John

Gradually clouding over here. I've been looking at Mars plus a few doubles with the Vixen and the seeing is not too bad. Mars does seem small now though, even at 265x Some darker areas still visible.

I suspect that's it for me here this evening but the scope is still out, though covered.

2 minutes ago, callisto said:

No such luck here....tipping down 

We are forecast to get that tomorrow

I tried some higher magnification views (166x) but the seeing is not great when you boost the image scale. They look nice and sharp at 50x-80x though and to see them both hanging there against a deepening blue sky is a real treat

You would never know that they are actually over 700 million km apart !

I'll leave the scope out for Mars later and maybe other stuff although the forecast is for clouds from mid-evening onwards.

3 hours ago, RobertI said:

My thinking was that Rowan have the know how to produce a lightweight mount to rival the Scopetech, in addition their heavy-duty AZ100. 👍

I still strongly feel that there is a niche for a decent quality, high capacity alt-az mount somewhere between the Skytee II / Ercole and the higher end AZ100 / APM Maxload. Something around £500 perhaps ?

I had originally hoped that the AZ100 might be that mount but, understandably, that product can't be produced at that sort price point. So the niche remains.

4 hours ago, tomato said:

Crikey, when I see how many scopes FLO offer, this list really tells you about the impact of the pandemic. 

I thought that when I saw the webpage that FLO have put together

Galilean moons just popped into view now. No sign yet of Titan though.

@Mark at Beaufort - hope you don't mind me piggybacking on your thread ?

Some scope observing going on at the moment:

Switched to the 8mm Ethos again (83x / 1.2 degree true field) and they are both visible with a little sky each side of them if I get their position angles right in the field of view.

According to Cartes du Ciel the planets are separated by almost exactly 1 degree in the sky just now.

I've just picked them up with my Vixen ED102 from my back garden.

They were right against the field stop edges in the 8mm Ethos but easily framed by the 13mm Ethos @ 51x magnification. Jupiter a small slightly flattened disk with vague hints of equatorial belts and Saturn showing it's ring system but no moons against the light sky.

Nice to see

On the bonus side, the nature of the sunlight in winter here, as it falls across the landscape, can be rather lovely.

I've just come in from a rather nice, if muddy, rural hike having really enjoyed extensive views across to Wales and in the other direction the Mendip Hills and Somerset Levels

The most distant hill is Glastonbury Tor:

I don't think I've ever bought a new achromat other than the TAL100R back in 1999 which at £250 with a mount and good eyepieces, delivered from Siberia was quite a bargain I think.

46 minutes ago, AdamR87 said:

Thank you all for your helpful replies! Sounds like a Barlow lens is the answer (and maybe down the line a zoom eyepiece; that looks useful).

 

Hopefully this will give me something more like what I was hoping for. I didn't have huge expectations, maybe something the size of a lentil for Mars! But certainly more than just a pinpoint.

Thanks again!

It should look something like this at around 150x with a small scope. The darker areas can be difficult to discern depending on conditions. Smaller than a lentil probably !:

I bought one of these 32mm Erfles once, believing the magazine advert that they would deliver a 60 degree AFoV !

Of course they are limited to around 50 degrees by the 1.25 inch barrel. In fact the one that I had showed a slightly smaller AFoV than the 32mm plossl that I already had and it was not quite as well corrected

Another blooper was a 55mm ex-military plossl in the 1.25 inch format. No field stop in that one but still like looking down a drinking straw of course. 

Nice report Mark.

I just used 11x70 binoculars to observe the pair this evening - too many clouds about to set a scope up. A touch over 1 degree between them tonight I think.

Tomorrow evening might be OK here in which case I'm going to get the Vixen 102 ED with the 8mm Ethos onto the pair should be able to comfortably fit both into the FoV

6mm, 5mm or even 4mm will be much more use. I rarely use 400x with my 12 inch scope.

I was referring to 40mm in the 1.25 inch fitting.

40mm (and sometimes longer) in a 2 inch or larger fitting can be spectacular eyepieces.

Nice piece !

The eyepiece looks very much like the Skywatcher 32mm Panaview. I guess they could be the same ?

