Equinox ED80 to mid-priced larger refractor or high-end similar size refractor?

[carldr]

Hi guys,

I'm in the process of choosing a new telescope in preparation for getting some astronomical darkness back. For what I want to spend, I have a maximum of £2,000 in mind. The new 'scope will mainly be used for imaging.

To give me an option between the ED80 and the 9.25" SCT I already have, my current thinking is to go for a something like an Equinox ED120 or a 130mm refractor.

I'm happy with the Equinox ED80, and with the Televue TRF-2008 field flattener/reducer I have, the field is flat enough for me to not really notice any distortion with it.

But, I see that other people have progressed from the Equinox ED80 to a high-end refractor of a similar aperture and focal length.

My Equinox ED80 was £450, the Borg 77EDII comes in about £2,000 depending on whatever options I choose. That's some difference!

So my question is, is that a route I should consider? Are the high-end refractors of a given aperture much that better than mid-priced ones?

[johninderby]

How about something like the Altair Astro 115

http://www.altairastro.com/product.php?productid=16380

Quite well regarded.

John

[carldr]

Hey John,

Yeah, I saw that reviewed in Astronomy Now, and it does look very interesting. The many reports of Altair Astro's poor customer service puts me off ordering from them though.

How close in quality is that to, say, the Borg 101?

I guess my real question is, are the high-end refractors really worth their money given the mid-range stuff seems so well regarded. Is a "normal" user like myself really going to notice?

Regards,

Carl.

[johninderby]

The same scope is available under several other brand names. Telescope Service, APM, Astro-Professional etc..I've never used a BORG 101 so I can't really comment, although I think they're rather expensive for what they are. If cost wasn't a consideration I'd get the new TEC110 Fluorite Triplet.

You can now get scopes that are pretty close to the high end stuff for very reasonable prices nowadays. It's the last 10% in performance that the high end scopes deliver where the prices increase exponentially.

I've been using the WO FLT98 Feather Touch for a while and that's one also to consider. Brilliant scope.

William Optics FLT 98 Aluminium with Feathertouch 3" Dual Speed Focuser

http://www.iankingimaging.com/show_products.php?category=64

John

[carldr]

Hey John,

The Borg 101 is only a couple of hundred pounds more than your WO FLT98, so it's definitely in the same bracket (presumably, the quality is similar too?)

But anyway, if the difference is of the order of 10%, then I'm not sure I'm at the point of spending exponentially more for that 10% just yet.

So, I think you've confirmed it for me to go with a larger mid-priced refractor. That Altair Astro 115mm refractor is hard to look past to be honest, it fits in between the two scopes I already have nicely.

I'll see if anyone chips in with any thoughts first though!

Regards,

Carl.

[Rossco72]

Olly seemed impressed with the 115 and that's a fairly good recommendation!

[ollypenrice]

How much do you gain by spending a fortune? I can tell you because I have spent a fortune! I have, for the business, a Takahashi FSQ85ED at about £3.5k and a six thousand dollar TEC140. They are both utterly, totally, fantastic. For imaging the Tak is the more fantastic because it is faster, offers two focal lengths and has an inherently flat field. the TEC needs a flattener though I get away without one. Viewing the night sky in the TEC is a joy. I'm not getting into refractors, reflectors, aperture or anything else here. I'm talking only about joy!

How close will you get with something a lot cheaper? Very close. How's that for honesty?

In imaging the big difference comes in the stars, which are smaller and tighter in the premium scopes and come out the right colour because all the wavelengths come to the same focus.

The absolute mechanical integrity of the premium scopes means pleasant handling and total confidence. It's nice to have.

Only the best beats an ED80 at that aperture. In larger apos, I've used the meade 127 (very good) and the Altair 115 (even better.) But they all chase the premium scopes harder than you might think. Just my opinion, but I have no regrets about either of my expensive buys. They are worth it to me.

Olly

[BPO]

Hi carldr. In all honesty, I can say that I don't know of anyone who has ever regretted buying an Equinox 120. Along with the MN190, it is one of the best-kept secrets around, especially for AP.

[fatwoul]

Yeah, I saw that reviewed in Astronomy Now, and it does look very interesting. The many reports of Altair Astro's poor customer service puts me off ordering from them though...

You're right to be cautious of any supplier, especially one that has received plenty of poor reviews. However, I can only speak for my own experience of Altair, and I have found them to be good overall. Their weakness, I think, is communication, and it seems like a lot of the problems that develop between them and customers can be traced back to this communication issue.

They've looked after me well. My pier was sent out promptly, and my dome arrived sooner than I expected it to. They've even helped me resolve a couple of small snags (of my own creation) with my dome.

I'd say give their triplet a try, I've heard several good reports of it, and if I had a spare £1600 (and wasn't in love with my Mak-Newt) I'd be giving them a ring.

Hi carldr. In all honesty, I can say that I don't know of anyone who has ever regretted buying an Equinox 120. Along with the MN190, it is one of the best-kept secrets around, especially for AP.

Shhhhh!

[brantuk]

Taling about the 115 EDT - can anyone explain what this is all about and if it's worth having:

"A laser interferogram image (in 532nm green light) of your individual lens is available for an additional fee of £85"

Sorry to hijack the thread but I think it's relevant for anyone getting this scope - been looking at it myself

[ollypenrice]

A laser interferometer is a device for measuring surfaces. There is a good article by Roland Christen of Astro Physics here, but it doesn't read like the Beano!!

http://geogdata.csun.edu/~voltaire/roland/APO_testing.html

The significance of the 'green' bit is twofold. It lies in the middle of the visible light spectrum and, as RC's article explains, no lens is fully apochromatic so the middle of the spectrum seems a reasonable place to start.

