Skywatcher Mak 127 & EQ3 Questions

[Nomad Z]

Hi All.

I'm a beginner with some questions about the scope and mount that I'm considering buying. Before that, though, a bit about myself and my circumstances...

I live in a flat with no option for back garden observing, so the equipment needs to be transportable by car. I'd rather not have to lug it too far once at the viewing site, but the car is a 4x4, so I can drive up dirt tracks and the like to get away from car parks and light pollution. I'm a mechanical design engineer and tend to appreciate mechanical stuff that is well made and works smoothly. In my line of work, dealing with angles, shapes, sizes, in 3D space is bread and butter. I can navigate using a map and compass. I read somewhere that astronomy is a learning hobby, and I'm fine with that. I have a very good pair of 8x42 binoculars that I use for terrestrial stuff, but haven't used so far for astronomy.

My knowledge of astronomy is fairly limited, although I believe I have a reasonably good understanding of how the night sky changes through time due to rotation, orbits and obliquity of the ecliptic. At a practical level, I took an interest in archaeoastronomy years ago, when I read that an ancient site near me might have been a prehistoric observatory. This led to me spending a long time with a DOS planetarium program, studying the motions of the moon in great detail, through which I discovered the nutation period and that the site in question was aligned to the rising moon's southernmost standstill. This culminated in my observing the rise of the midsummer full moon in 2006, from the site, with the lower edge of the rising moon just above the top of a prominent small hill in the same direction. The attached photo is a grab from the video I shot, and shows the moment when the moon cleared the distant horizon (the dark mound in the middle is the nearby hill, and the horizon is the mid-dark area between that and the moon). I had started investigating this in 1998, so seeing it for real after waiting 8 years was a big moment!

Anyway, I've been feeling that it's time to indulge in some observing with a telescope, just for my own pleasure and curiosity rather than anything akin to research. I've been reading and watching YouTube videos as much as I can, as well as quizzing a colleague who's a keen amateur astronomer. My main interest is observation - I have no particular desire to get into astrophotography at a serious level, but it would be nice to maybe get some photos occasionally. Having initially wondered if DSOs were possible, it would seem that aperture is what makes the difference here, and that a suitable aperture is likely to mean a scope that's larger than I'd be happy to carry around and store. My main interests are the sun (with an objective filter) and moon, primarily Saturn and Jupiter of the other planets, and whatever star clusters and other targets I can get a decent view of. A bit of terrestrial use would be nice as well, but isn't a major thing.

I've read loads on the pros and cons of manual and goto, and have come to the conclusion that I can see reasons for having both. Until recently, I wasn't even aware that goto was a viable option for beginning amateurs, so my initial expectation was that taking up the hobby would entail learning the night sky and doing manual alignment and tracking. I would still like to take that approach, but I would also like to make use of goto and motorised tracking. To an extent, I feel that I can't say which I would prefer (if any) until I try them both.

Having narrowed down the options for a scope and mount, I'm leaning towards a Skywatcher Maksutov 127 and an EQ3 mount. I'm in two minds about the goto aspect - I can either buy the EQ3 Pro with all the bits fitted, or I can get the manual EQ3-2 and the goto upgrade kit. The difference in cost between the two options isn't a factor. What is more important is the ability to convert the mount between purely manual/mechanical and goto. It seems that the fitting and removal of the kit is pretty easy (and should be a breeze for a mechanical engineer). An advantage of the getting the EQ3-2 and goto kit is that I can split the spend by starting with the manual mount and add the kit later (not a big factor, but helps to ease the cashflow, and if it turns out that I really like manual, I have the option of not buying into goto if I don't want to). In terms of budget for the initial outlay, the £650-700 for the above is about the upper limit unless there are serious shortcomings that I'm not aware of. Happy to spend a bit more further down the line on things like eyepieces, but I see the scope and mount as things that are unlikely to be changed. Basically, I'm after good kit that will do the (mostly planetary) job well without spending silly money.

So, some questions about the candidate equipment...

Is this scope a sensible choice for what I want to do (solar system, clusters, brighter objects, general cruising about and learning)?

Am I right in thinking that the mass and moment of inertia of the scope is comfortably within the capacity of the mount? (As a mech eng, I'd rather it was over-engineered a bit - I was put off the cheaper basic goto-only package because it seemed that the mount's capacity was near the limit with the Mak 127.)

