its pivot (force x perpendicular distance from pivot). This can be changed by (a) adding counterweights or (b) increasing the distance between the weights and the pivot (i.e fixing the weights lower on the counterweight bar). Some equatorial mounts are also designed to be counter-weight side heavy (such as my Vixen SXD, which can fully counterbalance a 3kg scope without counterweights). As a practical point: I need 4lbs of counterweight on my SXD to balance about 13lbs of scope and camera when using a 4" refractor.

is it important/recommended to oversize a mount? i.e 20lbs rate mount for 10lbs scope. or as long as scope is less than rated it's fine?

Yes. When buying Celestron/Meade/Orion/Skywatcher mounts, its a rule of thumb to divide the load capacity by about 1/2 or 2/3 to get an optimal weight. Overloading the mount will cause it to track less accurately, resulting in stars that look like streaks or jiggles. Also do clarify with each mount and load number if it means instrument only (as in telescope) or instrument + counterweight. On the other hand, high-end mounts such as Astrophysics/Paramount/Takahashi generally don't require you to divide by a factor although it still not a good idea to load it to the very limit. Unfortunately these mounts are usually very much more expensive, but well made.

how much extra weight does accessories add to the scope? (lens, filters, camera, etc)

A fair amount, actually. Don't forget the guide scope/guide rings, camera adapter, autoguider. Filters usually don't add significantly to the weight. As a guide: my 8" VMC200L weighs about 10lbs "naked" but when mounted with 80mm guidescope, tube to guide rings, guider, camera, it weighs in between 20-25lbs, depending on configuration. On the other hand if you're well aligned and using a short focal length (less than 500mm) then you may not need a guider hence your setup will only weight that of the scope, scope rings (to hold it!) and the camera.

can stacking of lots of fast photo using alt-az be equal to long exposure using eq

Yes and no. Can you produce images of the same target: Yes. Will they be as good as true equatorial mounted scopes (for deep sky objects, not planets): No, without special equipment. When imaging in Alt-Az you have to account for field rotation as well as movement of the object. This is because as an object rises in the sky, it also rotates relative to a fixed perspective from the earth (due to the Earth's rotation). Thus your exposures will have to be short to eliminate field rotation. Also, you will probably also want to image objects near the horizon to further reduce the speed of rotation, which is the worst orientation for getting clear pictures. If you are keen on Alt-Az imaging, special mounts such as the Celestron CPC mounts with Hyperstar/Fastar adapters on the SCTs (converting an f/10 scope to f/2) will allow you to expose quickly enough to avoid this effect. These can be used as very competent scopes as well. You will, however, need to buy a smallish form factor astronomical CCD unless you're using a very large scope. Otherwise you can buy a high precision alt-az mount with field de-rotator but these tend to be more expensive than buying a good quality equatorial mount.
However, on planets this is all moot because planets are so bright that a 1/30s exposure is sufficient, hence rotation is a non-issue.

[Gary]

@cloud_cover Thanks for the counterweight explanation. I stand corrected. Forgotten the fact that we did not need to use any counterweight when using a DSLR mounted on my cg5 - the counterweight side was heavy to enough to balance it. Having a mount with a heavier counterweight side design of course increases the total weight of the setup.

[lin00b]

for mounts, would a wedge on an alt/azi be comparable to an eq?

does GEM and eq. mount mean the same thing? whats the difference?

currently i'm looking at some lightweight mounts such as ioptron ieq30. any opinion on this? from youtube vids it seemed lightweight and portable. any suggestion on similar mounts?

cloud_cover thanks for the tips. my primary aim is for visual - dso visual - hence medium sized aperture (currently 5-6" seem to be a nice balance between aperture and price and portability). but it would be nice to take some average shots and post on fb.

[Gary]

Hi lin00b. In regards to your first post "something that can be sneaked into carry on luggage in planes," and working in a more rural location, a few questions:

(1) How often do you fly back and forth from KL to the rural location?
(2) Do you need/want to bring the whole set back and forth for every trip?
(3) Do you have access to a vehicle in the rural place?

