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Everything posted by John
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BST Starguider 12mm vs StellaLyra LER 12.5 - Attempted Comparison.
John replied to Chris's topic in Discussions - Eyepieces
Good job Chris - I enjoyed watching that I think you took just the right approach - describe what you see and the experience rather than worrying about detailed specific technical diagnosis -
My one’s longer than your one..... 😉
John replied to Stu's topic in Discussions - Scopes / Whole setups
You could use 80mm F/15 refractors as truss poles for something like that ! -
I've been looking through some snaps we took on our trip to Florida last February, which seems a long time ago now . I came across the one below that I took at the Kennedy Space Centre in front of the Shuttle Atlantis exhibition hall. My other half is stood at the bottom of the right hand SRB. This is a BIG piece of hardware The exhibition of the Atlantis shuttle inside the huge hall is very impressive as well - it's turned on it's side and is literally hanging right in in front of you. Highly recommended visit for all space nuts
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Putting ED objective in a Lyra 102mm achromat
John replied to StevieDvd's topic in Discussions - Scopes / Whole setups
I guess that the objective used in the Altair Starwave Ascent 102ED would be suitable: https://www.altairastro.com/starwave-ascent-102ed-f11-refractor-telescope-geared-focuser-467-p.asp I'm not sure that the objectives are available separately though ? Is the current objective in your Lyra 102 F/11 in good shape ?. Apart from a little less false colour, an ED doublet replacement might not deliver much in the way of improvements. The objectives used in the Lyra F/11 achromats were pretty good I seem to recall. -
Thanks Jeremy - I will enjoy reading those over my coffee and Jaffa Cake later today
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Fascinating stuff from NASA's APOD: https://apod.nasa.gov/apod/ap050401.html
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I've been telling myself that for years 🙄 I've not bought one since December last year, so that's something !
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My one’s longer than your one..... 😉
John replied to Stu's topic in Discussions - Scopes / Whole setups
If you could do it, masking the Tak FC 100 down to 80mm would give you an F/9.25 scope to compare with the Scopetech 80's -
My one’s longer than your one..... 😉
John replied to Stu's topic in Discussions - Scopes / Whole setups
My (limited) understanding is that the brighter diffraction ring means that more energy is going there rather than into the airy disk which can be because of modest amount of spherical aberration There might be other causes as well though. -
Single most useful stargazing accessory?
John replied to heliumstar's topic in Observing - Discussion
I don't recall that and, if so, I broke it very early on in the thread !: -
Astronomy kit supply shortages - are you part of the problem?
John replied to Shimrod's topic in The Astro Lounge
I've only purchased a few used items over the past 12 months so it's not me ! -
My one’s longer than your one..... 😉
John replied to Stu's topic in Discussions - Scopes / Whole setups
What would be interesting would be to compare the performance of a faster ED doublet with one of these long focus achromats. Something like the Skywatcher ED80 at F/7.5 perhaps ? Obviously the faster scope could show a wider field of view but could it compete on planetary, lunar and double star observing where the long, slow refractor optics should provide an advantage ? I'm sure we all have views on what the outcome might be but it would be interesting to do a methodical comparison -
Lovely report Neil Looks like a super place to observe from as well
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This is the sketch I made using my ED120 refractor a little while back at 257x. The "Pup" star is on the E side of Sirius A so it trails "behind" Sirius as it drifts across an undriven refractor / mak-cass / SCT field of view:
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Which scope for planetary f10 / f12 / f15
John replied to Charlie 2436's topic in Discussions - Scopes / Whole setups
Now there's a line that would create a lively thread in it's own right -
I've owned the 30mm and 40mm. The 30mm edge correction is not that great. I believe that the 35mm is better corrected and the 40mm better again proving sharp across the field even in my F/5.3 12 inch dob. The exit pupil diameter is rather over-large using the 40mm though so the 35mm is probably the best compromise in an F/6 scope.
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I have the Ercole and the Skytee II. They will hold heavy scopes but to get steadiness to allow the TOA 130 to really show what it can do at high magnifications I think you need something more substantial, with slow motion controls. I ended up with a T-Rex for my 130mm F/9.2 triplet but they are long out of production now. I think the Rowan AZ100 is the best of those listed so far. There is the TTS Panther of course but the price takes a major leap up again there: https://www.peak2valleyinstruments.co.uk/page_3569452.html
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Sky Watcher Evostar 150ED Ds Pro.
John replied to Soligor Rob's topic in Getting Started Equipment Help and Advice
Hi, I don't think there is a better option at that price to be honest with you, even though the ED150 has had a substantial price hike recently. The other option is the APM 152 ED F/8 which is nearly £1K more currently. There are a few members of this forum who own the Skywatcher ED150 and they are very pleased with theirs. This owner is UK based: https://www.cloudynights.com/topic/693379-first-light-with-a-skywatcher-ed150/#entry9965092 -
What a night ! Well done for keeping focused on astronomy despite all those distractions ! I'm lucky that I do all my observing from my back garden so, apart from the odd bat and hedgehog, it's all quiet out there.
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My one’s longer than your one..... 😉
John replied to Stu's topic in Discussions - Scopes / Whole setups
Very interesting Stu - I look forward to more on these scopes in due course Petty much a waste of time trying to observe here this evening. Got a few glimpses of stars in small holes in the otherwise rather thick clouds. Glad you had better luck -
Great report The Tele Vue DeLite's seem to have gained a really excellent reputation from the feedback I've read on them, including your own I must get around to trying one someday soon !
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My one’s longer than your one..... 😉
John replied to Stu's topic in Discussions - Scopes / Whole setups
Iota Cassiopeia ? -
My one’s longer than your one..... 😉
John replied to Stu's topic in Discussions - Scopes / Whole setups
Interesting stuff Stu A brighter 1st diffraction ring is the main difference between my Vixen ED102SS F/6.5 and Tak FC100-DL F/9, interestingly. Don't know if you have a view of Auriga but Theta Aurigae is a nice uneven brightness double. Not all that tight though. Zeta Herculis later on ? The closer pair of Tegmine will be beyond 80mm I think but you might see a "notched pair". Edit: Zeta Herc is a bit unfair on 80mm's really I guess -
Clouded out more or less 100% tonight, so no "Pup" star
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My one’s longer than your one..... 😉
John replied to Stu's topic in Discussions - Scopes / Whole setups
Interesting comparison. I hope you have clearer skies than I have here Stu Both should show very little to no CA according to the Conrady and Sidgwick standards. It will be interesting to see if either scope has any advantage in other areas due to the focal ratio difference. F/12.5 is going to be a bit easier on mounts. It's good that traditional instruments of this type are still available to buy new. They practically died out a few years back.