161 replies to this topic

[Psion]

Hi all, I received the Zerochromat few days ago. The telescope is very light (complete with a rings, a dovetail and a focuser 14.4kg) and is easy to operate. The collimation is very easy and quick. Maybe you remember my last test about Istar Asteria TCR 204-8 R35, I enclose a similar pictures taken by Sigma DP1 and zoom eyepiece Vixen 8-24mm. You can see, CA not detectable, specially by the eyes.

 

 

 

[Mark9473]

Well there's a lot more to optical quality than just CA. Looking forward to your further tests.

[jrbarnett]

Hi all, I received the Zerochromat few days ago. The telescope is very light (complete with a rings, a dovetail and a focuser 14.4kg) and is easy to operate. The collimation is very easy and quick. Maybe you remember my last test about Istar Asteria TCR 204-8 R35, I enclose a similar pictures taken by Sigma DP1 and zoom eyepiece Vixen 8-24mm. You can see, CA not detectable, specially by the eyes.

 

Zerochromat_test-6.jpg

 

Zerochromat_test-5.jpg

 

Zerochromat-5.jpg

Well corrected for secondary spectrum.

 

Looking forward to your optical quality review.

 

Regards,

 

Jim

[Psion]

Lot of days was cloudy, today is nice weather. I'll make a star test and Ronchi test.

[BillP]

What are the specs on this again?  Focal ratio?

[jrbarnett]

Lot of days was cloudy, today is nice weather. I'll make a star test and Ronchi test.

Great!

 

Would it be possible to do a daytime image with one of your 8" Newtons at the same magnification, to compare the daytime image quality of the Zerochromat with a similar aperture reflector?

 

Regards,

 

Jim

[jrbarnett]

What are the specs on this again?  Focal ratio?

203mm f/12.

 

"From the wavefront error, it can be gleaned that the Strehl ratio for the 'Zerochromat' is over 0.995, and diffraction-limited over the field of view. Stars are perfect pin-points over the entire field, and at high powers, the Airy disc and rings are textbook."

 

http://www.zerochrom...t/features.html

 

OTA weighs 22# and includes a motorized Moonlite focuser.  Special intro price of $4500 USD.  Actual price $5250 USD.

 

- Jim

Edited by jrbarnett, 16 September 2014 - 10:07 AM.

[Benoit]

I am also in the middle of testing a zerochromat, i'm in the San Francisco bay area.

 

So far, I can confirm that the CA is very well corrected but still working on a few problems before doing a more rigorous wave front test (will probably use a Roddier test initially)

 

-- benoit

[Terra Nova]

That is a very interesting and attractive telescope. Reminds me a bit of the old folded Unitron refractors, though they were babies compared to this one.

[Psion]

 

Lot of days was cloudy, today is nice weather. I'll make a star test and Ronchi test.

Great!

 

Would it be possible to do a daytime image with one of your 8" Newtons at the same magnification, to compare the daytime image quality of the Zerochromat with a similar aperture reflector?

 

Regards,

 

Jim

 

 

I haven't 8" equipment in my area now, but what result you expect from that? Newton will be better CA corrected, but this is not important, isn't it?

[jrbarnett]

 

 

Lot of days was cloudy, today is nice weather. I'll make a star test and Ronchi test.

Great!

 

Would it be possible to do a daytime image with one of your 8" Newtons at the same magnification, to compare the daytime image quality of the Zerochromat with a similar aperture reflector?

 

Regards,

 

Jim

 

 

I haven't 8" equipment in my area now, but what result you expect from that? Newton will be better CA corrected, but this is not important, isn't it?

 

Daytime same site, same target image quality comparison.  Maybe compare the TEC 140 to the Zerochromat on the same chimney at the same magnification (i.e., same scale) to see if the Zerochromat is delivering more data as its larger aperture says it should be.

 

- Jim

[Psion]

I make only Ronchi test today, because is a terrible seeing. I think the telescope is not excellent, but quality of picture is very good. Vega is in a centre FOV and I cannot see any CA on magnification 100x  (Panoptic 24mm). Stars are pinpoint from edge to edge, also in Panoptic 35mm. The sky is rather bright (20.35 MSA), but I can see NGC 6992, 6960 without problem, after that, much better with Lumicon Deep Sky filter. Globular M15 is beautiful and I can resolve lot of stars in it. The telescope resolve Epsilon Lyrae without problem with small magnification, but seeing is blurring a picture in the eyepiece. A colours on the stars are very good visible (like Albiero).

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[SteveC]

Here's another link with scope details,

 

http://www.zerochrom...-refractor.html

Edited by SteveC, 16 September 2014 - 07:26 PM.

[chboss]

Very interesting telescope, I was hoping for a long time to hear some hands on experiences from users.

Looking forward to more reports.

