RobertI

Happy birthday GP-C8! I fine combination of scope and mount. My 21 year old 'G8' is still going strong, although the original mount (a non-goto celestron CG5 on an aluminium tripod) is now rarely used and the OTA sits on a variety sturdier mounts and tripods. The mirror is as pristine and dust free as the day I bought it thanks to the enclosed tube. Still the best scope in my arsenal for globulars, galaxies and (probably) planets .

6 hours ago, John said:

As we approach the time of year when the wonderful constellation Orion is on show together with it's showpiece deep sky object Messier 42, the Orion Nebula, I thought that I would share a couple of information sources that I have found very interesting and that have stimulated me to look a little bit more carefully and curiously into this amazing target when observing it.

Very informative article and inspiring video John, thanks for posting. This object deserves more time and study when I observe so this will really help to get something new from it. 

1 hour ago, Don Pensack said:

I reviewed these eyepieces and binoviewer a while ago in the context of a small refractor review:

https://www.cloudynights.com/articles/cat/cn-reports/telescope-reports/cn-report-william-optics-zenithstar-80-st-r1390

I encourage owners of them to utilize another brand of OCA to enable the focal plane to extend backwards sufficiently, or to eliminate the OCA entirely

if the scope has enough focuser travel.  And to use other eyepieces.  These do not perform well.

Thanks for the link to your review Don, makes interesting reading. It sounds like the binoviewer/eyepiece combo is likely to perform ok in my C8 but may struggle at higher mags in the ED102 which is faster at F7 (more challenging for the supplied eyepieces) and requires a Barlow? I hope to find out if the weather ever settles! 

8 minutes ago, jock1958 said:

Like you @RobertI been dithering around with which bino’s / extenders to buy, I eventually bought a second hand set of WO’s for my Tak FC-100DL, however haven’t had a chance to check them out due to the endless stormy weather. 
As soon as weather clears up will give them a go and see what they are really capable of, barlows & extensions included!! 

Look forward to your reports - feel free to add to this thread. 👍

9 minutes ago, Lockie said:

Some kind of focus? Check, image merges? check. Sounds very positive Robert   I bet 175x will be fine for Lunar and planetary when the seeing is average or above. I'm looking forward to your BV adventures!

Thanks Chris, I'm really looking forward to observing Mars and Luna with them.

16 minutes ago, globular said:

In your SCT:

If you add your WO binos into your usual visual back/diagonal/eyepiece holder then you're adding around 100mm to the light path which is about 310mm extra on your C8's focal length (there is about 3.1x factor in C8s). 
So if you're currently at F/10 it will become a F/11.5.

I don't know what type of C8 you have nor what visual back arrangement you have; but it might have an optical path length of 145mm or more, especially if you've gone 2".
This can be reduced to about 70mm if you select a diagonal with a very short light path.
This saves some optical length so you'll now only add (100-145+70)*3.1 = 77.5mm to your focal length compare to your current visual set-up (if the 150mm guess/assumption is correct).
So now, if you are currently F/10, you will only move out to F/10.4 with binos.
(Although it's more likely you're currently already at F/10.5 (or more) and will, with this short as possible set-up + binos, move to F/11).

If you can arrange your scope so you can look straight though with your binos then things move back down to something much closer to the optimal back focus and F ratio.
If you have the Edge C8 then, with your WO's straight into a visual back (no diagonal), you will be pretty close to the 133.35mm optimal back focus for the scope and be operating at the scope's optimal F/10.5.

Personally I think I'd use the shortest possible good quality prism diagonal I can find and live with operating at F/11 in comfort rather than F/10.5 doing contortions.

Thanks Globular, very informative. I'll be using a WO 2" diagonal (see below) which screws directly onto the scope, eliminating the visual back, so hopefully not too bad butlonger than a 1.25" prism diagonal. Actually I do have one of these so could try if the results with the 2" are not so good.

