Captain Scarlet

I know these don't fit with the usual technical Solar photography for which this section is intended, but I couldn't resist posting these pictures of tonight's incredible sunset. Colours exactly as they appeared to the eye. Handheld, Canon 300 f/2.8L on EOS 7D2 & 6D.

13 minutes ago, merlin100 said:

Is de-ionised water any good for cleaning it?

yes, it's distilled, means final rinse-over won't leave any residue

If it’s just dust then leave alone. But if it’s pollen or anything sticky or growing then it likely needs attention. There look to be some splodgy areas on that, maybe mould growth on some spots? I’d at least give it a rinse in warm soapy water to get rid of those.

Cheers Magnus

Not sure the appropriate place for these pics, seeing as Star, Planet and Moon all feature. But all from the same patio twilight this evening...

A Merlin (which I’ve only ever seen once), camping out in the field, and 21.6++ skies at night. What could be better for the soul?

Really enjoyed reading.

Magnus

Very glad to hear it. Expensive accident averted 🙂

See where I’m pointing. Poke an Allen down into them to loosen the grubs. I’ve fitted an adm saddle instead of the stock one but it has the same puck.

1 minute ago, WicklowSkies76 said:

I have a spare, secondary saddle for the AZ mode but don't think they are the same?

no i think the spare doesn't have a puck, it screws onto the bar

first thing I'd do is unscrew those grubs, remove and take a look at the puck. the pics show where they grip on the puck itself

... here we go ...

The rear of the saddle is a round "puck". I can't remember whether the puck is integral to the saddle or bolted to it, I THINK it's integral. That round puck fits into a round recess on the mount itself and is held in place by 3 grubscrews. It sounds as though these grubscrews might be loose. If so, do not put a scope anywhere near it until all is secure, 1/2 inch movement sounds like a lot...

7 minutes ago, John said:

The manual is not really clear...

It seems that these days many scope manufacturers have a universal online manual. It's called Stargazers Lounge.

incidentally, my "hall of mirrors" from about 2m in front of the scope all looks very concentric, except literally just one "disc" out of the 10 or so, towards the back, that's sticking out a bit. Which tells me that all's not perfect, but doesn't really tell me what it is that's out.

The situation is probably more serious for you as the RC has hyperboloid mirrors as opposed to the spherical (I think) ones for my Mak - spherical much more forgiving.

🙂 No, lower slopes of Mt Gabriel to the right (East) and Mizen Head just off the left hand side. We’re almost as far as it’s possible to get into the Atlantic!

I've decamped to SW Ireland to work from home for at least a couple of months. No neighbours for 250m and no anticipated social contact for 2 weeks. 3 cats and one wife for human contact.

Night one after arriving, suitably shattered after a 12 hour car-ferry-car journey and I'm greeted by a lovely clearish night.

SQM-L 21.65 at 9:30, not too bad with a bit of wispy cloud around. I had my beloved Nikon 12x50 SE bins, but mostly having been in SW London for the last few months it's the naked eye that overwhelms me.

@Ships and Stars's Auriga's Ladder an easy naked eye feature. Beehive Cluster easy naked eye with no dark-adaptation. The whole of Ursa Minor. Venus' phase obvious through the bins, resting against a wall. Funnily enough Ally's Braid, which I call B-2 bomber, not so stand-out through the bins as I've seen it before, perhaps it had a bit of cloud in front of it.

Anyway, enough to whet my appetite to keep me interested for weeks of isolation and pretending a dining room chair is an office chair...

M

PS at least my view from the office is an improvement

I am in the middle of precisely the same situation, not with an RC but with a 6" Intes Mak which I completely dis-assembled, and am in the process of recollimating. It's the same situation as yours because with this Mak, both primary and secondary are adjustable, just like an RC.

I took 3 steps:

1. lined up the focuser axis to the primary axis, a la kitchen table collimation,

2. pointed the primary directly at the centre of the secondary (I also used a Glatter)

3. adjusted the secondary to "symmetricize" the reflection of the laser onto the primary, in my case getting the reflected dot back onto the laser source

Out looking at Polaris, I got EXACTLY the squashed diffraction star-test shape you showed, and I re-collimated the secondary until I got nice concentric rings, just like you. At that point, the actual view of the stars through an eyepiece was lovely, refractor-like.

But when I got inside, and put the laser back in to the focuser, it was clearly NOT pointing directly at the centre of the secondary, the reflected spot from Glatter laser to secondary was hitting the face-plate of the laser a good few millimetres out. But the actual star views in this configuration were nice. Clearly though they could be better.

This is where I am at the moment. My working theory is this:

step 2 above is quite crude, and very likely quite a bit out as you're only judging the primary centering to the centre spot at a very short distance.

What I think is happening is the primary is out, and after adjusting the secindary to the symmetrical star test, the primary is being very beautifuly compensated by a particular orientation of the secondary.

this is precisely where I am too.

My solution (which I heven't done yet but this is my plan):

Inside, put the Glatter in to the focuser, and note the orientation of its misdirected reflection back on to the facing-plate of the laser. Adjust the primary to bring it back, not all the way, but maybe 2/3 the way (because the secondary is "higher power"). Adjust the secondary to complete the centering.

Go back out into the field and get the symmetrical star-test back using just the secondary.

