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Nice first light for 150PL


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Had a great session and first light last night with my new (previously loved) 150PL. I purchased this scope specifically for observing doubles, so I was very interested to see how it would get on. Having introduced it to my venerable Skytee 2, I ventured forth.

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I started with the crescent moon and Venus which looked gorgeous in the darkening azure sky. At a low power the dark maria were plainly visible in the darkness of the earthshine and the illuminated crescent was showing some lovely features, including Mare Crisium and Cleomedes nearby by with an interesting scattering of small craters on the flat crater floor. Venus was showing a nice gibbous shape but, oh my, I forgot about the diffraction spikes you get with newts!!

Into the back garden and out of the wind to do some deep sky stuff, having let the scope cool for at least an hour. Starting with a quick star test on Polaris the image was dancing all over the place - clearly not a good night for tackling my pre-prepared list of doubles. Polaris's companion was easily visible, and slewing over to Alnitak, its companion was also clearly visible in the glare at 240x -  a promising start as it has proved to be tricky on nights of poor seeing. Next was M42 - at low power it was, as always, stunning, with the wings curving a great distance into the darkness and the trapezium beautifully resoved with tight stars. Higher magnifications showed the trapezium floating in the mottled pattern of the box shaped core, with an inky black hole nearby.

A short interlude followed for dinner and to thaw frozen hands and numb toes. When I returned the seeing seemed to be much better, so I thought I'd have a go at the E and F components. At 150x I couldn't see anything apart from the fours stars. Cranking up to 196x I could immediately see a very faint fifth member,  but no sixth. But I persevered and eventually I could make out a sixth member, flitting in and out of view, but 100% there. I honestly didn't know where the E and F should be located beforehand and checking my results on-line confirmed the catch. This is the first time I have caught the F component in any of my scopes, so to say I was chuffed is an understatement -  a great result for the 150PL!

A quick look at the Eskimo nebula - very obvious with a star like core and extensive fuzzy shell. Then, flushed with the success of the Trapezium, I thought I would try a couple of more challenging well placed doubles. First was 57 Cancri, with its two mag 5 and 6 components separated by 1.5" - once found, this was a clear split at 196x, which made it closer than anything I have ever split in the C8 or the 100RS. Very pleased. Apologies for the drawing which does not show any field stars - my hands were really cold!

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Nearby was STF1338 in Lynx, a closer double with its mag 6 and 7 components split by just 1.0". I didn't really expect to be able to split them, so I cranked up the magnification to 240x and to my amazement, I found that in moments of stillness, the split was evident. Most of the time it was a clear elongation of the pair, but in those brief moments, a black line appeared between the two. Checking my estimated position angle confirmed I was not imagining it. Oddly the position angle and magnification difference of both pairs was almost identical and I had to check I was not looking at the same pair again!

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I did feel that the scope and conditions would allow more magnification, but I didn't have the equipment, so a new eyepiece or barlow is next on my list.

Overall I'm extremely happy with the scope. It's double splitting ability lived up to my expectations and despite it's relative bulk, it was a joy to use - somehow the eyepiece always seemed to be at the right height and in the right place!

However there were some niggles, and the star test which I performed under the improved conditions later in the evening, was, to be honest horrible! I'll post more information in a review of the scope, and hopefully get some opinions of more experienced members. But I guess the proof of the mirror is in the splitting, and it was pretty darned good at that tonight.

Clear skies. :)

 

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What a great start with your new scope Robert. I hope the star test 'issue' turns out to be nothing; if you were splitting doubles that tight then it can't be all bad! Nice job on E and F, they really do pop out when the seeing allows.

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28 minutes ago, Stu said:

What a great start with your new scope Robert. I hope the star test 'issue' turns out to be nothing; if you were splitting doubles that tight then it can't be all bad! Nice job on E and F, they really do pop out when the seeing allows.

Thanks Stu. I'm really looking forward to getting more into the world of double star observing!

I've posted more about the star test problem here.

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8 minutes ago, cotterless45 said:

That's a great scope, I spent many a happy hour with this most useful long Newtonian. Nothing wrong with optics to get such a tight split . Enjoy !

Nick.

I second that. It's a great scope, I've also spent many a happy hour using it to split doubles and it is amazing on the moon and planets. 

Avtar

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Great Post those double stars are ones I have not looked at yet, scope performing brilliantly and you had clear skies something I've not had for over a month + enjoy the 150pl ideal for those doubles. 

Paul 

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Thanks for all the comments. I forgot to mention that the last time I used a 6" F8 Newt was 35 years ago, when I had a Fullercopes ota on a Charles Frank mount. Picture of my little roll off obsy in my parents garden. Spent many happy hours with that scope, it felt good to be using one again.

 

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A beautifully written write up Robert. I had zero doubts you'd be happy with the views as a fellow owner. It's slightly alarming to hear you had a bad star test though, f8 should be much easier to figure than f5 so very surprising. As others have said you surely wouldn't be able to split such tight doubles with a bad mirror so hopefully that's re-assuring.

On the flip side, if it is a bad mirror, just imagine what a good 1/10th wave mirror would do! :D 

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11 minutes ago, Lockie said:

A beautifully written write up Robert. I had zero doubts you'd be happy with the views as a fellow owner. It's slightly alarming to hear you had a bad star test though, f8 should be much easier to figure than f5 so very surprising. As others have said you surely wouldn't be able to split such tight doubles with a bad mirror so hopefully that's re-assuring.