24 minutes ago, Louis D said:

It will definitely work in your C8, but it will requiring moving your mirror forward which will increase the focal length a few hundred millimeters I believe.  It will also induce a bit of spherical aberration by moving the mirror well away from the optimal design position.  It might be visible at high powers or it might not.  Some people are sensitive to it while others are not.

Oh yes, I’d read about that effect in SCTs but forgotten it, so actually using the BVs without a Barlow would give more than the 100x I was expecting, possibly closer to 110x or 120x? And the the 1.6x might give closer to 200x? 

Thanks for the info on Barlows, very helpful, I now understand the meaning of ‘shorty’! 👍

Thanks @Paz and @ShrewView . Yes I think I may need to invest in the WO 2x and 3x glass path correctors if I want a decent range of mags with that scope/eyepiece combo although it doesn’t look like I can get less than about 60x.

8 minutes ago, Louis D said:

Which of your many telescopes were you using the BVs in?

I get 3.0x magnification with the optical nose piece of a vintage Meade 140 2x Barlow screwed onto the front of my Arcturus (similar to OVL) binoviewers.  I have no trouble reaching focus in my limited in-focus Dob with this combo.

Hi Louis, I was using in the 102ED-R (hiding in the title of the thread! ) - I was particularly interested in trying it on this scope as I was not sure how it would work (I'm confident it will work in the C8). It's good to know you can get focus in your dob, it might be that I can use the binoviewers in my 150PL in that case. Interesting that your 2x barlow becomes 3x, whereas my 1.3x barlow becomes 5x!! I guess all barlows would behave differently in this setup? Never quite got my head around barlows!

After agonising over which binoviers to get I finally went for the William Optics which come with some nice 20mm eyepieces and 1.6x barlow nose piece.

This afternoon I had a chance to try them out on a distant rooftop, around 250 feet away, which I don't think quite equates to infinity from a focus point of view. The quick summary is that although I could JUST focus on the rooftop using the provided 1.6x barlow (B in diagram), I don't think I will quite be able to manage it on a star at true infinity.

However I used the 1.3x element from my Baader classic barlow (A in the diagram) and I WAS able to reach focus with 30mm of focus travel left. I worked out (by comparing numbers of bricks visible) that this combination gave me around 175x magnification - probably a bit high for plantary/luna but hopefully should give good results - what do people think?

I didn't think to try the 1.6x barlow screwed in to the Baader Barlow (effectly acting as an extension tube) - I think this would probably give enough backfocus and a magnification of between 60x and 100x (I'm guessing at how much effect the extension will have).

So at least I can reach focus in some form and I can also merge the images nicely, so looking very promising.  

Something for Luna and Mars....

Ingenious! What is the app btw?

9 minutes ago, Fozzie said:

tbh Rob, although I have a really nice ra finder, on a baader base I usually use a rigel qf with the base fixed to the centre hole on the first ring..  I'm looking at potential using a smart phone adapter to see how accurate an app is for some kind of goto function.. this attaches using a photo quick release plate.

If it works I'll write it up..

But primary finder will be the rigel qf 

Thanks Fozzie, yes good point about using a 1x finder,  I have to admit I was planning on fitting my Rigel Quickfinder aswell, I only really need a 'proper' finder when I can't find reference stars on moonlit night, but 90% of the time the Rigel QF is absolutely perfect. I'd certainly be interested to see how you get on with the smart phone option though......

I’d be interested to know what finder arrangement you end up with @Fozzie. I have mounted a small 6x30 finder using the mounting screws on the focuser - it’s nice that it rotates with the focuser, but really is too far down the tube and difficult to get low enough to look through. So I will be looking at trying a finder solution further up the tube somehow, not sure how yet as the obvious places are now occupied by a handle. 😕
 

Edit: I guess a RACI finder in the same spot is the obvious solution, I prefer straight through, but might be my only option? 
 

Sorry if I am diverting the thread btw! 

Great report and an interesting selection of objects. 👍 

Great to see you with a working obsy again Chris - you deserve it! I marvel at the speed with which you managed to complete this. 👍👍

6 hours ago, Lockie said:

RC's in the Obsy 

Looks awesome Chris!

