John

34 minutes ago, GTom said:

Mind you it is an Achromat, for that f8 is a bit fast. The f15 would be great for planetary.

I believe that the Istar R35 objectives handle CA as well as a conventional achromat with a focal ratio 35% slower so it should be the equivalent of an F/10.8 conventional achromat.

This is what Istar claim - I've not tested one personally.

3 minutes ago, Mr Spock said:

CO says cloudy. All I see at the moment is blue sky. If it stays like this I'll get the big lad out for a few tight doubles and maybe M13/92 etc.

CO says cloudy here as well ...... and it is 😌

It's thinnish stuff though so you never know, it might clear away.

I hope your skies stay clear 🤞

8 minutes ago, IB20 said:

Have you parted with the 12” dob @John?

Yes. It was a tough decision but it took up a lot of room and we have grandchildren now so needed to de-clutter a bit. Refractors can be stored away safely but a 12 inch F/5.3 solid tube dob is difficult to hide away from lively, enquiring small folks.

I may re-acquire a larger aperture scope again at some point but for now I am managing without. 

Currently all my scopes are refractors ranging from F/6 to F/9.2. 

As long as the optics are close to apochromatic I guess F/8 would be pretty optimal (I am a visual astronomer only) but I don't actually currently own a refractor of that exact focal ratio.

When I've had newtonians I have found F/5.3 - F/6 a good focal ratio range for visual use.

2 hours ago, Piero said:

- N22T4

- docter

- APM XWA 9, 7, 4.77mm

I assume the paracorr2 does not count as an eyepiece, despite the fact that Barlows are not allowed here.

Out of interest, if you had to dispense with paracorr, how would that affect your choices ?

3 hours ago, Giles_B said:

Much better sky quality last night, and much better views - I spent two hours (1-3am) outside with 2/3 of this time spent viewing Saturn with a barlowed 9mm eyepiece - i.e 267x - I found that the Baader Contrast Booster gave me the most consistently good views of the Cassini gap and brought out some of Saturn's banding. The improvement for Jupiter was less profound, but still satisfying. Difficult to tell how much of the difference was down to the filter and how much to the conditions.....

 

Jupiter does not generally respond as well to higher magnifications in the way that Saturn does. I usually find that I need to step down the magnification to get the best contrast on Jupiter.

I'm glad you have seen some improvements though 🙂

I seem to recall that we have discussed Dubhe / Alpha Ursae Majoris sometime in the past ?

It is a double star and seems to be considered to be a really tough one to split. According to Stelle Doppie the brighter component is magnitude 2.02 and the fainter one magnitude 4.95. Add to that a separation of just .81 arc seconds and we have a challenge for most scopes I think 😬

Despite Dubhe being rather low tonight, the seeing was very steady so I had a look with my 130mm F/9.2 refractor. I was not hopeful of getting a clear split of this pair but I thought it might be possible to see some indications of elongation. I had not researched the position angle of the pair so I think I went into this with a reasonably open mind. 

I gradually ramped up the magnification through 300x, 400x and found a "sweet spot" image of the star tonight at 480x. I studied the star for a good 30 minutes and during the most settled moments of seeing I was consistently detecting a bulge on the side of the airy disk of the brighter star. Sometimes this took the form of a brightening / thickening at one point in the 1st diffraction ring. At other times more of a "lump" which appeared to be stuck on the side of the airy disk.

As I became more certain that I was seeing something over and over, I made a quick & dirty sketch of a heavily enlarged airy disk with the position of the lump / bulge shown. My estimated position angle for the centre of this "feature" was around 330 degrees or on the north west side of the main star.

Once the sketch was made I consulted the sources / references that I could find on the web (including the Stelle Doppie database) and found that my PA estimate was in the right ball park for the secondary star of the Dubhe pair. 

Not a split or resolution of course but perhaps a fair indication that this is indeed a very close double star.

I've included my very crude sketch below and would be interested to hear from anyone else who has observed Dubhe looking for this split and how they got on 🙂

I'm definitely coming back for more when the star is higher in the sky 👍

57 minutes ago, John said:

Nice steady night here. I have got a lovely split of Lambda Cygni at 312x with my 130mm refractor. According to the Stelle Doppie website the split between the A and B components is .91 arc seconds with respective magnitudes of 4.73 and 6.26. The position angle is very close to 0 so the B star is pretty much due north of the A star. Simple view - just 3 points of light in the eyepiece field (there is a C component around 80 arc seconds apart from the A-B pair) but very satisfying 🙂

Just added comet C/2023 E1 ATLAS to this evenings haul of targets.

Rather small and diffuse comet in Cygnus tonight between Deneb and the small triangle of stars in Cepheus. The Heavens Above website has this one at magnitude 8.8 but it looks somewhat fainter than that frankly. It's relatively close to Earth currently, around .391 AU from us. 