Hope you enjoy using it

I expect many of us have got similar experiences Michael. Things that "seemed a good idea at the time"

Many years ago I was in an astro dealers showroom and had the choice of a 32mm plossl or a 40mm. Went for the 40mm not realising that the true field visible with the 32mm would be practically the same.

The 40mm plossl does have it's uses in slow scopes like mak-cassegrains I believe. I didn't have one of those though.

We "live and learn" as they say

24 minutes ago, Peter Drew said:

I don't have an equipment wish list, can't think of anything I would like that I haven't already got.    🙂

I'm in a similar, fortunate, position. Need to get rid of some stuff really.

I could do with some more clear skies though but I suspect that will be on everybodys wish list

8 hours ago, Louis D said:

It's not accurate for measuring apparent field of view.  It doesn't take into account magnification distortion across the field which can vary widely.  The 26mm Meade MWA is an extreme example of this.  This method only gives you the true field of view which can be converted into the effective field stop size once the true focal length is known (probably from exit pupil diameter).

There are several methods to determine the apparent field of view based on projecting light through the eyepiece and measuring the projected circle or cone of light coming out of the eye lens.  The more accurate method is to split the exiting light cone across a sheet of paper and measure the angle with a protractor after tracing the edges onto the paper.  I use the more involved method that requires measuring the eye relief distance from the top of the eyepiece, the distance from the top of the eyepiece to the wall, and the diameter of the projected circle.  Then there's a trigonometric calculation.  I've found it a bit less accurate because it can be difficult to determine the exact eye relief distance and the diameter of the projected circle for certain eyepiece designs.  The formula is AFOV=2*arctan([circle_diameter/2]/[wall_distance-eye_relief_distance]) if you want to go this route.

The best method to project a circle is to put the eyepiece in a telescope and project light into the front of the scope.  Barring that, project light directly into the field end of the eyepiece after blocking it in a miter box to keep it from moving and to keep everything aligned.  Make sure to back the light away from the eyepiece until you get a sharp edged circle projection.  At first, I had the light too close and was getting fuzzy edged image circles as a result.

The exit pupil is where the cone of light exiting the eyepiece is at its narrowest.  Move a card back and forth until the projected circle is minimized and measure that distance to the eyepiece.  This can be difficult for some eyepieces that have a poorly defined exit pupil due to aberrations.

I stand corrected with regard to determining AfoV

What method does Earnest in Russia use ?

His data and opinion seems to be held in high regard by many

1 hour ago, Second Time Around said:

I remember the H.W.English catalogue well as I had regular copies and bought some items from them to cobble together a scope.  I seem to remember they advertised in Exchange and Mart.

Was their address Rayleigh Road, Hutton, Brentwood, Essex?

Yes - here is the front of one of their old catalogues:

There was one small section of the Exchange and Mart that covered astronomical gear and that was about the only place that you could find contacts for these firms. There used to be a shop in Praed Street, opposite Paddington Station as well that sold some astro bits but I've forgotten it's name ?

When "Astronmy Now" launched in 1987 their classifieds section provided an important new home for these supplier adverts.

I still find it incredible that you can watch this stuff happening live from the other side of the Atlantic.

We visited KSC in late February this year. Had no idea then of what 2020 held in store ........

57 minutes ago, CedricTheBrave said:

how do you measure that?

Drift timing is probably the most accurate method:

http://www.mikehotka.com/Measuring_field-of-view.htm

6 minutes ago, Kimboman said:

Superb reading, lots of memories of those early days when we made most of our kit.and I still do good old army surplus

I've still got an H W English catalogue of optical components somewhere. I think it was mostly made up of ex-Government items but I used to spend hours looking through it and wondering how I could cobble something exciting together 

@DAVE AMENDALL - Ken Fulton was American. He sadly passed away in August this year. I have the sequel to the book but I've yet to read it.

Even the 4mm VT is a a usable eyepiece, or at least easier to use than the later 4mm "flat top" styles. The VT lifts the eye lens towards the eye which helps with the tight eye relief.

Baader included a sort of "mini volcano" top in their Classic Orthos but personally I think they could have taken that a little further. The ended up with more of a fumarole than an proper volcano !