Captain Scarlet

I have 2 Revelation 2” dielectric diagonals. One for use in Ireland and one for use in London, so I don’t have to worry about hoiking one back and forth and potentially forgetting one.

I accidentally took the London one on my latest trip to W Cork, and naturally I accidentally left it there. So I have both my diagonals in Ireland whilst I’m in London.

I do have a little WO 45 deg erecting prism here though, and it’s that I’ve been using with my 105 f/6.2 refractor lately. It works, but produces a sharp diffraction spike on bright things. Looking at the off-focus diffraction pattern of Vega, for example, it produces a beautiful vivid mesmerizing kaleidoscope of all the colours of the spectrum.

So, I’ve ordered a Baader-Zeiss 2” prism and am excitedly expecting it shortly.

When I get my dielectric mirror Revelation back to the UK, likely October, I’ll do a proper comparison between the three: the 45, the Zeiss and the Revelation mirror.

M

... I think it also remembers various “enhanced accuracy” settings as well, such as so-called PAE re-centerings. I think these as they accumulate have the potential to thoroughly confuse the handset. I now routinely reset to factory settings to clear all those and reestablish my alignment star settings before every alignment.

2 hours ago, johninderby said:

Think you need a field mower like this. 😁

I've been pulled into a pond by one of those, an old Allen Scythe, desperately struggling to disengage the drive

1 hour ago, Betton said:

... Thanks for the feedback, mate. What exposure times do you get with your set up?

Ah, there you have me ... for now I am visual only.

And @wimvb is right about the bearing thing - my EQ35-M has bushes not bearings.

M

Ah yes, Graff's Cluster and (perhaps actually also known as?) "Tweedledum & Tweedledee". One of the very first astro objects I looked up after first getting in to this pasttime and taking a (terrible) photo very close to Altair...

3 hours ago, Ouroboros said:

... I did find that the polar scope on my newly bought AZ-EQ6 mount was misaligned. Frankly I think that's unacceptable for something so expensive ...

I agree, but it seems to be ubiquitous.

I now have 3 polar scopes, one on each of my Astrotrac, AZ-EQ6 and lately on my EQ35M. They have all come out of the box severely misaligned, and, worse in my view, all 3 with serious parallax. I have fixed these problems on all of them, but the one on the AZ-EQ6 was cemented into the mount and its individual components cemented together, and took huge effort and courage to remove from the mount and to adjust to fix the parallax. As you say, unacceptable.

I have the EQ35-M, and I really like it. The model is fairly new, and because it's designated EQ3-something, I think people assume it has the same load capacity as all the EQ3s, which is not the case. I think SW have got their marketing wrong here, I'm sure people have been put off by the nomenclature.

The EQ3-2 has a stated load capacity of 5kg, whereas the EQ35-M has a stated capacity of twice that: 10kg. It has no problems at all handling my 7.5kg APM-LZOS plus bits.

M

Absolutely stunning

I would suggest setting up a DSLR on a tripod in a rather dark room, set its ISO as high it can go, sit yourself in front of it and take a few shots of your face using a remote. Then in bright conditions, take a similar shot with a ruler held up to your forehead to give you a measuring scale. I've been meaning to do just this for a while, just not got around to it yet.

My understanding is that your pupil will dilate in dark conditions very quickly, like a matter of seconds. It's your rods' dark adaptation that takes much longer, but you're not measuring that.

Cheers, Magnus

On 08/09/2019 at 22:55, tooth_dr said:

I just missed this visually last night, as when I came in and sat down in the observatory it was just on the screen from the all sky camera.

Any idea what’s going on? Is it a reflection or a meteor that broke up into pieces?

 

TIA

Adam. 

If you zoom in and stretch it a little in Photoshop, you can just about see what it is:

1 hour ago, johnbaz said:

I've never counted but I think I must have around 50 bino's now!!...

Wow I thought I was bad ... you make me feel much better

1 hour ago, Scooot said:

Thanks Magnus.

I used Pixinsight. No darks, bias or flats. I can’t use the usual Image Integration though because of the lack of stars to align on, so I use the FFT Registration script which seems to work very well on the moon.

Also I used my equatorial platform so I had some basic tracking to keep the moon in the fov whilst imaging. 

Thanks. Yes there aren’t many alternatives when it comes to Lunar stacking. I’ve had a couple of very good results with FFT Registration in PI, but when I tried it on a load of quite noisy and hand-held (therefore significantly randomly rotated) eclipse pics it completely failed no matter how hard I tried. Autostakkert the same.

