296 replies to this topic

[jrbarnett]

The glass is an f/8 triplet using FK-61 and a Lanthanum element.

$3999

We have our minimums, but nothing published. It has worked out very well for the rest of the EDT lines and our scopes over the past decade.

Delivery would be Early Spring 2018, Possibly late February if everything went perfectly.

That's pretty amazing.  The Kunming 6" doublets were $3000 with just "so-so" color correction.  Assuming these are truly apochromatic or nearly so, a $1000 premium is pretty modest.

 

Best,

 

Jim

[jrbarnett]

Before buying such an high end refractor, I alway have a look to some websites that share several tests reports. Always interesting...

Other data and foucault test can be found on the web also.

 

Wolfgang Rohr in Germany        http://rohr.aiax.de/hp_new/

AiryLabs in France*                    http://airylab.fr/rapports-de-mesure/

Tommy Navratil blog Austria       http://interferometrie.blogspot.fr

 

*(test reports are available on the French site only .fr, not the .com)

 

Why searching such data on the web?

 

Because a large apo refractor is a very special telescope, almost irational, It deals with passion.

Getting such a refractor is a quest, and getting some numbers is a part of this quest...

 

That said, and to be more rational, manufacturiang such a large triplet with a constant and good quality is not easy. It requiques state of the art lens figuring but also state of the art cell machining and assembly and fine tuning.

Concurrent products (i.e. larger triplets than 120mm) have shown a variable quality from sample to sample, from excelent to lemon.

 

So the quality control is a key point for these large triplet and providing the customer with guaranted specifications is a good idea.

On the other hand, $4k for 150mm of unobstructed, collimated, reasonably quick cooling aperture that meets or exceeds the diffraction limit (hopefully; ~0.80 Strehl of better) in at least three visual wavelengths when focused on green, seems entirely rational to me.

 

Reflector apologists aside who incessantly try to diminish the negative impacts of central obstructions on contrast using theory, an eye trained in using large aperture unobstructed scopes understands that central obstructions, even tiny ones, have a material adverse impact on actual contrast in the field.  The beautiful thing about refractors is that they don't need theories like contrast transfer or that below a certain size central obstruction theoretically shouldn't be detectable.

 

Refractors kick arse precisely because they don't hide behind excuses.  That is, they have no obstructions to hide behind.  

 

- Jim

Edited by jrbarnett, 11 November 2017 - 05:04 PM.

[olivdeso]

 

 

 

Before buying such an high end refractor, I alway have a look to some websites that share several tests reports. Always interesting...

Other data and foucault test can be found on the web also.

 

Wolfgang Rohr in Germany        http://rohr.aiax.de/hp_new/

AiryLabs in France*                    http://airylab.fr/rapports-de-mesure/

Tommy Navratil blog Austria       http://interferometrie.blogspot.fr

 

*(test reports are available on the French site only .fr, not the .com)

 

Why searching such data on the web?

 

Because a large apo refractor is a very special telescope, almost irational, It deals with passion.

Getting such a refractor is a quest, and getting some numbers is a part of this quest...

 

That said, and to be more rational, manufacturiang such a large triplet with a constant and good quality is not easy. It requiques state of the art lens figuring but also state of the art cell machining and assembly and fine tuning.

Concurrent products (i.e. larger triplets than 120mm) have shown a variable quality from sample to sample, from excelent to lemon.

 

So the quality control is a key point for these large triplet and providing the customer with guaranted specifications is a good idea.

Not all testing sites are non biased.  I've seen Rohr cop a fair amount of flack for biased reports, or reports that aren't representative of what others have found, suggesting bias, or worse, a dislike for a certain manufacturer.  I tend to take online report sites like the above with a grain of salt.  Anyone on the Internet can write anything that they like - it doesn't means its true!

 

 

 

I agree concerning Rohr test reports. At the other hand, Rohr shows data and interferograms, not only his conclusion. So there is still a lot a valuable information on his website.

 

 

The test reports of the 2 other websites, show that in real world, .91 Strehl withouth significant astigmatism is already very good for a large triplet.

 

 

I mean, theorical Strell is one thing, actual strell,  measured on manufactured instruments is another thing and this is what counts at the end.

[Phil Cowell]

 

The glass is an f/8 triplet using FK-61 and a Lanthanum element.

$3999

We have our minimums, but nothing published. It has worked out very well for the rest of the EDT lines and our scopes over the past decade.

Delivery would be Early Spring 2018, Possibly late February if everything went perfectly.

That's pretty amazing.  The Kunming 6" doublets were $3000 with just "so-so" color correction.  Assuming these are truly apochromatic or nearly so, a $1000 premium is pretty modest.

