SiriusB

On 28/08/2020 at 23:33, Don Pensack said:

AgenaAstro.com in the US sells these.  And, they sell to the UK.

However, it wouldn't be cost-effective unless importing a hundred of them.

Can you get them at FLO or RVO?

Good heads up,as a wide selection @ Agena astro....

Every time i'm of a mind to order  &  'blow the expense of shipping to UK' one or more  of the sizes i require ends up out of stock, so not managed it yet.

Can't help feeling there's a gap in the market as yet untapped in UK?

Ok, the item price is low ~but i bet the markup's pretty good!

So,would FLO, or another retailer~ care to take this on??

10mm Baader classic ortho? (50 afov) 'bout £50, Zeiss design lens (though not Zeiss manufactured) according to Baader.

You did say for planetary, so only the centre sharpness,contrast etc etc matters.

Find my circle T orthos sharp very nearly to edge in f5 refractor,even though i think design specs for orthos are >= f6 ?

I have BCO 10mm,  it's not bad at all. IMO,good coatings, I may complete the set!~ though not sharp to edge as it's a 'wide'  ortho.

If you can carry a 6" Newtonian, an 8" would be little more effort or size really IMO.( & worth it.)

   Any Astro shops reasonably local you could visit to check all this out?

Otherwise,if you want truly portable you looking at smaller short tubed instruments.

I Dunno about Astrophotography & Dunno if technologie's moved on~ but back in the days of 35mm film, a zoom lens AND a teleconvertor was a big no no  in terms of picture quality.

Ok ,if it was a case of taking a  shot vs no shot, like if you was a photo journalist running 1600asa or something, but not for quality....& that's what you astroimagers crave isn't it?

Of course, i'm still stuck back in 1980's 😉 or was it 1970's ?😁😁

Many thanks to you both.

I'll invest in a tin of wild thyme then.

I'm sure Hammerite USED to do this colour?,but it seems to have been dropped from the range.

(Yes Hammerite,It's not top of not my prettiest colour list either)😉

Any suggestions ? Or do i need to update it to more of a Synta white?

6 hours ago, John said:

I wonder if it is going to be simpler and lest costly to add some locking screws to the current arrangement ?

Yes, maybe OP can post pic of existing cell & people can pitch in with suggestions?

My recollection of early O.O. newts was the secondary adjustment  was more a  faff than the primary?

A little late to the party~ but I love what you've done Doc.

A very sympathetic renovation & update that looks fabulous.👍

Very impressed, I hope you enjoy using the mount as much as it would appear you've enjoyed breathing new life into it.

(From  another then teenager who wandered round No 63  in the 80's gazing with awe @ the big refractors on the Mk IV)

On 09/08/2020 at 14:21, wookie1965 said:

This is what I have to contend with only its local council so nothing I can do, I did ask for a shield to be put up and they did this is the result so the shield was a waste of space.

Yep,all those LED streetlights they've put up have far more glare than 'good' old sodium lighting. I'm often seen walking the streets after dark in sunglasses these days 😉

I'd suggest it rather depends on the  fl. of your scope(s)

having 1mm increments is not all that useful on 500mm fl, maybe a lot more so on 2000mm?

I've found it helpful having  a wide range of fl's to match the seeing/transparency conditions.

But be warned it can degenerate into spending more time swapping ep's than actual observing!

Usually  over time most people end up with a few ' favourites' though.

I've a rule of thumb, any scope i've owned 2"-12.5" thus far. about 50x mag is ALWAYs handy.

If you're looking for an excuse to buy more ep's~ don't~ just buy. 😁

Can always sell on if not needed.

From what you've described, (astigmatism) it doesn't sound like dirty eyepieces to me

I'd expect dirty EP's to lessen contrast.

FWIW A good few years ago i bought a camera lens that looked like it had seen serious professional use, Nah!,~abuse.

I only bought it because at the time that focal length almost never came up 2nd hand & was NLA new.

