Ljungmann

Daystar says: "STANDARD SE GRADE filters are specified as: Spectral uniformity: The mean peak wavelength of all 12 mm. dia. areas shall be within 0.5 Angstrom of the full aperture wavelength measurement and PROFESSIONAL PE GRADE filters are fabricated and qualified to very high uniformity tolerances to the specification of Spectral uniformity: The mean peak wavelength of all 12 mm. dia. areas shall be within 0.05 Angstrom of the full aperture wavelength measurement." Daystar says that every Quark will meet the SE uniformity. This means that a filter can vary from minimum SE to PE quality. And will have a bandwith from about 0.5 to 0.25 A. I do have a test sheet from my 0.6 A Quantum SE filter. It has a mean peak wavelength of 0.16 Angstrom all 12 mm. dia. areas. If you look at the data about 75% of the filter area are PE quality. The SS filter are PE quality. A note: My Daystar etalon is an old Del Wood ATM etalon. In the Quark tests I will look at the uniformity and will see if there are areas what I will call completely off band. If it is somewhere in the middle of the field, it is a no go. Towards the edge it is ok. The biggest problems I do see is that the filter can not get on band at all. That is a return to the seller. The most delicate problem I do see is a lack of contrast. It is a big problem. The transmission profile of a mica etalon can vary a lot. You can se the details, but it looks like that you are using sunglasses while you look at the Sun. In my world it kills the filter. If you don't know about that part of the filter world, you are lost in space.... We did notice the problem many years ago in a direct test between to great h-alpha filters and a brand new Quantum 0.4A filter. We tried a lot of configurations until the only explanation was the mica transmission profile. To my knowledge the biggest problem with some Quantum filters has been in that department. I do the combo Quark tests with a 5x or 2.5x Powermate. The 2.5x on the Baader 8" Triband and the 5x on the 80mm or 60mm APOs. Without the Powermates with the normal Quarks. Denmark is a small county🙂 But most Quarks are more than okay and are a great value! I do have a Quark - a Calcium filter and its a good filter.

It is me who helps buyers in Denmark when they need an opinion about their Quark filters. If the seeing is okay, it takes 5 minutes to do it. I short visuel inspection where you just point the filter towards the Sun. If there is any variations it is a bad filter. I use a 8" Baader Triband SCT or a 80mm APO to evaluate the filters bandpass, spectral uniformity, finesse and the h-alpha center line setting. I use my 0.3A SolarSpectrum and 0.6A Daystar SE Quantum filters in the process. The Quantum filter is a former ATM filter from Del Woods. I did order a spectrographic scanning when Daystar did the upgrade. It is easy to do the test and give my astro friends an idea how they filters do behave. I still dont understand the quality control at Daystar.