 

Best,

 

Jim

 

Jim,

  The prototype I can confirm is truly apochromatic. 

Edited by Phil Cowell, 11 November 2017 - 10:47 PM.

[Planethunter80]

 

 

The glass is an f/8 triplet using FK-61 and a Lanthanum element.

$3999

We have our minimums, but nothing published. It has worked out very well for the rest of the EDT lines and our scopes over the past decade.

Delivery would be Early Spring 2018, Possibly late February if everything went perfectly.

That's pretty amazing.  The Kunming 6" doublets were $3000 with just "so-so" color correction.  Assuming these are truly apochromatic or nearly so, a $1000 premium is pretty modest.

 

Best,

 

Jim

 

Jim,

  The prototype I can confirm is truly apochromatic. 

 

Gentlemen I know these scopes are far beyond my pay grade. However they are precisely what still keep me interested in astronomy like a little kid. Dreaming of possibly owning a scope that I may never have the chance to.

 

It's that dream,that inspiration,that longing and desire that keep us going on a day to day(or night to night)basis. So I guess a lack of knowledge(as well as some ignorance as to how lenses work)keep me from really being preocuupied with any type of numbers what so ever.

All I would love is a scope that produces a tack sharp image with the ability to make me feel as if I am in orbit around the lunar surface.

 

So I guess what I am truly trying to say is that it's scopes like this prototype that make me look at the website for the scope(like a little kid in the 1970's)looking at a Sears Christmas catalog and dreaming each night of that one item I would give up all my toys for 5 years to have for just one Christmas.

 

No matter what the final numbers may be I am just thankful that Astronomics(and others)put out these scopes so I can feel young one more time as the pic of this refractor gets my pulse racing and my heart pumping. To me it's Absolutely Beautiful and that is what means the most hands down!  

[daquad]

AT152_Focuser.jpg

Close up of focuser

Your 3.7" focuser, the dew cap, rings, 2" twist-lock adapter and carry handle are the spittin' image of those on my APM 152 ED Apo.  You can rotate the entire focuser and independently rotate the housing of the 2" accessory holder.  So the camera, or whatever you are using can be rotated without rotating the entire focuser.  I love this focuser; buttery smooth,rock solid and can hold anything I can put on it.  I wonder if Kunming is the manufacturer of the AT?

Attached Thumbnails

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[daquad]

 

Does anyone know the Strehl of the APM 152 doublet? A lot of visual folks are happy with that, whatever it is. Also wonder about the 140. I know that may seem a bit off topic but I am curious in a comparative sense.

Mine was 0.93 and performed great. The AT152 at 0.92 should outperform the APM. Nice indeed

 

I'm confused.  Why would the AT triplet at 0.92 strehl outperform the APM doublet at 0.93 strehl?

[mogur]

 

[jay.i]

Well my question is, the AT152EDT should outperform the APM140 how? Could be CA, SA, field curvature, sharpness, or many other things that I don't know enough about to mention. Heck I barely know enough about optical aberrations to even be capable of discussing them. But I think it's important to clarify the statement.

[MGD]

I think he was talking about his former APM152 not an APM140. In that case he may be correct about a .92 triplet beating a .93 doublet since they both use the same ed element basically. At least that's how I understood his statement,maybe he'll clarify. 

Mike 

[daquad]

I think he was talking about his former APM152 not an APM140. In that case he may be correct about a .92 triplet beating a .93 doublet since they both use the same ed element basically. At least that's how I understood his statement,maybe he'll clarify. 

Mike 

I thought the comparison being considered is with scopes of same aperture.  Hence my question how can a 0.92 triplet outperform a 0.93 doublet?  It is possible, of course, if the triplet's strehl were effective over a broader spectrum, but that data is not available for the AT.  Strehl comparisons mean very little without a knowledge of the applicable wavelength range.  My APM 152 ED APO has a strehl of 0.95 at 0.55 microns, but the average strehl from C to F wavelengths is 0.8.

 

OTOH, if the comparison is between a 152 triplet of strehl 0.92 and a 140 doublet of 0.93, then I would certainly expect the triplet to be the "better" scope optically.  First, the triplet has a larger aperture and second, being a triplet, I would expect it to have a high strehl over broader spectral window.  But again, those strehl values mean little if given only for a single wavelength.

 

Dom Q.

[CounterWeight]

That is what I thought... scopes in the list, which is selective and incomplete, just to demonstrate the prices and apertures from commonly known names in the industry.  I thought the point was it is a very, very reasonable price for a ~150mm triplet of a known quality, and I agree. 

 

Also agree about the importance of Strehl ratio in different visual bands, the polychromatic Strehl, averages being what they are...  at least you know it was looked at and measured for real world.  Brings into focus the overall expected performance.  If three crossings used and if all three are .91 to .93 then I think many, many folks might be happier than expected.  But who here has that info for their scope?  I know Takahashi publishes their info, but it's not universal to all manufacturers.

