Kobayashi Maru

3 hours ago, Paz said:

I have both and I would also recommend interstellarium, its easy to use and the field guide is also good.

Can I ask why the preference? My main concern re Unanometria is that it's a book rather than spiral bound so may be difficult to use in the field. I do like its map scale though.

Purchased new telescope when I’m wanting to do a lot of observing…clouds….so many clouds. Get a clear night after weeks of clouds. Set alarm for 2am. Woke up to observe…full moon. 

I assume this is the correct forum?

Looking for a step up from the Cambridge star atlas. Interstellarum or Uranometria all sky?

Both are approximately the same price.....I probably can't go wrong but views would be appreciated. I suppose I should also consider their supporting guides.

Thanks in advance.

46 minutes ago, Peter Drew said:

I don't think there is a lot more to know.  🙂  Mounts can be balanced nicely but still somewhat out of balance with their support pier or tripod.  To be considered isostatic the whole system needs to be in mechanical balance.  A Dobsonian mount satisfies this condition.

Surely something in astronomy cant be as simple as you first expect! I'm going to need a lie down.

14 minutes ago, markse68 said:

I had to look it up. There was a Tuthill isostatic mount that seems to be a forked equatorial but instead of a tripod and wedge it uses longer legs on one side and incorporates the equatorial wedge into its structure. I guess it keeps the c of g central within the 3 legs rather than it being weighted to one side as it would be with a tripod and wedge. Which i guess would make it more stable. @Peter Drew probably knows a lot more

Mark

Yeah I saw that as well. 

Originally I saw the TSS Panther mount referred to as isostatic. https://trackthestars.com/tts-160-panther-telescope-mount/ . Someone on SGL made DIY solution with similar mechanics.

I think some other reversed fork mounts are also referred to as such.

One day Ill get into imaging/EAA....but so many wires!

I already spend way too much time tweaking my scopes...I would have to give up my day job!

...and the size. A 10 inch is a big boy. Mine is a solid tube and pretty awkward to move about. The truss dobs would be easier but have other issues obviously (collimation, light shrouds, set up).

I would reiterate the benefits of tweaking the mount on the cheaper dobs.  Replacing the needle bearings with Teflon pads did wonders for my 10" GSO.

Do these sorts of eyepieces work well (or ok) in F5 scopes?

Out of interest the Actual astronomy podcast (not affiliated) has a resent episode on the history of the 100mm Taks...there are quite a few. Interesting listening as they also go into the history of the company.

Please forgive my ignorance but what is an isostatic mount?

I know what one looks like and I think I understand why they would be well balanced and easily panned...but what makes them isostatic?

- The counterweights ensure even balance in altitude

- The fork would help with torsional forces when panning

Is that it? If that is it wouldn't a T mount with a forked tiller also be isostatic?

1 hour ago, Dave-P said:

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 ...

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.

On 04/03/2023 at 04:28, Franklin said:

These kind of scopes are made to a price, when I started out in the 1980's buying a 4" Apochromat was the stuff of dreams. A decent 4" achromat was over £1k back in those days and a lot of people would build their own telescopes using a mirror kit or even grinding their own mirror. The young newbies of today don't realize how lucky they are.

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!

Thanks for all the replies.

the mythic telescope idea is interesting. I’ve always wondered how much magical thinking there is in astronomy. Is it similar to hifi with their god speaker cables etc.

13 minutes ago, jetstream said:

If I were you Id be seeking a Tak .... your location helps... IMHO.

Yeah. There is also that matter of diminishing returns I suspect

10 hours ago, Paz said:

One thing I notice is that as you allude to they are best when they are complimentary to each other.

I looked at length at 120-130mm refractors as I was aiming for downsizing to just 3 scopes, a 72mm refractor for travel so that had to be small, a 14" reflector for epic sessions, so that had to be epic(!) and being big/heavy didn't matter, and a third scope in between.

