Louis D

1 hour ago, John said:

I've owned 127mm and 180mm  maks for a short time but I've never used one of the little ones. I have refractors from 100, 102mm, 120mm and 130mm but I was attracted by the sheer cuteness of the 90 mak

Hopefully the 'fracs don't gang up on the poor little Mak in storage. 😲

20 hours ago, GiorgioF said:

Factory has to manage a single code for raw material. With same tube, make the focuser and spider holes in different position will also save time in assembly line....

That's probably the real reason for most commercial Newts.  They aren't all that way.  Here's the Takahashi Epsilon 180 ED f/2.8 Newtonian Astrograph Reflector as a counter example having its focuser right at the end of the tube:

On 22/07/2020 at 03:04, pequod said:

Thanks Red Dwarf, that really helps me. Also thanks to Star Forming.

Just an FYI, our user handles are Louis D and Dr Strange, respectively.  Red Dwarf and Star Forming are our member "rankings" based on number of posts.  Your ranking is Vacuum.

You should be able to observe most solar system objects, open clusters, globular clusters, planetary nebula, and a few bright emission nebula and galaxy cores from your location.  Most galaxies, faint nebula, and comets tend to be a no-go from suburban skies (Bortle 5-6) because they tend to be faint and diffuse, blending in to the background sky glow.  Aggressive nebula filters such UHC and OIII can help with nebula, so there is hope on that front.

On 21/07/2020 at 14:21, Paul63 said:

P.S have been looking also at the  DSV-1 where could this be purchased from in the U.K 

As far as I know, Raul at DSA only does direct sales.  I have both the DSV-1 and DSV-2B mounts, both bought second hand.  His wait time for mounts can be weeks to months, if he responds to your emails at all.  He seems to be concentrating on making and selling the DSV-3 mounts right now.  I highly recommend the DSV-2B over the DSV-1 mostly for the axis locks.  I use heavy eyepieces like the ES-92s and don't like the wild swings in altitude when swapping eyepieces on the DSV-1.

I would imagine @Don Pensack could point you to the best current contact for ordering custom made BST Starguiders if you're serious. 😉

On 22/07/2020 at 09:20, cwis said:

Just as an addendum, AltairAstro in the UK do next day delivery  - and I have just taken delivery of a shiny new 24mm UFF.  

First impressions - they need to get another photographer for their website - it looks a lot nicer in real life!  

 

Definitely let us know what you think of it once you've had some time to evaluate it.  I've found it to be very usable with eyeglasses and mostly sharp across the field.

7 hours ago, Alan White said:

Thank you for all the answers folks.
I had a good idea what you would say anyway,
but sometimes asking and getting confirmation is a good things.

I have to say me dislike of undercuts has slewed my thinking here, 
the DeLites I had and sold were great, they really were, sold over raising funds and undercuts.

Realising my varying recent mistakes has been a tad expensive, but lessons learned.
You know what you like once it's gone!

At this focal length, there's also the APM High eye relief Flat-Wide 84 degree 12.5mm to consider.  It seems to be well reviewed except for some possible EOFB.  It has no undercut on it's insertion barrel.

12 hours ago, SmoothOperator said:

Oh okay my mistake, I’d read it was 50 x the aperture.

50x the aperture in inches for high contrast objects like double stars.  Low contrast objects like Jupiter don't respond as well to high powers.

12 hours ago, SmoothOperator said:

You’ll have to forgive me as I’m a bit of a novice and I don’t fully understand some of the language you’ve used like corrected field of view, what sort of effect does this have when looking through the eyepiece as opposed to an Uncorrected field of view?

Corrected meaning lacking in aberrations such as outer field astigmatism and field curvature.  If you let an object drift through a poorly corrected wide field eyepiece, it will get blurry by about 50% out from center to edge, thus negating any advantage to the wider field for an undriven scope such as yours.

9 hours ago, SmoothOperator said:

Also, based on what you’ve said would you suggest that instead of spending the money on the EP set in the URL I’ve copied or would it be better to spend it on a decent 8mm eyepiece which combined with the Barlow lens will give me my 300x mag?

I would pick up the 5mm, 8mm, and 15mm Starguider BSTs as others have recommended as well as a 32mm Plossl similar to the one in the kit.  Later on as funds allow, I would add the 35mm Aero ED for widest field views.

Saturn's rings are apparent with just about any telescope.  The difference is how sharply defined they are.  If everything is well executed and collimated and seeing conditions are steady, Saturn should look like a fake cutout pasted onto the sky.

Generally, about 30x per inch is what I figure for Newtonians, so about 240x max for your 8", which is where you are today.  The secondary obstruction and spider vanes tend to cut down on contrast at higher powers relative to an APO of equal aperture.

In particular, you'll be severely limited by UK seeing conditions, so 100x to 150x might be more realistic for Jupiter in particular.  Do you notice more detail in Jupiter at 240x than at 120x or are they simply bigger and more washed out?

Saturn's rings and Mars can take more power due to being of higher contrast.  On high contrast objects like double stars, you can try to push 300x or more.  If you want to go for 400x, I would recommend a 12" scope minimum and steady seeing conditions.

More expensive eyepieces have better lens polish leading to less scatter, better multicoatings, better stray light control, and wider and better corrected fields of view (especially in scopes faster than f/8 such as your own).  However, on axis, a well executed, cheap eyepiece can still perform very well.  Mainly, contrast and resolution on planets will suffer a bit.

AFAIK, the only commonly used focal reducers for visual usage are the ones for SCTs.  But, they are more complex than just a simple focal reducer and are matched to the scope's design.  Someday, I want to put one of the Celestron types on the back of a 127 Mak just to see how usable it is since there are no designed Mak focal reducers to my knowledge.  I have a feeling it will vignette 27mm diameter field stop eyepieces at the very least.