The lens was scratched, the lovely multicoating was all but non existent, the focusing sloppy, the camera shop were obviously a bit embarrassed selling it as they insisted on sending for a CLA before i bought.

All that said, i never noticed it took worse pics than my mint or near mint lenses.???

Make of that what you will.

Unfamiliar with the application, but short(in particular) poly timing belts t5,t10 series or whatever really don't need a lot of tension to work correctly.

Too much tension will be a strain on the (small?) motor/worm bearings .

Aim for minimum tension without slipage would be my advice.

I make it around 45-50 seconds,from one side of field to the other!

This is one reason Dob owners like wide angle Eyepieces. 🤑

50 minutes ago, Nair al Saif said:

So  let’s say I use a 50degrees eyepiece and a Barlow plus 10mm.

1200mm focal length.

 

How long would I have until Saturn/anything went out of view?

But you won't be using 240x mag very often in the UK,whatever scope you buy, only on the best nights(maybe!)

On 10/08/2020 at 09:39, JeremyS said:

This was an interesting task @SiriusB - thank you!

I had a go last night with the Tak TSA 120, with eps Lyr almost overhead. Transparency was lacking but seeing was quite good.:

x64  resolved, notched (Pentax XL 14)

x69  resolved, notched (Nagler 13)

x72 wider pair split, other pair resolved (Tak LE 12.5 or Fujiyama Or 12.5)

x85 both pairs easily split (Pentax XL 10.5)

PS, that is a helpful diagram on splitting double stars posted by @John

 

Hi Jeremy, I'm pleased it's sparked some interest.....some seeing the double double for the first time,some honing their observing skills.

 Been mostly resolving clouds here this week, did get a couple of short breaks.

One night had 70mm achro out,  wider pair split @ 71x, tighter pair needed 100x to (just) split.

About the same result as the 80ED.

That suprised me, was expecting to need some serious magnification  with a cheap 70mm lens.

Seems a lot of people were around the 100x mark to split both the other week~ seeing dominating?

Had the 120 Evo out, cleanly split both pairs @ 80x in somewhat unsteady air (not split 100% of the time, had to wait for the steady momments)....

So maybe aperture  is still king.

Hopefully we'll get some particularly good seeing, as somtimes in August you do~ in my recollection.

Then the 'big boys' will  truly shine i think?

Mods,I hope this is ok? No connection between myself &the  auction, just thought someone might like a heads up, kinda classy bit of kit  IMO.

Be nice if an SGL member ended up buying...& reviewing.

https://www.ebay.co.uk/itm/Fullerscopes-4inch-f15-refractor-and-pillar-mount/124295922982?_trkparms=aid%3D333200%26algo%3DCOMP.MBE%26ao%3D1%26asc%3D20140728113935%26meid%3Df333de0cb57c4fbdbc22dab224c9bc60%26pid%3D100148%26rk%3D4%26rkt%3D4%26sd%3D174387667656%26itm%3D124295922982%26pmt%3D0%26noa%3D1%26pg%3D2059210%26algv%3DItemStripV3&_trksid=p2059210.c100148.m2813

.....if i hadn't rather overspent on astro stuff just recently i'd certainly be interested!😳

Fullerscopes...ahhh that takes me back to the 1980's 😄

I've been dogged by cloud before midnight since i initially posted.

Just been out with the 80ED.

@50x , nope nothing.

@ 66x  wider pair split.

Up to 85x, is it,Hmmm? Honestly, i could not say 2nd pair was split.

@100x both pairs split, but i can tell seeing not great.

Was working in deep twilight, transparency poor & seeing not so good. experiment over for tonight as high cloud's moved in & it's a school night. Bedtime!😉

@  Pixies. Great you found Iota Cas. Possibly my favourite double (triple) Especially in an Achromatic refractor where the colours seem somehow "enhanced"

...& they told you CA was a bad thing.😄

With large aperture or fast achro, maybe you could use a filter to dim/ or clean up the view?

