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Post by nobody on Sept 25, 2015 2:19:53 GMT -5
Hi
Do you automatically get any "paperwork" with an iStar objective lens?
I'm curious whether there are specific test results for the individual lens.
Or just average monochromatic Strehl and minimum PV figures for the lens type?
Perhaps there is no paperwork at all in the box?
The reason I ask is because lens types are regularly superseded.
Which means that earlier lens specs and details no longer exist on the iStar website.
Thanks
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Post by Viktor Z. on Sept 25, 2015 12:08:37 GMT -5
Hi Do you automatically get any "paperwork" with an iStar objective lens? I'm curious whether there are specific test results for the individual lens. Or just average monochromatic Strehl and minimum PV figures for the lens type? Perhaps there is no paperwork at all in the box? The reason I ask is because lens types are regularly superseded. Which means that earlier lens specs and details no longer exist on the iStar website. Thanks Hi nobody, Yes, I got paperworks for both of my lenses, 6" f8 R30 and 9" f7.7 Fraunhofer, that included a five year (!) warranty for each achromatic lens. I got test report for my 6" lens, and I did not get test result for my 9" lens. It may be useful to see test reports, but I better like to see under the sky what my scopes can do. I am not aware if any company provides test reports with Strehl and P-V to specific Faunhofer achromats anymore. My lens surely meet requirements for visual astronomical observations. Both of my iStar scopes' performance far supercedes Chinese Fraunhofer optics that I compared to. My scopes both were and are able to perform well at x300 magnification seeing permits, that's not bad at all from short focal length large achromatic objectives. Chromatic aberration is expected as normal behaviour of this design, especiially at shorter focal lengths. And CA can be improved by using i.e. Baader Semi-Apo filter, Fringe-killer filter or Chromacorr if desired so. I like to use these aids only for Mars and Jupiter otherwise, they are not needed. I was curious though, how my larger lens matches to theory? The Zemax modelling result of a theoretical 9" f8 lens shows similar performance to my real 9" achromat under the stars:) I hope I could answer some of your questions. Viktor
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Post by Ales - iStar Optical on Sept 25, 2015 21:16:10 GMT -5
Hello Nobody and everyone, iStar stopped supplying test reports with lenses one, maybe two years ago, I dont remember exactly. I was warned by few people when we started supplying test reports with each lens. They both told me that it is only going to bring headache for iStar and many fiery discussions on astronomy forums. And yes it did. So after 2 years supplying test results, we stopped sending them with each scope or lens. We still lab test each lens and yes, we do have a test report for all lenses. But we do not share them publicly and will not share them publicly. These test are used to determine if a certain lens meets the quality criteria or not. This means that we will not ship a lens which would test out below our quality specs criteria. On our website, we still supply spot diagrams for most lenses, those missing spot diagrams will get one soon. A spot diagram will give anyone a really good idea of how their lens/scope will perform under the skies. Each iStar lens or telescopes purchased directly from iStar automatically carry a 5 year limited warranty. If such lens is purchased thru one of our dealers, even without paperwork form iStar, the warranty is still valid and in effect, and runs for 5 years beginning the day of purchase. I belive this explains, thank you for bringing this up, best regards,
Ales
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Post by nobody on Sept 26, 2015 2:12:02 GMT -5
Hi Viktor and Ales Many thanks for your helpful replies. Regards n
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