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A question about AP objectives

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#1 Astrojensen

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Posted 11 September 2013 - 04:23 AM

A Starfire 130 EDT has come up for sale here in Denmark. And no, before you guys go on cheering me up to buy it, I can't afford it. However, a discussion has broken out on the forum where it has been offered, about whether this particular scope was air-spaced or oil-spaced. I claim that all EDT's were oil spaced (apart from the 155mm f/9 prototype) and that it's the EDF's that were air-spaced (because they were much faster f/ratio). Others claim this one is air-spaced. The lens cell clearly say: 130mm f/8 EDT. It's NOT the later 130mm f/8.35.

So, who is right? I'm fairly sure I'm correct here. Also, the fairly good pictures we've seen of the lens show no hint of spacers.

Links to solid documentation I can use to beat them with (or myself!!) would be much appreciated! :grin: ;)


Clear skies!
Thomas, Denmark

#2 Jon Isaacs

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Posted 11 September 2013 - 04:59 AM

This is a question that would be best answered by Roland himself, the A-P users group, Astromart or an Email...

Jon

#3 Paul G

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Posted 11 September 2013 - 05:14 AM

I have a 130 f6 EDF and it is oil spaced, I believe the EDT's were as well, Can't find an appropriate post by Roland on the ap-ug since Yahoo changed the format.

#4 Fomalhaut

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Posted 11 September 2013 - 06:54 AM

In 1992, I went to Baader Planetarium in Mammendorf/Munich in order to buy a new AP-130 EDT. I was shown two scopes which I tested by means of the edge of a roof against the sunlight. These two scopes did not meet up to my criteria. At that time I owned a Vixen-Fluorite 102/900 the color-correction of which they couldn't meet. Mr.Baader told me this was due to a wrong batch of Schott-glass having been delivered to Mr.Christen and not knowingly been implemented at least in these two objectives.

Finally, Mr. Baader provided a beautiful and even air-spaced (!) AP-130 (identified by its spacers in the objective). This instrument indeed was in the same visual class as my Vixen mentioned above. After carefully scrutinizing, I wanted to buy that instrument right away but was told it had been made "on special order" for a special client. I was offered instead to wait for a new oil-spaced 130 but this time I refused and went Tak.

Hence, at least one of these air-spaced AP-130 triplets exists or existed.

Chris

#5 vahe

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Posted 11 September 2013 - 07:53 AM

130, 155 and 180 EDT’s were introduced in late 1992, with few exceptions they were all oil spaced.
I ordered my 155 F/9 EDT from the very first run, when the scope was ready and just before shipping I received a letter from Marj asking me how I wanted my EDT to be assembled, air spaced or oil spaced, she recommended going oil spaced for many reasons including much higher light transmission due to lack of internal reflections, a problem with all air spaced lenses.
Oil spaced was not very common at the time and some folks preferred air spaced just to be on the safe side, I went with oil spaced.

Vahe

#6 M13 Observer

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Posted 11 September 2013 - 10:41 AM

A Starfire 130 EDT has come up for sale here in Denmark. And no, before you guys go on cheering me up to buy it, I can't afford it. However, a discussion has broken out on the forum where it has been offered, about whether this particular scope was air-spaced or oil-spaced. I claim that all EDT's were oil spaced (apart from the 155mm f/9 prototype) and that it's the EDF's that were air-spaced (because they were much faster f/ratio). Others claim this one is air-spaced. The lens cell clearly say: 130mm f/8 EDT. It's NOT the later 130mm f/8.35.

So, who is right? I'm fairly sure I'm correct here. Also, the fairly good pictures we've seen of the lens show no hint of spacers.

Links to solid documentation I can use to beat them with (or myself!!) would be much appreciated! :grin: ;)


Clear skies!
Thomas, Denmark


All AP130EDF, sometimes erroneously called AP130EDFS OTAs and all AP130GT are oil spaced. The "S" letter stood for "small focuser" and there is only one size of focuser ever offered on the AP130 scope. As far as I know, all f8 and f8.35 AP130EDT OTAs are oil spaced as well. Why one was engraved f8 and the other f8.35 I have no idea since they are identical focal lengths (155mm f7 oil spaced objectives which failed testing likely due to edge defects machined down to 130mm). Just to denote the two different runs made I guess.

#7 sg6

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Posted 11 September 2013 - 12:28 PM

Thomas, oddly stumbled across this:

AP Lens

Doesn't say, or I cannot see, which are oil/air spaced, but a good read.

#8 RussD

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Posted 11 September 2013 - 04:42 PM

Ask for a picture of the lens. On some of the early airspaced AP lenses, it looks like Roland used thin kapton tape like material as a spacer. It is orange in color. These short spacers were mounted radially between the lenses. The oil spaced lenses had the same orange tape wrapped around the edge of the lens stack making it difficult to see from the front. The air spaced lenses are obvious when looking down the front end because you can see all the spacers.

