Dave-P

8 hours ago, 900SL said:

Oh, and whilst I am on, why don't retailers include clear dimensions with things like adapters and plates and brackets?

The number of times I've cancelled a prospective order because there is no drawing showing bolt holes and setting out dimensions is legion. How can I tell if it will suit my current arrangements?

Fully agree, the lack of dimensions on a lot of these expensive CNC-milled objects is criminal. Think I've found a TS Optics plate that will do the business (and has dimensions for bolt holes). Just need to double check that my telrad base will fit between the rings on it. Currently only seeing the long version of the the WO Vixen plate, which would cause dew-shield issues. Be a shame to put it straight on the chop-saw to hack it down a bit.

Quick update to this - whilst I was weighing up the pro's and con's of FPL51 Vs FPL53 ,fate intervened and I stumbled across the attached on Astrosellbuy (or is it buysell...).

An Altair 102 F7 EDT APO triplet, picked up for slightly less than a new FPL53 doublet. A credit to it's former keeper. Just rigged up this afternoon, expecting clear skies late April or so...

9 hours ago, Kobayashi Maru said:

Welllll……when I say teeth I mean those we picked up after our farther had beaten us to death the day before for complaining about the lack of stars. Inky blackness….We used to dream of inky blackness! All we had was clouds! And we couldn’t even them due to the death beating of the day before…of course things were tougher back then.

You had a farther? I had to differentiate myself from my siblings by a rudimentary process of cellular division, floundering around in the primordial soup....

1 hour ago, Kobayashi Maru said:

Grinding your own mirror!? Luxury!!! When I was young we had to make our telescopes out of used drinking straws and the bottom of coke bottles which we ground with our teeth! Try telling that to the young ones today and they won’t believe you!

You had teeth? We had to spend months on end spitting gravel at the bottom of coke bottles to try and get a decent figure on them. And that was before they'd invented stars, we'd spend night after night staring into the inky blackness, waiting for the big bang to happen ...

29 minutes ago, Franklin said:

The problem I had with the Ascent 102ED f/11 was, not only a much longer, heavier scope but the supplied rings attached via one bolt each at the center of each ring and at that point the ring is at its thinnest. My worry was that the bolts were only secured to the rings by just a couple of threads and this is why I opted for the wider plate which enabled me to bolt through at the sides where the rings were much thicker, allowing much more length of the bolt for fixing. The scope was absolutely rock solid after this upgrade over the stock plate. The one I used in the picture came from TS Optics but I've seen William Optics supply them as well.

That's exactly what worries me, the rings are so thin, and I'll have to hacksaw the bolts back to avoid scratching the tube, so there may only be 5 or 6mm holding. Think I'll use a dovetail plus 2 bolts to get first light, but I'll order up a wide plate dovetail as a "forever fix" today. Thanks everyone.

I know that, logically, 2 bolts should be fine. Think it's the lack of redundancy in the system that bothers me, if one bolt failed it would rapidly become "not fine". With 4 bolts, one could fail and fineness would still prevail 

11 minutes ago, Franklin said:

I had the same worry when I had the f/11 version of your scope, my solution was to get a Vixen plate with an extra wide top and with that I could secure the rings with two bolts on each side. Expensive but rock solid.

 

Can you remember where you picked that up? Struggling to know what I'm searching for...

28 minutes ago, Kobayashi Maru said:

An old engineer (my father) tells me a 1/4 inch bolt will hold about 1 tonne in tension. While there will be a little shear force in your setup I suspect you should be good.

It's not the bolts that worry me, more the fact that they're only going 7 or 8mm into soft aluminium

Thanks!

Welcome Bogmonster!

Is it true that Irish Astronomers use two finderscopes on their telescopes?

To be sure, to be sure...

Sorry....

Hello, just picked up a 2nd hand Altair 102mm f7 refractor with the CNC tube rings that are quite common on these. Looking to attach to Vixen dovetail, but the only way this would seem to work would be a single M6 bolt on each tube ring through the dovetail (rings can take 5 M6 bolts each, but spacing not helpful). Is 2 M6 bolts enough, or should I be looking at some sort of plate between rings and dovetail? Thanks.

2 hours ago, mikeDnight said:

Am I missing something with the vote questions John? Q) I often/always use go-to or push to.

Q) I do not use go-to / push to. 