If so...

Can the EQ3 Pro be converted to an EQ3-2 with no electronics or button pressing whatsoever? (Does it come with the slow motion cables in the box?)

If I get the EQ3-2, will adding the polar scope make initial alignment much easier and quicker? (It's supplied with the EQ3 Pro.)

In terms of precision, is there any difference between the EQ3-2 & kit and the EQ3 Pro? I'm thinking of things like getting the bits attached such that gear meshing is good. Would either of them have precision issues if the goto bits are removed and refitted?

About the only misgiving I have about the mount is possibly the tripod it comes with. If I want to upgrade this later, what kind of fitting is required? Can I use anything that has a 3/8" screw? (I have a couple of good photo tripods, as well as an old surveyor's tripod converted to a static 3/8" screw.) If it needs a specific fixing, is the steel-tubed tripod for about £100 a significant improvement over the supplied aluminium one?

I'm aware that the supplied eyepieces aren't great, so would expect to upgrade them at some point. How much can the viewing FoV be increased before a wider FoV EP stops making a difference? In other words, is there a maximum EP FoV to suit this scope?

As an OTA or with the EQ3, the scope seems to come with a red dot finder. Is it worth changing this to a finderscope?

I understand that Maks are susceptible to dew. For late evening use in south east Scotland, what would I need to add to counteract this? (The scope would be stored in a fairly cool hall cupboard, in whatever carrying case I decide on.)

Is there anything else I need to consider?

 

[Cornelius Varley]

Hello and welcome to SGL. Personally, I would go for the EQ3 Pro instead of the standard version. The mount doesn't need to be used as a goto mount if required, the star alignment routine can be skipped and used as a basic motorised tracking mount. You will find a motorised tracking mount more useful than using slo-mo cables, walk away from the mount and return and the target will still be centred - you can't do that with manual cables. Also, you will need some form of auto tracking for imaging, you will so feel the need to take photos of what you see in the eyepiece.

[Cosmic Geoff]

It depends what you want to do... There is little crossover between visual and astrophotography kit.

An EQ-3 mount would work, as the Mak weighs only about 3Kg, but if you don't do any astrophotography an alt-az GoTo mount would be significantly cheaper and more portable, but as you say more wobbly. (I bought a used EQ-5 just so I could put my Mak on a more solid mount.) You could get one of the new 'Freedom Find' mounts that can be used as a GoTo or pushed around manually.  The latter may have a higher weight capacity, as they are bundled with 6" Newtonians.

The Celestron 5 SE costs a bit more but seems to come with a better mount and tripod, and maybe the option of an equatorial wedge. 

You will at least need a dew shield (can be home made).

[Alfian]

Can't comment on EQ3-2/Pro question but just to say the Mak127 does go very nicely on the EQ3.

[Nomad Z]

Thanks folks.

I'm aware that tracking has its advantages, but I'd like to experience the fully manual thing in any case. I've seen two indications that the EQ3 Pro kit includes the slow motion cables in the box, although possibly from a few years ago, so I think I'll write to a vendor or two and see if that's currently the case.

I had noticed the freedom find mounts, although wasn't aware that they had that feature. I'd have to say that the WiFi control with a phone puts me off rather a lot. Also, the payload appears to be 5kg, while the EQ3 is 7kg, so still over the scope's mass, but not by as much.

Ian, good to know that the Mak 127 and EQ3 are a good match.

On astrophotography, I do not intend to get into this in any sort of serious way. From what I can gather, it can be very expensive and, while I could deal with it technologically, it simply doesn't interest me enough to go down that route. My primary interest is very much visual and any thoughts of taking photos are more along the lines of holiday snaps than serious photography. What I was thinking of was maybe getting a used Micro 4/3rds body at some point in the future to use for the astro holiday snaps with a tracking mount. No more than that, I'm in no rush to try it, and if it's not practical with the gear I'm considering, then that's fine and doesn't change anything.

Something I forgot to ask about is the size of the EQ3. I've been round countless web pages, and haven't found physical dimensions anywhere. I have a large Peli case that's looking for a purpose, so I'm wondering if I could get the scope and mount into it. If anyone could provide some basic overall dimensions, it would be much appreciated. In particular, the length along the polar axis, the height from the underside of the tripod interface to the dovetail when everything is orthogonal, and if possible the overall width with the goto motors fitted.