Very nice. May I ask what software you used for the stacking?

Cheers, Magnus

37 minutes ago, kirkster501 said:

Most ingenious to use the other scope as a weight, first time I have seen that done..  Most ingenious indeed. 

How did you get the saddle of the "counterbalance" telescope to grip the counterweight bar?

You have got me thinking......

Yes as @vlaiv says, this mount comes as standard with a special "2nd scope saddle" which screws and clamps onto the end of the counterweight bar through a hole in its centre. By its nature, clamping onto the small flat end of the bar, it's unlikely naturally to be in parallel plane to the main scope saddle, and in my case it certainly wasn't. It has a pair of adjusters for one axis, up/down, but not for the other (left/right). I've read of others on here who've complained about the same problem.

BTW the manual advises not to use both counterweights and a 2nd scope, which obviously I've chosen to ignore here.

M

I had a similar experience. Having got it rather easily through my refractor via goto, and having a very good RDF spot on (literally!) I thought it should be easy through my 15x56 Zeiss bins. Not so - I couldn’t see the pair through the bins and I knew I was looking at the right place. Weird.

A quick session for me last night to try out my new pier extension and to see if I could find this. Luckily my goto went straight to it, unmistakable, never seen Neptune before so v happy. Best for me at 108x through my 105, definite bluish colour and nice contrast to phi aqu.

M

My understanding of a sky at, say, 21.3, means that the patch of sky being measured has the same average brightness as if each square arcsecond contained one star of mag 21.3.

With only your rods working at that level of brightness, that’s a shade of grey.

M

6 minutes ago, Cornelius Varley said:

There are some very expensive high end eq mounts that don't even have a bubble level. The reason being that whether the tripod is absolutely level or not makes no difference to the correct operation of the mount.

Yes quite.

I do however hanker after a Fell Bubble Level mainly because it’s a thing of beauty and engineering excellence.

Although what Cornelius Varley says is right, if you’re like me you’re Irritated by supposed “instruments” being completely unfit for their one purpose in life.

All the _bubble_ levels I have, including the one in my very expensive Berlebach Planet tripod, are miles out.

Even most of my small rule levels I’ve had to throw out, being up to 0.8 degrees wrong. These things have but one job to do!

So I’ve resorted to paying a little bit up, £30 ish for a 6-8” one is about right, and getting ones that are accurate and survive being dropped. Stabila is good.

It’s not going to make much difference to my observing, alignment software can easily cope and allow for it, but it makes me feel better...

Cheers, Magnus

Home Position and Polar Alignment position are two totally separate things:

Polar Alignment position involves rotating the bar until 0 is at the top in the reticule and 6 is at the bottom. You then adjust the alt az adjusters to get Polaris or Octans into the required position.

Home Position is where the scope sits on top, pointing towards the celestial pole, and the counterweight bar points directly down. You achieve that by using a spirit level on the bar so that it's horizontal, then  using the scale to rotate it exactly 90 degrees.

Once you've set them both to the accuracy you desire, it's worth marking them with, say, coloured tape.

Cheers, M

There are 2 main types of mount, AZ and EQ. For a beginner, AZ is the most intuitive, it’s what terrestrial photographers call “pan/tilt” - you rotate side to side and up and down to point. To track things in the sky as the earth rotates, both axes need to be changing: a bit sideways and a bit up or down.

The other sort is EQ, which can be imagined as the same as AZ, except the whole thing is tilted so the side-to-side axis is tilted towards the North or South pole. This means that once you’ve pointed the scope at a celestial object, only the (tilted) side-to-side axis needs to be moving to match the earth’s rotation. The other one stays locked. There are other considerations (eg “field rotation”) but they only really affect things if you’re talking very long-exposure photos.

The process of pointing the axis towards the pole is called “polar alignment”.

Your mount is an AZ mount, which the goto controller recognizes, and which means it doesn’t offer it as an option since it’s not relevant.

OK more than 50 words but I did my best.

The Gagarin one fits the bill length-wise, but tonight I’ve gone for Cassini

... my wife is away until Sunday, what Astro/NASA/TelescopeEngineering YouTube should I watch tonight? Or future nights?

suggestions please...

... in the meantime this arrived today. 16” extension pier to go between my Uni tripod and eq3-5m and/or skytee2. It weighs nearly 6kg!

On 31/08/2019 at 17:06, johninderby said:

Things for collimating the new Bresser dob. 👍🏻

... precisely this is currently top of my shopping list. I’m not sure how long I’m going to be able to hold out...