71 replies to this topic

[stevew]

I have seen quite a few of these Astrophysics Star 12, 120mm refactors for sale on the used market lately.
I think they were made in the 1990s.
Any one know how they perform compared to todays Astrophysics scopes?

Steve

[ryderc1]

The Star 12's were primarily air spaced doublets. A few were oil spaced.
Their color correction is on par with the Tak FS series doublets, so not as color free as current AP scopes, which are triplets, but still very good. The Star 12 is a rather lightweight scope so doesn't demand a heavy duty mount.

[Clint McQueen]

Ed Ting has a review of the scope on scopereviews.com
Favorable, if I remember correctly.

[johnnyha]

Its a great question because they come up occasionally on the used market in the 2k range which seems like a killer deal for an almost 5" AP refractor.

[vahe]

AP produced three doublets in the past two decades.
The Star-12 was the earlier model, not bad for visual, after all it is an AP.

Then AP offered two other doublets in 92, these were offered for a very short time and were discontinued in favor of triplets that were in higher demand.
The two were Star 130 F/8 ED and Star 155 F/9 ED, I have never looked through these but those who have tell us that visually they are about as color free as the triplets. Occasionally one will show up in AstroMart, but these are not as plentiful as the Star-12.

The Star-12 is not up to current AP refractors, but as someone pointed out you will see some color around bright objects if you look carefully.

Vahe

[GlennLeDrew]

I once owned a Star-12, which I bought in '91. I loved it! It suffered only a very small degree of longitudinal color on such things as Venus and Vega. I don't recall any on the other bright planets, and little if any on the Moon. Any color that was there quickly 'disappeared' as far as my consciousness was concerned. Actually, atmospheric dispersion was usually the more annoying 'fringing' I would encounter.

For a visual scope, even to this day I'd probably have a hard time finding much to fault the Star-12 when compared to same-aperture scopes of current vintage. Sure, there will be some performance difference color-wise, but for the price, it represents excellent value that should fully allay any residue of envy of owners of the newer kids on the block.

[stevew]

I think I've seen 3 for sale in the last month.

Steve

[RichA]

I owned one. It was good, but not fantastic. Side by side with a Meade ED at the time, detail on Jupiter was about equal, the 12 having somewhat less colour. On an inch per inch basis, I thought the Vernonscope (AP lens) 94mm was better. I had three of them.

[SteveG]

I wanted a Star12 back in the early 90's - real bad!! I remember dreaming of owning that scope. I don't know what they're selling for today, but now there are probably better options, like the EON 120 which has a sliding dew shield & rotatable focuser.

[Scott99]

I wanted a Star12 back in the early 90's - real bad!! I remember dreaming of owning that scope. I don't know what they're selling for today, but now there are probably better options, like the EON 120 which has a sliding dew shield & rotatable focuser.

Interesting, not many would prefer a chinese crayford over the 2.7 inch R&P machined AP focuser. Not to mention the pedigree of the lens.

[SandyHouTex]

Actually the lens is probably better. I don't believe FPL-53 existed back when the Star 12s were made.

[Clive Gibbons]

I *think* Rolando was using FPL-52 back then.
Lanthanum glass mating element?

[SteveG]

Either way, I would easily prefer a brand new f7.5 tube, rotating focuser, sliding dewshield, FPL-53 optics that are highly regarded, over a 20 year old f8.5 AP tube. The WO Megrez 120 is the version I'm most interested in, but I don't need the digital focuser.

[Jeff Morgan]

I *think* Rolando was using FPL-52 back then.
Lanthanum glass mating element?

I got interested in these a while back and mined old posts (primarily from Roland Christen) on the the Yahoo groups, Refractor and AP. I ended up buying one last one month. No observing report yet, still lack a suitable mount. (And of course, it is winter so my sessions are more limited the last being almost a month ago.) Working on the mount part.

RC responded directly to one of my posts, the glasses were Schott KzF2 mated to Ohara FPL51 ED glass in a traditional Steinheil flint leading doublet configuration. It would seem the reason would be to protect the uncoated ED element, and it has been stated that the Steinheil offers some advantage in cool down.

From what I have found in various related posts (using search keywords Steinheil, Star12, KzF2) KzF2 seems to be the key part. It was discontinued in the early 90's due to environmental concerns (lead used in the manufacture IIRC). Much like the famed "NASA glass", none of the replacements offered the overall performance in doublet configuration. I too briefly considered one of the newer Chinese doublets for less money, but in light of the lesser correction coupled with faster focal ratio, cooled off on the idea. And of course the Astro-Physics cache. And BTW, the older AP focusers are still leaps and bounds above the import Crayfords. The tolerances are so tight you can hear the air hiss out of the tube when you rack the focuser, and no issues with heavy loads.

