Refractor on Alt-Az mount question

[oreu]

Until now I've only used a reflecting telescope on a Dobsonian mount (Skywatcher Heritage 130P), but am thinking of getting a refractor on an Alt-Az mount (possibly a StarTravel 120).

As I have no experience with this kind of setup, I'd like to know if, as with the Dobsonian, you can easily 'glide' through the sky just moving the OTA with your hand while viewing at the same time?

Thanks for any advice.

[John]

I use this sort of setup all the time. It's just as easy to use as a dobsonian mount. Some alt-az mounts have slow motion controls (eg: Skywatcher AZ-3 and the Vixen Porta) but the "push only" ones like the AZ-4 and the Giro are just as easy and effective to use in my opinion.

I use an ED120 refractor on a Giro type mount and a 4" ED refractor on an AZ-4 mount.

The only caution I'd add is that refractors 5" and over in aperture are really big beasts and alt-azimuth mounts that can handle them need to be robust and well engineered.

[orley]

The AZ4 has adjustable clutches which allow gliding or holding in a fixed position. Simply loosen or tighten the clutches to suit. The mount comes with a pan handle to aid movement, but I find pushing the scope just as easy. Handles my 100ED frac easily. Having the scope correctly balanced helps.

[ak47]

i have the AZ4 mount with aluminium tripod - its lightweight and portable while still solid and stable, just perfect for my skymax 127.

it doesn't have small motion controls  like the AZ3 but it is super easy to operate - just push and point the scope to wherever you like, even directly at the zenith (where the AZ3

fails) . 

[Joseki]

I've been using my Evostar 120 frac on a AZ4 (steel legs) and it's been fine up to x240 ish (i.e. max I would want to use on a non-tracking mount anyway), there's a bit of wobble at high mag but it damps down quickly enough, I'm in no rush to upgrade but I can see a SkyTee-2 mount would make a nice upgrade.

[Moonshane]

I am completely pro dob but recently sold an AZ4 head which worked extremely well with a 6" f5 newt I have and would be great for a short achro refractor.

I find the Giro I bought to replace it a lot more user friendly lthough balance is more critical.

John's right though that any of the good quality AZ mounts are just like using a dob on a tripod. in fact, it is possible to mount the heritages on a tripod and use as normal (but obviously at a much more convenient height).

see

http://stargazerslounge.com/topic/158307-heritage-130p-transformation/?hl=heritage+130#entry1600108

[Grotemobile]

This is my 4" refractor on a Vixen EQ-3 mount.

Works very well.

Steve.

[Moonshane]

that's a good solution to point your EQ mount straight up, giving an Alt-az equivalent.

I did it with a Vixen GP mount once.

[AndyWB]

in fact, it is possible to mount the heritages on a tripod and use as normal (but obviously at a much more convenient height).

Or you could just use the dovetail! I slide my Heritage 130p onto a normal AZ4 mount when trying to show things to friends - it's much easier to be at 'standing height' rather than my usual sitting.

Though I'm tempted to get a Giro head for it too, for a twin mount - H-alpha and, eventually, white light...

[Moonshane]

oh yeah ! I didn't realise they had one! 

[oreu]

Thanks everyone for the replies, that's been really helpful.

The Alt-Az mount that comes with the StarTravel 120 is the AZ3, and I just wondered if this is also suitable for moving about the sky in a Dob-like fashion?

[Moonshane]

I have never used an AZ3 but as far as I can see you release a clutch and move the scope yo where you want ti 'dob style' but then use the slow motion cables to track.

If you can afford the AZ4 this would be a far superior option in my opinion.

[Jim Smith]

Yes.  I use my 120mm refractor on an alt-az mount with great success.  I recommend that you get a decent finder.  I'm not sure what the standard finder on the StarTravel 120 is like. The SkyWatcher 9x50 raci finder works well for me.

[happy-kat]

The az3 can move almost like a dob but the scope has to be in balance when I tried mine in fact this reminds me I was going to make a balance bar for it.

[John]

The AZ-3 is easy enough to use but you will find that the scope tends to tip backwards when it's pointing at an altitude of more than around 60-70 degrees. This is because the centre of gravity of the scope tube is set a few inches above the altitude axis of the mount with the AZ-3. The altitude axis can be tightened to control this but too much and the smoothness of operation at lower altitudes becomes adversely affected. 

At one point I had an AZ-3, AZ-4 and a Skytee II with different scopes on. The AZ-3 has a Celestron C5 in the pic below, my Vixen ED102 is on an AZ-4 and the Skytee II (on the left) has the quite heavy Intes 6" maksutov-cassegrain on board. With the very short and light tube of the C5 the AZ-3 works well but I felt my Vixen 102 was just a bit too much for that mount and the Intes Mak-Newt would have flattened it !

[oreu]

Thanks again everyone, I've learnt a lot from this thread.