If your answer to (2) is no, you may leave your setup in the rural place semi-permanently. That gives you some more allowance for a heavy/better setup.

If answer to (3) is also yes, then even more so.

If you fly very frequently back and forth, perhaps an AZ grab-and-go visual setup in KL and a heavier duty setup in the rural place for both visual and imaging.

[lin00b]

I'm more or less full time at the rural location. I only go to the city (kl, sg) once in a blue moon. I dont plan on observing in the cities. most of my observing will be at the rural area.

why i want an airline portable set (and yes, plan to carry the whole set for my trips) is for oversea travel to different latitudes. i.e europe, states, nz, etc. dont happen very often, but i like to prepare for it. i'm ok with only hand carry the scope, while checking in the mount if it comes to that.

for now i have no plans of getting multiple scopes. my main criteria is "airline portable dso visual"

another question, hows the performance of non-eq goto for photography?

[cloud_cover]

Given your criteria I think the best bang for the buck would be a medium sized dobsonian you can handle, more or less permanently at your rural site. One thing about being on the equator: We get to see a very large proportion of the sky such that there are few targets in the northern or southern latitudes that we can't see from here.
Then for your travel scope, get a smaller refractor on a tripod mount or maybe just some nice 50mm binos
If you do go into AP, then you probably can save up the pennies for a better, heavier mount and wheelie bars so you can roll it into position. Don't bother with lighter Eq mounts: unless your imaging setup is very light, they're not useful for imaging.
Yes, Eq. and GEM are pretty much the same. A wedged Alt-Az mount will be the same as a GEM but you will still need to polar align, which may be more difficult depending on they type of wedge used.
Regarding goto non-Eq mounts for photography, see my post on Alt-Az imaging. I presumed you meant a tracking Alt-Az. Manual Alt-Az is NOT USEFUL for imaging (except for terrestrial objects)

[Gary]

@lin00b - Two telescopes for some of us is kinda not considered "multiple". LOL. It only becomes multiple when we lost count or refuse to count them.

If your budget can afford 2, especially if you delay your tracking eq mount option and go full az light-weight manual option to free up more $ in your budget, this may be a viable option which may let you enjoy the best of 2 telescope design worlds.

"my main criteria is "airline portable dso visual" ". Good. You are getting clearer and clearer what you want.

DSO can be generally classified into 3 types:

(1) nebulae
(2) galaxies
(3) star clusters

No single telescope design can view all 3 of them very and equally well.

Even within one of these categories, some of the objects look better in one telescope design compared to another. But generally, when people refer to DSOs, (1) and (2) comes to mind, so generally a bigger aperture has an advantage. But if your priority for nicer star clusters is higher, you may prefer a refractor design and compromise some aperture.

For me, observing Pleiades is already good enough reason to get a decent refractor regardless of whether star clusters are classified as DSO or not, let alone other star clusters that look great with pin-point sharp stars across its wider field-of-views (compared to typical SCT/MCT for example).

So my point is continue to stay open with your choice of telescope options while researching for "airline portable DSO visual" and open to the idea of getting 2 telescopes of different design and enjoy them for what they are mainly designed for.

[Gary]

Speaking of airline-portable telescope, just came across this while doing some dob research - Gary Seronik's 8-inch airline-portable dobsonian telescope that only weights 7kg. It was featured in March 2013 issue of Sky & Telescope.

Check out his online article which is meant to complement that published article:
http://garyseronik.com/?q=node/206

[antares2063]

lin00b:

The most airline portable scope i feel (in my opinion) is a 80-90mm refractor with retractable dew shield. (the dew shield can slide inwards and outwards, hence making the overall tube length shorter)

Speaking from personal experience, when i was young i lugged a Celestron 150mm Newtonian with CG4 and aluminium tripod legs to go Australia with an army friend . Didnt pass security so had to check in all luggage. Collimation was horribly out when we landed at Aust.

If you wish to hand carry the scope up the plane, i think only a refractor can make it.
In addition , in future if u want to branch out into imaging, most refractors have average f-ratio (f6-f9) making long exposure times unneccesary. Hope this helps.

Regards,
Junwei