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Celestron EDR100 Apo first light


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At last I have had the chance for a (all too quick) look through my new Celestron EDR 100 refractor. Identical optically to the Skywatcher Equinox series, with the rear element being FL53 Ohara glass from Japan, this is my first apo.

I'm a frac man through and through and a big fan of older long focus refractors not least due to their great depth of field and colour correction (why not join the Vintage and Classic Scopes group, see the Community/Social Groups tab above, plug plug:p?)

I have to say a big part of the attraction of this scope was the price, including as it did a complete manual CG-5 mount with the 2" stainless steel legs, as well as a decent 9x50 finder, 20mm plossl and diagonal-all for £475 (thanks James at FLO:hello2:)...compare that to the Equinox OTA at c£635! Ok, the Celestron has a R&P focusser, but so do Taks(!), and I have to say that so far this focusser is a gem...very smooth, lots of travel and takes 2" EPs to boot.

I've mounted the ED100 on my Bresser Meade Mon 2 mount, and put my 5" Tal on the CG-5. The Mont 2 suits the ED100 beautifully, very smooth and well able to hande the scope.

As I was also testing a Pentax 80mm achro I just bought on the same night, I was confined to Mars and the (almost Full) Moon, and Polaris for the star test. Firstly, Mars. I have never observed Mars "properly" before, apart from about a month ago with my Tal 5" refractor before I got the Celestron...I have to say it was disappointing then but I know now (thanks to SGL members) that this was due to the "boring" face of Mars being towards Earth at that time, plus poor seeing.

This time it was very different..I could see a very clearly defined white Polar cap, with a large land mass beneath it, with clear, irregular edges. To the bottom of the disk, was another large, dark land mass with a smoother edge which was paler at the edge than in the centre. I could not see a southern polar cap.

The best magnification seemed to be around 150x -180x using Baader Orthos 6mm and 5mm at 900mm F9...I could go higher but didn't see any more detail and the sharpest view was at these levels. By the way, the Pentax held up very well on Mars too, being only 80mm aperture, but razor sharp, and showed pretty much everything the ED100 did, just less brightly. Its F12.5 and I just think the longer the FL the better on planets.

I then looked at the Moon, far too bright really but I used a Tal Moon filter and looked at the limb, as it was just past Full and just beginning to wane. What I was looking for now was the colour correction. I was not disappointed. The moon just looked grey, and razor sharp. No violet. No yellow. No colour at all, and it was so bright, even with the filter in. I have heard lots of arguments about whether an ED doublet is a true apo or not..I can only say that to my eyes I saw no colour at all, and so that is good enough for me. T

Finally, Polaris. I often look at Polaris, while I'm aligning my mounts, and, growing up with achromats I was used to it appearing as (and being described as in older astro books) a bluish white star. Well, through the ED100, it is white, pure white. No blue at all. Also, the faint companion, mag 9, was very easily seen at x50 and the pair accepted magnification up to 250x no problem. Nice, round, airy disc and a diffraction ring around Polaris, and the faint companion always clearly visible with direct vision.

All in all a very satisfying first light. All too short, but enough to confirm that these scopes are as good as the reviews say they are! So, if any of you have £475 burning a whole in your pocket, I think SGL have one or two left...and if you don't need the CG-5 mount and accessories, sell 'em! You'll find plenty of takers for CG-5s, theyr'e good mounts, and you'll have got a great Apo OTA for around £300 brand new!:)

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Hi Dweller,

To be honest, I don't know as yet..I really need to get the 5" out while the "detailed" face of Mars is towards us...any idea how long this will be for? (at the moment it's in its' Siberian "coffin" case as I have more OTAs than mounts:p).

My guess is that they will be fairly similar in detail visible, but brighter in the Tal..I found that the total lack of CA with the ED100 made the image seem very sharp - I wasn't seeing any halo of false colour, however slight, around Mars.

I also wonder if some Eyepieces "match" some scopes better than others? I think my Baaders seem to perform better on my older long focus fracs (and now the ED100) than on my Tal 125 and 100s..is that just me, or do you think certain brands/designs of EP work better on some scopes than others?

I will try to compare them both this week, if the weather allows..Also the Moon waning should improve the sky contrast. Will let you know what I find:)

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Nice report !.

I had one of the early Skywatcher ED100's (same optics as your scope) and it was superb - definately a "why, oh why did I ever sell it" scope. Fortunately I found my Vixen ED102SS a couple of years ago to replace it and that offers comparable views, albeit at the faster focal ratio of F/6.5.

Having recently aquired a couple of larger acho refractors now (as you know !) I'm sort of coming in the other direction to your self, ie: from smaller apo / ed refractors to larger achros. It's been fascinating comparing the 3 scopes (4" ED + 5" and 6" achos) over the past couple of weeks. I'll have to think about pulling together my thoughts into some sort of review but I need to gain some more experience of using them on DSO's - it's all been planets, lunar and double stars so far .....

The EDR100 seems a great package for the money - the OTA would fare pretty well on an alt-az mount as well if you fancy something a bit more "grab and go".

Edited by John
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Here is how mars will look tonight at 20:00UT

Yes, excellent. I saw the dark area in my skymax 127 Maksutov last night

at x150. It was in and out though with only fleeting appearances lasting a second or so.

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