DaveL59

thinking a bit more on this, you might be able to determine which side to best adjust by alternately closing one eye and see which side seems the most offset (or keep both eyes open and cover/uncover one objective at a time)

hi Richard

Porro designs I've worked on don't all have prism tilt screws, some use small shims under one side of the prism to achieve tilt, tho these are not adjustable without dismantling. Al have a metal strap to secure the prism and some cemented also. Cemented prisms do mean you can't easily tilt them to adjust but that's not to say that the prisms weren't shimmed to the required tilt and then cemented so they can't easily move. The other method is to have the prisms set into place and correctly aligned to each other and mount the objectives in an eccentric ring, so you adjust alignment by rotating the ring which alters the image position at the eyepiece.

As Peter says, if you can unscrew one objective barrel a little you may find the image diverges/converges to suit your optical requirement. If that's the case then the objective lenses may well be eccentrically mounted and that'd be where you would adjust collimation. Only thing then is if you've had to unscrew more than a tiny amount the barrel can tilt a little in use, or work looser, neither of which would help the image stay "true" to your adjustment over time or even during use.

If the body is fully rubber coated then unscrewing the barrel would mean cutting/removing the armour and reducing any resistance to future moisture ingress. If that's the case take a close look at the objective end. Usually there's a beauty ring, or you'd peel the rubber coating away a little to reveal the lens retaining ring, below that would be the eccentric rings. Ideally you need a lens spanner to be able to slacken and remove the retainer without risking damage to the lens though, 2 small screwdrivers can work but one slip and... Adjusting eccentrics can be time consuming, working out which way to turn and the effect on the image, not losing position when tightening the retaining ring up etc, but can be done if patient.

I'd suggest only work on one side initially and see how that goes. Do you know which eye of now slightly offset, or is the condition affecting both?  Just thinking if it might be best to start with the one that you know is offset and adjust that side of the bino first. If both then adjust for your less dominant eye, perhaps? This is just a guess tho, ideally you don't want to offset the alignment on one by very much so you may end up having to make a smaller adjust on each objective to get a better balanced image for you. 

Worth noting also, these would then be specific you your needs, nobody else would be able to use them without getting the effect you currently do and eyestrain/headaches.

could be, but wasn't going to take any chances, not knowing what if any regulation there is in the pack itself  

I bought a LiPo car jump start unit, came with a car ciggy socket outlet too, was Yaber 20000mAh unit. Only BUT was I measured the output before hooking up and it was 16v, my SynScan upgrade manual says 15v max. So I added a 12v buck converter in-line from the ciggy socket to a 2.1mm plug to go direct to the mount and that gives a steady 12v to feed the GoTo. Not really had the chance to use it out under the stars, but spend a while testing and familiarising myself with the operation of the controller/mount, so had it powered and sweeping to targets for a good 45 mins and it hardly drained the battery pack at all.

Nice and light and compact compared to a lead battery unit, some advertise they're perfect for telescopes but I'd check the fully charged output before hooking up...

ahhh the IR for the CCTV here draws them because of the little bugs that swarm toward them. One of my outdoor cameras has 5 spiders competing for the IR light. Fine in the day but sure messes up the image at night with reflections off the webs and the huge glowing long-legged alien biengs that appear across the image from time to time

looks good, well done! 

now for a star test and see how well it improves the views. As you pass focus either side you should get an airy disc for each star, hopefully they're nice and circular and focus snaps in nice and sharp. Don't fret if still a little out tho, enjoy the scope and the views and revisit later on

3 minutes ago, Anthony1979 said:

I dont seem to get the clips while the cheshire in 

Yeah that can be an issue, a collimation cap might be better for this step if you have one. Is this the case regardless if the focuser is cranked all the way in/out?

you don't want to shift the secondary mirror in/out the tube so just slack the centre screw a tiny bit - like 1/4 turn or so, to allow you to tweak the tilt screws to get the primary fully into view. Better to tighten one and see how the image changes then you can back off one of the others to increase the tilt angle if needed. If the image went in the wrong direction, back that screw off a little and try another one. Work slowly and methodically and just small adjustments on one screw at a time.