It's not cheating~

I think that's what proper double star observers do when pushing the limits, bung in a green filter or something.

Won't help here, i don't posess one.

11 hours ago, John said:

Last night I managed to split both pairs of Epsilon Lyrae with a 90mm F/11 refractor (cheapie !) at 74x. I was using a 7.2- 21.5mm zoom and gradually adjusting until I could just see the thin black gap between the star pairs.

I got Pi Aquilie with the scope as well but that needed 180x !

I use these guidelines when I'm working out whether I've got a split or not although I sometimes also throw in the terms "snowman" and "peanut" because that's what not-quite split sometimes looks like !

The above pairs were clearly "split" to me last night (and a few others too):

Thanks John,a good graphic, "split" is what we're looking for i think,less open to interpretation?

Ps. No cheating! Just be honest, no prizes, it's a challenge, not a competion!

I know i've got pretty average eyes & pretty average scopes.

Look forward to the results with interest.

Mods~ hope this is ok, feel free to move. Thought it might be interesting for beginners?

For Beginners:

Epsilon Lyrae is a double double star. If you haven't already seen it, please try to find. Currently riding high in the sky.

Your challenge is:

                              With your telescope, what's the minimum magnification you can resolve it into it's four components? 

And for the purposes of the challenge,I mean a clean split, & by that i mean you can see dark sky between all four components (google 'Dawes limit' for more info)

Now i did set myself this challenge a few years back,using 80mm & 100mm but i've forgotten the details now, so i'll be out with my ED 80 in due course.

FYI, Splitting the double double is possible in an 80mm, maybe even a 60mm?, so most telescope owners should be able to partake.

If you're the lucky owner of a 200mm apochromatic  refracto & have the eyes of a hawkr, you'll probably resolve at lower mag than the rest of us, lucky you.

THERE ARE NO RIGHT OR WRONG ANSWERS! But it may help hone your observing skills.

Don't worry if others post lower magnifications at a given aperture. It doesn't necessarily  mean your eyes or telescope is bad. Practice & you'll get better.You are training your eye.

& if you're  genuinely bad at double star resolution, you may have good planetary resolution skills (i haven't!) or maybe your eyes pick up faint nebulae well? Were all made a little different.

Tips for beginners:

When the atmosphere is steady you'll find splitting double stars easier.

One pair is a lttle easier to seperate than the other pair.

Often,splitting double stars is something listed as something "to do" around full moon. True, but a little easier when the moon is less bright none-the=less.

I suspect of the factors affecting the result, seeing is the most important, visual acutity the 2nd, with telescope type & optical accuracy trailing behind.

Please post Telescope aperture, type & magnification used.

Hopefully we'll all learn something.

Sub challenge:

No telescope? No problem. Can you split Epsilon Lyrae into 2 components with the naked eye?

Meant to be semi difficult.

FWIW When i was younger, under a darkish rural sky, i found this not particularly difficult. Now older, & under suburban skies, it's no longer possible.😞

4 hours ago, dweller25 said:

I had a 150 F/8 helios refractor on a Vixen GPDX and it was only just ok - an EQ5 would not be very stable whilst focusing at high power.

I also found CA was too much for me and none of the CA filters helped much.

A 7” Mak - which is a folded frac 🤪 would be a better option perhaps ?

4 hours ago, John said:

I reached similar conclusions here eventually.

The best "big achromat" experience that I had was with the Bresser 127L which is F/9.4 so not a lot of CA really and pretty well corrected.

When you're trying to make a decision, always one or more people throw something extra into the mix 😃

Worth mulling the extra options over.

I'm now better informed thanks to SGL members, but no more clear on deciding!

4 hours ago, John said:

Be aware of the size difference and therefore mounting requirements of the ED150. The gold scope is my ED120. An EQ5 is right at it's limit (even with the steel tube legs) of a 150mm F/8. I used a driven CG5 (EQ5 with 2 inch steel tube legs) with the 150mm F/8's that I owned (I've owned 3 or 4 over the years) and that was just about OK. Probably a motorised focuser would have helped keep vibration down more. The get the most from a 150m F/8 refractor something more substantial is needed really such as an HEQ5. The Celestron AVX is a bit more sturdy than the EQ5 and has 2 inch steel tripod legs.

