DaveL59

Hi Paul, no my 100RS came with that focuser fitted, as per pic it's held with screws around the collar where it fits over the main tube.

Not having seen one in real life I can't say if the chamfered part would unscrew nor if the thread would match another diagonal body, so something you could try when you get it in your hands maybe. I expect that collar is used in part to pull the diagonal tight and square into the focuser tube and part to allow easy rotation of the diagonal when adjusting for the angle of the scope on an EQ mount. Simply slacken the locking screws a little, turn and re-tighten. No risk the diagonal drops out onto the ground 🙂 I would say tho, do be careful tightening the screws and don't use too much force else you can strip the threads in the metal body. The one that holds the finder on mine I found had part stripped and the finder wouldn't hold securely. I had to drill and re-tap a size up to sort it so I now use nylon thumbscrews to avoid a repeat. For collimating, there you have 2 units to consider as it happens. The OTA itself you would adjust the focuser and/or objective lens so that it is all concentric around the focuser drawtube and the focuser is square vs the objective lenses. The objective lens cell has set screws at the edge that are used to tweak the lens for alignment so shouldn't need any shims. A laser would likely be the most useful for that as the other Dave showed in his fettling thread where he replaced his focuser, but hopefully won't need doing. The other unit is the diagonal and that has small set screws in the back for adjusting the mirror tilt, again no shims needed. I haven't had to adjust either on my 100RS so can't guide but there may be other long-time members here who have and can advise better if you find you need to. Mark is right in that longer thumbscrews could be used to hold a regular 1.25-inch fitting, but that wouldn't overcome the lost 5mm or so that the black outer collar takes up and may also introduce some tilt, but until you try you won't find out for sure. A parfocal ring on the nosepiece might address tilt tho as it'd act similar to that chamfered collar on the TAL diagonal. A prism diagonal may do enough to cover that lost distance, may not. Has me wondering now too, do the TAL metal bodied barlows fit into that focuser collar when inserted into the scope? Then I guess the diagonal into the barlow and away you go?

It's actually Trevor that's asking as he's just bought a 100R, I'm just adding thoughts as I already have the 100RS with 2-inch R&P focuser so no issues, as you said shorter OTA and long focuser drawtube. That flanged design is also on their 100RS 2 to 1.25 inch adaptor as I recall as on that I can ease off the lock screw and rotate the diagonal with no risk it drops out. Clever design, simple engineering solution. Agreed tho, shorten the OTA and refit the focuser then if you need more outward focus use an extension tube to make up for the lost length. Just a case of being able to make it secure, fabricate a flanged collar perhaps to fit onto a regular 1.25-inch barrel. Or perhaps a parfocal ring a couple mm away from the base of the nosepiece to give the locking screws something similar to grip against.

Hope you do manage to find out a bit more about it, does look like a quality piece and if the glass is in good shape you may even find it useful to spy on the birdies in the garden once cleaned up 🙂 It might be worth contacting the science museum tho as their web page says they have 10 meters of shelf holding catalogues etc so you may be able to get a search and copies, not sure if they let you go browse for yourself. Archival material relating to the firm of H.N. Irving & Son, instrument makers | Science Museum Group Collection

ahh I see now, so that tapered collar is for the locking screws to hold it in place when you loosen them to rotate the diagonal I expect. The rest of the nose is likely 1.25-inch (or might even be the russian 32mm std) but of course the collar with the thumbscrews on the focuser tube prevents a regular 1.25-inch unit being inserted far enough and maybe then affects the focus range (lack of in-focus). Makes me wonder tho if that black collar can't be unscrewed from the focuser drawtube? Would give more inward movement but you'd then need to find a way to lock the regular diagonal/eyepiece in place.

as an off-the-wall suggestion tho I've no idea how well it'll perform, you could rent a lens: Tamron (Nikon fit) SP 150-600mm f/5-6.3 Di VC USD G2 to hire at LensesForHire Perhaps we can persuade @JOC or @johnfosteruk to try a couple moon shots to illustrate what you might get that way. Can't comment re your scopes as I don't have any like those or what you'd need to get a camera hung off the back and focused. 🙂 I would suggest you get the lens out and check, renew any silica gel sachets in the case too, just in case. They do like a regular bit of sunlight to keep them healthy... edit: reading into their page, maybe not compatible with your D3300 but if they have the G1 available that might work, so best to ask if it'd suit. Or they also have Sigma versions.

you having issues with the app as well then, mark? Paul on another thread found that manually firing up the camera app before starting the explorer app got him going, hopefully.

any chance you could post a pic of it Doug? I guess the barlow won't then fit direct into the focuser tube either?