You may well end up with the secondary slightly offset from where it started but right now you need the primary fully showing in the eyepiece so you know the secondary is reflecting all the light the primary is collecting

ok, first you needed to adjust the secondary tilt to get the primary fully centred to the secondary - as in the full primary mirror and edge clips evenly in view. After that you adjust the primary tilt. You're aiming to tease the secondary just a little when looking into the eyepiece to get the primary fully in view, so small undo on one screw and tighten on another till you get the tilt where it needs to be.

From the image it looks like the secondary isn't getting a full image of the primary so while you've centred the dohnut marker the mirrors are still out of alignment.

It can be a painful process, I know. Tho saying that, nothing like shimming prisms in a binocular to get that aligned, each step was dismantle, try making another slightly thicker/thinner, reassemble and retest... took me something like 5-6 hours on that pair. You certainly learn patience, the value of a gentle/light touch and v fine movements and just when you feel like giving up you hit the right setting and suddenly it feels great to have beaten it.

Maybe take a break for a bit? At least once its done you'll only really have to tweak the primary occasionally and the secondary rarely once you've got it sorted  

looks pretty centred and circular

best take a break if its getting frustrating, that path can lead to over adjusting and more frustration. Then when you restart, find a couple bits of coloured card/paper so you can blank off the primary (insert it partway into the tube below the secondary) and behind the secondary so its easier to see its shape. Then get the secondary central under the focuser as a first step and concentrate on the effect of the 3 tilt screws. You may have to shift it up/down the tube using the central lock screw and then adjust the tilt screws to get it true. The gently nip up the lock screw to secure it in place.

Once the secondary is central remove the cards and get the secondary aligned to the primary with small tweaks on the tilt screws, you should be able to see the 3 clips on the primary carrier evenly spaced, ignore the shadow of the focuser tube. Lightly nip the lock screw up to secure that position and then you can look to adjust the primary. Undo the lock screws just a little and then observe the movement in the eyepiece as you turn each of the primary adjusters, you're now aiming to get things aligned to the centre spot. you may well have to go back and tweak the secondary slightly again just a little. Once done, nip up all the lock screws and recheck, repeat etc.

Can take a bit of effort and a LOT of patience but once done you should get nice sharp focus across the FoV, only way to know for sure will be a test on the stars, you may still find a small tweak is needed. That said tho, don't fret about it, enjoy the views for now and look to sort it laterwhen the patience quota has restored a bit 😉

So the springs arrived today and now installed in the mirror cell. They're quite stiff but not compressing them much since they are around the length needed to allow the mirror to float on them while adjusting collimation, which only needs a mm or two movement at each fixing point. Once the locking set screws are tightened the mirror doesn't seem to move at all so should be fine when handling or moving the scope about. Note that the springs fit into a recess on the end plate so some of the 40mm length is lost so you'll only really get a lift in the range of 28-32mm but that seems in the right zone to achieve focus.

Here's the completed assembly with the bits listed in prev post.

just watched it, amazing how things developed over the last 700+ years into what we have now and the work Hubble and others did to build the library of knowledge available to us today.

I'd agree, the synscan upgrade fitted to my EQ5 doesn't have clutches, so while you can release the axles and swing the scope around to be generally pointing where you want, fine motion adjust would have to be via the hand controller to drive the motors. Then you've lost alignment and the scope park/home position, GoTo wouldn't be useful again until you redo the star alignment. No idea if it'll R/A track if you use it that way, not tried it myself.

