Captain Scarlet

Very jealous of you all who’ve seen E & F. I’ve had a few determined goes but no joy. Even when Orion is high, my view is directly over a nearby row of flats, so I’m never going to get undisturbed air in that direction, I think.

A whole selection of variously sized and headed bits of threaded stainless steel, to completely replace all those on my old Intes Mak...

I too am a Mac user, and use Pixinsight, albeit not very intensively. For Lunar images, I find that FFTRegistration in Pixinsight works well, as long as the rotational differences are not too large between images (or between each image and the selected reference image). For example, if I take 100 still images in sequence using an alt-az mount, occasionally re-centreing the Moon in the frame, FFTRegistration works very well. If I hand-hold the camera, where the rotational translations are bigger and more random, I can't get it to work at all: my final "stacked" image is ghosted all over the place. Annoying, as those images are from the Lunar Eclipse a few months ago, I'm not sure what to do with my data. Anyway, back to the point, all the above may well also apply to Solar imaging... Cheers, Magnus

... while I await the arrival of screws bolts etc to reassemble the scope, I though I might make up my collimation kit and do a bit of practise on my Skywatcher Mak 150. I plan to use the technique called "kitchen table collimation". Accordingly, I built myself a target, a square of thin ply, with the target taped to the front, and a 1mm pinhole at its exact centre with a head-torch LED right behind it. To constrain the very bright source to just the pinhole, there are 2 layers of black tape and a layer of Aluminium foil between the middle of the target and the hole in the ply. The idea is that the pinhole source gets reflected back by the primary mirror, and you line everything up by placing the reflection back on top of the centre of the target. This ensures the target is precisely in line with the optical axis of the primary. Then you look through a collimation cap at the back of the scope to see whether all those rings are concentric. Luckily, in this case, it was all spot on. My *Skywatcher* Mak 150 needs no adjustment. A very useful exercise ahead of doing it all from scratch for the Intes. deliberately slightly offset here to show the source and the reflection back onto the target:

I also have an LZOS 105/650, and on it I very recently directly compared a Baader Zeiss prism diagonal with a revelation dielectric mirror diagonal. Not with a binoviewer though, just single eyepiece (TV Delos). I used Venus during late afternoon as the target. The Zeiss prism diagonal showed significant CA, the revelation mirror absolutely none. It was as simple as that. More recent still, on my Intes Mak, f/10 (as opposed to f/6.2 for the LZOS), there was no discernible difference (no detectable CA) between the two diagonals. Both 2”. Cheers, Magnus.

My fixings arrive on Monday, so I'll have to wait until next weekend to start the rebuild. In the meantime, after @dweller25's mention of the dovetail and how it's attached, I had a look. Although the screws are just as old and shoddy-looking as the rest, they are doing a good job securing the dovetail to the main tube. There's a pair of bolt-and-nut arrangements at each end, and a line of screw-in bolts all along the bar, all secured with a longitudinal strip inside the tube. They also double up as internal baffle-ring holders. Similarly the finder fixing arrangements: built like a tank. I think I'll leave all that as is for the time being, though I may upgrade to rings in due course. Photos documenting the same: (actually @Richard136 might be interested in this )

A couple of 3/8” photo bolts to allow me to attach a dovetail to the tripod foot of my 143mm widefield refractor (aka Canon 400mm f/2.8). Hopefully much more stable on my skytee2 than the skinny photo tripods I’ve had to use to date!

Only pluck demonstrated so far! Skills remain to be seen. Fingers crossed! M

I saw that from the CN thread too, and checked mine out once I'd dismantled it, funnily enough I don't think mine is cammed, everything is quite circular. I'll check again but I suspect that arrangement might have been an upgrade from when mine was made...

Good question, I haven't paid any attention to the actual steel tube yet, apart from a bit of bending on the dew-shield. While I await my fixings to arrive, I'll take a look at that. Pop rivets certainly won't do!