 

best regards

Chris

[wh48gs]

Here's another link with scope details,

 

http://www.zerochrom...-refractor.html

 

What those plots show is that the green to blue/red separation is about 0.6mm, or f/4000 secondary spectrum. But since spherochromatism is roughly as pronounced as defocus, the actual error is smaller, comparable to f/8000 secondary spectrum  (same longitudinal aberration produces twice larger p-v error than spherical aberration at paraxial focus, and 8 times larger than at the best focus). Best focus, as it is the case in the presence of secondary spectrum, is not the green focus, but shifted somewhat toward blue/red. The error in blue (at the best focus) is about 1/3 wave p-v, and in the red closer to 1/2 wave. The averaged red/blue error is about 0.4 wave, which is the level of 100mm f/30 achromat, whose polychromatic visual (photopic) Strehl - also at the best focus shifted from the green focus - is about 0.91 (deeper red and violet are not shown, but they are of little consequence in visual observing). Since the correction in blue is somewhat better than in the red, and eye sensitivity in dark conditions shifts toward the blue end, the actual chromatism correction should be still little better than in a red/blue balanced 100mm f/30 (200mm f/60) achromat.

 

Vla

[Psion]

I made test between TEC140 and Zerochromat. I make only White Balance, any others. In both telescope was a picture better (sharper and better contrast).

 

The Zerochromat is very good also for DSO like a galaxy, a globular, a cluster and a nebulas. I tested a few 2" star pairs, very nice resolution with an Airy disks. I will test some 0.6" pairs.

Attached Thumbnails

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Edited by Psion, 21 September 2014 - 03:28 AM.

[GlennLeDrew]

I gather these are afocal images. If so, there are variables which can affect such a test...

 

- The camera may not be equally centered and aligned in both cases, and so eyepiece aberrations can make a differing contribution.

- If different eyepieces are used, results are immediately suspect.

- A difference in system f/ratio (at the camera's sensor) will result in improper image scale for comparison. That is, do not strive for identical image scale if aperture differs, but instead identical exit pupil (with the same camera lens zoom and f/stop settings). Aberrations can only be properly compared at given system f/ratio when imaging, or given exit pupil when visually assessing.

[Psion]

Yes, any test such like this is only orientation, it depends on a lot of parameters. For me is important, Zerochromat is very good optical design, you can reach a big diameter for nice money and it has 40% of weight compare with 200mm APO refractors.

[jrbarnett]

I made test between TEC140 and Zerochromat. I make only White Balance, any others. In both telescope was a picture better (sharper and better contrast).

 

The Zerochromat is very good also for DSO like a galaxy, a globular, a cluster and a nebulas. I tested a few 2" star pairs, very nice resolution with an Airy disks. I will test some 0.6" pairs.

Thanks!

 

Very helpful reference , even with variables considered, consistent pretty much with what I'd expect of 45% greater resolving power, and to my eye (and it could be because of color saturation differences) there looks to be maybe just a hint of magenta or deep violet on the stack and wire in the Zerochromat image that is missing in the TEC shot.

 

- Jim

[Psion]

I can see in original pictures from a Zerochromat little bit better resolving on a darker brick structure. The Zerochromat has twice more light from the sky (+ 1 magnitude) and I can use very comfortable eyepieces 12mm, whilst for the TEC 5mm. Both telescopes have advantage and disadvantage. The camera sees more violet than eyes (specially in the night), indeed.

[ATM57]

I am also in the middle of testing a zerochromat, i'm in the San Francisco bay area.

 

So far, I can confirm that the CA is very well corrected but still working on a few problems before doing a more rigorous wave front test (will probably use a Roddier test initially)

 

-- benoit

So... Are we having fun yet?

 

Scopejunkie

[Psion]

I am back from a 3 days astronomy party in our country. I very surprise from the telescope and it has very good optical design. I observed a lot of objects last night. The telescope has flat FOV and stars are pinpoint from edge to edge in my 35mm and 25mm Panoptic eyepieces. Nebula like M42, M17, M16 or small planetary nebula looks like from a much large telescope than 200mm.

Today I observe the Sun with my friends (I use 35mm Panoptic and Zeiss Mark V binocular head with two 25mm Panoptic). They say, "fantastic picture". I make a picture, but original from an eyepiece is much better. I can say, TEC 140 is a brilliant telescope for observing the Sun, but the Zerochromat is a winner and degrade the TEC, sorry, but this is true.

 

I believe, Peter makes new second telescope and it could be like APO TMB!

 

 

[Astrojensen]

Okay, now I'm definitely very interested.

 

 

Clear skies!
Thomas, Denmark

[george tatsis]

Just wondering after these comments how many folks have started checking what they have left in their bank accounts.    

 

George

[ATM57]

       

Just wondering after these comments how many folks have started checking what they have left in their bank accounts.    

 

George

I'm one of them. This scope has generated an itch that I may have to scratch.

 

Scopejunkie