I'm pretty new to telescopes myself but somehow seem to have collected a few in a short space of time! To me the dob just doesn't seem user friendly (yeah others will disagree) but bumping the tube to shift your view seems too crude and inaccurate compared to slow-mo screws on the EQ mounts. For a beginner I can imagine it being very frustrating trying to make tiny adjustments until you get a feel for just how to... To me a decent EQ or AltAZ seems a much nicer engineering solution, tho for sure you get more aperture/£ going the dob route. Catch-22 tho as if it ain't working for you, interest rapidly wanes and you give up altogether, just my 2 cents 🙂

The only dob-ish scope I have is the tiny NatGeo 76/350 so not a fair comparison, I know. To make very small movements is fraught with overshoots and irritation I find. Had originally got that as maybe something the grandaughter could use for looking at the moon etc, being so compact but am not so sure having played with it. Now think the Tal-M would be a better bet for her when I make it able to use just one pier tube to get the OTA down to her height  

I've a Skywatcher 130 Newt on EQ2 mount, reasonably light to move but being a long tube still awkward to carry out to the garden in one go, usually take the OTA off and do that in 2 moves. Once roughly N aligned its easy to follow objects with the slow-mo controls and reasonably smooth, does have the RA motor unit too when I want to use it. Being lazy I rough align to N with a compass which seems to work ok for visual. 

The Tal-M and Tal-1 newts are heavier but easier to lift and shift being pier rather than tripod mounted and again the slow-mo controls make fine shifts easy. For the Tal100RS refractor on EQ5 I've upgraded that with a SynScan goto dual motor GoTo. Wanted to be able to motorise RA to give relaxed viewing and maybe try some imaging later on, but landed on an EQ5 with synscan upgrade and tripod for a nice price so bought it. Had to transfer the motor drives to the EQ5 that came with the Tal as the one it was fitted to sticks in a couple places, but now it runs slick and smooth. Sadly not had a chance to use it under the stars yet, what with weather, poor skies, work and family stuff but I have tested it and done some learning in daylight, so think I should be ok. Being techy I guess too that I'd gravitate to this type of toy   Alignment shouldn't take much more than a few mins from what testing I've done so far.

As with most things new, patience is key as things can take a while to learn with frustration and setbacks along the way. I spent a year overhauling binoculars so when I started getting telescopes I was already comfortable with dismantling optics and collimating (much easier that aligning 2 sets of optics). All my gear has been sourced S/H via the bay and while some could do with some restoration (paint and mechanicals, not optics/mirrors) I feel I've bought reasonably well and end result is a selection of very useful gear that I'll enjoy using and restoring. 

In the end the real choice is yours, either try to overcome the frustration and learn how to use the dob, perhaps practise in daylight on distant targets and learn the touch needed to nudge it, or if poss try to meet up with someone who has a GoTo and can show and maybe let you try it so you know if it works for you, before spending a wedge only to find that it isn't. Are you OK finding your way around the skies with binoculars? That may be a low-cost way to learn how to navigate if you've not already tried it. I'd say if you do opt for a GoTo, do the same as I have, play with it in daylight when you can see what you're doing, learn how to do the 1/2/3-star alignment routine and select targets, park the scope in the home position etc. That'll save lots of frustration when you actually want to be using it in the dark and maybe reduce your setup time aligning it to just a few mins.

HTH

1 hour ago, Carbon Brush said:

If weight is important and you have funds, and you want a solution that works safely out of the box, use a Tracer power pack.

If you want to save money then a lithium battery car jump start can be good. You need to arrange your own (low cost) fusing and connectors. If you have the skills this is a very affordable method.

Lithium is typically 1/3 the power to weight ratio of lead acid and has good current delivery for power hungry dew bands.

Hope this helps, David.

Be sure to check the output voltage if you opt for the LiPo car jumpstart type packs, the one I recently bought was 16v which is a bit high for the SynScan on my EQ5. Easily solved with a suitable buck converter between the pack and the scope tho and hopefully will be a good easily portable solution at low cost. I've no dew heaters (yet) so can't say how these would affect runtimes. I'd posted about this one on another thread here.

Alternatively, if you can stretch then a LiFePo battery would give good capacity options at much lighter/smaller size than equiv lead batteries, in theory can be a direct drop-in replacement in some UPS. you can go lower mAH on these than for lead as they run more consistently with less volt drop as they drain, so 10Ah LiFePo vs 17Ah for lead, say.