Nice steady night here. I have got a lovely split of Lambda Cygni at 312x with my 130mm refractor. According to the Stelle Doppie website the split between the A and B components is .91 arc seconds with respective magnitudes of 4.73 and 6.26. The position angle is very close to 0 so the B star is pretty much due north of the A star. Simple view - just 3 points of light in the eyepiece field (there is a C component around 80 arc seconds apart from the A-B pair) but very satisfying 🙂

I think the 2mm and 5mm on sale are from this range:

Sky-Watcher | Sky-Watcher Global Website (skywatcher.com)

I tried a couple from that range a few years ago and they were not very good 🙄

I hope it is OK to post this but I just wanted to point out, to any prospective buyers, that 2 of the eyepieces in the advert below are possibly not as described:

U.K. Astronomy Buy & Sell (astrobuysell.com)

The 15mm and 25mm Vixen LV eyepieces are fine.

The 2mm and 5mm eyepieces, I believe, are the same as the old Skywatcher LE range and not Orion Optics Lanthanums as described.

These Skywatcher LE's seem to sell new for £25-£30 and quite a bit less than that used.

I could be mistaken but I think "caveat emptor" applies here. 

Meanwhile, 52 years ago:

The Apollo 15 Hammer-Feather Drop - Moon: NASA Science

32 minutes ago, JeremyS said:

I wasn’t until you mentioned it, John.

But looking at the weight, I think of my back 😳

My back is not that good either , come to think of it 🤔

@F15Rules / Dave has hit the nail on the head, as usual - refractor aperture fever gets rapidly bad for the wallet and the physical well being 😌

If only the darn things didn't look so good 😬

Hope you get some clear skies to compare them under soon Stu.

My zoom comparison is proving hard work - hard in the sense of getting much observing lately !

Anyone else glimpsing furtively from time to time at that lovely looking Istar 150mm F/8 refractor that has gone onto UK Astro Buy & Sell today ?

I know I am ! 🙄

(I can't really do anything other than look just now though 😌)

I've no connection to the advert of course.

10 minutes ago, RyanL said:

Yeah, It is a bird Jones but I only paid £6.50 for it on eBay so thought why not. I do have a Heritage 100p that has better contrast but planets are tiny in it.

I've been looking at the Skymax 127 and it's definitely on the list. How's the field of view in it?

Using 1.25 inch eyepieces the max true field of view would be just over 1 degree (2x full moon diameters). That assumes you use something like a 32mm plossl eyepiece.

The 127mm maksutov-cassegrains do a great job on the moon, planets and double stars. They are compact and portable. You will need to use a dew shield with one but those don't cost much and are also light.

Sky-Watcher SkyMax-127 AZ5 Deluxe | First Light Optics

I believe your current 114mm scope is of the bird-jones design ?

You may well get a nice surprise on how much of an upgrade something like the above linked scope would be.

Just now, Cornelius Varley said:

The qualifying requirements have changed, see my post.

Thanks Peter 👍

The UK Astro Buy & Sell website is your best outlet here in the UK I think. There is a classifieds section on this forum but there are access rules as set out in the Code of Conduct for the forum:

"The Buy & Sell section
Access to SGL's buy and sell section is a privilege that has to be earned, You can do this by accumulating 50 posts to view / buy from the classifieds and 250 posts to place an advert in the classifieds.
This has been initiated so that people can't just join the forum so they can off load or buy up astronomy equipment.
Posting an advert on behalf of someone who is not a member of SGL or on behalf of a member not entitled to post an advert is not permitted.
Linking to an external site to highlight an item you have for sale is not permitted on our boards.
Please note that the Buy & Sell section is primarily for our members personal "astronomical" equipment.
Any commercial use of this section will have to be cleared by Admin PRIOR to any sales activity."

One trick that I tried this year with Venus, suggested by @Stu I think, was to observe it using my Lunt solar wedge with the ND and polarising filters removed. The wedge on it's own passes through just 5% of the light but it does so across the whole visual spectrum and the optical quality of the prism within the wedge is excellent. I found that this method delivered glare-free, sharp and contrasty views of the 2nd rock from the Sun with my 100mm and 120mm refractors.

Of course I was VERY careful to replace the filters within the wedge immediately after using it for Venus so that it was ready and fully safe for solar observing again.

54 minutes ago, Franklin said:

Another review on the Vixen SD range I've not seen before.

VIXEN SD115 S - the largest APO refractor from a traditional Japanese manufacturer (astro.cz)

Interesting that 115mm is the largest aperture refractor that Vixen currently market.

In the past they have had 120mm, 130mm, 140mm and 150mm Petzval and ED refractors. They have clearly decided to concentrate on a smaller range these days.

I hate to mention the "C" word but good collimation is important to getting good sharpness and contrast. 

I find that I get the best contrast of planetary features when observing when there is still plenty of light in the sky. As the background sky gets darker, the more subtle contrasts and colour tints get noticeably harder to see.

If you can combine the above with the target planet being as high above the horizon as possible, and stable seeing, the results can be spectacular.

I can hear Fred Truman's voice now: "Well there's a funny thing Brian - a chap out on the boundary with a telescope of some sort. I wonder what that is all about ???. Anyway back to the action. The bowler is currently Holding, the Batsman's Willey"

😁

53 minutes ago, JeremyS said:

Did you ever have a N26, John?

My N26 has about the same TFOVas the E21, though the E21 will likely have a darker background 

I have not owned / used a N26 Jeremy but I have read some great things about them.  I have owned the Nagler 20mm T5 and 22mm T4 and enjoyed those.