Search found 5362 matches

by David Frydman
Sat Jan 02, 2021 4:29 pm
Forum: Observing
Topic: Sun Dogs & Spectral Arc
Replies: 10
Views: 89

Re: Sun Dogs & Spectral Arc

I saw an all sky halo display in Finland about 1980. It was the most beautiful sight I have ever seen observing the sky. There were numerous and some very rare forms. Complete horizontal arc. Forms opposite the Sun. There were two suns, one false. There was probably a third hidden behind a building ...
by David Frydman
Sat Jan 02, 2021 4:14 pm
Forum: Observing
Topic: Attempt at HU Tauri Occultation 27 Dec 2020
Replies: 11
Views: 81

Re: Attempt at HU Tauri Occultation 27 Dec 2020

My old 123mm f/5 refractor goes from 16x with an old Kodak 38mm Eyepiece. 4.7 degree field. The drawtube is 3 inches diameter. The telescope has no finder as it doesn't need one. There are modern 3 inch eyepieces, maybe also bigger. The Yerkes refractor drawtube may be 5 inch diameter. The 123mm ref...
by David Frydman
Sat Dec 19, 2020 9:31 pm
Forum: General chat
Topic: Meet Simon Ploessl
Replies: 4
Views: 61

Re: Meet Simon Ploessl

Although Plossls are now plentiful and have been used in military optics regularly, they were not so common in the 1950s and 1960s as astro eyepieces. Orthoscopics and Kelners were the normal better eyepieces available. I still use the orthos and Kelners more than Plossls. As well as Erfles, which w...
by David Frydman
Fri Oct 02, 2020 2:21 pm
Forum: Gallery
Topic: Mars 01 Oct 2020 Eyepiece Sketch
Replies: 6
Views: 388

Re: Mars 01 Oct 2020 Eyepiece Sketch

Wow.

Regards,
David
by David Frydman
Sun Sep 27, 2020 4:28 pm
Forum: Observing
Topic: observing from bed
Replies: 33
Views: 1202

Re: observing from bed

George Alcock's large binocular was a Schneider 25x105 with 45 degree inclined eyepieces. These had triplet, probably uncoated, objectives. Unfortunately when these objectives were distributed to the U.K. the components got separated. They were bought by different dealers. Some bright spark commerci...
by David Frydman
Fri Sep 25, 2020 2:37 pm
Forum: Observing
Topic: observing from bed
Replies: 33
Views: 1202

Re: observing from bed

The view of Mars through Horace Dall's closed attic window using his world class 8 inch Maksutov at 400x was unbelievable. It was the equal of my 12.5inch Dall Kirkham in my garden. His camera obscura from indoors provided daytime views that were just spectacular. His photos of a church gutter at 17...
by David Frydman
Fri Sep 18, 2020 10:24 am
Forum: Gallery
Topic: New Igloo built on the Sun.
Replies: 20
Views: 829

Re: New Igloo built on the Sun.

I would take great care before becoming a solar observer.
One mistake can damage eyesight.

I suggest observing Mars and other objects first to build up experience.

Regards,
David
by David Frydman
Thu Sep 17, 2020 9:46 am
Forum: Observing
Topic: Early Mars Viewing
Replies: 51
Views: 2013

Re: Early Mars Viewing

Saw Mars as a disc at 25x in Opticron MM2 52mm spotting scope.
No detail seen.
2020 Sept 17 02.10UT.

Hand held against window glass.

Regards,
David
by David Frydman
Thu Sep 10, 2020 10:26 am
Forum: Absolute beginners
Topic: What to look at?
Replies: 11
Views: 557

Re: What to look at?

The finder should be aligned with the scope, say on Polaris.

The scope with the 10mm eyepiece, or first with the 25mm eyepiece if Polaris is not in scope field.

Centre of finder with centre of scope view.

Regards,
David
by David Frydman
Mon Sep 07, 2020 7:12 pm
Forum: Observing
Topic: Early Mars Viewing
Replies: 51
Views: 2013

Re: Early Mars Viewing

Hi Nigel, For planets in daytime without optical aid it is essential to know the position exactly. Central vision is used and this is less than 2 degrees Also the faint planet must be exactly in focus with glasses if necessary, but I did not need these when younger. The air must be clean and transpa...
by David Frydman
Mon Sep 07, 2020 2:36 pm
Forum: Observing
Topic: Early Mars Viewing
Replies: 51
Views: 2013

Re: Early Mars Viewing

Once I saw Mars with unaided eyes in daylight at magnitude minus 0.9 by placing it on top of tree. I have seen Jupiter many times in daylight with unaided eyes. Mars is not particularly difficult in daylight with a 10x25 binocular. I still have not seen Mercury in daylight without optical aid, altho...
by David Frydman
Sun Aug 30, 2020 9:21 am
Forum: Absolute beginners
Topic: Did I see Mars?
Replies: 13
Views: 532

Re: Did I see Mars?

Hi Simon, I would suggest a 6mm or 6.3mm eyepiece as The Barlow means removing the eyepiece, fitting the Barlow and putting the eyepiece back. As the scope is undriven this is fiddly. The 25mm eyepiece gives an exit pupil of 5.2mm. If you have astigmatism this might be the reason for the headache. T...
by David Frydman
Sat Aug 29, 2020 7:02 pm
Forum: Absolute beginners
Topic: Did I see Mars?
Replies: 13
Views: 532

Re: Did I see Mars?

If a Barlow isn't included then a 6mm eyepiece gives 200x and a 7mm eyepiece 170x. It depends on finances. Skywatcher offers different eyepieces as does Explorer Scientific and others. With a Dobsonian, wide field eyepieces are easier at high power to allow longer observing times. But narrower field...
by David Frydman
Sat Aug 29, 2020 6:42 pm
Forum: Absolute beginners
Topic: Did I see Mars?
Replies: 13
Views: 532

Re: Did I see Mars?

Assuming the focal length is about 1200mm, then the 10mm eyepiece gives 120x. This should show some detail. The 25mm is too low power to see detail at 50x. If a 2x Barlow lens is included it would give about 240x with the 10mm eyepiece. I would try that on a steady night. The cooling time depends on...
by David Frydman
Fri Aug 28, 2020 2:35 pm
Forum: Absolute beginners
Topic: Did I see Mars?
Replies: 13
Views: 532

Re: Did I see Mars?

The street light shouldn't make a difference. Was the telescope properly in focus? What magnification/eyepiece was used? Probably 150x should be used, with 200x in better conditions. There should be a white pole cap and markings on the disc. However, dust storms on Mars can obscure everything. Even ...