John

I managed to get NGC604 with my 100mm refractor tonight at 64x. Pleasing result given the weather we have had recently.

Some clear sky again (!) and it's both steady and transparent 😲

After some obligatory Jupiter and Uranus viewing (Saturn had dropped out of sight by the time I decided to put a scope out) I thought I'd have a go at some deeper sky stuff. The 100mm scope was not the greatest choice of course but the brighter galaxies were showing quite nicely and also M110 which showed that the transparency was decent.

After a little sweeping around (it's close to the zenith tonight) I managed to locate M33 in Triangulum and I was getting hints of the giant star forming nebula NGC 604 in the outer reaches of that galaxy. Boosting the magnification from 38x to 64x confirmed this faint fuzzy spot of light next to a foreground star. Quite pleased for the 100mm refractor to get this. Feels like proper observing 🙂 

Assuming that the scope is equipped with a red dot type finder, make sure that the finder really is aligned with where the main scope is pointing.

Using a low power eyepiece (25mm - 30mm focal length) in the main scope can help it to act as the next step in finding things after the red dot finder has got the scope pointing generally at the right patch of sky.

Stick with well known "showpiece" targets with a small aperture scope. You will have more chance of finding these and, more importantly, recognising that you have found them, in the eyepiece !

Just now, Stu said:

...I must say, one of the things I like best about the AZ75 and AZ100 is that it doesn’t seem to matter how heavy the scope (within capacity) the motion stays smooth without counterbalance. Without revisiting old topics (😉) when mounts perform like that, the simplicity of just moving the scope by hand can be very simple and satisfying.

Agreed, on all counts 🙂

I've owned a Tele Optik Giro Ercole alt-azimuth mount for a few years now. Although it's beautifully made and I really like it's simple but robust design, I've never been quite happy with the motion around the azimuth axis. No matter how carefully I balance the mount (and balance is important to the smooth operation of this type of mount) I have found just too much "sticktion" in the azimuth movement. Probably unfairly, I relegated the mount to a cupboard and only used it occasionally. I had hoped that the azimuth axis would ease over time and with some use but that didn't really happen. My Skytee II, although more crudely engineered and finished, operated much more smoothly and became my primary mount for my 100mm, 102mm and 120mm refractors.

I have recently dismantled the azimuth axis of the Giro mount to see what is going on in there. The original blurb on the mount stated that the bearings are "totally free of lubricants" but mine did seem to have some rather sticky grease that had been applied at sometime during it's life. I carefully cleaned all that off, re-assembled the mount and tested it with a couple of different scopes on board (with careful balancing again). Unfortunately the result was no better and the azimuth motion remained far too stiff for my tastes. So a "no-lubricant" approach did not really work, at least for my Ercole.

I took the azimuth axis apart again, cleaned it all again and then applied some decent quality white lithium grease. Not too much though - a thin film around the bearing surfaces and down the azimuth shaft that sits within the curvaceous body of the mount. I re-assembled the mount and was pleased, and a little surprised, to find that it's motion around the AZ axis was much smoother. It's now very close to the "butter smooth" motion of the altitude axis. Over the past couple of weeks, during the short clear patches, I have used the Giro Ercole with all 3 scopes mentioned above and found it a really pleasant and satisfying experience. With the 100mm and 102mm refractors I've even found that the mount is quite useable without the counterweight bar and counterweight fitted. With the 120mm refractor a small amount of counterweighting is needed so I use an old Vixen 3.2kg weight with that scope. With the smaller scopes, using a 1.8kg counterweight delivers a very smooth and well balanced rig which is a delight to use. 

Clearly, with my example of the Ercole mount, there is a "goldilocks" amount of the right sort of lubrication to create a really satisfying operation and I seem to have hit on that with my latest work on the mount.

Now that it is so pleasing to use, I can enjoy the sheer simplicity of the Giro Ercole mount coupled with it's capacity to provide very a stable platform for observing with refractors up to and including  the 7kg F/7.5 ED120. 

I have the Skytee II and also the superb T-Rex alt-azimuth when I want slow motion controls but I do enjoy the sheer simplicity of the Ercole design with it's fine seemingly unbustable engineering. Plus it's nearly 2kg lighter than the Skytee II, which is a bonus.

As owners of the excellent Rowan AZ75 and well sorted dobsonian mounts have found out, if a mount is really well engineered, properly balanced the need for slow motion controls diminishes as well because adjusting an objects position within the field of view, even at high magnifications, becomes 2nd nature - you start to do it unconsciously as you observe.

I'm very pleased that my Giro Ercole is properly sorted now and will, at last, become a very regularly used tool when I am observing with my 100mm - 120mm refractors 🙂

Here is the Giro Ercole mount on my Berlebach Uni 28 tripod. Now it really feels like an excellent combination of German workmanship 

Lovely Dave - nice to see a well baffled drawtube 😁

When I had a 12 inch solid tube dob I kept it in the corner of our dining room. My other half (a gardener) occasionally threatened to fill it with soil and grow something in it, if I misbehaved 😬

On one of the SGL star parties a 20 inch dob arrived being towed behind the owners car in a small horse box and was lowered down ramps using an electric winch. Very impressive !

