Christoph Kaltseis is a Photoshop expert and an experienced astrophotographer. 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. The Hubble Space Telescope team has been using his method for over 2 years. If you receive any damaged items on your delivery, please state the full extent of the damage on the driver’s delivery note when signing for the goods. High quality optical filters are not cheap. Hence, it is also no surprise if observers complain about „unaccountable“ picture deterioration when using cheap filters in front of binoculars, tele-compressors or Barlow lenses, either visually or photographically. The higher the magnification, the softer and more blurred the picture appears when using a cheap filter, for both visual and photographic observations. Both thread sizes come with our proprietary pitch - which is not the same for the female and male threads. Also a only mag 16.2 faint C/2022 U2 (ATLAS), which is overtaken by the mag 5.8 bright C/2022 E3 (ZTF), could be photographed:

The Baader C2 SWAN-Band-Filter with ≤ 15 nm Half-Band-Width isolates the two C2 lines at 511 and 514nm – leading to a contrast gain for comet hunters! If you cancel you must return the goods to us at your own expense. You are responsible for the risk of loss or damage when you return the goods, so you should take out adequate postal insurance to cover their value. Based on these considerations, soon after the release of their new CMOS filter range, I asked Baader Planetarium if they would lend me a CMOS blue filter Baader RGB B-Filter – CMOS-optimizedThe images were taken on January 29, 2023 directly from the outskirts of Mannheim, Germany. The test series consisted of exposures with a normal LPS luminance filter (Hutech IDAS LPS-P2) and single exposures with the Swan band filter. The Baader C2 SWAN-Band-Filter with ≤ 15 nm Half-Band-Width isolates the two C2 lines at 511 and 514nm. Ich habe beide Filter an C/2023 E1 (ATLAS) verglichen. Komet Atlas ist derzeit (Mitte August 2023) noch um 9m5 hell und damit von einem dunklen Standort aus etwas für zumindest größere Ferngläser. Der Komet ist recht groß, 6'. Today, filters are placed in the optical path of the telescope, even well in front of the focal plane. This definitely requires some degree of plane parallelism and accurate production of the filter glasses.

In the old days, colour filters for visual planetary observations were not screwed in the front part of the eyepiece, but were simply placed between the eyepiece and the eye. Plane-parallelism of these filter glasses was not important, because they were not in the optical path of the telescope.

Please allow 3 working days for us to process a return. We will organise a suitable date and time for our couriers to collect the item Quite often we receive requests for a single filter in an off-standard size. In all cases we are sorry that we must answer as follows: 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) thread The commercial disadvantage of this technology lies in the fact that we cannot produce any filter size by simply cutting it from a sheet. For custom-made filters in a requested size we need a minimum production run of 250 pieces. Each filter coated individually, with sealed coating edge (NOT cut out of a larger plate with coatings left exposed, read more)

I just bought LRGB 36mm unmounted filters. I have question: which side of filter should be placed towards telescope? Is it better way of distinguish than "more shiny surface towards telescope"? Just in time for the introduction of this new C2 Swan-Band filter, a bright comet, comet C/2022 E3 (ZTF), offered itself as a test object and one of Baader Planetatrium’s customers (Mr Andreas Bringmann) was one of the first testers. The image of that comet is below and was taken from a city with an almost full moon. The image easily shows the amount of “doubly ionized carbon” (the carbon excited to glow radiates only in the wavelengths 511 nm and 514 nm ) emitted by the comet. The filter shows the complete extension of the ion cloud around a comet:The Swan-Band filter is indeed a very special filter with central wavelength at 512 nm and ≤15nm half-width – for the first time without any O III transmission. It is therefore suitable for a variety of unusual applications some of which require further investigation, whether as an “O III parallel filter” to better remove stars from the image, or as a solar filter in a previously inaccessible section of the spectrum. We would be pleased about your experience reports also apart from the comet photography. Der Himmelshintergrund war mit dem Baader-Filter deutlich dunkler, das Bild ansprechender. In etwa wie der Vergleich von UHC (ohne S) und [OIII] an Nebeln. Das war von den Bandbreiten her auch zu erwarten. The comparison between the luminance and swan-band images clearly shows the true power of the 15nm Swan-Band filter over a full-spectrum luminance filter. The doubly ionized carbon from Comet C2022 E3 (ZTF) is clearly visible in the images taken with the Swan-Band filter. Due to environmental influences such as light pollution, these are completely absent in my luminance images.