The case is a Peli 1600...

https://peliproducts.co.uk/1600-protector-case.html

The scope will fit along the long dimension easily, and along the short dimension if the diagonal is taken off. Both orientations leave plenty of space, but it's hard to say whether there's enough for an EQ3 with or without motors.

 

 

[symmetal]

Hi Nomad Z. I bought an EQ3 Pro a few months ago. It did come with the two slow motion controls in the box.  I can give you the dimensions you asked about tomorrow. It looks like if you remove the motor assemblies then it becomes a normal manual mount though it could be a little fiddly fitting the motors back to get good meshing. The mount is fixed to the tripod by a bolt (M8 I think, I'll check tomorrow) passing through the tripod head from underneath up into the base of the mount so it wouldn't fit onto a photo or your surveyors tripod. The top of the tripod has a recess into which the mount base fits. I don't know how much better the steel tripod is over the aluminium one it came with.

Alan

[Dave In Vermont]

Nomad Z - you are about the most knowledgeable newcomer I've ever seen come in here! Wow! It looks to be you've done more than anyone to know the way you intend to do this. I stand highly impressed, Sir!

I can't help you regards fitting all into a case, or the exact model of the mount. But I can tell you the SW 127mm F/15 Maksutov is the most popular Maksutov on the market - and for very good reasons! These excel at very sharp contrast views. If the rather narrow field-of-view is understood (FOV) - then you've made an excellent choice. And for bringing to different locations, these are known to be good at maintaining collimation (optical-alignment) if bumped around a bit. And it's diminutive size truly belies it being a very powerful telescope.

So I'm sure you'll be very pleased!

Congratulations -

Dave

[symmetal]

Hi again Nomad Z. Here are some pics giving you dimensions info. The bolt screwing up through the tripod head into the mount base is actually M10.

 

As you can see it won't fit your other tripods easily. The post sticking up on the top of the tripod is what the azimuth adjustment bolts push against for polar alignment. Adjustment bolts with black plastic heads are shown at mount base in above photo.

You can see the attachment points for the slow motion cables above. The Dec motor is fixed by the bolt from the top. It looks like you have to remove the two tiny screws holding the cover on the RA motors to get at the motor mounting bolts.

If you need any other info let me know. 

Alan

[Nomad Z]

Many thanks for doing this, Alan. It's looking very promising that the EQ3 Pro will fit into the Peli case, although I'd probably need to position the axes in some way that works best and maximises the remaining space for the related electronics and scope attachments. Using the side view photo with the dimensions inserted into a scale drawing to get an idea, there are some possibilities...

 

 

The pink outline is the periphery of the case, and the dashed yellow line represents 25mm of high density padding. The hinge for the lid is at the top of the images (so shown how it would look if laid flat and opened). Hard to how well things would balance, although the counterweight bar would need to come off, so that and the weights could be used to even things up. The DEC motion would need to be spun round a bit to reduce the 18.8cm dimension - it's too close to the max internal height of 20cm (meaning virtually no padding), but it should be possible to reduce that overall width by maybe 4-5cm.

On the tripod fitting, could it be a 3/8" bolt? An M10 would measure about 9.8mm with callipers, while 3/8" would be about 9.2mm. No matter - it's not a straightforward fit to a normal tripod in any case, although it's not impossible to make a bracket or adapter of some sort that the yoke from the supplied tripod can be attached to.

I got an answer from a vendor regarding the slow motion cables, which said that they aren't included. However, they are pretty cheap, so it's no problem to order them if they really aren't in the box.

I think I'm almost at tipping point with this. My plan at the moment is to order just the scope and mount and get familiar with the operation indoors while I sort out the case. Then I'll get out and have a play with it while I consider what else I might want to order (on top of the slo-mo cables if they aren't there). I've been looking at eyepieces, erecting diagonals, finderscopes, etc, but I think that stuff will wait for a bit.

About the only other things I'd order with the scope and mount would be a star atlas and plansiphere, so suggestions for good ones would be appreciated.