Car batteries, well just don't drain them much below 50% charge if you want them to last, and keep it charged or again life will shorten. Lead batteries do need more "maintenance" in this regard vs other types.

have been thinking to try this with my Fuji S100FS bridge, is only 14x (400mm) tho. Was considering fixing it to the skywatcher 130 EQ2 with the RA drive to allow longer exposures but not got around to it yet given the fiddling about I've been doing with other scopes. Guess the EQ5 with synscan might work better if I could mount it on the back of the 100RS somehow...

thought I'd update. Ordered 60mm allen head bolts and 40mm setscrews to lift the mirror a bit more and also some longer springs with 1.5mm wire. Sadly the springs are way too stiff, well IMHO as I'd not want to overstress the threaded holes in the mirror carrier so I've ordered up some 40mmx8mm OD x 1.2mm wire ones which will be fitted when they arrive. The bolts are only threaded at the far end and when screwed all the way give a mirror lift of approx 30-31mm. Handy as that's around the sweet spot for the distance to lift I believe. The 40mm setscrews ideally could've been 5mm longer but I didn't find that length when ordering, they seem to do the job fine tho.

Parts ordered:
M4x60mm:
https://www.ebay.co.uk/itm/M4-M5-M6-M8-A2-STAINLESS-STEEL-ALLEN-BOLT-SOCKET-CAP-SCREWS-HEX-HEAD-DIN-912/221307549544?ssPageName=STRK%3AMEBIDX%3AIT&var=520187427009&_trksid=p2057872.m2749.l2649 

M4x40mm
https://www.ebay.co.uk/itm/M4-M5-M6-M8-A2-STAINLESS-STEEL-FLAT-POINT-GRUB-SCREWS-SOCKET-SET-SCREW-DIN-916/232246807222?ssPageName=STRK%3AMEBIDX%3AIT&var=531471400554&_trksid=p2057872.m2749.l2649

Springs:
40mmx8mmOD, 1.2mm wire 
https://www.ebay.co.uk/itm/Compression-Spring-8-20mm-Outer-Dia-10-50mm-Length-Stainless-Steel-Various-Sizes/283335191701?ssPageName=STRK%3AMEBIDX%3AIT&var=584260830435&_trksid=p2057872.m2749.l2649

Rough collimated which is fun when the mirror literally floats about (no springs) but got it reasonably ok for a quick test. Vixen 25mm I was able to focus on some treetops a couple hundred meters away with the rack extended most of the way out. On testing with a Vixen NPL 10mm, focus was a little under halfway raised and was easy to achieve, giving nice views of Saturn just now. Adding a regular 1.25 (tal) 2x Barlow worked fine too, so I feel it was a good result overall.

These particular screws will give the option to lift the mirror further up the tube, tho the setscrews will run out of usefulness if more than a few turns, so not really advisable. If I do need to be able to pull the mirror further back down the tube I can always cut the threaded section a bit longer to suit, luckily I have a tap and die set to do this with, but if you don't then maybe best to find bolts that are threaded on a greater length of the bolt than these ones.

I don't really think stronger springs will make much difference really as their main purpose is to keep the mirror fully raised vs the screw tension while collimating. The setscrews lock the adjustment and the combination of the pair of screws at each adjustment point is what keeps the mirror stable.

Will let you know how I get on with these 40mm springs once they arrive and post a pic of the setup once I've all the bits fitted

so having swapped the tal-M back to original mirror position, I've used the longer screws and springs I'd fitted on the tal-1 mirror cell and rough collimated. Tal-M now comes to focus fine with the tal-1 32mm bore EPs and gave nice views of the moon. The Tal-1 focused fine with regular 1.25 Ep's (tal and vixen) tho I think slightly longer screws might be better but will see how it goes 🙂

Only thing is the tal-1 EP's are very tight going into the tal-M focuser and impossible on its barlow. The tal-M 15mm has a taper at the end and seems slightly narrower bore, so thinks I'll have to mod these to reduce the bore a little and add a chamfer so they fit more easily.