Russ

#9 Mike Clemens

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Posted 11 September 2013 - 07:36 PM

yep here is the AP152/12 lens I had that was airspaced
http://www.pbase.com.../image/68838946

#10 Erik Bakker

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Posted 12 September 2013 - 06:20 AM

The faster EDF' s from 1996 and younger are definitely all oil spaced.

The first fast 130's at f/6 were called officially EDFS as per Astro-Physics literature (as in short), as opposed to the EDF that was still f/8 (= "longish") at that time. Later on, the 130mm f/8 were no longer made due to the small demand for f/8 and high demand for f/6 lenses. With now only one 130mm in production (the f/6) there was no longer a need for 2 names.



#11 R Botero

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Posted 12 September 2013 - 07:51 AM

Yes, my AP152EDF f/7.5 (only two made according to Roland) is oil spaced. Mike Sidonio down under has the other one and has taken some amazing pictures with it. I'm only visual.

#12 Paul G

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Posted 12 September 2013 - 09:06 AM

The faster EDF' s from 1996 and younger are definitely all oil spaced.

The first fast 130's at f/6 were called officially EDFS as per Astro-Physics literature (as in short), as opposed to the EDF that was still f/8 (= "longish") at that time. Later on, the 130mm f/8 were no longer made due to the small demand for f/8 and high demand for f/6 lenses. With now only one 130mm in production (the f/6) there was no longer a need for 2 names.


According to Roland, the S stands for focuser type (2.7"):

Link

#13 Peter Natscher

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Posted 12 September 2013 - 08:36 PM

Except the 160EDF and my new 175EDF are air-spaced spherical triplets polished and coated on all six sides.

The faster EDF' s from 1996 and younger are definitely all oil spaced.

The first fast 130's at f/6 were called officially EDFS as per Astro-Physics literature (as in short), as opposed to the EDF that was still f/8 (= "longish") at that time. Later on, the 130mm f/8 were no longer made due to the small demand for f/8 and high demand for f/6 lenses. With now only one 130mm in production (the f/6) there was no longer a need for 2 names.



#14 RussD

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Posted 16 September 2013 - 04:44 PM

I am pretty sure there are some air-spaced 178 f9 starfires out there. The AP literature from the time listed it as an option along with options for color correction...better corrected for visual or at the time photography. One of the 178s that came up on Amart recently appeared to be air-spaced based on the images of the lenses.

#15 Jeff B

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Posted 16 September 2013 - 05:05 PM

I am pretty sure there are some air-spaced 178 f9 starfires out there. The AP literature from the time listed it as an option along with options for color correction...better corrected for visual or at the time photography. One of the 178s that came up on Amart recently appeared to be air-spaced based on the images of the lenses.


Yes indeed, a few were air-spaced as were some of the 6" F9's, of which I had two samples at one time. Thermally slower to respond than the oil spaced jobbies but mighty fine lenses. I wish I had one of them back.

Jeff

#16 Joe Aguiar

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Posted 17 September 2013 - 07:32 AM

This is a question that would be best answered by Roland himself, the A-P users group, Astromart or an Email...

Why should the poster go to astomart whats so special about that site that can answer this question and not the thousands of users here??
joe

#17 Paul G

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Posted 17 September 2013 - 10:15 AM

Well, Roland is a regular poster on Amart. Not going to get that here.

#18 Joe Aguiar

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Posted 17 September 2013 - 10:52 AM

really why would he be a regular poster on there but not here?
joe

#19 Paul G

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Posted 17 September 2013 - 11:29 AM

You would need to ask him that question.

#20 Joe Aguiar

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Posted 17 September 2013 - 11:31 AM

well i cant iam not a member of that site but instead of me taking over this thread i may post that question but thx for that info paul

#21 RussD

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Posted 17 September 2013 - 12:26 PM

The apug yahoogroup has a number of posts on this topic.

See: http://groups.yahoo....abase/4/records

There is a list there estimating numbers of scopes produced and lens types.

Also take a look at the thread "How many scopes have been produced"

http://groups.yahoo....ns/topics/64033

Good reading!

Russ

#22 jrbarnett

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Posted 17 September 2013 - 04:37 PM

Post deleted by Scott in NC

#23 Joe Aguiar

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Posted 17 September 2013 - 05:18 PM

Post deleted by Scott in NC

#24 Scott in NC

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Posted 17 September 2013 - 07:30 PM

After discussion by the moderator team and some judicious editing, this thread is now being returned to the forum. Let's please keep this thread on topic and continue to discuss AP objectives. This is not the place to discuss the policies of Astromart, Anacortes Telescope, or Herb York. Thanks!

#25 Astrojensen

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Posted 18 September 2013 - 04:25 AM

After discussion by the moderator team and some judicious editing, this thread is now being returned to the forum. Let's please keep this thread on topic and continue to discuss AP objectives. This is not the place to discuss the policies of Astromart, Anacortes Telescope, or Herb York. Thanks!


Ah, dang! I missed the fun! That'll teach me to keep an eye on my own threads. :grin:


Clear skies!
Thomas, Denmark






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