 

Dave, thanks for the kind words. I knew virtually nothing about this stuff until a week or so ago, so it's been a bit of a learning curve. I'm aware that the scope has a max FoV of around 1°, and I think that's an acceptable compromise given what appear to be its strengths. I was wondering why the FoV is limited and was doing some reading last night. From what I can gather, it's related to the AFoV of the eyepieces, and that the longer focal length ones with a wide AFoV only come in 2" mounts, meaning long ones in 1.25" mounts have a narrower AFoV, while the wide shorter ones constrain the possible TFoV because of the increased magnification. In other words, I suspect I'd have to go to a much more expensive and/or larger scope to use 2" mounts, and that's not an option.

[symmetal]

A 3/8" bolt will screw into an M10 nut but it will be a loose fit and can strip the threads if tightened hard. An M10 bolt won't fit an 3/8" nut. I tried an actual M10 bolt and it screws nicely into the mount base so it's definitely M10.

I'm pretty sure you'll get the slow motion controls included with the mount. I ordered mine from FLO and they have them shipped direct from the Skywatcher distributor to your address. It was a sealed Skywatcher box I received and incide was a box containing accessories like screwdrivers, plastic mouldings to hold the Synscan and interface box to the tripod legs and the two slow motion cables.

Alan

[ronin]

Whatever EQ you get then you will realistically need a polar scope, even for visual some polar alignment is required. Remember that it is NOT the scope that is aimed at the rotational axis it is the mount. The mount remains aimed ath the rotational axis whereas the scope can be aimed South.The 2 are unrelated.

Motors and goto are very, very useful and I suggest that if you get the 127 Mak then a goto is almost essential, the relatively narrow FoV is the cause of this. Even with a 30mm eyepiece you may manage to miss whatever object visually and even if the goto misses (fair chance anyway unless good alignment) then at least some will be in view. Do not go thinkin that real astronomers do not use goto, do you know anyone that nudges or uses twiddle cables on Hubble, Gaia or the scope on Hawaii or in Chile. Seriously doubt that you will ever hear anyone shout "Hey Bob, push Keck another tenth of a degree to the left the target is getting close to the edge"

It is the FoV of the scope that is my concern, I own 1 and have used several others and manual locating and tracking with a Mak just leaves me nervous. I recall at a public evening on a non-driven one that it was 2 people looked at the moon, I placed the moon in view and on the edge 2 more looked, I reset the moon, 2 more looked ......... That was a 32mm plossl on a Meade 90mm Mak, so a slightly wider FoV then the 127 will deliver. The amusing aspect was people realising how fast the moon moved, had more comments about that then anything.

If you find the tripod too shaky then you can possibly fit it to an EQ5 tripod or get a pillar mount for it, if you have a workshop available then design and build one. I intend to for myself, the idea being to end up with something that that collapses to a compact state.

Concerning eyepiece and FoV you are to all practical purposes limited to a 32mm plossl, they supply the widest. Owing to the way it all works then 30/32 ploss will deliver the sam as the 40mm plossl and the Starguider 25mm will also produce the same FoV. I say 30/32mm plossl as I am never really sure there is a real difference.

If you search and get lucky there is wider, the Antares W70 25mm should deliver a slightly wider field but they are difficultish to locate now. And one of the US manufactures made a 50mm 1.25" plossl - no idea about these so the result may not be any greater. But always worth a laugh. Search out Parks I think.

 

[Nomad Z]

Cheers Alan - I can live with M10 quite happily (a better option for a custom fitting because a variety of fixings are easier to find in the UK, while 3/8" can get you funny looks from anywhere that isn't a camera shop, and they don't sell loose nuts and bolts).

I ordered the bits today from FLO. They were able to confirm that the polar scope is included although the control cables aren't, while another vendor said the polar scope wasn't, and that the control cables might be. It's coming direct from the distributor, so I'll know soon enough. I got the scope and the EQ3 Pro, and added a 45° erecting prism for terrestrial spotting (I'll try it on a photo tripod that has a 3-way geared head first).

Ronin, yes, I get the basic idea of the EQ mount, where the alt-az bit at the bottom is aligned to place the RA axis parallel to the Earth's rotation, and stays fixed, and that the RA and Dec bits do the aligning of the scope.

My only experience of using a scope manually is getting a look through someone's solar scope, which had the sun in full view with some space around it (FoV maybe 1° to 2° at most). The movement was quite clear, but it wasn't so rapid that I felt I was having to chase it all the time (although it was shortish looks - he brought it into work, and others were getting a look as well). I'm not denying the usefulness of motors. At first, I was considering getting the manual EQ3 and adding the goto upgrade later, but came to the conclusion that tracking and goto are too advantageous, so I'm leaning more towards motorised as being primary, with manual being something to try out.

