Startravel 120 & AZ4 combo vs 200 Dob.

[zedzed]

Hi all,

Been looking for a scope for a while - and was pretty sure I was going to get a 200 dob.

However - My kids are getting a little older and we're all set for a few camping holidays this year (and the dob. couldn't come with me due to size). Given that my backgarden isn't great for viewing (trees plus house in the way of the sky!) and my nearest "dark site" is about 45 minutes drive away, I wondered whether I should go for the ST120 on an AZ4 instead. That way I can take it with me on holidays, but still get some use of it when I'm at home. I'm thinking the ST120 (instead of the 102) to get as much aperture as I can.

I'm interested in DSO / Messier - but I'd still like a peak at the planets every once in a while. No imaging. Budget £300-ish.

2 questions:

1) How does the ST120 on AZ4 compare with the 200 dob? Will I be compromsing (too much) my home viewing (and occasional dark sky visit) for the 2 or 3 weeks in the year I'm away camping?

2) Does anyone in the UK (or ship to the UK) sell this combo? Everyone sells the ST120 on the AZ3 - but I've heard the AZ4 would be better/more stable. The extra weight of the AZ4 doesn't bother me.

Thanks,

Dez

p.s. How many posts do you have to have before you can see the "classifieds" section in here ... and is it as active as Astro B&S?

[SteveRob]

Hi Dez,

I think you need 50 posts to see the "classifieds", I may be wrong, other SGL forumers may know better.

Cheers

Steve

[NGC 1502]

Hi Dez. Tough call giving scope advice, what suits one person may not suit another, but here goes...........

I've had a 200mm Dob, and have borrowed a SW 120 F5 - here's a link to the SW and what I found (for what my opinion is worth of course.......)

The 200 Dob is a brilliant all rounder, just has to be the best value scope around, it could sustain a lifetimes interest, with no real need to upgrade, if basic observing is your thing, as it is for me. It will give better results than the SW 120 F5, on almost all objects. A bit of maintenance is needed of course, Newts need to be kept in collimation, but I wouldn't let that put you off.

However, the SW 120 F5 is a great scope too. Gives a surprisingly good view of Jupiter, if you can live with the purple halo. Reducing the aperture with a simple cardboard mask helps with that, and some use filters, don't know if that helps, perhaps others may say what they think. A 120 F5 refractor scores of course if you are a wide field junkie like me, large objects like the Plieades, Beehive (M44) Kemble's Cascade and loads of others are a joy. You will need a nice low power wide field 2" EP for that. The scope is also mostly maintenance free and more portable.

Don't know how the 120 would be on the AZ4, it was a bit too heavy on my Astro-Tech Voyager alt-az mount, but usable.

Like I said, tough call giving advice...........

You need 50 posts for the buy & sell section here on SGL.

Hope that helps, Ed.

[Moonshane]

yes, quite right. 50 to see the classifieds and 250 to post on them (i.e. sell). You can contact a seller after 50 when you can see.

I think the 120 on an AZ4 would be a good buy. it will be very very good on wide field, especially from a dark site and OK on planets and moon but it's better as a wide field instrument. another option is a 150mm f5 newt on the AZ4. this would work very well too and preferable to my eyes.

the 8" dob would be far better on all targets I feel but if space is an issue then it is quite a big scope. I use on in my space club for year 5 kids and they use it easily.

personally, I feel the dob would be by far the better buy but that's me and I'm not you

if you can, buying used would be a good thing especially if you can buy off a member or visit with someone experienced. you save a lot that way and can sell at almost or no loss.

[zedzed]

Thanks for the advice. Sounds like the maybe I should stick with the 200 dob .... and then start saving for the 120/AZ4 for next year! Or maybe just buy a car with a bigger boot so the dob + family + camping stuff can all fit in!

[Stargazer_00]

Just wanted to chime in here, having just bought an ST120 myself for grab and go to completment my 10inch dob, you can't currently purchase an ST120 on an AZ4. - only AZ3. If you want AZ4 (like I also do) then you'll need to buy the mount seperately and either keep both or flog the AZ3.