All in a pretty good result I think, as I can leave the tal-M as original and it'll be a handy scope for popping in the car boot and for the grandaughter to look through. I plan to reverse the threaded insert in the pier so it can be used with just the lower section for her 😉

I guess now I know it'll all work the way I hoped it'll be time to strip both down and sort doing a refurb as time allows. Need to sort the finder on the tal-1 too as its focus is loose and rattles, as does the primary mirror I noticed when I had the cell out.

yep seen those, aerial in a can making it v directional and a cheap way to achieve a bit of extra range. There's a fair few wi-max designs too so if the aerial is removable then these might be workable, even better if you can mount outside. Do watch out tho when aiming these at the house, try siting the receiver so the incoming beam isn't directed at living or sleeping space, unless you want to glow in the dark 😉

it's a repeater I think so will broadcast out and looks like it LAN connects back into your router. I'd hope it can have SSID and MAC security enabled to at least improve security if needed. If it does plug back into your router to reach the internet/internal LAN then you can at least control some of that with vLAN and firewall rules, perhaps, depending on the quality of your router that is.

In most regular housing areas I've lived I can "see" quite a number of WiFi and other devices, worrying to think how insecure some of them are too, but that's their issue 😉 Folk really don't seem to think about security much if their new device is plug and play etc, then blame the manufacturer when they get breached because they couldn't be bothered to check things. Same with all these "smart" IoT devices proliferating out there...

An option might be to use a spare WiFi router on the side of the house facing the shed? Or in a window facing that way. wire linked back to local LAN on the internal router and WAN side turned off (unless it has ethernet WAN - cable type). Set it with different SSID's and put it into a suitable housing to protect from weather - problem will be shunting heat tho... A proper AP will cost in the £80-£200 region so better to run the long cable as planned.

Problem with WiFi with extended range is of course going to be that you can't control where the signal goes or who might see it. Can see James with a line of cars parked up in the area all freeloading 😉

another option might be laser link devices tho how they fair in rainy days I can't say, likely expensive tho.

Have you tried high gain aerials on the wifi gear to improve the link, or directional wi-max types, might get you hooked up without having to run cables in?

plus you'd have immunity to any spikes from lightening which you need to put filters in for cabled connections 😉

Downside tho of course, cost and getting pre-made lengths of the fibre to run unless you fancy learning how to DIY all that and chance getting it right.

For my place the shed isn't far so I just ran some cat5s in trunking along the base of the fence, with suppressors each end. The mains in there doesn't look too clever  (previously done before I rented this place) so I didn't even try powerline. Besides which of course my network is segmented with vLAN's and I didn't want my main server/internet etc exposed outside the house itself so this kept it simpler.

I've supressors now on any external cable feed into the house, phone, satellite etc. After storms a year or so back with lots of low sheet lightening etc when my desk phone just died all of a sudden just around a big burst of bright flashes in the sky. I figure a few £ is worth reducing the chance of more major damage in the future 🙂

nope - fibre would be the way to go. Then volt differentials across earth etc ain't a problem 🙂

One office I worked in years ago had to use fibre between the sections and each had its own power feed and earth and regular ethernet just couldn't handle the couple volt differentials

thing with powerline is they work best if you aren't crossing the consumer unit, i.e., both on the same piece of ring/wire. They used to recommend bridging methods if crossing between rings esp in larger houses but not sure if the later MIMO types need that any more. For what is effectively a long-line with potential for loss in both voltage and signal and perhaps potential drop on the earth wire too, might be a struggle to get it to stay in sync or attain stable speed if it does make the link.

Should add too - any electrical noise will knock the signal down to v poor levels and that can be something as simple as an LED lightbulb, cheaper ones tend to be quite noisy and you see drops or speed drop of 50% or more. Motors too (washer etc) if they induce any noise can be a problem as will heavy current draw on the cable.