I'll see how it goes with the tripod before I do anything. The surveyor's tripod I mentioned is a possible candidate for a replacement, and I do have a workshop (with a lathe and milling machine), so there is scope to either make an adapter that takes the top of the ally tripod, or to duplicate that part to allow the mount to be fitted to the surveyor's tripod directly without taking the ally one apart.

I plan to hold back on eyepieces for now - best to get to grips with the ones that come with the scope and see what I think, then find out more. I suspect there will probably be a bit of shopping for accessories at some point, but not until I have some direct experience behind me.

[Geoff Lister]

Do you really need an equatorial mount?

I have the Skywatcher Skymax 127 Mak, with Synscan GOTO (I have 2 of them - see below). The AZ-Alt mount makes for a very portable setup, as you only have to get the tripod's bubble roughly level, and the "Brightest Star" alignment does the rest. If you go for an EQ mount, you will have the 3.8kg of the Mak OTA, plus another 3.8kg of balance weights, and you will have to do a polar alignment each time you set up the tripod. My first "real" telescope was a Celestron Astromaster 130 Newtonian on an EQ mount, and I found it a pain to set up and use. The Skymax is much more user-friendly.

The Skymax mount is supplied with a little satchel, containing a battery holder for 8 AA-size alkaline cells. I replaced this with a 10-cell holder to take the 1.2V NiMH rechargeables, but have found that the most reliable source of portable power, is a pair of 6V 2600mAh NiMH batteries "borrowed" from my radio-controlled model yachts. These will give a comfortable 5+ hours of observing before the voltage drops too far.

The 127 OTA has a long dovetail plate, with a pair of 1/4 - 20 UNC tapped holes close to its balance point. These take the standard photographic tripod clamping screws. On a tripod, the dovetail plate is now at the bottom instead of the side-mounting on the Skymax mount. This is OK as the diagonal rotates to compensate, but the finder scope is lower down on the tripod - not a big problem.

As mentioned earlier, the 127 Mak OTA is very robust. I bought a second setup to take to my holiday home in France. The OTA travelled in hand luggage (the security guys requested it went through the scanner independently of my backpack) and the rest in hold luggage. I have not had to touch the collimation screws.

The glass of local red wine is optional, but certainly improves the observing. The stick-on hook on the front of the mount takes the battery satchel, and ensures that it rotates with the mount. Here, the eyepiece has been replaced by a modified Philips 900 webcam, and I added 32mm holes in the tripod bracing plate, so the eyepieces can be kept in size order.

Geoff

 

[Nomad Z]

I have no idea whether I need an equatorial mount, but that's what I chose. Admittedly, it was driven somewhat by a desire for something more substantial that would also offer me the option to use goto or manual. While manual may end up being the exception, it would seem that an EQ is the better choice for that. The additional setup time isn't really an issue so far as I can see. There'll be a 20-30 minute drive each way and whatever time spent observing, so a few minutes setting up and breaking down isn't much in the overall scheme of things. Plus, I'm an occasional large format landscape photographer, and that's just about all preparation, travelling and setup, for an exposure lasting a fraction of a second. So, I suspect I have the mindset for it.

Anyway, the scope and mount have arrived. I set things up indoors to give it the once-over. It all seems to work insofar as the bits screw together and the motors make the thing slew and track. I'm happy to report that the slo-mo cables were in the box, as well as an odd-shaped bit of metal that turned out to be a bracket for mounting the motor control box. It has a flat plate with a hole at the end, and a round can-shaped bit at the other. It gets screwed to the underside of the tripod head using the main bolt that holds the mount. The motor control box holder is then clipped onto the round can shape (ie, it represents a 1.75" tripod leg). The slo-mo cables can be used as soon as the power is cut - no need to remove the motors (from something that I read, I was under the impression that one of the motions wouldn't allow this, but it's not so). Also in the box was a dovetail - same overall size as the one on the scope, but with only two 1/4" tripod sockets (4 on the scope's dovetail). It's also green anodised aluminium. The handset firmware is version 4.37.xx, which I presume is pretty up to date (I've seen places offering standalone v3 and v4 handsets).