I recently acquired an Intes 6” Rumak Maksutov Cassegrain telescope, seduced by rumours of their famed optical quality. The Rumak-Mak differs from the more familiar Gregory-Mak (such as Skywatcher’s) by having a separated and adjustable secondary mirror attached to the front correcting lens, rather than a Gregory’s non-adjustable mirrored spot. This allows more degrees of freedom for the optical designer, and the possibility of correcting a wider range of aberrations. The scope was clearly quite old, but in reasonable shape, in particular the primary mirror and corrector plate which both looked immaculate. It came with a steel screw-on baffled dew shield, somewhat rusty on the inside, which must have been sat on at some stage of its life: it was bent into an oval at the open end. Leaning on it again and a bit of micro-surgery with pliers sorted it out. All the visible screws on the scope were such as would not be used today, a combination of soft worn slot-headed screws and part-rounded-out Philips-heads. Most of the screw-heads in fact, both for collimating and holding things together, had signs of lots of use and wear. I was worried I wouldn’t get enough purchase on some of them if they proved stiff. The focuser comprised a knob on the scope’s back plate, in common with all other SCTs and Maks I’ve seen. However, in use it was horrible: lots of slack, wobbly and clunky. A couple of sessions looking through the scope confirmed that I was going to have to collimate it, even though I did manage to see Mercury’s 50% phase one evening in Feb 2020 through a mask of trees. A Rumak’s adjustable secondary AND primary meant that collimating a scope like this was going to be not dissimilar to collimating a Ritchey-Chretien: difficult, but rather important for best performance. Perfect, because I love technical challenges like this. This scope had obviously had some fairly heavyweight “collimation” done to it in the past, to judge by the worn state of its collimation screws! To collimate either mirror using the six screws for each meant I would need to know exactly how it was put together and what each screw actually did. Were they “adjust-and-lock” or “push-pull”? The only sure way to find out was to take things apart and have a look. The combination of all fixings being tarnished and worn, a focuser in desperate need of servicing and my need to find out how the collimation adjustments worked, meant only one thing: Complete Tear-Down. Genuine Yipee. Tear Down Interestingly, the other thread on CN describing an M603 disassembly, https://www.cloudynights.com/topic/580999-intes-micro-alter-m603-dissection/ , shows that our two scopes, despite having the same designation (Intes M603) have some quite big differences, especially in the focus-knob area! I think mine is significantly older. I couldn’t find any date-marks anywhere when I took it apart, but the rear of the primary mirror did have a hand-written “No. 117”. Hopefully between these two threads, all bases can be covered! My strategy was: - Take everything to bits - Replace all screws, grubs and bolts with new stainless-steel torx or hex fittings - Clean and re-lubricate everything - Reassemble - Re-Collimate Informal Description with Pictures The following steps and pictures paint an informal picture-guide to the tear-down. Later on I’ve assimilated this into a series of more detailed formal steps which will be useful in reverse when it comes to re-assembly. The rear plate was removed from the main tube by unscrewing six slot-headed M4 countersunk screws, all of which moved and came away easily. This revealed a double baffle-tube, a large toothed ring and the primary mirror, all sticking up from the centre of the main rear plate. The inner baffle tube, the longer of the two, was screwed directly into the external flanged “back” at the rear of the scope, which was in turn attached to the actual main rear plate of the scope via three pairs of heavy-duty collimating screws. Fiddling with these six collimation screws therefore changed the orientation of the whole main baffle tube with respect to the main back plate: it was this mechanism that collimates the primary mirror. Some of these screws had obviously been heavily used with much torque! Around the outside of the inner baffle tube sat a shorter outer baffle tube, which had a raised flange 2-3 cms from the rear plate, on which sat the primary mirror. The large toothed ring beneath it allowed the outer baffle tube, and hence the primary mirror, to slide up and down the inner one, driven by the external knob and a little gear plus a threading mechanism. The primary mirror was held onto its flange by two retaining rings sitting atop it, each held in place on the baffle tube by a tiny grubscrew. The retaining ring closest to the mirror had its own flange. The size of the primary mirror can be seen in the picture of me holding a set of micrometer jaws set at 150mm: the scope is specified at 150mm, so the mirror is considerably oversized. Removing the mirror revealed a ring of some sort of contamination around its central hole. It turned out this was greasy dust on top of the mirror, not under the coating