1891 replies to this topic

[25585]

Tele Vue enhanced aluminium mirror diagonals have served me well.

[flamsteed_19]

Hello,
Last Saturday I tested the Agema SD130 SN005 extensively with an Astro colleague in terms of color purity with a view to the waveform test report. In order to reproduce the information from the report, various prisms were used. A Baader/Zeiss 36, an M44 from Zeiss and a 2” Baader/Zeiss. I personally use a 2" TV Everbright mirror. Enough material to compare the Agema and the present test protocol under the real starry sky.
First of all, we were unable to understand the test results of the waveform protocol! But let's be more specific: We tested the color purity of the Agema, SN005, on Regulus and Vega. Unfortunately, the seeing was not always optimal. At 230x (4.5mm Delos) on Regulus, the Agema with the Everbright in focus does not show any false colors, intrafocal a slightly reddish ring, extrafocally this shifts into a slightly blue ring. When the prisms were used, the star test visibly deteriorated and the false colors increased. Larger prisms, clearer false colors. Conclusion, the optics of the SD130, SN005 are designed for use with a diagonal mirror, not a prism. This also makes the suggestion made in this thread to use prisms for the longitudinal chromatic aberrations tested from the waveform protocol unnecessary. But I would also like to emphasize once again that even on Vega, no CA can be seen in focus; the previously described CA only appears defocused. But this real image of Vega also does not match the star test shown in the waveform protocol, the real star test looks different. The statement made in the protocol that the RC index determined means that the SN005 is a semi-apo is not comprehensible. At this point I will not question the waveform protocol or even speculate about the result.
Anyway, I'm more than happy with this Agema, as my astro colleague said, if you can focus on the individual stars in M13, there is little doubt that this is an apo and that's how it was. A comparison between a TEC 140FL and the Agema is still pending, but I will report back then.

Holger

Hi Folks,

 

I would like to add some thoughts on our test with the prisms to put it in some (more) context. Actually, the seeing was bad most of the time. That‘s why we skipped any star testing attempts. We focused on the mirror/prism comparo.

With the mirror I couldn‘t see any CA on Castor, Vega (still quite low) or Regulus in focus. When moving the focuser intra/extrafocal, a slight red/blue ring became visible. Using the prisms these red/blue rings were more pronounced the bigger the prism got. The Wellenform report would suggest the exact opposite. This is at least surprising and suggests that an interferometric test of S#005 should be repeated several times in its (the lens) current state to get reliable data points. The current Wellenform report is not in line with our observations. Neither me nor Holger (I assume) will invest money in interferometric tests as the lens seems to be a very good one. 

When the conditions are right (time, weather, seeing, etc) we will do a comparison between S#005 and my TEC 140FL (a very good sample according to our Jupiter observations but no test report). We will then focus on airydisk uniformity, diffraction rings and so on. 

To give a comparison from memory regarding semi apos: I know the Zeiss AS 100/1000 and AS80/840 from first hand experience, two excellent true semi apos with a blue hue around bright objects like Venus. Agema S#005 is far superior than these two in that regard.

We‘ll keep you posted. In the meantime, be nice to one another.   

 

CS Jochen

[Holger aus Brandenburg]

Hi, Holger. Thank you for sharing your experience and I'm glad that you are happy with your scope.

I also appreciate you commenting on your comparison with prism and mirror diagonals; your conclusions match my experience. I can tell you with certainty that my TEC 140 and TSA 120 prefer my baader bbhs mirror diagonals to my baader bbhs prism diagonnals. I only use prisms with my SCT.

Just one person's opinion, but the only color I care about is IN FOCUS. For example, my SVX doublet shows plenty of color out-of-focus but none that I can discern in focus at high power on targets like Vega. In fact, the color I see with this doublet near focus helps me bring stars to perfect focus.

But, for me, color is only one dimension of performance and I'm probably not as obsessive about it as some. I am, however, very fixated on a clean, intense airy disk with a faint first ring and no hint of coma, collimation, astigmatism, pinching, or other junk light in the outer rings. I have several refractors that struggle with this criteria and I am interested in whether you have seen any evidence of these issues with your Agema? I also wonder whether you saw evidence of the zones depicted in the report - even modest zones are easy to see when star testing.

Lastly, how quickly does it cool and how well does it handle falling temps? I really like how much faster my doublet cools versus my triplets. Some of my triplets take a loooong time to cool (I'm not just talking about absence of a heat plume) and struggle with falling temps.

