15 minutes trying things

[Brasspoodle]

Since buying a Skywatcher 120/600 Achromat on an AZ3 a few weeks ago I find I can accomllish 15 minute sessions in the backyard (7km from the city center) that are very rewarding. I've not searched out any new objects just yet as I'm still in the phase of testing out which eyepieces work well, which filters work well, whether balance is an issue, what objects are most rewarding etc.
Tonight the seeing was okay (quite still 8/10) but the transparency was down due to lots of thin cloud drifting about (6/10). I started by looking at Jupiter with a Pentax 5mm XW, a 2x barlowed 8mm Delos, and the 2x barlowed 5mm (which required an in-travel adapter in the 2" 90° Quartz diagonal to reach focus). I added a Baader Semi Apo filter to the chain, and while it didn't do a lot it did help to see some detail in the unbarlowed view. My favourite was probably the Pentax 5mm at 120x with the Semi Apo (the barlowed 8mm was a close second). The single speed focuser is quite stiff but after I found 'the spot' I was getting nice complex detail in the lower band and the hints of two additional bands above and below the main two. The colour with the filter was quite good (not too yellow) and reminded me of the view through my old 8" Dob. 

The next target was M42 keeping the same set of eyepieces for some close up detail of the Trapezium and surrounding area. Initially I didn't remove the Semi Apo Filter and was surprised at the level of detail that was visible. Without the filter the whole object was a little brighter but hard to say (in these conditions) that I could see more. Trapeziums stars E and F weren't visible. Enjoyed scanning about the area at high magnification with the slow motion controls which are still a big novelty after coming from non goto Dobsonian mounted reflectors. 

The final target was the Eta Carina nebula. Even in my light polluted sky it's not too hard to locate the area with the naked eye. Despite being in a 'red zone' I find my backyard quite dark with enough surrounding trees to block street light. I looked at this nebula with an Astronomik UHC filter. In light pollution I find the O-III darkens the image too much. Under darker skies the O-III is unbeatable. I used a 17.3mm Delos which captured the whole object nicely, emphasizing the upper right bright limb and the dark lane that runs beside it. Lots of nice swirling nebula to the left with its angular intersection, and then a fainter patch below all this. I the tried my 13mm Ethos on this object (which gives the same FoV) fearing it might be a bit heavy but to my surprise it worked a treat. The extra magnification was great and the object at 46x was nicely framed with lots of surrounding sky. 

Overall a fun little session but very keen to attempt a few galaxies with this scope. Have seen the Spindle (NGC3115) with it from the backyard with a near full moon so hoping to catch Centarus A, the Sombrero and a few new one off the Bennett list at some point soon. Clear skies all. 

[happy-kat]

That was a packed 15 minutes. Given that cracking image posted last week with one of these in narrow band is it also possible to observe like that and see no CA? What happens if you look at a planet with such a filter?

[southernman]

Great write up!  I have the same scope (albeit on an az4) and a similar sky to yours , although I am slightly further south. These scopes perform remarkably well on DSO's especially if you can get away to darker country skies. The area around Eta Carina is a real treat and probably one of my personal favourites. In fact the reason I purchased this scope was to scan/explore the star fields in and around Scorpius/Sagittarius in a way my 6" frac and 10" dob couldn't.

Both Centaurus A and the Sombrero can in the right conditions be well worth seeking out.

 

Peter 

[laudropb]

Nice report of a very busy 15 minutes. Do you find that the AZ3 can cope with a 120 frac?

[Brasspoodle]

The Baader Semi Apo filter reduces just a tiny bit of CA in this short tube acromat. I expected a lot of CA when I got the scope so haven't been too dissapointed by it. The filter is helpful when the planet is relatively small in the eyepiece (when the CA threatens to overwhelm the detail). A Contrast Booster is probably a better filter to get rid of it all but haven't seen one second hand yet (the reason I thought I'd try the Semi Apo). Stopping down the aperture is perhaps the most effective way of dealing with CA and given Jupiter is quite bright and almost at opposition it's not too dark a view and I find I don't lose too much detail. Also the ED Barlow reduces a bit of CA which was noticeable in the barlowed 8mm eyepiece. I have yet to go down the route of buying vintage Swarovski eyepieces which deal with CA better. There's a point where an ED refractor might be a cheaper option!

 

As for the AZ3 and the 120 (it's a short tube f5) I've had moments close to Zenith when the Nylock nut won't hold a Barlow Delos eyepiece combination but I've been able to stabilize it by moving the scope as far forward in the tube rings as I can. Last night I had no drift in the altitude movement. The light weight aluminum legs I find okay. When moving the scope by hand in altitude there is a bit of vibration (and rather a lot of play in the motion of the mount head, although tightening the azimuth movement helps) but it all quickly settles at the eyepiece even at high magnification. This was all with the scope on grass though. The focuser on the scope is quite stiff too so that caused the mount to wobble but was really only a second or two before that settled. As a grab and go I can't complain and still like the novelty of the slow motion controls :-) Star hopping in light pollution is a bit painful given the general stiffness of the altitude movement and the extent to which the slow motion controls can cover the area before having to be wound back. Under dark skies it'd be a breeze I think given you could start out much closer to the desired object with the naked eye. I have been thinking about an AZ4 with stainless steel legs but really it starts to conflict with the idea that, as well a grab and go, this scope is also about economy. I wonder what Peter's (southernman) experience is with this? 

[southernman]

Interesting point about the az3 vs az4. My ST120 came with an az3 and I found it handled the scope quite well. However I gave the az3 away with a Meade 70mm f/10 refractor to a budding young astronomer. I mounted the ST120 on a small eq mount for a while but decided to get an az4. I had hoped to get the az4 with the stainless steel tripod but these were unavailable at that time here in New Zealand so I settled for an aluminium tripod instead. In use this setup has proved very stable and is easily light enough for me to actually grab'n'go. The operation of the az4 is very smooth and has a quality 'feel' to it. I certainly believe it to be a step-up from the az3. Unfortunately  I cannot comment on the tubular stainless steel version of the az4  although I have read here and on other forums that it is extremely stable and able to support scopes larger than the ST120 albeit with the penalty of some extra weight.

Cheers Peter

 

 

[happy-kat]

I have a balance bar I add to my Az3 as I like the movement to be easy and not stiff by having tight bolts which also help control vibration. I got the idea from the link below and use light weights I picked up from Astroboot though I think the staradventurer weight bar would have worked well for my ST80 but wasn't available at the time. 

Link here

[Brasspoodle]

Many thanks for your thoughts on the AZ3. At present the Nylock is doing its job despite a bit of stiffness in altitude which I'm currently okay with. I was showing a neighbour Jupiter through the scope tonight at 120x (Pentax XW 5) and manged to catch Io and Europa in a double shadow transit! Didn't use any CA reducing filters and seeing was very good, even with a few drams of various Islay single malts tucked away :-D