Oddly you can buy a ST102 on the AZ4. Having not used an ST102 I cant comment on it's use but the rationale I asked myself was "if you can afford ST120 and ST102 then why not buy ST120, see how it fares on an AZ3 and then decide if you want AZ4"

AS it turns out I'm now buying better eyepieces which are heavier than my current BSTs so tihnk I might want a better mount just to stop any unwanted slewing/dropping of focuser end by gravity.

I also believed at the point of purchase that the Slow Mo controls of the AZ3 were full range, like an EQ mount, where you can keep turning and turning and the mount keeps moving. As it turns out the slow motion is simply set to run on a small threaded section and does find a limit after a few miniutes of tracking an object. Once you reach the end of the slow mo tolerance you have to wind it all the way back to the other end and realign the scope. Then you can track in slow mo some more. It's not that bad as it sounds, you can get a good 10-15 minutes of tracking out of the section if you wind fully from one end to the other.

Alternatively, dont use the slow mo and nudge it

[Tiago]

Just wanted to chime in here, having just bought an ST120 myself for grab and go to completment my 10inch dob, you can't currently purchase an ST120 on an AZ4. - only AZ3. If you want AZ4 (like I also do) then you'll need to buy the mount seperately and either keep both or flog the AZ3.

Actually, you can buy them together. Just ask the guys to junk the prims and toss in a star diagonal, they'll do it for free.

http://www.teleskop-express.de/shop/product_info.php/info/p3944_Skywatcher-Startravel-120-auf-AZ4---Gro-feldrefraktor-120-600mm.html

The AZ4 mount copes very well with a ST120, no issues at all. Mine is the aluminum legged version and it's quite fine.

The only things the ST120 will win on the 200 Dob is taking less space for carrying around on trips, and those wide field views. It will also cool down faster, which may or may not be a factor (it is for me).

[zedzed]

Prims ... do you mean prism? Silly question ... what's the difference between an erecting prism and a star diagonal? Aren't most erecting prisms "diagonals" anyway? (i.e. let you see it at 45 or 90 degrees to the direction of the scope)? Or am I barking up the wrong tree here?

[Stargazer_00]

diagonals (90) use a mirror and erects (45) use a prism.

never seen a 90 prism, might exist but cetainly arent common.

[zedzed]

Thanks for you help - got it

[steve_bham]

I've got the 120 f5 scope and its def a keeper. Easily fits in a large sports bag for easy travel and the views you get from it are stunning

I was viewing the moon early and the CA is not bad at all in my eyes.

It will be a great scope to take camping with you.

[Stargazer_00]

I was just out between clouds enjoying m81 & m82. Certainly is a capable scope. Moon was okay. Jupiter Was too purple for me

[zedzed]

I've got the 120 f5 scope and its def a keeper. Easily fits in a large sports bag for easy travel and the views you get from it are stunning

I was viewing the moon early and the CA is not bad at all in my eyes.

It will be a great scope to take camping with you.

How do you find it on the AZ3? Some say it's at the limit of acceptable, others say really need the AZ4? The fact it's sold with the AZ3 makes me think maybe others are over fussy ... but wouldn't be the first time the manufacturer has it wrong and the people have it right ;-)

[steve_bham]

How do you find it on the AZ3? Some say it's at the limit of acceptable, others say really need the AZ4? The fact it's sold with the AZ3 makes me think maybe others are over fussy ... but wouldn't be the first time the manufacturer has it wrong and the people have it right ;-)

It's useable on the az3 especially with the slow mo controls. But lacks the smoothness of an az4.

[Stargazer_00]

From user experience the slow mo control, paticularily the left to right one, get right in the way. I'm considering detatching the left right one and nudging it. the up down on is fine as it tracks parallel to th focuser

[zedzed]

THanks guys, much appreciated. I guess what I'm hearing is that the ST120 is a capable scope and portable. I think it might come down to whatever I can source for cheapest ... if I could pick up a 200 dob or ST120 on AZ3/4 for £200 2nd hand I'd be happy with either