On the flip side, if it is a bad mirror, just imagine what a good 1/10th wave mirror would do! :D 

Thanks Chris, the purchase was a bit of an experiment, but I really enjoyed my inital session and I'm chomping at the bit to get out again. In fact I don't think I've ever enjoyed first light with a scope as much before. The star test is more of an irritiation than anything and a conundrum to be solved, and it hasn't spoiled anything. Based on the fun factor so far, I would seriously consider an OO VX6 in future.

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Thanks for the link John, a very interesting read. I suspect the F11 will lose some of the convenience of the F8, but lots of optical pluses.  At some point, because enjoy comparing my scopes, I am going to do a planetary head to head with the C8, which has performed brilliantly on Jupiter, but awful on doubles! I'm curious to see how the 150P gets on.

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2 minutes ago, RobertI said:

Thanks for the link John, a very interesting read. I suspect the F11 will lose some of the convenience of the F8, but lots of optical pluses.  At some point, because enjoy comparing my scopes, I am going to do a planetary head to head with the C8, which has performed brilliantly on Jupiter, but awful on doubles! I'm curious to see how the 150P gets on.

Or how about an 8" f8 Robert 😉

Seriously though, your comment about convenience shouldn't be underestimated. 1600mm focal length can be a little unwieldy and I tend to use it for lunar or planetary sessions, not for star hopping around many targets. The EQ platform really helps too.

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5 minutes ago, Stu said:

Or how about an 8" f8 Robert 😉

Seriously though, your comment about convenience shouldn't be underestimated. 1600mm focal length can be a little unwieldy and I tend to use it for lunar or planetary sessions, not for star hopping around many targets. The EQ platform really helps too.

Yes, good point Stu, if planets and luna are the main targets, then the eyepiece height is not going to vary that much.

My journey to the 6" F8 was realising how nice the Heritage 130P was, thinking that a slightly larger, closed tube newt with a R&P/crayford focuser would give even better results and still be super-convenient. It came down to a 6" F5 (nice a short, useable for EAA, but 'pin cusioning' effect visually, at least with my Hyperions) or a 6" F8 (less convenient, but brilliant for doubles/planets and edge to edge sharpness). I concluded that an F6 was probably a good compromise, but not many 6" F6's about (perhaps a gap in the market for a new StellaMira @FLO? 😉). In fact, during my research, many people said that the best 6" F8 scope is an 8" F6! But a 150PL came up used, and as I am currently getting more into doubles,  it seemed the answer for the time being. I will of course eventually run out of space for any more scopes!  

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1 hour ago, RobertI said:

In fact I don't think I've ever enjoyed first light with a scope as much before

That's wonderful to hear Robert :) One day I'll own a 8.75" f6.3 which I hope will perform well and be a great compromise for most things. Just need to get round to finishing it!

You do have nice old collection of scopes now :) 

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2 minutes ago, Lockie said:

That's wonderful to hear Robert :) One day I'll own a 8.75" f6.3 which I hope will perform well and be a great compromise for most things. Just need to get round to finishing it!

You do have nice old collection of scopes now :) 

Thanks Chris, looking forward to seeing the 8.75” F6.3, no rush! 👍

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Sounds like a nice, fun scope!

Stelle Doppie has STF 1338 with mags 6.7/7.1, sep 1.0 and PA 320, and 57 Cancri 6.1/6.4, sep 1.6 and PA 309. Are these the figures you used, as the PA looks a bit odd on your sketches, although I always struggle with the upside down and reversed images from a newt??

Chris

 

 

 

 

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8 hours ago, chiltonstar said:

Sounds like a nice, fun scope!

Stelle Doppie has STF 1338 with mags 6.7/7.1, sep 1.0 and PA 320, and 57 Cancri 6.1/6.4, sep 1.6 and PA 309. Are these the figures you used, as the PA looks a bit odd on your sketches, although I always struggle with the upside down and reversed images from a newt??

Chris

 

 

 

 

Thanks Chris.

Sky Safari said 7.1/6.1, 1.0”, PA322, and 5.4/6.4, 1.5”, PA311. So my mag differences are a bit wider than yours, but I think your figures are more accurate as I didn’t feel that there was a full magnitude difference between either pair. 

My sketches are not that accurate I’m afraid (added for interest!), my visual estimate at the time was that both pairs were pointing roughly NW, giving PA of 315 or so, which seemed close enough to confirm the catch (hopefully).

I believe (and hope) that the PA is measured counterclockwise through a Newt starting at North. 
 

I will try and work on my sketches! 😁

Edited by RobertI
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Nice report. I had a standard 150p for a number of years and spent many hours out on the balcony of my old flat. I had a limited view so would be out every clear night well into the early hours waiting for things to come around into view. 

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  • 3 weeks later...
On 29/01/2020 at 22:35, RobertI said:

This is the first time I have caught the F component in any of my scopes

Well, I obviously can't rely on my memory - looking back on a report from 2017, it appears I did pick up the F component in my venerable C8. It obviously wasnt that memorable at the time!

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