thankfully. The mirror off, and the focusing mechanism was revealed: crude but effective, assuming I could get rid of the wonkiness and tooth-slack. The back half of the scope all came apart rather easily and intuitively. Good. Almost everything, barring the mirror, now went into my Ultrasonic Cleaner. Those two whitish plastic brackets were almost black in parts when they went in! Next I removed the front bit from the main tube: the Corrector Plate assembly and Secondary Mirror holder. These six screws were worn-out Philips-head screws, and one was quite difficult to get moving. But the front plate came off easily enough. Disassembling the secondary mirror assembly proved ostensibly simpler but rather more risky. The front plate comprised six collimating (push-pull) screws, three cap-head and three grubs, and a central locating-pin. The three cap-head screws were completely loose, although the heads showed signs of wear! They were so loose I could undo them with my fingernail, and they were the “pull” screws, threaded directly into the secondary holder itself. The three smaller screws, grubscrews, were very tight and quite difficult to remove without damaging the slot-heads. I had to proceed very slowly and carefully. Once all were free, the front plate still wouldn’t slide off. I noticed there were three further tiny pointed grubscrews on the SIDE of the cylinder, holding it in place. Two came out perfectly easily. The third one, however, took ages. The slot-head was far from centred on the top of the grubscrew and I had to be VERY careful not to simply tear the thin part off with my precision screwdriver. But I got there eventually. I have to admit I baulked at removing the Corrector Plate (the big lens on the front) from the scope’s main front ring. It was not designed to be adjusted and looked perfectly good to me. The secondary mirror, once removed, had some similar contamination around the edge to that of the primary, but again I ascertained it was on top of the coating not underneath, and hence easily removable. Also, the central locating-pin was rather rusty. The mirrors and corrector plate went into protective custody, as shown, and the remaining parts now reside in a cardboard box, awaiting my 50-odd miscellaneous new stainless screws, grubs and bolts from accu.co.uk. Formal Description, in Steps: i. Remove the 6 countersunk screws holding the main rear plate to the main tube; ii. Notice the two retaining rings around the baffle tube sitting atop the primary mirror: they are each locked in place with a tiny grubscrew. Loosen these tiny grubscrews and lift the rings off the baffle tube (note that the one next to the mirror itself has a small flange – this sits adjacent to the mirror); iii. Remove primary mirror and set it aside; iv. Main rear plate central hub: unscrew and remove all 6 screws from the back plate (3 large, 3 smaller) – these screws hold the hub to the rear plate and also act as the collimation mechanism; Also notice and remove a single screw on the side of that hub, just next to one of the pairs of holes. This screw screws into the aluminium ring holding the plastic brackets, and effectively locks the non-moving part the baffle-tube focus mechanism; v. Unscrew the silver-metal “back” from the rear central external “hub” – take care, as this is what secures the whole baffle-tube assembly to the rear of the scope. Hold the baffle tube as you unscrew; vi. Remove and set aside the main rear plate, the black “hub” and the white-metal rear securing “back”; vii. The large toothed white-metal disc: the plastic brackets attached to this disc contain a coarse thread which meets a thread all around the outside of the black baffle tube. Unscrew the big disk all the way off the tube; viii. Dismantle the toothed focus-ring by unscrewing the 4 screws securing the whitish plastic brackets to it. The brackets will come away, together with the aluminium disc securing the white brackets. NOTE THE ORIENTATION OF THE SINGLE THREADED HOLE IN THAT ALU RING, IT’S OFF-CENTRE TOWARDS THE BACK END OF THE SCOPE. ix. The inner and outer baffle tubes: notice a single screw, in the pic next to the number “19”. The screw attaches inside to a small brass sliding block which slides up and down a guide channel in the inner baffle, keeping the two tubes aligned as the outer mirror-holding tube slides up and down for focus. Be careful not to drop and lose the small brass notch when you separate the tubes! x. Front of scope: unscrew and remove the six countersunk screws attaching the front plate to the main OTA; xi. Secondary mirror: unscrew and remove all 6 collimation screws from the collimation plate, keeping the front plate upwards to avoid things dropping out; xii. With a long precision screwdriver, loosen the three tiny almost-invisible sideways-pointing grubscrews, which lock the secondary collimation-plate in place. Be careful not to touch the corrector plate while doing this. xiii. Lift out the front plate, to reveal the back of the secondary mirror itself; xiv. Carefully remove the secondary mirror, and escort into protective custody; xv. The End. Re-Assembly and Collimation Watch this space…