 

 

Jim,

  The prototype I can confirm is truly apochromatic. grin.gif

 

This 'at the eyeball' is in the end what really matters though isn't it?

[Jon_Doh]

 

The scope will fall between .90 and .92 Strehl.  We asked about going higher, but the added expense would take the scope to a price point that I wasn’t willing to approach.  

Does that mean if an example slips through at .93 it will be rejected?

 

It will be returned to its Chinese manufacturer who will relabel the refractor and place it for sale on AliExpress.

[daquad]

That is what I thought... scopes in the list, which is selective and incomplete, just to demonstrate the prices and apertures from commonly known names in the industry.  I thought the point was it is a very, very reasonable price for a ~150mm triplet of a known quality, and I agree. 

 

Also agree about the importance of Strehl ratio in different visual bands, the polychromatic Strehl, averages being what they are...  at least you know it was looked at and measured for real world.  Brings into focus the overall expected performance.  If three crossings used and if all three are .91 to .93 then I think many, many folks might be happier than expected.  But who here has that info for their scope?  I know Takahashi publishes their info, but it's not universal to all manufacturers.

 

 

Jim,

  The prototype I can confirm is truly apochromatic. grin.gif

 

This 'at the eyeball' is in the end what really matters though isn't it?

Unless you are into AP.  Then it is what's "at the chip" that really matters.

[Adam E]

 

That is what I thought... scopes in the list, which is selective and incomplete, just to demonstrate the prices and apertures from commonly known names in the industry.  I thought the point was it is a very, very reasonable price for a ~150mm triplet of a known quality, and I agree. 

 

Also agree about the importance of Strehl ratio in different visual bands, the polychromatic Strehl, averages being what they are...  at least you know it was looked at and measured for real world.  Brings into focus the overall expected performance.  If three crossings used and if all three are .91 to .93 then I think many, many folks might be happier than expected.  But who here has that info for their scope?  I know Takahashi publishes their info, but it's not universal to all manufacturers.

 

 

Jim,

  The prototype I can confirm is truly apochromatic. grin.gif

 

This 'at the eyeball' is in the end what really matters though isn't it?

Unless you are into AP.  Then it is what's "at the chip" that really matters.

 

THAT is what I would love to see.  And, not a heavily processed image.  I would love to see nothing but a simple stretch on a bright starfield, even just a linear stretch, or even better, raw data.  I just want to see a starfield with no processing other than a stretch.  No saturation adjustment, no fringing refuction, and no sharpening.  Amazing or disappointingly colorful, I would love to see point blank what this guy will do at an imaging chip.

 

Opinionated / interpreted visual star testing is, to me, one thing, but hard data is another.  Is there CA, and if there is, does the price tag make it tolerable.  Thats where I end up when thinking about making the APO leap of faith at something not made by the big names and expensive makers (AP, Tak, TEC, LZOS, etc...).

Edited by Adam E, 15 November 2017 - 08:11 PM.

[jay.i]

See, Adam, I truly intended to do photography with my setup when I bought it. I still do. But after using it and seeing things with my eyes, I just couldn't bring myself to put a digital CMOS sensor behind it. It felt so cold. So wrong. How could I take such a beautiful view and reduce it to only a few million pixels?

 

These days, I still would very much like to do photography, and I would trust an unedited image (given some parameters to know it hasn't been altered) more than I would trust a single person's opinions from one or two nights out. As cold as it may be, the digital rendering of the image will likely find more flaws than a human eye, and is still, in my opinion, the better way to judge optics. One can gain actual quantifiable data by analyzing the optics with camera sensors, and that will be more scientific than a visual test any day. But, a visual test is still just as important, as minor flaws picked up by a camera may not matter for even critical visual use. I still think both forms of analysis should take place if one claims to be seriously judging optical quality - digital and analog, as it were.

[Adam E]

Jay, I can appreciate your viewpoint, and to each their own, but think of me as a cold blooded reptile.

 

I would just like to see the pudding, as it were.  My pudding that is, imager-chocolate, not that vanilla visual stuff. 

[stevew]

 

 

Does anyone know the Strehl of the APM 152 doublet? A lot of visual folks are happy with that, whatever it is. Also wonder about the 140. I know that may seem a bit off topic but I am curious in a comparative sense.

Mine was 0.93 and performed great. The AT152 at 0.92 should outperform the APM. Nice indeed

 

I'm confused.  Why would the AT triplet at 0.92 strehl outperform the APM doublet at 0.93 strehl?

 

The color correction in the triplet should be better than the doublet.