I looked at some 120-130mm refractors in the flesh and was worried about their size/weight and that I might need a more serious mount and that setting one up would be in the same league of challenge as the vx14 in which case the vx14 would probably get used and the big refractor would probably not. So I thought longer about the point of a 3rd scope. In the end I decided it had to be a general purpose great grab and go scope, I e. did not have to be small but did have to be fast and flexible and l easy to set up so it filled a gap that didn't compete with the 72mm or 14" and I ended up with a smaller 3rd scope than I initially wanted.

The above is just my own story and everyone would have different choicesabput a good mix of scopes that would work best,  but the thing that helped me was considering scope purpose again in detail and seeing if that helped to solidify a choice.

Regarding your starting point a challenge you have is that a 10" dobsoinian is a great visual scope and so anything else is going to have to have a specific advantage over that to make you motivated to use it once the novelty has worn off.

This seems a good approach to me. I’m in NZ , have fairy good seeing, and I’m not too far away (30mm) from pretty dark sky’s. I have a feeling a 100mm may make to to those dark sky’s more often

9 hours ago, ollypenrice said:

TEC 140. Superbly built, wonderful views, corrected for visual (but a stunning imaging scope with the dedicated flattener.) A really great scope entirely free of Hospital Green and flashy red anodising!  (Yikes, I hope Jeremy doesn't read this...)

lly

A second hand one is/was available on trademe here in NZ. $15k nzd. Ouch

16 hours ago, Mr Spock said:

Completely the opposite  The better the optics, the better the view. Unless all you want is low power wide field.

My question was badly phrased. It’s more around whether a triplet or quadruplet makes a discernible difference. Seems like they may but with diminishing returns?
  

9 hours ago, AlcorAlly said:

I’ve had this mount for a few months now. It's rock solid and very smooth with both my 3 inch refractor and 6 inch reflector.

I tried AZ5 before but was getting quite a bit of wobble with the reflector. With Spica on Innorel RT90C with a center column I'm getting no vibrations even at 150x powers. 

The motions are butter smooth when the mount is well balanced. 

Thanks. Nice to know. Do you use the counterweight with the refractor?

1 hour ago, jetstream said:

It can be... depending on the optics.

The very highly regarded Tak 100mm doublets are excellent visual telescopes, however some other doublets might not fare too well and be subject to sample to sample variation IMHO. Mind you its possible to get a "good one" . Maybe most are good, I dont know.

I do know that when you buy a Tak what I see in mine you will see in yours. My TSA120 is a superb telescope, my SW120ED doublet average. My older 90mm Stellarvue triplet is a vg scope but not in Tak territory contrast wise on the moon and planets.

Its said that refractors by nature are small telescopes, always will be small telescopes, regardless of aperture so it makes sense to buy the best you can afford.

If I had a choice in refractors and could spend on a 120mm triplet or get a 100mm Tak doublet for the same price, Id go for the Tak doublet.

Gerry

Thanks Gerry...that is quite an endorsement of the 100mm Tak. I imagine the TSA is amazing. I may have to start saving my pennies. 

23 minutes ago, jetstream said:

The TSA120 is a nice scope.

A very nice scope. Does it being a triplet help visually? I'm not too concerned about weight, I have the 72ed for that, just wondering if the difference between a doublet and a triplet is apparent?

Just found this thread on page two. Seems pretty close to what I'm doing.

Hi all

I currently have a sw72ed and a 10' dob. seems like a nice complimentary pair. Visual only. Low tech mounts

I'm looking to start searching for my next scope. I have acquisition fever. My immediate reaction is a 5 inch apo/achro or a 6/8" mak/cass but as I'm relatively new to this game I'm not sure what would be a better fit. Anything up to Takahashi prices would work, although I assume that for visual I don't need perfect optics.

Any recommendations would be much appreciated.

49 minutes ago, Dave-P said:

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

The bolts would still have to pull through 7-8mm of aluminium. Even with the leverage of a long scope that would require a huge amount of force. The scopes tube would deform and collapse well before the bolts pull out. Just did a quick google search. There are calculations you could do but the first result seems close enough. https://www.eng-tips.com/viewthread.cfm?qid=292990

TLDR - 5/16th bolt with 5/8th engagement has a pull out resistance of about 6.8 tonne. The plate itself would fail well before you reach that i imagine.

28 minutes ago, Dave-P said:

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.

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.