It would be great to see star test images from a few of these scopes.

Best, Stephen

Hi Stephen,
thanks for your answer. I agree with you, the only thing that matters is whether there are no false colors in focus - and this applies to the Agema SD130. And yes, CA is just one way to evaluate the quality of an optic. According to the Wellenform protocol, #005 should have some zones here. Unfortunately we couldn't check this last Saturday because the seeing was too bad. We will try to catch up on this as quickly as possible. But of course we are largely dependent on the external conditions and the timing has to be right. But the first observations were very good. Moon at 300x still sharp and rich in contrast. But we will see. Since the Wellenform protocol does not fully reflect the impression of the CA, this could also be the case with the surface defects. I'm relaxed and open to the result. Ultimately, despite these "defects", the Wellenform test gave a result of 96% Strehl... that's not so bad :-). The test report from Astroshop shows 97.2%. Both results are well above the guaranteed values ​​of a Zeiss APQ at the time. I think you will also be able to achieve excellent results with the #005

Best regards
Holger

[George Blahun Jr]

The discussion about the mirror vs prism diagonals is an issue that I am still attempting to evaluate in my SD130.  The New England weather this winter and the fact I'm building a new house, has not permitted me to come to any firm conclusions.  I have been using combinations of Baader prism and mirror diagonals with a prism based Baader MK V binoviewer and a Zeiss mirror binoviewer.  I can see some differences in the various combinations, but with variable conditions and numerous eyepiece combinations and the longer and shorter light paths of the combinations, I have yet to make a firm decision, but I am leaning towards the mirror diagonal as giving marginally better views.  To complicate things further, I have tried on a few objects when possible, straight through viewing without a diagonal.  Candidly, since my time to view has been so limited, I was more interested in enjoying the views and not trying to evaluate the minute differences between various accessories.  I'm sure I will ultimately have more data to share, but it may take a few more months before I get to that point.  The scope itself remains superb and I have no complaints about it. 

Edited by George Blahun Jr, 01 May 2024 - 10:02 AM.

[Sacred Heart]

" Candidly, since my time to view has been so limited, I was more interested in enjoying the views and not trying to evaluate the minute differences between various accessories. "

 

 

This definitely sounds like someone who has their priorities right.

 

Joe

[vahe]

 Ultimately, despite these "defects", the Wellenform test gave a result of 96% Strehl... that's not so bad :-). The test report from Astroshop shows 97.2%. Both results are well above the guaranteed values ​​of a Zeiss APQ at the time. I think you will also be able to achieve excellent results with the #005

 

 

Based on what I read in my old APQ literature Zeiss has given average Strehl of 0.95 for their APQ triplets, this number reflects polychromatic Strehl based on three colors, I have no clue what their monochromatic Strehl would be, Zeiss literature only offers the Poly Strehl.

.

Vahe

[saemark30]

https://apq.de/en/pr...ts/150-1200.htm

The new APQ 150mm polychromat is .988

[25585]

" Candidly, since my time to view has been so limited, I was more interested in enjoying the views and not trying to evaluate the minute differences between various accessories. "

 

 

This definitely sounds like someone who has their priorities right.

 

Joe

 

I buy gear to use with my scopes to enhance enjoyment. I am not OCD about it, so long as I like the results. 
 

The issue with what I see, I judge on what I spent. For a SD130, I would want top quality triplet performance, because for less than the SD's price, I bought a TOA-130 NS OTA. (Difference would be less with a better focuser). My refractors get used for general purpose visual, they are not exclusive star &/or planet &/or Moon tools, DSOs look beautiful through them too, and so do daytime views. 

[Sacred Heart]

 

I buy gear to use with my scopes to enhance enjoyment. I am not OCD about it, so long as I like the results. 
 

The issue with what I see, I judge on what I spent. For a SD130, I would want top quality triplet performance, because for less than the SD's price, I bought a TOA-130 NS OTA. (Difference would be less with a better focuser). My refractors get used for general purpose visual, they are not exclusive star &/or planet &/or Moon tools, DSOs look beautiful through them too, and so do daytime views. 