Beautiful scope! It really does belong on a nice EQ mount like that. The transfer on the side of mine is the same as yours by the way.

I am enjoying mine more with every view, both the ability of the optics (despite the modest aperture) and the convenience of that F7 tube. And the quick cooling time.

My only criticism so far is the twist lock 2" holder for the diagonal - when you try and twist it to lock it, the focuser also wants to rotate (it has a not very effective rotation lock screw). Would prefer a couple of simple screws to be honest.

Looking forward to your first light. 

1 hour ago, Fozzie said:

Word of warning, the state of the weather, serious cloud/rain penalty currently going on outside!

Bizarrely its clear outside at the moment, but I'm not expecting it to last.

I haven't tried Campbell's Hydrogen Star, looks interesting. I see that it is a mere 7.5" in diameter - I think to see this you would need a longish focal length. I have EAA'd some small planetaries with my RC6 at at its native focal length of 1350mm using a Lodestar camera and the images were pretty small - see below for the Catseye nebula which is 20" diameter and pretty bright so probably easier than Campbell's Hydrogen Star. So in summary, I would say it's probably challenge to reveal anything more than a tiny disc. I'd be interested to hear others' thoughts though. 

2 hours ago, Dantooine said:

Observation and a decent nights sleep is for me a good solution. 

I hear that!

2 hours ago, Dantooine said:

I’ve noticed quite a few people are starting to buy these over the last few months

Yes I see @Fozzie has just purchased one - nice to see.

I saw the Altair Astro stall at Kelling and they had a 150ED, 125ED and 100ED-R hanging off a Sabre mount - the 100ED-R looked tiny by comparison! But it's probably the only one I could face setting up on most nights!

On 11/10/2020 at 15:04, Space Hopper said:

Good news..........its finally on its way 😃

I should have it in the next 2 or 3 days.

A long wait to say the least.

Any updates?

2 hours ago, John said:

A good test will be the ease with which you can see the E & F stars in the Trapezium Group (Theta 1 Orionis) within Messier 42. Personally I've found that they can be really quite challenging in my 100mm / 102mm refractors but regularly visible in my ED120 and larger scopes.

It's a good old Autumn / Winter challenge

Tip: finding the "goldilocks" magnification seems to be important with these 

 

 

 

 

 

Thanks John, yes that will be a good challenge. Looking back through my log, I've managed the E&F with the 150PL, but not with the Tal100R, so it will be interesting to see what's possible.

Thanks for the comments.  I’m really looking forward to viewing some winter DSOs with scope. Orion was just peeping over the rooftops when I packed away - winter skies are on the way. 🙂

Had a lovely little Mars session just now with the 102ED-R mounted on the Skytee 2 and seated on my new Nadira observing chair. Seeing was really good and at 220x the disc was still sharp and giving up plenty of detail, the most interesting feature being a brightening at the northern polar region, what I assume to be cloud? I spent a good thirty minutes enjoying the views. 

I was discovered an interesting technique which seemed to really help pick out the detail - if I very slowly moved the planet back and forth across the FOV using the slow motion control, I could clearly pick out more detail than staring at the stationary object. It just seemed to bring details into sharper focus. I know a similar technique works picking up faint DSOs but not sure why it would work on planets? 

I have placed an order for a bino-viewer and really looking forward to trying this out on Mars. It dawned on me that this would probably hugely reduce the effect of floaters so making high power views more enjoyable. 

Final thought - the 102ED-R was up and running and giving sharp views of Mars at 220x after only five minutes of cooling from the garage. This same scope is also able to give a nearly four degree field of view for stunning wide fields. What a versatile scope the 4” ED F7 refractor is. 🙂

36 minutes ago, Mark at Beaufort said:

Sorry to read this. I bought a Celestron SCT in 1999 from their retail shop which I visited to purchase.

I also bought my current 8” SCT from their Tring shop in 1999. The David Hinds name has been around since I started in Astronomy and will be greatly missed.