I need to spend some more time with scope balance, but it seemed pretty good with just the lighter weight at the very end of the bar. When I get a chance to try slewing it in more directions to force it to orient in different ways, I'll see how the balance is and adjust if needed.

Haven't looked through the scope yet, but it seems to be a nicely made bit of kit. That changes somewhat with the bits that get added on (red dot, EPs and diagonal). They exude a cheap plasticiness that isn't inspiring. Hopefully, they'll be cheap and cheerful, but I'll see how things go when the opportunity comes along to get out and use them.

The scope came with a lightly padded carry bag, and I elected to use this for now when I realised that he mount and its bits would fit into a largish fishing bag that I wasn't using and forgot I had. It's a fair heft that I wouldn't want to walk a long way with, but it'll be fine for the distances I expect to cover. If I feel these don't protect enough, I can look at the peli case. The tripod seems okay for now - more rigid than I expected, so I'll see how it performs before I start having ideas of cutting up lumps of metal and screwing them to the big surveyor's one.

In other news...

I sorted out a red light torch. Screwfix (in the UK) are doing a little single AA LED torch for 7 quid. It's focusable, and it so happens that the lens in front is held on with a screw-in retaining ring. Undo that, the lens comes out, stick a bit of suitable plastic in there and put it back together. Even comes with a battery.

I picked up one of those self-contained jump starter things from Halfords with the 17Ah battery and two 12V sockets. Fully charged (from almost full) last night, and worked fine today. It'll probably live behind a seat in my Land Rover and can be charged from that as well.

I downloaded the 32-bit Win version of Stellarium and was surprised to find that it runs on an old Win7 netbook computer (2gig RAM, I think). I had expected it to refuse to run when it saw the graphics chipset, but it manages to work at 3fps. I'll need to find one of those USB-to-serial things and have a play.

The Met Office says tomorrow night is clear from about 9pm to midnight, and dry from midday onwards. If that doesn't turn out to a falsehood, I should have a chance to get out and align the polar scope and red dot, have a go at aligning the goto stuff, and hopefully look at some celestial objects. Haven't done anything about dew yet, but I'll see if I've got some stuff that I can use to cobble something together. If not, I'll just have to take my chances.

[symmetal]

Hi Nomad Z.

Glad to hear it's all arrived and you've got it all working OK. I admit I never tried the slow motion cables, assuming the motors would need to be disengaged, but anyway that's a bonus. Also you found out what the metal bracket thingy is for which is more than I did.  I just fixed the control box to a tripod leg with a velcro strap.

The latest Stellarium is more versatile with regards to graphics capabilities, with older versions needing certain versions of OpenGL installed assuming the chipset supported it. If it doesn't find any suitable hardware it will revert to software graphics rendering which is probably what yours is doing as you have a low frame rate.

A foam camping mat cut up and wrapped around the end of the OTA makes a good dew shield, or a piece of cardboard will do at a pinch. 

Let's hope the forecast is correct and you get a chance to try it all out. Good Luck! 

Alan

[Nomad Z]

I hadn't thought of a camping mat. I have an offcut from an exercise mat made of similar stuff (and with a black rippled surface on one side) that's a long strip 8" wide - would that be enough to work? I assume the idea is to get it to extend beyond the objective, so about 7" would be doable.

The forecast turned out to be a double falsehood. I had gone out earlier to check the alignment on the polar scope and red dot in daylight, with the intention of returning home to have something to eat and then head out to the site for around 9pm or so. When I was back home, I checked the forecast again, and it had changed to a one hour period of clear sky from around 9pm. I debated whether to go anyway, but reasoned that I'd struggle to see much until later, and even if I did manage to get the mount lined up on Polaris, I'd be fighting cloudiness almost right away. Didn't seem worth it, so I decided not to go. another forecast check at 11pm showed that it was clear after all, but it was too late by then - would have been well after midnight by the time I'd got there, got set up, and allowed for cooldown, and that's getting rather late for me given time for observing, packing up and getting home again (I get up early - 5:30 to 6am). On check the last 24 hours this morning, it looks like it had been clear all night from 9pm, so I should have headed out anyway.

A bit annoying, but not the end of the world. I wasn't expecting to get much astronomical use of the kit until maybe the end of September when it's getting dark in the late evening. (Would like to get some terrestrial use in, though.)