I'm not sure if that answers how many do and how many don't use one or the other. If the latter question is ticked, doesn't it imply the scope doesn't move at all? Surely one or the other must be used, even when dialling in coordinates using setting circles? 

 

John should have included an "I am a pedant" option 😀

Purely manual at the moment, still quite newly into the hobby (visual only). Learning the relationship between the constellations and the objects is at least half the fun at the moment.Think I'm learning a lot more through star-hopping and paper atlases than I would via goto. I will use Starmap on my phone very occasionally if I get totally confused. Using 7x50 binoculars to get the hang of new "routes" before using the scope. I find that I'm starting to pick out some fainter objects with the naked eye now (beehive cluster, double cluster, etc) just because I've learned where they sit in relation to brighter stars. Think I've still got a few years to go building up a decent working knowledge of the northern skies.

Although I can see the obvious benefits of goto for people tracking down faint galaxies with massive focal length scopes, or astrophotographers who are impatient to gather as many hours of data as they can.

1 hour ago, AstroMuni said:

Try looking for any 130mm reflector rather than SW130pds specifically. Its not going to be exactly cheap ! but you should get them in the £25 range. Cheapest will be to build your own using a sheet of plastic along the lines of a Bahtinov mask.

I have been searching for generic items but the market seems fairly bare. Strange for a hobby where utterly niche accessories are the norm...

35 minutes ago, markse68 said:

what diameter is the tube?

 

Inner diameter measures at 150mm, outer at 165

Hello, does anyone know how/where to source a replacement dust cap/end cap for a reflector, specifically a Skywatcher 130p-ds? Not finding much online, would rather not build something. Thanks.

I currently wear bifocals (not a fan of varifocals, to me they  seem designed to make your eyes lazy, the middle prescription just made me feel mildly drunk), so I've got to be careful to keep the lower pane out of the way when approaching the eyepiece. Have fairly heavy brows, so was going to look for a pair of smaller frames with single vision optics where the lens fits closer to the eyeball to maximise eye relief. Guess I need to phone round the local opticians to see if any do specialist glasswear. Have a sinking feeling that they're mainly chains/franchises who do "standard" and various flavours of "thinner". It would be good to find one who was properly into their optics.

Thanks folks.

One for the glasses wearers - just wondering if anyone had any opinions regarding whether thinned (high RI) glasses lenses made seeing easier or worse at the  eyepiece?

Thanks everyone for the input, suspect there are slightly too many responses now to do post by post replies, but thought I'd chime in before we descend into an astronomical version of West Side Story and things get really ugly between the Fracs and the Newts 😀

I'll add a couple of clarifications to my original post, which I didn't mention first time round as I had no idea the discussion would go quite so deep.

- A 4 inch refractor was always the plan. My first telescope was/is a 70mm Celestron Traveller, which I'd never used as much as I should, mainly because the lack of fine adjustment on a photo tripod killed the fun of. So, after a load of research, the end point was always going to be one of the new 4" refractors on a half-decent mount, but rather than blow the cash in a one'r I set out to get a mount first, just to check that fine adjustment was as useful as I'd hope with the traveller before splashing out on the better scope. I was about to pull the trigger on a mount and tripod when the 130 P-DS with mount came up on FB marketplace, and I bit their hand off to get it. So owning a Newtonian was a complete accident, but it seemed decent enough to act as a stop gap for a few months while I got into the hobby. And, yes, fine adjustment proved transformational to my viewing pleasure.

- A couple of other reasons that I want a Refractor (as well as the portability, convenience, etc that others have suggested) - can be used for terrestrial viewing, and doesn't flip things on both axis (just getting into star atlases, and the double reversal of Newtonians is a PITA for me). 

- I wear glasses and have astigmatisms in both eyes, so require LER eyepieces with any telescope. When you factor this in  with the quality/design of eyepieces required to perform well in a fast Newtonian, the range is really limited, and getting pricey. A fast Newtonian can never really be considered to be a remotely cheap scope for someone who wears glasses, assuming they want an eyepiece or two.