We have one of these at my astro society observatory which I get to use from time to time 🙂

Final spot of observing for me this evening comprised my first look at some of Orion's gems this season as they peeked above the rooflines.

Rigel, Alnitak, Sigma and Eta Orionis nicely split - welcome to the cloudy UK skies Orion ! 🙂

Seeing has improved a bit here so a bit more magnification could be used to watch the GRS as it neared the end of it's transit. The South Temperate Belt seems well defined as it follows the southern edge of GRS across the disk. Thinner but nearly as dark as the South Equatorial Belt. On the disk area in advance (west) of the GRS the STB seems more or less absent for a while before becoming visible again. I think this break in the STB is due to a large vortex immediately to the SW of the GRS. 

I found Uranus nearby as well. It's disk (3.8 arc seconds) seems pale grey/green to my eye tonight. 300x showed the disk very obviously.

Two ED elements in what I guess is a doublet objective - why ? 🤔

I've had a few shortish periods of observing Jupiter this evening with my 100mm refractor.

Here, the seeing is not so good so 130x or so seems to be the most useful magnification. Some interesting structure in the north equatorial belt and a couple of festoon-type features in the equatorial zone. Quite a hard fight to tease out the details though and plenty of clouds about to increase the challenge further.

I had a quick look at Theta Aurigae - 4.5 arc second separation but a big difference in component magnitudes - mag 2.6 and mag 7.2.

Not a great night for observing by any means 🙄

I was lucky enough to have a look through a couple of 20 inch scopes at SGL star parties.

On one of those occasions the owner asked me what I wanted to see and I suggested M51 followed by M13. Those views will be with me for the rest of my life 😲

13 minutes ago, scotty38 said:

It does on the 103 and 120 but the 140 and 185 have this different approach 

Sorry, I missed this post just now. I agree - different approach depending on the aperture for the Askar Apo's. I was blinded by the lure of the "big ones" 🙄

6 minutes ago, scotty38 said:

Ok that’s good to hear but definitely this telescopic arrangement rather than screw in?

Certainly telescopic (with a lock) on the LZOS refractors. I've been concentrating on the 140 and 185 Askar Apo's and they have a telescopic extension but looking at the details again it looks as if the 120mm and 103 have a screw in extension section. 

1 minute ago, Starflyer said:

Don't be tempted to overtighten the locking screws, you can distort the mirror cell and get odd star shapes. All they need is the lightest touch.

That's sound advice 👍

2 minutes ago, Stu said:

Thanks John. No, I don’t really know much of that! I tend to use a laser for collimation on Newts. I can’t actually relate what I was seeing with your images though so I need to have another go.

I find that the the 45 degree face of the cheshire needs to be really well illuminated to see the reflections clearly.

30 minutes ago, scotty38 said:

Any thoughts on the retractable tube being a tilt magnet at all?

APM/LZOS refractors have used a similar approach for years. My LZOS 130 is 17 years old and has an extension tube at the focuser end. No signs of droop with it even with a 2 inch diagonal plus 21mm Ethos installed. The Askar approach looks even better engineered than the APM/LZOS one I think.

9 minutes ago, Stu said:

Watched the video, some good stuff in there. One thing I didn’t get at all was the use of a Cheshire. All I could see was a bright circle and cross hairs, nothing of use. What was I doing wrong??

Apologies if you know this Stu. What we are looking for is the reflection of the illuminated face of the cheshire. It shows on the rear faces of the lens elements as two small disks of light with a dark central hole. Ideally they will be one on top of the other. If the objective is tilted or the focuser is askew, they show as two disks not overlapped or even side by side.

Apologies again if you know all this and have seen such illustrations before.

13 hours ago, Franklin said:

I know this thread is about 4" ED F7 scopes and they are great but there is something in an F9 4"doublet that works and the DL combines this, not only with fluorite glass but Takahashi's legendary optical figuring, definitely a keeper if you do downscale, I would think.

I was attracted to the F/9 100 Tak because I already had the F/6.5 Vixen. I was on the look out for a Vixen FL102 at that time but, as is often the case when you start to look for something specific, they became like hens teeth to find 🙄

3 hours ago, Rusted said:

.... You don't buy a telescope in isolation.....

Quite right. With the 185mm there are the mount, the observatory and the divorce costs to factor in ........ 😬

2 minutes ago, Nikolai De Silva said:

Hoping for clear skies!

 

So are we in the UK 😒

2 minutes ago, paulastro said:

I'm not trying to tempt you John, but I'd like to see a pic of the 140 on your T-Rex altaz.  🙂

Evil man ! 😈

That looks pretty good to me @Stu 👍

I keep looking at the 140mm F/7 triplet. For quite a while I was interested in the APM 140mm F/7 ED doublet and now here we have a triplet at around £1K less !!! 😲

The 185 is amazing as well but I'd need a massive new mount for that whereas the 140 would go very nicely on my T-Rex alt-azimuth 🤔

Who is going to be brave enough to start a "Ménage À Trois" thread ? 🙄