I played around with the balance a bit, and found that the heavier weight about half way up the bar is better (I used one of those spring weighing scales to pull on the bar near the big locknut in both directions, and tweaked the weight's position until the bar moved with the same pull both ways). When balanced, it takes about 1kg of pull to overcome the inertia and friction - with the small weight at the end, it was a bit less than 1kg in one direction, and more like 1.5kg or so in the other. On the Dec axis, the scope rotated much more easily both ways and the spring thingy wasn't much good, but I managed to judge it by how easily it dropped once moving with a touch of a finger. I marked the positions on the bar and dovetail with a marker pen (may well change with different attachments on the scope, but at least I have reference positions).

I found that the repositioned weight just grazed the plug on the top of the motor control box in the position I was using for that, but moving it around a bit kept it clear. I'm thinking of maybe finding another way to attach the metal bracket - it's a bit of a pain having to completely remove and refit the tripod bolt to get the bracket on and off.

The alignment of the polar scope and red dot were surprisingly good - both got a little tweak, although I'd need to verify with an actual star. Hard to say how close the red dot is because I don't have an EP with a reticule, but it does get pretty close to what I perceive to be the centre of the view through the main scope. I did a bit of terrestrial spotting once I had done the alignments, and was quite impressed. I was able to clearly see cairns on hills nearly 11 miles away. Focussing seemed fine - easy enough to go either side of sharp and then home in. I was quite surprised at the amount of vibration resulting from focussing or touching the EP, but it did seem to settle pretty quickly (didn't time it, but maybe a second or two). I had the scope set up a bit high on the tripod and struggled a little to get a good view down into the 90° diagonal, so it was a bit tricky to look for long without nudging it slightly. I was quite impressed with the contrast given that I was looking through a lot of atmosphere. The 45° prism should arrive in a few days, and I'm looking forward to giving it a try with that. I've yet to try the scope on the photo tripod with the geared head.

 

 

[symmetal]

Hi Nomad Z,

You were unlucky with the weather but at least you got familiar with scope operations. You could use a velcro strap to hold your motor control box to the tripod leg like mine and avoid the counterweight knocking it. It holds it firmly.

For my ETX 125 Mak many years ago, I bought a flexible focus cable similar to this, to reduce the vibration when focusing.

Flexible focus cable

I did a quick search but nothing came up as a source today. As you have a workshop you could make your own. 

Alan

[Geoff Lister]

On ‎27‎/‎08‎/‎2017 at 09:17, Nomad Z said:

I hadn't thought of a camping mat. I have an offcut from an exercise mat made of similar stuff (and with a black rippled surface on one side) that's a long strip 8" wide - would that be enough to work? I assume the idea is to get it to extend beyond the objective, so about 7" would be doable.

That sounds good to me. The 7" is a good compromise between length and rigidity. I made a shield with cloth-covered cardboard, with several coats of PVA glue to improve rigidity. Stick-on Velcro strips hold the shield onto the objective ring. After time, I found that the outer end of the shield was going a bit oval, so I added a circular former, made from the top 1.5" of a thin, black plastic, 7" diameter, flower pot.

[Nomad Z]

Alan, that Velcro strap fitting looks much neater, and I'll very likely go with something like that. I'm finding the current setup with the metal bracket and plastic holder a bit of a faff. I was out with the scope last night and found the focussing wasn't too bad - a bit shaky during focus, but it seems to settle pretty quickly.

Geoff, I ended up making a dew shield using a bit of Sports Direct yoga mat (the 4mm thick black stuff). I put a couple of strips of black gaffer tape on it, and then put self-adhesive Velcro onto that (on the basis that the wider gaffer tape will have better adhesion). The length of Velcro along the seam means I can roll it up tighter for carrying, and also put a little bit of tension on when fitting to help make sure it's sized to get a bit of friction round the tube. It's about a foot long with probably 2" overlap on the tube, so about 10" extension. No flopping was evident and it stayed in place. It seemed to work really well - I had condensation on most bits (especially the eyepieces), but the front object remained clear.

[Geoff Lister]

I have had similar problems when the dew sets in. The shield does a good job in protecting the objective, but it is the eyepieces, and particularly the finder (RDF or finderscope), that suffer from foggy vision. The spare eyepieces can be moved into a covered box, but the finder is more difficult to protect.