-The 130 P-DS is an astrograph first and a visual scope second (it seems that most of the sub f6 Newtonians on the market are also designed to this brief also). I did toy with buying a coma corrector to see if it helped, but my recessive common-sense gene kicked in at this point and said "it wasn't what you wanted, it doesn't perform like you need it to, so move it on". Likewise this also applies to wasting time flocking the interior or any other mini-projects which wouldn't change the fact it was a cheap fast Newtonian, and which would also probably knock money off the resale value (it's a really clean scope, and I want to move it on in original condition).

- I remain unshakeable in my belief that a f7 refractor will be easier on eyepieces than a f5 Newtonian. Even with my "best" eyepiece ( 30mm APM UFF which I got to see what the best the 130P-DS could do would be) I've had the sensation that its focus is on a knife-edge and if my eye strays 1 micron too far forward then it will become flaky. I've done some reading and found others who confirm this effect from fast scopes, especially Newtonians, where the eyepieces are "nervous" or "unhappy" despite making a fair image. Agree that the consensus is that f8 is the point of true "eyepiece unfussiness", but I humbly assert that f7 is a lot closer to f8 than f5 is.

- Yes, appreciate the AZ5 is the weakest of the mid-range alt-az mounts. Recently moved it onto the 1.75 steel tripod after I picked up on on ebay, transformed the stability, It'll do for a year or two, then I can get a Skytee or similar for the tripod and add a slow Newtonian to the setup for DSOs, should I feel the urge (though, on this topic, I'm pretty disappointed there's only one 6" f8 readily available these days, and seemingly no 8"ers above f6. Seems like the manufacturers no longer car about visual observers).

As for the "dangerous ideas" being floated (sheesh...) I'm aware I'm not buying Hubble. But I do like visual quality, and appreciate quality optics in photography e.g. Nikkor vs Hoya/Sigma. Guessing this is the same sort of ballpark as FPL51 vs FPL53

Thanks all, I'll let you know what I go for

cheers,

Dave

2 minutes ago, Stu said:

I think the general consensus remains that if you can afford it without putting yourself at financial risk then go for the fpl-53 scope, the cost difference over years of ownership will be irrelevant but the performance difference noticeable.

I'm fortunate enough that risk of financial ruin isn't a factor. Just performing due diligence to ensure I'm not being "that idiot" who's chasing the most expensive option for no good functional reason.

1 hour ago, Rob said:

All that being said. As always, see if you can try before you buy?. It may help your choice. Look for local Astro meets etc. 

Rob

Not easy up here (Aberdeenshire) no retailers at all, and the local astronomy clubs just seem to do talks. So it'll be a bit of a punt, whatever I do. Though I am picking up from here that:

-Yes, I will notice seriously improved views over the 130 P-DS with either 102, and 

-Yes, there is a noticeable improvement in the FPL53 for visual (concern had been that it would be an "imaging thing")

So, thinking both glass types make worthy scopes and with the FPL53 the only thing I'd regret would be the price.

Hmmmmm.... 

The 2 most readily available seem to be the TS for FPL51 and the Starfield for the FPL53. Both f7

I'm figuring that there won't be a lot in it and that, in a funny sort of way, the 130 p-ds and 102 f7 refractor are essentially the same scope with differing optical systems. The PDS has a big secondary for it's 2" focuser, though it will have just a smidge more aperture. Focal length is practically identical, so eyepieces will work the same, just hoping that the hike in optical quality would be fairly staggering.

 Though, all assumption at this stage.

Hi all, currently looking at getting a lower-end 102mm ED/APO for purely visual use.

Currently using a Skywatcher f5 130P-DS Newtonian, which I got a great deal on used, though I bought mainly for the ccompanying AZ5 mount (whole kit was about the new price of the mount). Actually been really enjoying it as a first proper scope for the last few months, bit finding it doesn't play well with some cheaper eyepieces, so going to move the OTA on. A refractor was always the long-term plan, and I figure that at f7 the 102mm scopes will be a lot easier on the eyepieces.

So I'm aware that most of the current 102mm scopes are closely related, and the two main doublet flavours would be FPL51 ED/semi-APO and FPL53 APO, going for around £600 and £900 respectively. Just wondering if, for purely visual observation, there would be any compelling reason to choose the more expensive glass (apart from knowing it exists). Thinking of things like improved contrast, sharpness, eyepiece compatibility. Figure lower CA is the obvious advantage. It's going to be a long-term purchase as a do-everything scope, though at the moment I'm finding open clusters much more entertaining than the planets.

Any thoughts appreciated.