Also consider Astro-Physics emphasis has been on imaging refractors, which means a much higher performance bar. A KzF2 doublet might have been fine with the film emulsions of the day, but in the early 1990's the writing was on the wall for film imaging. Doublets would not be good enough as CCD imaging machines, and they disappeared from the AP line-up.

[The Ardent]

I found a collection of Star 12 reviews here Message #737950

[Jan Owen]

I still have *my* Brandon 94, which I bought in 1990 when they were new, and I have NO intent to ever let it go...

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[Jeff Morgan]

Thanks the the links Ray, there are some items there I missed!

[Scott99]

the glasses were Schott KzF2 mated to Ohara FPL51 ED glass in a traditional Steinheil flint leading doublet configuration. It would seem the reason would be to protect the uncoated ED element, and it has been stated that the Steinheil offers some advantage in cool down.

FYI some of the early marketing info for these said the ED element was uncoated. However, I've had two different Star 12's and the FPL-51 rear element was coated in both, I suspect they found a way to coat them.

[Jeff Morgan]

FYI some of the early marketing info for these said the ED element was uncoated. However, I've had two different Star 12's and the FPL-51 rear element was coated in both, I suspect they found a way to coat them.

Progress marches on. It does appear that ED lenses today are coated, if one is to believe the marketing.

In mining some of the old posts, it now appears that the discontinuance of the Star12 was more of a marketing issue. The Star12 was an effort to go against the smaller Genesis SDF and Tak 102 at close price points. The typical AP customer however wanted higher end triplets, and the decision was made to devote production capacity to the better corrected triplets. The unavailability of KzF2 must have happened thereafter. Interestingly, RC posted there is a Chinese equivalent but internal quality makes it unsuitable for lenses (at least, lenses that meet his quality requirements). It's been interesting to piece together the history of the model.

The unit I purchased does not appear to have been used much over the years (or in the last several). There was a layer of some type of residue stuck on the tube with no interruption or disturbance by tube rings. Perhaps residue or outgassing from the foam case lining? It did clean up nicely with Naptha. The pinion gear was bent, apparently in shipping. Fortunately AP still has replacement parts for the older focusers. During replacement, the focuser grease was still clean! The lens also looks like Roland finished it yesterday. I'm anxious to get it out under the stars. Naturally availability of the mount I would like for it seems to have evaporated on Astromart. Back out to the workshop to get the alt-az completed!

[stevew]

Jeff, Youv'e got to post a couple of pictures of your new Star12.

Steve

[Don Allen]

Yeah Jeff... :rules:is:rules:

[Jeff Morgan]

Yeah Jeff... :rules:is:rules:

Ok, ok! I'll take a few photos tomorrow morning and post them around lunch time.

[Jeff Morgan]

As requested, photos of the new (to me) Astro-Physics Star12 ED. I did a few measurements previously with the AP MaxBright diagonal and 48 Brandon eyepiece. Overall length is 46-1/2 inches. I put a (gasp!) Telrad on the tube, and with that installed equipment, the balance point was 26-1/2" from the end of the dewcap. Not to worry, I won’t defile the AP by attaching a Telrad directly to it (I took enough grief for putting one on my 8” D&G). I’m building a Berry-style alt-az mount for this scope and will put the Telrad on the altitude bearing of the mount itself. I’m also watching the classifieds for a suitable equatorial mount.

AP originally listed the weight of the OTA at 11 pounds. Postings from previous owners on various Yahoo groups indicate the tube is usable on mounts as light as a Super Polaris, and that it’s light weight and rapid cooling makes it an excellent quick-look refractor.

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[Jeff Morgan]

Close up of the decal.

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[Jeff Morgan]

The focuser, one of the older style 2.7” units. There are a pair of threaded finderscope attachment points at the 10 o’clock and 2 o’clock positions. Given the relatively short focal length of the scope (1016 mm) it can serve as its own finder scope. In addition to the MaxBright, I will use a William Optics 2” Amici diagonal with a 48 Brandon for this task. This will turn the Star12 into a 21 x 120 RACI finder scope with a 2.1 degree field. Of course the 31 Nagler can push the field out to about 2.4 degrees, but I really wanted the scope to showcase the 48 Brandon. Once on target, I can swap to the MaxBright.

The hex head cap screws (three total) hold the endplate on the tube. On the underside are two set screws to secure the thread-in focuser body.

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