 

That ED120 looks tiny! ( but i know it's not.)

   Thanks again John, the practicalities of lugging a 150 in & out regularly start to become apparent.

Maybe better for those with an obsy.

2 hours ago, mikeDnight said:

I had a SW 150 F8 (Helios) for years and it was very nice. The CA didn't really bother me, in fact I thought it was pretty well controlled considering the scopes short F ratio. Three of my friends bought the 150 F5 version, which was terrific as an RFT/comet seeker and in many ways hard to beat. I though, wanted the F8 as I wanted a more general purpose scope that would perform well for lunar and planetary viewing. One evening though, while at my local astro club, someone with a twisted sense of humour decided it would be good to pit the 150mm F8 refractor against a Vixen FL102  fluorite apo. The target was Saturn and the 102mm Vixen left the 150 Helios in the dust. The level of fine detail in the Vixen simply wasn't there in the Helios. However, as a rich field comet seeker, the 150mm F8 achromat was spectacular. Deep sky in the 150mm was gorgeous, and galaxies, tiny globulars I'd never seen before, and nebulae just glided effortlessly into its field of view. The Orion nebula put on quite a show, displaying a beautiful pearlescent green hue, and the spiral structure to the Whirlpool galaxy M51 was seen with ease from a dark site, as was the bridging arm linking it to its satellite galaxy. Horses for courses I suppose! Comets were my first love and for years i anchored after a nice 6" F8 achromat, a desire fuelld after reading Leslie C. Peltiers Starlight Nights.

My 150mm F8 was mounted on an EQ4, which just about handled the tube, although the Chinese tripod was not really up to the task. I later replaced the tripod for one that was much more substantial. Ideally though, such a scope would come into its own mounted on a good altazimuth.

Thankyou Mike,

                           That's exactly the sort of helpful personal experience that could help me or others avoid a poor choice & buying twice(or more). 👍 SGL.

So from What you & others have input so far:

Could 'get away with' a 150 f8 on a EQ5.

Need to weigh up the balance of DSO vs Planetary observing. vs how much i'm prepared to spend.

A smaller ED would be more fulfilling on planetary/lunar observing  than the big achro.

Sounds like a 120 ED would be snapping close at the heels of the Evostar 150 even on DSO?

14 minutes ago, mikeDnight said:

First, it depends how you define"better views".  Brighter yes, but I've seen many smaller aperture refractors show noticeably better definition and sharper views that leave the 200p lagging obviously behind.

As for the 120ED vs 120 evostar, with regard to lunar and planetary  the 120ED is truly in a whole different league. And even on deep sky the 120ED is sharper and brighter, so it might be a mistake to side line it at this stage.

Duly noted Mike.

Had a 200p on loan, thought the views were pretty good. Certainly excellent bangs for your buck.

Found the locating & tracking of objects less than exciting, all down to personal preference i guess.

For me, EP needs to be @ bottom of tube & need some  slow-mo's whether it's, alt-az or Eq.

Re ED120, if i were to spend >£1k I might as well splurge the extra for an ED150,unless i'm missing something?

Still hoping an achro 150 might scratch the itch.....

for less £.

Still waiting for an appraisal on eq5/ 150 ota visual viability, as being of the old school a non goto mount is pretty much essential.

Can you de-goto & manual slo mo a heq5/ eq6 i wonder? 

@ My last home location, seeing seemed to get pretty shaky @ =>120mm,(in hollow) current home location is looking more promising thus far.... might justify extra aperture?

12 minutes ago, John said:

Sounds about right.

@cotterless45 gets some great views with his 150mm F/8 - look out for his reports in the observing section

Thanks again John, will do!