Never had a problem using one eye even tho I've used a lot of binoculars for daytime stuff too and 2-eye is preferable to me in those situations. But then if you use a still or video camera a lot you're usually working one-eyed then too. For sure back when I did use an SVHS camera with B&W viewfinder it wasn't fun trying to work with the other eye open and seeing full colour, very disconcerting lol.

Depending on what camera lenses you have to hand you might be able to achieve it that way too. I've managed a few shots using my 100-400AF zoom on the A77ii and also with double-stacked x2 TC's on the back of an old Zeiss f2.8 180mm Sonnar which I guess takes that combo up to 1080mm F11 ish. You do need a good tripod ideally, tho I and also Olly have grabbed shots hand-held. Not sure how they'd blow up to the size you're thinking tho. I've yet to pop the camera on any of my scopes for a shot at the moon so can't give you a comparison against the camera lens combos tho. Plan on doing that but so far opportunity hasn't knocked.

Actually, since its an HP, did you register it for warranty with HP at all? Might be worth contacting them too as they may wish to be helpful since it is just out of warranty. No guarantee of course but ya don't get if ya don't try...

no worries Paul, its worth getting it to work as it is surprisingly good in use. This post may help you locate the log files when you have that enabled: and this post further in the same thread

ahh now that's the almost impossible question to answer really. It's likely pre-70's and does have the makers plate but is incomplete in that there's no original tripod or details of its original mounting (ship etc). It does look very well made and of good quality and reading his obituary that's not surprising at all. Is there any sign of haze or fungus in the glass (fuzzy look when shining a light through it) etc., which could affect its value in terms of optical usefulness. Thing is as with most items it's worth what someone will pay, but if it had historical value and provenance documented that'd set a guide for insurance or auction. It could be worth as little as £50 to over £100 or more depending on those and rarity. Sorry that's not a lot of help, likely its worth more because of the family connection that left it to you than its monetary value.

it may have once had a wooden tripod like this or been screwed down onto a fixed part of a railing or similar. A nice vintage piece if you can determine a bit about it but not so easy if they didn't have any records about it to pass on with it. Not finding any similar pics of yours but seems they were a well regarded maker and were quality items too. Myself I picked up this old black leather and brass vintage scope back in 2020 that the seller said was his dad's and tbh looks maybe home made but it works pretty well and is a nice curio too.

going to be difficult to help much I'd think unless you can maybe give a little more info. What diameter is the front lens and length of the body etc might help but that'll depend on how much info has been collated and placed on public record that we can search. Also when looking through it is the image right way up? I see there's a 3-inch 1975 telescope on pcclick but it looks significantly more recent that your one which has the old single pivot bracket to mount it. Does yours stand on that base or is there a screw thread in the base to attach it to something else? Quite likely/possible it was a spotting type scope or for ships use rather than for astro given the size but that's just a guess.

looks very handy, tho these day's I'm not often using serial devices much compared to when I was in the field and hooking into computer systems and peripherals. Thanks for sharing tho, might come in handy when I next need to use the car diags cables 🙂

might be worth having a chat with this fella and see how he got on with his mod and what focuser he originally had if he's prepared to part with it if its a different one to yours, assuming you've the same length OTA...

I think you can re-install on a device that is registered with no issues, I did that with mine when I heard they'd updated the object database as I hadn't seen it auto-update. It didn't ask for the registration code as it already had that in registry I expect so I doubt it gets counted. Pity there's no option for us to manage our registered devices other than going to Celestron support, something they should maybe have thought to offer. How's the light levels in the area you're trying this out in? If there's lots of stray light that can hit the mirror then that would affect the ability to grab star images. Have you taken a look on the phone files to see if it has anything in the logs or saved images? You enable that in the starsense menu under location tho can't remember where it'd store them. I expect support would want you to do that anyway to see what the app is reporting.

might be worth trying a re-install of the app and see if that makes a difference.

