John

It was mediocre here earlier. Still clearish though so I'll give it another try and see if things have improved. The transparency is not good so if the seeing is still poor as well that doesn't leave a lot of options

Interesting report Baz

"....the view was equally as good as the ED or possibly slightly better...."

That caught my eye. Can you be more specific ?

Resolution, contrast or something else ?

Usually, with Skywatcher newtonian focusers, you use the 1.25 inch adapter when using eyepieces of that size or the 2 inch adapter when using 2 inch eyepieces. Focus issues are often caused when both these adapters are used at the same time (ie: 2 inch adapter > 1.25 inch adapter > 1.25 inch eyepiece). At least that how it's been in the past and the solution has been to just use one adapter or the other.

What can add to the confusion is that when you use both adapters you can actually get the scope to focus on terrestrial objects that are relatively close. It is when you try and focus on an astronomical target that the focus can't be reached.

Maybe Skywatcher have changed the design of their focusers recently though ?

21 minutes ago, cajen2 said:

But perhaps @almclis right: there looks to be some truss tube projecting below the screw.

Looking at that photo again, I agree.

Those truss tubes do need to be fully extended.

Good spot @almcl

I misread your post and thought you were referring to focuser tubes

While there were some clear patches low down towards the west from here earlier, there was a long thin bank of cloud right along the horizon in that direction which I suspect provided a hiding place for Comet Leonard. So still no sighting of it for me

46 minutes ago, mikeDnight said:

That would have been my dream scope. Do you still have it stored in your loft John? 

I wish

I've never seen one outside of a catalogue.

13 minutes ago, almcl said:

Can't be sure but are the truss tubes fully extended?  If not, that might account for lack of focus.

The focuser drawtube is racked all the way inwards in the photo that has been posted.

21 minutes ago, Victor Boesen said:

With my solid tube Skywatcher 250PX I had to also use the 2" extension tube (50mm long I believe) to reach focus with 1.25" eyepieces if I remember correctly. If not, someone please correct me!

I think it is the opposite - you need to use either the 2 inch or the 1.25 inch adapter, but not both together.

As above - the dual axis kit's top speed is 16x whereas the SynScan EQ5 can slew up to 800x.

In practice, with the dual axis kits, slewing is done manually and then the drive speeds are used for centering the target.

5 hours ago, rl said:

A word in favour of the 12" option, as most opinions are going the other way I might just play Devil's Advocate.

I'm at retirement age and live under Bortle 4 skies according to CO. Perhaps one rung above average on the fitness ladder. 

I have a 14" OO dob and several small refractors (GT81, SDHF75, ST120). It takes me the same amount of time to set up the Dob as it does the refractors on a Vixen portamount. Certainly it takes a lot more calories to lift but setting it up is no great inconvenience.  Both are kept in the garage. Some of the refractors are triplets; the cooldown time is just as long as the big dob. And the deep sky views through the 14" are predictably better than the small refractors. Generally planets too. 

I think I accept that there will come a time when I can't handle the 14", and it's probably not that far away. But until then I'll get as much use out of it as I possibly can! 

The other thing about the 14" is that for the same magnification as the refractor, the exit pupil is a lot bigger which helps with floaters. 

Common sense has to apply; no way is it worth a hernia, but if you can hump the thing around I'd go for aperture while you can! And an observing chair is a very good accessory. And a 10" might be a good compromise. A more valid question might be ..can you lift it without knocking the collimation out of kilter? Maybe that's the real convenience argument for refractors

Good luck either way.

I'm with you on this. While I have 4 really excellent refractors from 100mm to 130mm in aperture, it is my 12 inch dobsonian that has given me the most "wow !" moments and the most "firsts" during the decade that I've owned it.

And my 12 inch dob (also an OO) is as quick to setup as the refractors as well

26 minutes ago, Voyager 3 said:

It is interesting to note that the so called top tier planetary eyepieces all have better transmissions in the yellow-red region compared to the wide fields . A good exception is the radian , which some swear by for lunar/planetary so nothing to he surprised at . 

This maybe the reason why observers feel that Jupiter/Saturn has better structures with all those orangish-creamy bands, swirls,barges stand out better in the ZAO , Pentax orthos et all .