And from the reports I have read about the color correction of the doublet [very good] the triplet should have excellent color correction.

Edited by stevew, 15 November 2017 - 09:57 PM.

[jay.i]

I can absolutely see both sides though, that's the thing. The emotional part of me is really drawn to visual observation, taking in the inexplicable with one of your core senses, as close as you can get. But the intellectual side of me revels in knowing -- the extra detail retrieval in post-processing helps one truly inspect something with more precision. The emotional part of me says that feels too processed and detached from the real thing, but the brainy side says there's just as much truth in the images as there is in what you see with your eyes, if not more. I would love to do some widefield (~500mm) Ha imaging, to see what my eyes can't. There is so much interesting detail to be seen, and since I can't see it with my eyes, it doesn't feel as "wrong". You can tell I'm conflicted about this whole visual/imaging thing...

[glend]

Everyone's vision deteriorates with age, starting from about age 21. Most do not accept that, claiming their eyes are trained, how averted vision enhances their powers, etc. Claims that most any eye specialist will debunk with the facts of visual changes due to age, environmental factors,etc. No two observers will see exactly the same thing the same way, which is why any visual assessment of a telescope is subjective.

[Wildetelescope]

 

 

Does anyone know the Strehl of the APM 152 doublet? A lot of visual folks are happy with that, whatever it is. Also wonder about the 140. I know that may seem a bit off topic but I am curious in a comparative sense.

Mine was 0.93 and performed great. The AT152 at 0.92 should outperform the APM. Nice indeed

 

I'm confused.  Why would the AT triplet at 0.92 strehl outperform the APM doublet at 0.93 strehl?

 

The real question is to what wavelength does that Strehl number refer?  A doublet with a StrehI of 0.95 in the green region could easily drop below 0.8 out in the red and violet parts of the spectrum(check out the APM website to see this for the 152 mm Doublet curve.  For what it is worth,  I would speculate that a Triplet mated with the appropriate glass elements would provide a more consistent performance over a wider range of wavelengths than a doublet.  Otherwise, why add the third element?

 

Here is an even BETTER question.  What does that drop off on the edges of the visible spectrum really mean for what the individual sees at the eyepiece?  Some people report seeing no color with that particular scope(APM 152 ED doublet), while others claim to see some small amount. I believe them all.   I suspect that says more about an individual's eyesight and seeing conditions than it does about the scope itself:-). In the end I think if the Triplet (or doublet for that matter) gives you good contrast on Jupiter at high magnifications, and shows little or no color on Jupiter on a bad air night, and lets you split some challenging double stars, you got a good deal for 4K.  This is more or less the performance I get out of my vintage AP 5 inch triplet, that does not have a single FPL 51 or 53 element in it.  I would pick up the 6 inch version of an 80's vintage Starfire in a heartbeat.   The caveat is that I am more visual in my observing and not too picky when I do image.   More serious imagers may legitimately prefer the newer high end scopes, which is perfectly understandable  

 

I guess my point is that if they execute the design well,  the AT 152 triplet has some very real potential to be something special, and provide a break through into the "big refractor" territory for a larger portion of the community.  I am looking forward to seeing how this turns out.  

 

JMD

[RogeZ]

I think it was already described by other users, but i would believe the polychromatic strehl of the triplet being higher overall. The APM152 that I had was a terrific scope but a triplet made of the same glass should outperform it. A small difference in strehl at one wavelength wont compensate for the overall better color correction. AP should be much better in the triplet as well. FK61 is a capable glass with a good design and execution.

 

Now, what I would ask Michael to do is make sure that the scope has enough accessories to support the extra cost/weight of the triplet.

 

I'm talking FF, FR, 3" FF, 3" FR, etc. This scope will have a much bigger following if it can be used for other than visual. 

 

I have a CGEPro gettting ready for this scope I will be ordering one Mid-March...

[mogur]

I think the number of people using this scope for AP will be in the 1% range given the mount it would take.

[glend]

The ability to detect color, any color, has more to do with the intensity of the light source activating your color receptors in your eye. The visual observer has to have a very bright sky object to be able to detect color, as usually its going to be shades of grey thanks to our eye design. This is why imaging is an important tool in the determination of colour correctness.

As far as the comment of the mount required is concerned, the AT152 would hardly be noticed by a CGX, or a G11. The jury will be out on its suitability for imaging, as there are many fine Triplet APOs in the market. We need an imager as a Beta tester.

Edited by glend, 18 November 2017 - 04:36 PM.

[Phil Cowell]

. The jury will be out on its suitability for imaging, as there are many fine Triplet APOs in the market. We need an imager as a Beta tester.

Well if your in Centeal NY, bring your imaging camera. I have an AP900 you can setup with the AT152 on.