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APM 152 ED APO #002

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#101 Richard Low

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Posted 02 January 2013 - 11:36 AM

James using the APM 6" f/8 Chinese ED Doublet. Kindly note that the dew shield is not extended in this photo

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#102 Astrojensen

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Posted 02 January 2013 - 12:08 PM

An even more interesting test would be a comparison between the APM/LZOS 6" f/8 doublet and the new APM ED 6" f/8 doublet. The LZOS doublet is much more expensive, but is there a difference?


Clear skies!
Thomas, Denmark

#103 Gord

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Posted 02 January 2013 - 12:39 PM

Richard, James,

Thank you for taking the time to conduct these tests and share your results. It's very useful to the entire community.

The results seem to match what was expected, the softness in the image coming from the red defocus as seen in the graphs. Related to that, everyone should commend Markus for all the effort he has put in, and for being forthcoming with showing all the design details for everyone to see. Good job Markus! :waytogo: It would be nice if all manufacturers did this.

It didn't sound like you had a lot of time to conduct the testing and I only saw a brief mention of the moon. Did you have a chance to compare images on the moon? Was the softness in the image still present (or more/less obvious)?

Thank you again,

#104 Saied Mabrouk

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Posted 02 January 2013 - 01:12 PM

I'd love to hear how the view through an 8" SCT with a very good Star Test and which is well collimated, compares directly with this APM 150 ED APO, with respect to the amount of details visible on Jupiter!


Thanks James for the great report.
I would also be interested in comparing the APM 152mm ED APO to a good 8" SCT.

#105 Saied Mabrouk

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Posted 02 January 2013 - 01:23 PM

Thanks again James, Richard and all for your comments for making this a great thread.
It looks like the year 2013 will be the year of Chinese made 6" (152 mm or 150mm) ED and APO scopes.
I just came across a Skywatcher on Astronomics website called "Quantum 150ED APO 150mm f/7 ED triplet" using FPL-53 glass with carbon fiber tube priced at $6,999.
I wonder if others 6" Chinese ED APOs will appear under different names and sold by different vendors.

I just found the Quantum 150mm F/7 triplet on OPT website and is in stock for $6,995. It is possible other vendors would have it as well.

#106 F60.4

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Posted 02 January 2013 - 05:18 PM

Thanks both of you for this report. Much appreciated indeed.

#107 James Ling

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Posted 03 January 2013 - 06:11 AM

I'd love to hear how the view through an 8" SCT with a very good Star Test and which is well collimated, compares directly with this APM 150 ED APO, with respect to the amount of details visible on Jupiter!


Thanks James for the great report.
I would also be interested in comparing the APM 152mm ED APO to a good 8" SCT.


Hi All....

Already spoken to my astronomy friends, and this coming weekend, which is two more days from now, going to do another shoot out at one of my friend's house, whereby he will use his 8" edge HD.

And to make things a little interesting this time, we will use his DBK 31AU03 AS camera to shoot the Jupiter..., and you can see how he reproduce the following photo with his Orion 100 F9 ED using this camera....

Regards

James Ling

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#108 Scott Beith

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Posted 03 January 2013 - 08:55 AM

James and Richard - I appreciate the time both of you took to provide us with not only the results of the testing, but also the photos of two great looking scopes. Thanks guys and keep the reports coming! :bow:

#109 SteveG

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Posted 03 January 2013 - 02:15 PM

This comparison was between a $4,000 2-element ED APO and an $11,761 3-element triplet.

I think the 152 ED will trounce the 8" SCT.

A much better comparison would be the ED152 against a TEC140 ($4k vs $5.5k).

#110 Saied Mabrouk

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Posted 03 January 2013 - 05:12 PM

I agree, comparing the APM 152mm ED F/8 with the TEC 140mm F/7 would also be instructive as they are close in price.
But I am not sure that the 152mm ED doublet will "trounce the 8" SCT".

#111 Gord

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Posted 03 January 2013 - 06:36 PM

I would also agree that it's not a foregone conclusion if it is a C8 Edge. Recent Celestron's have been showing very well and even among those there are are exceptional ones. I would not write any recent C8 (Edge or not...) off before hand.

On another note, I mentioned this in the other thread (on color correction).

James, do you have access to a prism diagonal? Especially a quality one, or at least equivalent to the mirror diagonal you will be using?

As I mentioned there, Valery made a comment that a prism would improve the red correction and worsen the blue. It would be a good test to see if there is an effect.

Clear skies,

#112 Saied Mabrouk

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Posted 03 January 2013 - 08:14 PM

Regarding the prism diagonal, some claim that the Celestron prisms made from BK7 glass does help the Red color correction more than the amount it worsens the blue in ED refractors.
I think it would be worthwhile to try the BK7 prism with the APM 152mm ED.
The 1.25" celestron BK7 prism diagonal is readily available.

#113 Bill Barlow

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Posted 03 January 2013 - 08:16 PM

Or even a comparison between the APM 152ED and a very good sample of a C9.25 given it's slightly different optical design and primary/secondary mirror f ratios. Much larger apertures than a C8 or C9.25 should outperform the APM 152ED by a larger margin.