What emerges in RC's article, and is reflected in the vitriolic exchanges which many discussions of this and anything else optical seem to engender, is that interpretation is the key. For this I can take you no further and will stand back at a safe distance.

Using the same machine and different tests/interpretations two manufacturers might arrive at different values for the accuracy of the optical surface in question.

The popular conception is that what you want to see are parallel lines on the test image. That is my understanding but I will no doubt get it in the neck from all sides just for going that far! I have no competence in the interpretation of these tests, nor do I claim any.

The French magazine Astronomie bench test all review scopes and include an interferogram on which they comment. One refractor, for instance, showed outstanding colour correction, actually better than the TEC140, but the Zygo test showed slight miscollimation. At least, this was the mag's explanation for some deformation in the lines.

Personally I set store by how good the real image looks at the EP, in a star test and on the CCD. Are the corner stars sharp and round when zoomed in on? Do blue stars throw up haloes? When you have a tight double, in which one star lies within the perimeter of the other on the RGB stack, do you see clear colour distinction in the small one even though it lies within the larger? (I think this is a good test, I must say, but I can't quantify scientifically. The FSQ is brilliant at this.) If the answer is 'yes' to all these questions then I doubt any buyer being disappointed with their purchase.

Olly

PS I think I originally found the Roland Christen article by following a link from John (in Derby) so my thanks for that.

[GazOC]

IIRC there is a German (or maybe French) site that tests across the range of visible wavelengths which obviously preferable to just testing in green, esp. where refractors are concerned.

[carastro]

I was one of the people who complained about Altair Astro about two years ago and as said above it is really communication that is their weakness. They have more than made up for the problems I had with them and I have used them again since as I now find I have a good rapport with them.

Carole

[brantuk]

Thanks Olly - I'll give that "non beano" thing a good read. If I'm going to get into decent refractors I'd like to know what I'm buying. Much appreciated

[Whippy]

IIRC there is a German (or maybe French) site that tests across the range of visible wavelengths which obviously preferable to just testing in green, esp. where refractors are concerned.

AFAIK it's the red end of the spectrum where most APO's tend to struggle in relation to colour correction (hence the need for IR cut filters when imaging with 'fracs) so testing in the Green part of the spectrum, while useful doesn't give you the full story.

Tony..

[ollypenrice]

AFAIK it's the red end of the spectrum where most APO's tend to struggle in relation to colour correction (hence the need for IR cut filters when imaging with 'fracs) so testing in the Green part of the spectrum, while useful doesn't give you the full story.

Tony..

Interesting point. I shoot through UV/IR, as do most refractor users I suspect. In the general way of things I find that the control of blue stars is the acid test which many of the sub-premium scopes fall down on. It was the one weakness of my Meade 127 for instance. I've never had any imaging problems with red, I don't think. In visual observing it might be the reverse, I don't know.

Olly

[Whippy]

Indeed Olly, I noticed in my old ZS66 that the colour correction was nowhere near as good as say, the FLT98 or ZS110 but from what I've read, the visual spectrum is relatively easy to correct, but it's the near red/IR that's the 'real' acid test.

Have you tried not using an IR cut filter on your FSQ? The story goes that the Taks are corrected into the IR as well as the visual wavelengths so star bloat shouldn't be so much of a problem. That is only what I've read mind, not through personal experience .

Tony..

[GazOC]

Interesting point. I shoot through UV/IR, as do most refractor users I suspect. In the general way of things I find that the control of blue stars is the acid test which many of the sub-premium scopes fall down on. It was the one weakness of my Meade 127 for instance. I've never had any imaging problems with red, I don't think. In visual observing it might be the reverse, I don't know.

Olly

I ***THINK*** it is Olly. I seem to remember reading somewhere that some refractors corrected one way better suit imaging, some corrected the other way suit visual.

[GazOC]

AFAIK it's the red end of the spectrum where most APO's tend to struggle in relation to colour correction (hence the need for IR cut filters when imaging with 'fracs) so testing in the Green part of the spectrum, while useful doesn't give you the full story.

Tony..

Exactly.

[Whippy]

Of course, the easy way to eliminate all of this theory and myth would be to just use narrowband filters!

Tony..

[GazOC]

Or buy a Newt....

[Whippy]

Or even a Mak-Newt...

[ollypenrice]

Fair enough. I'm probably conflating two issues in talking of colour correction and blue haloes, though some apos are devils for creating them. Noel even has an action for reducing them so it must be a widespread problem. In my case the ZS66, early Genesis and Meade 127 were guilty of bloating the blue. It remains one of my benchmark observations when I look at refractor images. As you say, reflecting has its positives!

Olly

[Whippy]

TBH though Olly, this is half the problem isn't it. What you hear and read about isn't necessarily what you experience or the actual hard facts (if there is any!). Refractors are normally at the heart of any argument on an astro forum!

Tony..

[ollypenrice]

They are, aren't they! Strange. I guess there are similar battlegrounds in other areas of interest. Digital versus analogue in HiFi? I know nowt about it but I dare say it rumbles on...

Olly