Repeat the last 2 steps until you've completely homed in to perfection.

Maybe we can both do this and compare notes...

If you're patient, read my account here, the latest post on the 2nd page shows where I am with this, thinking at the time of writing I'd cracked it, but not quite...

Cheers, Magnus

P.S. my Glatter is dead on, I tested it over 26 metres...

3 minutes ago, Ships and Stars said:

... I'm afraid to try either of the Delos/Pentax XW line now in case I ...

I was going to keep out of this, being a Delos man myself, but oops too late I couldn’t resist!

Having once again "indoor-collimated" using my new technique, Monday night was just too temptingly clear to resist using Polaris to try to fine-tune, in spite of being a School Night. I'm now WFH anyway for the foreseeable future, so an extra hour in the morning would compensate.

Using the indoor-collimated setup, stars were, as expected, more or less points (unlike my horrid smear from a week or so ago), but nonethelss even at 43x wide-field obviously highly aberrated diffracted-comet-shaped horrors. Confirmation that indoor collimation is really a very rough starting point.

The high-magnfication defocused diffraction ring for Polaris was, at 250x, a bright outer nearly-circle with a bright point and squashed rings bottom left. I worked out which of the three secondary collimation screws was appropriate for that position, and adjusted it a small amount in a random direction. The pattern seemed to get worse and it certainly was worse when I had a look at best focus. So I'd adjusted the wrong way. At least now I knew which way I needed to go.

After a very slow process of adjusting screws, re-locating and centering Polaris as it moved away due to the adjustments, sometimes out of field in which case I had to change "down" eyepiece to find it again and change magnifcation back up, I finally managed the spot into more or less centre of the now-circular rings. By now the direction of the much-reduced aberration was slightly different so I switched collimation screws, and suddenly, bang, I found myself looking at textbook defocused diffraction rings, or something very close.

With not a little trepidation, I moved the focus-knob to actual focus, and my goodness! Nice Airy disc around Polaris, and symmetrical.

I changed from 250x back to my Panoptic 35mm to get a wide-field 43x, and suddenly I seemed to be looking through a high-quality refractor, lovely sweet pinpoint stars everywhere, lots of different star colours, it reminded me of the view I'd had through @Stu's Tak a while ago. It was after 11pm by now, I needed to look at something definite before I went to bed so I eventually found Castor (no finder so was hunting around a bit) and beautifully evident pair even at 43x.

I went to bed well pleased I'd finally got this little Intes performing. I don't really count this as First Light, so I'll round off before long with a First Light and some pics of its restored state.

Somehow I’ve managed to accumulate 3 Maks, 2 SWs and an old 150mm Intes, so you could say I’m “into” them.

I am seriously envious of that monster. How much does it weigh?

M

52 minutes ago, stuy said:

Hows the collimation going ?? 😀

Having satisfied myself the primary is collimated properly, I worked out another way of achieving first-order collimation of the secondary indoors, without looking at difficult-to-compare concentric circles on a target through a collimation cap, or via the hall-of-mirrors from the front of the scope, which I have found to be a very rough guide. Rather, if I put a laser in the focuser eyepiece, and look through the front of the scope, I can see the reflection of the facing-plate of the laser, reflected in the secondary and the primary. Which means I can see both the laser source and its returning dot reflected off the secondary. I just need to adjust the secondary until that dot coincides with the source. I did that, and now await a clear night for some real stars. Or the delivery of my tactical high-intensity torch to shine at a ball-bearing.

Tonight is clear, tomorrow I'm WFH, so I'll have a go tonight...

Cheers, Magnus

15 minutes ago, lnlarxg said:

Phewww least you saved the secondary!

Yes probably a bit difficult to replace! Phew is right.

I decided to re-test the primary-mirror axis and Baffle/focus-tube collimation with the external focuser attached, as the external focuser likely has its own axis. Sure enough, it was slightly off (the laser in the focuser pointed at a point 2-3mm different from my artificial star and its coincident reflection from the primary). I shimmed the meeting-face of the Revelation focuser on its rotatable dovetail-ring, and established that there is one position where all three dots coincide. I set it there, and locked it down.

To do that, though, I had to remove again the secondary-mirror boss to create a hole for the laser to get through. In the process of doing that, THE SECONDARY MIRROR FELL OFF!!! Wow. As the picture shows, the glue was very old with almost no "stick" left. I'm glad it did, as it would otherwise likely have happened at night in the cold while the scope was pointed up. And would therefore have landed on the primary.

I also removed the not-especially useful central pin the the middle of the secondary front-plate, and will keep it removed to allow a permanent hole for a laser to be able to shine through. I'll keep it covered with some sort of plug or tape though.

I re-glued the secondary to its plate, and it's now curing:

I had planned to start fine-collimating the scope today with an artificial star at the bottom of my garden, but this episode put paid to that.

17 minutes ago, Stu said:

... i found it very awkward to get my eye behind it next to the eyepiece, so I switched it round ...

I just tried that and it doesn’t seem to work, something’s wrong...

9 hours ago, DaveS said:

Under really dark skies the milky way can (Supposedly) significantly lower the SQI.

I can attest to this. My place in SW Ireland is nominally 21.8, I measured 22.02 last Easter one night, but with the MW overhead it’s easily a whole magnitude brighter.