25585,

 

I too use my scopes for everything, except daytime use.  Visual, Imaging.  I, when I was looking for a larger refractor, was considering a SVX130T, never thought of a Takahashi.  From a thread of mine, someone mentioned Agema Optics.  I knew nothing about Agema Optics at that time.  The SD130 and SVX130T at the time were both priced about them same, SD130 being a little more.  After researching and finding out who was behind Agema, and from what previous customers said, I ordered it, SD130.  Yes, an air spaced doublet, performs like my CFF triplet. I say like because it is not fair to the CFF because it is a 92mm and the Agema is a 130mm.  Huge difference in viewing, I only just started to dabble in imaging with it.  Waiting on the flattener.  So fear not, this doublet performs like a triplet, it is an apochromatic telescope. I focuses three beams of light with two pieces of glass instead of three.

 

This scope brought me back to eyepieces.  I just got in from viewing open clusters and globular clusters as well as a few double stars.  I'm bortle 5 - 6 skies, my neighbor has their house corner lights on. When M13 was high enough, with a 8mm Delos I seen some individual stars in the cluster. The Beehive Cluster was wow, that was with a Celestron 40mm 2" eyepiece, my 22 Nagler brought me in closer, was nice but too close to see the hive formation.  Split quite a few double stars, that was a job for the 8mm Delos and my 3 - 6mm Nagler zoom.  A week and a half ago, maybe 2 weeks, I was flying over the Moon with the Nagler zoom set to 4mm.  Never before see such detail in the floor of the Moon.

 

Bottom line, I'm glad I got this scope and I did not mind waiting a year for it, reason..from what others have told me I was going to get a super nice scope.  I did.  Mine is #11.  

 

To be honest, if you are looking for a premium refractor, though you may not have heard of Agema Optics, I say give them a look, a serious look, contact owners and ask questions, the hard questions.  I have looked through two TEC's, a 140 in Lowell Observatory AZ, and a 200mm in Flagstaff as well as my CFF 92 in Tennessee.  Yes, Agema is there with them.

 

Just my personal experiences,   Joe

[RichA]

It would be interesting to know how Agemas perform with bino viewers, which usually have prisms, and which bv to buy.

 

Do people normally put bino viewers into a mirror diagonal?

Straight through binoviewers, like the Zeiss units from Baader (adapted from Zeiss Jena Microscopes) which have no "tilt."  Only way to conveniently see anything higher than 30 degrees above the horizon.

[RichA]

Hi Folks,

 

I would like to add some thoughts on our test with the prisms to put it in some (more) context. Actually, the seeing was bad most of the time. That‘s why we skipped any star testing attempts. We focused on the mirror/prism comparo.

With the mirror I couldn‘t see any CA on Castor, Vega (still quite low) or Regulus in focus. When moving the focuser intra/extrafocal, a slight red/blue ring became visible. Using the prisms these red/blue rings were more pronounced the bigger the prism got. The Wellenform report would suggest the exact opposite. This is at least surprising and suggests that an interferometric test of S#005 should be repeated several times in its (the lens) current state to get reliable data points. The current Wellenform report is not in line with our observations. Neither me nor Holger (I assume) will invest money in interferometric tests as the lens seems to be a very good one. 

When the conditions are right (time, weather, seeing, etc) we will do a comparison between S#005 and my TEC 140FL (a very good sample according to our Jupiter observations but no test report). We will then focus on airydisk uniformity, diffraction rings and so on. 

To give a comparison from memory regarding semi apos: I know the Zeiss AS 100/1000 and AS80/840 from first hand experience, two excellent true semi apos with a blue hue around bright objects like Venus. Agema S#005 is far superior than these two in that regard.

We‘ll keep you posted. In the meantime, be nice to one another.   

 

CS Jochen

Didn't Zeiss have a 4 element S objective that had colour correction that was actually better than a standard apo?  I wonder if they'd ever sold any of them?

[nofung]

As an owner of an Agema SD 130 form the earliest branch, I would like to express my highest satisfaction with this telescope. Before I purchased the telescope, there was no reviews or prior experiences available for this particular doublet. And I was not 100% convinced by the strehl ratio graph and the use of fluorite, as I knew the graph represented the theorical limit and fluorite is no magic if not properly figured. However, I did learn that the owner of Agema, Ed Trygubov, made a lot of high-quality telescopes before. After reading the introductory post and articles written by Ed, I like his willingness to accept challenges and to execute a seemingly simple yet highly difficult design, that is the aspherical wide-gap doublet. The philosophy and story behind the company is what drove me to pull the trigger.

The SD 130 is the largest aperture I have as I will not benefit from larger aperture here in Hong Kong, so I do not have any side by side experience with other refractors with similar aperture.