One thing that I've noticed is that the characteristics of one eyepiece might make it a champion on, say, Jupiter while another is a little better suited to, say, Mars. Of course this could just be an excuse to own a wide range of eyepiece designs at short focal lengths.

Any excuse will do !  

30 minutes ago, neil phillips said:

These kind of instruments need a permanent housing. Always loved Newtonians They can produce the sharpest images. And large Newtonians Great resolution. Love that 10" F8. 

My 10" f6.3 Hits the sweet spot. Very canny design from OOUK. Short enough focal length to be able to be semi portable. Long enough to start to behave a little more like a planetary Newtonian. Yes times have changed. There are of course solutions to these large long instruments. Namely SCTs  Maks and now recently commercially available Classical Cassegrains But i still think for the enthusiast these long focus scopes. Do hold a interest

It's sold now but this long 8 inch newtonian caught my eye recently. Local to me as well:

https://www.astrobuysell.com/uk/propview.php?view=180708

6 minutes ago, Zermelo said:

That's an interesting table, John - more variation than I would have expected.

I'd be interested to know how the ES ranges compare. I have an 82° 6.7mm, and while it often exceeds my other EPs for sharpness, contrast and scatter, I do find (or perhaps imagine) that the image is slightly dimmer.  

The french magazine "Ciel et Espace" used to do really detailed and rigorous comparative tests of eyepieces which included an array of optical tests, light throughput tests, spot testing etc, etc. They stopped those some time back unfortunately - perhaps some of the "runners up" brands decided not to play ball any more !

There have been tests of eyepiece transmission from time to time in the past.

This is rather out of date now but covers a few types:

Eyepiece(1).doc

As Gerry / jetstream says though, this is less critical for planetary / lunar observing.

25 minutes ago, Ian McCallum said:

You'd think with the planets being up higher than earlier in the year, we'd have less atmospheric dispersion.🙄

I've found Jupiter better this year than last - hardly any AD. Saturn is lower so a little more affected by it.

Get the refractor AND a nice dob

2 hours ago, Mr Spock said:

I've had a look through a Tak and can say it is slightly better - slightly. When you add in a decent focuser it's nearly three times the price. Only the owner can decide if it's value for money but performance wise it's just not worth it.

Well that's the thing isn't it. The difference in price can get you a nice 10 inch dob AND some nice eyepieces and a lunt solar wedge to add to your fine 4 inch refractor so you can have an observational setup that can last a lifetime for the price of one "poodle".

10 minutes ago, Sunshine said:

Anyone know what “FPL” stands for?

From the Ohara website:

"In the course of Ohara’s long history, many types of optical glasses have been developed. In this catalog, you will find over 130 glasses which we have selected as our “recommended glass types”. Each optical glass has its own properties which are closely connected with the key chemical element it contains.

With this in mind, we have developed a new glass type designation system and the new names are used in this catalog. On the nd/vd diagram, located on the Optical Catalog webpage, you will see we have divided our glasses into groups. For each glass type, we have selected on or two chemical elements contained which are considered the most important and have used the atomic symbols of these for the first two letters of the glass type designation. The third letter of the glass type designation refers to the refractive index of each glass type within its glass group: H, M, or L for high, middle, or low. Lastly we assign a one or two digit number to each glass type within a given glass family. Thus each glass type is represented by the above-mentioned three letters plus a one or two digit number.

We are also adding the prefix “S-“ to indicate which of the glass types are ECO optical glasses and environmentally “Safe”. These glass types do not contain any lead or arsenic.

For example, the glass type designation for S-BSL7 is composed as follows:

S- stands for environmentally Safe
B represents Boron, one of the key compositional elements
S represents Silicon, one of the key compositional elements
L indicates a Low index within the BS group
7 indicates this is the 7th glass within this glass family

Along with Ohara’s glass type designation, the technical data sheets will show the six-digit code for each glass type. In the six-digit code the first three digits represent the refractive index at the helium line (nd) and the last three digits represent the Abbe number (vd). These six-digit codes are internationally recognized within the optical community.

So we just need to work out what the F and P stand for.