in case you really want to grab a TAL Barlow just seen this on the bay: TAL 2x Barlow lens 1.25" | eBay Can't say the price is fair nor high, certainly quicker and cheaper than importing one 🙂 (and no, its not mine lol)

oh you bad bad man, throwing temptation in his path 😄

Never seen/used a TAL-2M, was tempted to get one once which was boxed but it was too far to travel at the time. 6-inch mirror I believe so more light capture than the 1 so should be better views. The motorised mounts tho may need good checking over as if they have motor issues aren't simple to overhaul (the motor). Not knowing your focuser its hard to say re barlows that would work well with it, I have the one that came with my 100RS that is x3 I think and also the Lanthanum glass x2 which is very good, as below TAL 2x BARLOW lens 1.25” Lanthanum glass/ T ADAPTER | eBay If your TAL-1 has the russian model eyepieces then the x3 barlow on that won't work with the 1.25 inch systems tho you can use 1.25 eyepieces in it for the TAL-1. On other brands, the Orion shorty I've seen recommended but not necessarily for the TAL, then there's the upper price range that I've no experience of.

can seem that way as if a nice Telementor came up at the right price I'd be very tempted to add it to the collection, a good classic older japanese scope too perhaps if it was in its wooden box. Then again the conservatory has too many 3-legged things hanging about out there already...

Can't say for others but when I first went looking I was after a TAL, either the TAL-1 newt or 100 frac. A local TAL-1 was up for sale on the bay but the seller was very non-resposnsive and then it was marked sold days later. Found a NatGeo mini tabletop and while not great it was a tenner so what the heck I thought. It's actually ok after some fettling and a throw/giveaway as far as I'm concerned, sits in its box largely forgotten now. So then I found a SW130 long tube on EQ2 not far from me and got that while still looking for a TAL. It's been nice to use and the RA motor tracks well if a tad wobbly esp if there's a breeze. Then came up a TAL-M in its wooden case so of course I got it, smaller mirror but easy to pick up and head out to the garden and start viewing. Missing the 25mm eyepiece tho which was a drag. Just as I started a new job a TAL100RS came up so off to Coventry went I and returned with a proper scope 😉 While looking for an early TAL 25mm plossl for the M I found a local TAL-1 for sale so bought that just for that one eyepiece. Mad I know and I'd planned on selling it on but found a TAL 1.25 inch focuser so adapted it to modern eyepieces. I prefer this with slightly smaller mirror compared to the SW130 as its just more solid and stable. Then of course starsense explorer equipped scopes came along so I joined the herd and grabbed one, telling myself that it'll get passed on to my daughter/grandkids. It will but I've used it meantime for a few months while they complete moving house (good excuse huh!). Last came a curiosity purchase of a vintage 3-incher just because. For £20 how could I not 😄 Now I'm considering selling the SW130-EQ2 on as it never gets used of late and maybe gift the tiny NatGeo to a charity shop. After all there's only so much in the way of glass lenses someone really needs... (no please don't mention my binos or cameras lol)

Just did a bit of background searching and I expect you'll more find an issue with in-travel reaching focus (or not) with some eyepiece combos but many should work fine. So a case of suck it and see I think then determine what's best to do. However if you plan on putting a camera on the scope then out-travel could be a problem where an extender would work. edit: or are you also thinking for terrestrial use in which case you would need the drawtube to extend further out to achieve focus? For the TAL-M, I love it. Very capable and when left set up in the conservatory is an easy lift and drop to get the entire assembly out into the garden in one go, where I have to dismount the OTA etc on the longer scopes. Well the TAL-1 I can manage in a single lift being its on a pillar rather than tripod. The only issue with the M is you're stuck with the OEM eyepieces as the 1.25's are slightly loose and won't reach focus. You can of course shift the mirror up the tube to get around this but that then makes the in-built finder unusable or you switch back to the OEM eyepieces to sue then switch to 1.25's for main viewing. That said the OEM 25 and 10mm eyepieces are good and with the extension tube and barlow can hit x160 and still give a good image. Finding one that has all the parts is down to some luck I think and many show their working life in damaged paint but they are very solidly made and not hard to overhaul. Mine had the 15mm but no 25mm nor extension tube but I got around that buying an older TAL-1 just for the 25mm and then swapped the TAL-1 focuser for the later 1.25-inch version so the latter can be used with regular eyepieces (after shifting the mirror that is). I also modified the 2-part pillar on the M so that if needed I can run it with a single pillar section to keep the scope lower to the ground, was thinking for my grandaughter when she gets a chance to come out and look. There's also the Alcor which is smaller again and reportedly very good, I think @Stu here has that model.