Bill

#114 WarrenS

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Posted 03 January 2013 - 08:30 PM

This comparison was between a $4,000 2-element ED APO and an $11,761 3-element triplet.

I think the 152 ED will trounce the 8" SCT.

A much better comparison would be the ED152 against a TEC140 ($4k vs $5.5k).


Except adding dovetail, rings, finder, and case to match the 152's standard equipment, the TEC costs around $7000, per TEC's website.

#115 Richard Low

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Posted 03 January 2013 - 11:48 PM

On another note, I mentioned this in the other thread (on color correction).

James, do you have access to a prism diagonal? Especially a quality one, or at least equivalent to the mirror diagonal you will be using?

As I mentioned there, Valery made a comment that a prism would improve the red correction and worsen the blue. It would be a good test to see if there is an effect.


James, if we do get the opportunity to do another round of tests together, I will bring the Zeiss prism diagonal. I usually use this with my APM/LZOS 6" f/8 triplet, but that night I brought AP Maxbright diagonal to match with your APM dielectric diagonal.

#116 Mark9473

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Posted 04 January 2013 - 06:20 AM

What I think I recall from previous discussions is that for a colour shift effect from a prism diagonal, you want the "cheaper" BK7 based diagonals, not the high end ones that are said to use other glass types.

#117 Astrojensen

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Posted 04 January 2013 - 10:44 AM

There is no need to use anything else than BK7 in a prism star diagonal. I would be surprised if other glass types are used in high-end models.


Clear skies!
Thomas, Denmark

#118 Saied Mabrouk

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Posted 05 January 2013 - 12:07 AM

It was said in this thread that the Zeiss prism diagonal uses a higher RI glass than the BK7 glass.
Irrespective of what the prism glass is, it is a good idea that Richard will bring the Zeiss prism diagonal and hopefully James and Richard can report on how the two refractors perform with the prism diagonal as compared to the dielectric mirror diagonal. It will be a valuable piece of information.
My understanding is that the Zeiss 2" prism is rather heavy and it will help move the OTA center of gravity toward the focuser, a welcome mechanical side effect.

#119 Jeff B

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Posted 05 January 2013 - 10:13 AM

You know, that's an excellent image for a 4" aperture.

Very nice.

Jeff

#120 James Ling

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Posted 05 January 2013 - 01:09 PM

Hi Jef and All....

Although visually I have not seen through this Orion 100 ED scope, but from the image sent to me, I think it will be interesting to see whether can we image any difference between his ES127 ED triplet and C8 Edge, and my APM ED APO.

We are supposed to meet up tonight at his place for the 3 scopes shoot out, but due to the poor sky and weather condition, with clouds all over the place...We decided to change to tomorrow night, and hopefully the weather will be like last Tuesday , whereby the seeing condition is good for doing the 2 APM scopes shoot out...

In fact tonight I did my own observing at home, using my Ultima 2000 C8, and I can't even get a clear contrast view of Jupiter above 100X....
But I can still see the moon like star that appears in the same Jupiter view, which on that night of the shoot out between the 2 APM, I told Richard there is one more moon like object added to the 4 moons of Jupiter...
And if we knew is a double star, we would have try to split it that night....

Any way, if tomorrow night shoot out is successful, we can clear some of the interesting topics that has been discussed earlier, such as the contrast between the ES and the APM, as well as edge and the APM, and hopefully testing the prism diagonal, which not sure my friend has one, although I have the celestron erect type of prism diagonal...

Regards

James Ling

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#121 EverlastingSky

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Posted 05 January 2013 - 02:14 PM

Really looking forward to this upcoming comparison, should be very interesting to say the least, thanks for doing this!

#122 James Ling

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Posted 06 January 2013 - 05:40 AM

Hi All...

Is just another one and a half hours away from tonight shoot out at my friend's place......

Although weather is similar like last night, with a layer of clouds covering the whole Eastern sector....
But we will proceed for the meet up, unless the weather is becoming worst....

This time Richard's APM triplet APO will be there, and we will have minimum four scopes for shoot out....

My friend, Alfred has 3 mounts standby at his roof-top, so I just bring my OTA, without my losmandy mount....
Much easier this time......and we will start earlier at 8pm....

Will give a brief update tonight when I am back form the shoot out..

Regards

James Ling

#123 mblack

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Posted 06 January 2013 - 07:54 AM

Excellent James, best of luck with the weather.

I have a question if you don't mind. Could you tell me the measurement between the actual center of balance on the tube (mid rings) and the end of the diagonal?

I'm trying to determine if my portable pier is tall enough for the 152/1200.

#124 James Ling

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Posted 06 January 2013 - 12:04 PM

Hi David....

I have just returned home from my friend's house, and took this measurement for you....

The measurement from the center of balance to the diagonal is around 75CM....(focused)

Regards

James Ling

#125 James Ling

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Posted 06 January 2013 - 12:11 PM

Hi All....

Tonight weather is not good , with plenty of clouds covering the viewing sector that Jupiter rises....

As Gary and Clifford already arrived at Alfred home, I also proceed , and then follow by Richard....

The viewing deck is at the roof top, and we managed to set up the ES 127 triplet and the APM ED APO.....

This is the photo taken after the 2 scopes are setup....

Regards

James Ling

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