The announcement of this Starfield 102mm F/7 was one of the main reasons that I started my recent thread "Why do really expensive scopes sell ......".

Starfield 102mm F/7 = £899  Takahashi FC100-DF inc tube clamp = £2,300ish.

£1,400 is enough to make me think very seriously about that !

Just now, johninderby said:

Found this on CN.

Price of ED glass is substantially stable over time. FPL53 costs 18x BK7, FPL51 11x and FPL55 costs 15.5x.

Same source as my info I expect

28 minutes ago, Highburymark said:

With such excellent focusers (ie, no longer the component where the manufacturer has obviously saved money), these handsome scopes beg the question, exactly how expensive is FPL53 glass these days? Cheap enough for Skywatcher to use it in a glorified finder. It’s great news for astronomers, but not so great for brands hoping to justify a sizeable price hike for fluorite.

In 2017 Ohara FPL-53 was priced at 18x as much as BK7 crown glass. FPL-51 was 11x as much as BK7. That was from an Ohara price list. Apparently at that time Fluorite cost an eye watering 75x as much as BK7

I don't know if those relative costs have changed now or not.

1 minute ago, Ian McCallum said:

I tried stopping the telescope down to about f19, but was still getting some colour fringing around Jupiter. It may have been CA or atmospheric dispersion. 🤔

I suspect it was atmospheric dispersion. An achromat of around 50-60mm diameter at F/19 should be colour free to all intents and purposes:

4 minutes ago, bingevader said:

We had a similar experience to you Tony.

Clouds came and went, but everything a bit fuzzy.

Still an enjoyable evening.

I had a 1º locking nut fall out of the 8" 'scope as I removed it from the car (recollimated this evening)! 🙄

How was your evening John?

Similar although the other way around - things started a bit fuzzy (poor seeing) but got better as the evening went on. Trouble was, most of the visitors seemed to run out of steam after an hour or so. We spent the last 30 minutes just comparing the views in our scopes.

As my scope was cooled I set it up again when I got home and had another hour on various targets before the clouds came across.

I think the visitors to the outreach session enjoyed it but I think some might have wished that they had worn another layer or two

I really enjoy sharing the views through a scope with others - it's the thing I missed the most in astronomy over the past 18 months when we could not do it.

I'm glad yours and Xgaze's sessions went well

Whenever I'm doing some outreach and sharing the views John Dobson's words pop into my head that the most important thing about a telescope is how many people other than the owner, get to look through it

1 hour ago, cajen2 said:

Well, an update for anyone interested.

I now have a right old mixture of EPs from different companies:

6mm Svbony - supposed to be wide-field 

8mm BST Starguider

30mm Vixen NPL

(all very good, especially the Vixen)

and waiting for delivery:

OVL Hyperion zoom (used)

ES Focal extender'

and madly, a Pentax XW 14mm....... couldn't resist the discount! I just had to have a quality medium-length EP.

Hopefully, that'll be it for a while! 🤭

 

 

That's a pretty good set. The trouble is that having a really, really nice one can have a sort of domino effect on the desire for more of that quality

But your head knows that you have what you need to do the jobs that need doing even if the heart might say something else

I'm very poor at resisting I'm afraid

1 hour ago, SuburbanMak said:

Sirius was less Christmas-tree than earlier so spent time with many eyepieces & letting the star drift into view so I got a second or two of the crucial side with reduced impact from the primary.  Using this approach I had inconclusive glimpses of a “bulge” between “9 & 10 o’clock” with the Towa in the Baader Hyperion at 8mm - 140x and Classic Ortho 10mm at 120x.  Viewing on axis I had a fleeting second where I thought I might be resolving a ghostly dot but not sustained long enough to claim it as definitely seen.  Was great fun though and attempting doubles like this always feels like “proper” astronomy.  I will keep at it! 
 

 

Nice report !

With Sirius, it doesn't look like other double stars. The separation between the primary and the "Pup" star is currently a relatively wide 11 arc seconds (Rigel and it's companion star are 9 arc seconds apart) but the glare from Sirius A can easily extend out further than that so what we are looking for is a faint star gleaming through the halo of scattered light from Sirius A. That point of light is to the east of Sirius A so it trails behind the main star in an un-driven field of view.