Yes very clever. But i’d worry about stripping threads with such torque available. Better designed knobs in the first place would be better, I think. Though I do like those ADM clamps nonetheless. M

After today you’ll increasingly need to use a scope rather than naked eye, as although it’s at max elongation it’s now swinging round towards us and hence rapidly waning, ie getting more and more of a crescent. More difficult to spot to start with but more rewarding if you can find it! Next chance will be June...

Well on reassembly I’m going to get this thing fine-tuned to within a micrometer of its life so then I can hopefully reassure you that it is indeed a superb optical instrument!

... actually on reading around, as it's clear I'm going to have to re-collimate the Primary as well as the secondary (seeing as the Primary is currently in a cupboard in a box on its own!), the six screws at the back (and front) are not strictly "lock and adjust" but "push and pull"...

I’ve just completely dis-assembled the rear half of mine now. And I was wrong, there ARE primary-adjustment screws, and indeed, for the primary at least, the big-headed ones are locking screws, the small ones are grub-screws for adjustment. ive documented and photographed everything as I’ve gone along so I’ll start a separate thread in due course... M

Thanks ... I see that @dweller25 also features on that thread ! I will be going down that tear down route before long I think...

Thanks. No primary collimating holes for my 603. I would also assume @Sunshine’s analysis, but I vaguely recall reading that on some Russian scopes the adjusting screws are the tiny ones and the locking ones the big ones, but I can’t find where I read that!

I recently acquired an Intes M603 Rumak Mak Cass. I used it a couple of days ago to luckily catch Mercury as a half-disc. However, it does appear to need collimating, it has an SCT-style collimatable secondary, being a Rumak. As you can see from the attached pic, there are three pairs of screw-heads plus a central one. Before I resort to trial-and-error, does anyone have experience of these and if so, can tell me what screw does what? @dweller25 perhaps ... I believe you have the M703? Cheers, Magnus

No filter, apart from a tree, but reasonably high magnification, 250x. As it got lower it got mushier and mushier, more atmosphere and more twigs I guess. The half disc was discernible early on, when twilight was still reasonably bright. I guess the fact it was against a bluish sky acted as a filter in its own right. My advice for say tomorrow would be to start as soon as the sun goes down... M

My understandings are: - “fast” or “slow” comes from daylight photography, and I always interpreted it as bigger aperture => “faster” shutter speed and vice versa. Never meant to be anything more than a colloquialism. - f-number is a useful ratio that in most cases can act as a simplified 2-D substitute for the “solid angle” ingredient of Étendue, which is actually solid angle x an area (either pixel area or optical aperture), and which also is a fundamental property of an optical system. - Signal to Noise Ratio is ultimately determined by Étendue x sqrt(exposure) time (I think) of the smallest-etendue portion of the optical train. - for a given aperture and a given object magnification at the eyepiece, a “faster” scope will show exactly the same level of brightness as a slow scope. It is “aperture” that determines object brightness for a given object magnification, not f-ratio. Happy to be corrected... Magnus

Bidding on that auction site need not be stressful at all. You simply and coldly decide well before the auction ends the maximum you’d be prepared to pay, and submit that whole amount, regardless of what level it’s got to, with around 5-10 seconds to go. You either win it or you don’t: it’s simply a test of people’s maximum levels, and the beauty is if you do win, you only pay the next-best person’s amount plus a bit. No self-respecting ebayer ever actually “bids”. cheers (go for it )Magnus

Reverting to OT... I spent some time this afternoon/evening playing with my Intes 6” Mak and its new addition, the Revelation Crayford on the back. I managed to get Mercury through it, finding it at 42x then moving up to 250x, definitely a half disc but I was having to look through a tree at the bottom of my garden so its quality came and went, mostly went. Still, the first time I’ve ever managed to get a scope on that planet so very well pleased! M

I think you shouldn’t have loosened that big nut inside the housing. The little thumbscrew yes, but that loose bolt may now be allowing things to move that are not supposed to. The axes do not have bearings as such, they have bushings, which means they seem a little less smooth in their motions than if they had roller bearings. i have this mount, I really like it, though I am visual not AP. Magnus

What you describe (multicoloured twinkling) is often ascribed to Sirius. Mercury at the moment is mag -1.0, very nearly the same mag as Sirius and very low down too. So yes it could well be in my inexperienced opinion. M