9 hours ago, johninderby said:

0.5x focal reducers are common and cheap and. can be screwed onto an eyepiece.

https://www.firstlightoptics.com/astro-essentials-eyepieces/astro-essentials-05x-1-25-focal-reducer.html

In my experience, both the cheap 1.25" and 2" focal reducers add field curvature and some edge aberrations.  They also require a fair amount of in-focus.

7 hours ago, pequod said:

Some supliers list a reducer/corrector for photography. Why would I need this on an APO? Thanks, Ed

Most APOs have curved fields because the radius of curvature for most refractors is about one third of the focal length.  There are some astrographs (4 or more elements) and Petzvals with designed flat fields.  For the rest, you'll need to purchase a field flattener unless you use a really small imaging chip (planetary imaging) or buy a really long focal length refractor.  The shorter the focal length, the shorter the radius of curvature, the worse the corners will look.  Being an APO simply means really good control of false color.  It does not mean complete freedom from chromatism as in a reflector or flatness of field.

1 hour ago, crazzy88ss said:

Good point on a 2x barlow.

What exactly does "steady view" mean?  The scope itself is pretty solid on its mount.

How steady is the seeing in your area?  If the atmosphere is turbulent, there isn't much point in increasing your magnification because all you'll be doing is getting a closer look at blurry details.  Do stars twinkle at night or do they hang there in the sky like little Christmas lights on a tree?  Do bright stars show color flaring that rapidly varies at modest magnifications?  Those are signs of atmospheric turbulence.

27 minutes ago, sputniksteve said:

What is focuser backlash?

When focus doesn't immediately change when focus direction is reversed due to slop in the mechanism.

There's also adapters from Vixen/Synta finder shoes to Quikfinder base if you have such a base already on your scope.  I have one for my refractors, and it works great.

28 minutes ago, Nikodn said:

When I unscrew the lens element from the bottom of the lens and screw it onto the eyepiece what magnification do I get.

Generally about 1.3x.  You can figure this out for yourself with a ruler or tape measure.  Just measure the difference in width of the view without any barlow, with the barlow in the normal position, and with the barlow lens elements screwed into the eyepiece.

30 minutes ago, Nikodn said:

Also when I fit an eyepiece into the tube of the Barlow lens without the lens element what effect does this have on the focal length and magnification of my telescope. 

For refractors and Newtonians, none.  It's just acting as an extension tube.  You'll have to rack your focuser inward to compensate.  An extension tube can be handy for terrestrial usage when you want to focus closer than the stock focuser outward travel allows.

For mirror focusing telescopes like SCTs and Maks, you'll be extending your focal length slightly to reach focus further back with the extension tube.  This can also induce a bit of spherical aberration in the image because you're getting further away from the design intended focal length.

Dang, sorry to hear about your chronic pain.  I can relate as I've had my share of back and neck issues over the years.

I would probably lean toward getting an 8" Dob, have it setup in the backyard by someone with a good back on a leveled set of slightly raised pavers to protect it from ground dampness, and leave it there under a high quality telescope cover when not in use.  That way, all you have to do is pull the cover off to observe.  An 8" Dob is fairly easy to use while sitting and there are no tripod legs to have to work around.  All you have to carry out is an eyepiece case.  I would stick to smaller eyepieces because the weight of larger, premium eyepieces tend to add up quickly in a case.

I have 8x42 and 15x70 binoculars that I use for astronomy.  The 15x70 are right at the limit of hand-holding if you can sit in a lawn or camping chair and hold them by the objective end while jamming the eyepiece end into your eye sockets.  If I'm going to get out a tripod, I'll just get out a telescope with a binoviewer instead.

On 15/07/2020 at 14:09, Daf1983 said:

My maplin case is starting to fill up, even though it's not half as neat or as impressive as most on here. Celestron xcel lx x2 barlow, 8mm bst, 12mm bst, 30mm vixen npl, telrad, cheshire eyepiece and a red light torch (and the stock skywatcher 10 and 25mm which I'm regretting cutting a hole for😏). 

Still room for something in the 15-18mm range, and maybe a wide angle 2inch eyepiece when finances allow.

I keep my non-eyepiece accessories in a toolbox.  I keep my Telrads in a relatively flat cardboard box with closed cell foam wrapped around each for protection.  It frees up a lot of space in the eyepiece case.

On 16/07/2020 at 08:34, Captain Magenta said:

Unfortunately that method only works in Europe, and in the UK for now but for only a limited amount of time. In the US and shortly in the UK it'll only work using Imperial allen keys  

M

I don't know if Europe suffers from the same issues, but you never know whether you'll need a metric or USCS/SAE/standard (not Imperial) socket or allen wrench when trying to loosen a threaded screw/bolt.  Sometimes due to wear, neither set has a perfect fit.  It gets annoying at times.

Here's how the Meade 5000 Plossl 40mm looks in a field flattened AT72ED f/6 refractor (top) and in a Synta (Orion/Celestron) 127mm f/12 Mak (bottom).  The difference in scale is due to the difference in focal lengths between the two scopes.  However, it's pretty clear that at f/6, things get ugly toward the edge, but at f/12, it looks pretty nice.  You may need to select and expand the f/6 version to see the details.

7 hours ago, johninderby said:

Now who is going to buy one just out of curiosity? 😁

Already been done nearly 2 years ago over on CN.

They are 5 element, 60 degree, positive only eyepieces except for the 5.5mm which has 6 elements and might be negative-positive design.  They are very sharp in the inner 50% (30 degrees) and then get progressively worse to the edge in sub-f/6 scopes.  It's been rumored that they were resurrected as the ES-62 line of eyepieces since all the focal lengths match up.