![]() The moment you insert any type of filter into the optical setup, which consists of your specific camera, the appropriate flattener/reducer or coma corrector and the telescope, the filter becomes part of this unique optical system. There are usually three types of filters mentioned, when Energy Rejection. In H-alpha, the sun is far less bright than in white light, so there would be practically no light left to observe. Since it is occasionally asked: A Herschel wedge or a white-light front-filter cannot be used as an ERF because it also darkens the H-alpha line. Ideally, it reflects the solar energy energy instead of absorbing it and and does not heat itself up in the process as well - that's why these filters are called Energy Rejection Filters (ERF for short). If we look at the solar spectrum, it becomes clear that such a filter must primarily block visible light. At the same time, this prevents the air in the tube from heating up - the telescope remains close to the ambient temperature, and there are no air turbulences inside of the OTA due to temperature differences. This is done most effectively by a filter in front of the telescope. The purpose of an Energy Rejection Filter is to prevent as much solar energy as possible from entering the telescope in the first place and thus avoid excessive heating of the etalon of an H-alpha filter. It's not everyday that one could find a new sharpening technique or algorithm that would increase the sharpness of delicate threads of a nebula or dust lanes at the bright centre of a galaxy without significantly increasing noises or over-saturating stars in astronomical images. Christoph reveals the tricks he uses to get the finest details out of his stunning images: "The secret behind Christoph Kaltseis astro images" on Picture Instruments - News () Read a very interesting in-depth interview with Christoph Kaltseis on Picture Instruments about his experiences in astrophotography. The plugin has already proven many times that it can meet even the high quality standards in astrophotography. The tool sharpens images using APF-R with just a few clicks, even without much prior knowledge. The Hubble Space Telescope team has been using his method for over 2 years.Īdobe Photoshop has now introduced the easy-to-use APF-R Photoshop CC plugin for Christoph's complex process. In recent years, he has developed APF-R (Absolute Point of Focus), an innovative image sharpening process in Photoshop that has attracted considerable interest among experts. This filter can be mounted either inside of the 2" eyepiece or in the 2"/1,25"-reducer if you rotate it, you can change the brightness according to your needs by rotating the eyepiece/adapter.Īn additional IR-cut-filter is not necessary for visual use if you use the filters included with our Herschel wedge it *may* be helpful to achieve sharper images with a CCD if the camera does not have an integrated IR-filter - but then you will usually need the filter for deep-sky-photography, too.ĪPF-R goes online as official plugin in Adobe PhotoshopĬhristoph Kaltseis is a Photoshop expert and an experienced astrophotographer. Only then can it be replaced with the ND1.8, if the image is too dark.įor visual use, you must always use an additional filter behind the Herschel wedge and the ND3 - this may be the Solar Continuum (which is included with the Herschel), another ND-filter or the single 2" polarizing filter #2408342. The ND3-filter is included with the Herschel Wedge and must always be used for visual observations it may only be removed if you are using a camera for projection and very high magnification/ long f-ratios. And inspite of this - every now and then there comes another "dragonboat-eyepiece" were even our filters may not fit. ![]() It works for us and is a result of 20 years adaptation to fit our filters onto all crazy threads we have seen. We will not want to declare this as a standard and get bashed up for it. It is a mixture of a queer pitch and under-/over-dimensioning. Traditionally US-companies used to do a UNF-based pitch and the rest of the world went for metric threads - but these do vary from 0.5 to 0.75.įor this reason it does not make sense to publish our non standard pitch because our pitch is made to cope with all existing metric and US-pitch standards - and as said - our solution has evolved from sheer necessity. ![]() This is our own proprietary "emergency solution" for uniting a world were manufacturers all over the world copy from each other - to the point that there are almost a dozen different pitches in use for male and female threads. Our 1.25" filters have a M28.5 male (and M28.5 front female) thread / our 2" filters have a M48 male (and M48 front female) threadīoth thread sizes come with our proprietary pitch - which is not the same for the female and male threads. Collimation Tools, Cleaning and Maintenance Products.Barlow lenses, Coma- and Glaspathcorrectors.Special eyepieces (Guiding, Diascope etc.).
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