I make up some points for the quality and performance:
1. These is no question that the mechanic part of the telescope is among the top quality. The lock mechanism in the focuser is the best among all my telescopes.
2. Based on my observations, I do not remember any observed CA in focus. The sharpness of views through this scope make me convinced.  
3. It is heavy but build like a tank.
4. Ronchi double pass test result is attached, tops are inside focus, bottoms are outside focus, spacing of grating is 5 lines/mm.

 

 

I am proud that my scope has been shown in agema’s website and received its first light by capturing a stunning image of the solar eclipse. As I read through this lengthy post, I am surprised that there aren't more Agema owners, as I believed it would be a great success. I apologize for the delayed post, which should have been shared six years ago.

 

Kind Regards,
nofung

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[Kitfox]

^^^ That is about as boring as a Ronchi test can get  (127 LPI Ronchi screen?)...nice scope, nofung!  

[RichA]

The ronchi tests look a bit odd.  There is some minor edge issue, but I noticed the thickened bands at the bottom of the images.  Not certain what that indicates.

[peleuba]

The ronchi tests look a bit odd.  There is some minor edge issue, but I noticed the thickened bands at the bottom of the images.  Not certain what that indicates.

 

Can be diffraction or more likely the edge flattens out -  I do see an edge zone, not at the extreme edge - maybe a ¼ to ½ inch in from the edge.    This is probably causing the artifact in the bands.  But its really slight.  Like ~1/10 wave or less

 

To me, this looks like a very nice lens.  Very neutral and red and blue are balanced with nearly equal but opposite correction.

[nofung]

^^^ That is about as boring as a Ronchi test can get  (127 LPI Ronchi screen?)...nice scope, nofung!  

You are right. 5 lines/mm is equivalent to 127 lines/inch. The setup of the Ronchi double pass test is attached.

 

Good night

nofung

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[25585]

Of all the Agemas, I think the 130 is most desirable. There are plenty of 120 doublets, and 150 doublets, but the only 130  doublet is Agema's. Likewise for APM's 140mm ED doublet, the only one of its kind.

Edited by 25585, 02 May 2024 - 01:03 PM.

[French astro]

There are plenty of 120 doublets

Sorry ... and which ?

For me, the 120 is the most precisely desirable.

F8.7, fluorit doublet, and the icing on the cake, this magical sentence ''no Field Flattener supported''

The sd120 will never be soiled...

Edited by French astro, 03 May 2024 - 08:09 AM.

[weis14]

Sorry ... and which ?

For me, the 120 is the most precisely desirable.

F8.7, fluorit doublet, and the icing on the cake, this magical sentence ''no Field Flattener supported''

The sd120 will never be soiled...

The SD-120 is my choice too for the long focal ratio and focus on pure visual.  I fully expect mine to be around for as long as I'm observing.  Now, I just need it to get here...

[lwbehney]

Sorry ... and which ?

For me, the 120 is the most precisely desirable.

F8.7, fluorit doublet, and the icing on the cake, this magical sentence ''no Field Flattener supported''

The sd120 will never be soiled...

Agree and would add my belief it’s the most beautiful 120 mm refractor currently available in the world. 

[Jeff B]

The ronchi tests look a bit odd.  There is some minor edge issue, but I noticed the thickened bands at the bottom of the images.  Not certain what that indicates.

What Paul said Rich and also note there is a bit of line thickness variation from left to right as well.  I get this too sometimes and is typically related to small camera misalignments, especially inside of focus with fast (F7 and under) optics.  One of the advantages of digital cameras is the ability to just throw out bad shots instantly.   These are good images.  I'd like to see some white light images too as well as at focus images in white and green.

 

That is a very nice sample.  

 

Jeff

[nofung]

The previous Ronchi double pass test images were taken using a handheld cell phone. I have now repeated the test using a camera supported by a tripod for a better image quality. It is not easy to capture the image at focus and these are the best results I could obtain.

 

I have learnt a lot about the Ronchi double pass test through this forum. I would like to express my heartfelt gratitude to all of you who have guided me down this path of testing.

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[nofung]

green and red images.

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[jrazz]

That honestly looks fantastic. 

 

Looks like slightly better in the red and green which means these are for visual? Either way, impressive IMHO.

 

Is this the 130?

[Arhymage]

green and red images.

2 words - Ed Trigubov. I didn't even doubt that it would be something similar, despite the large number of skeptics.