Baader Calcium GEN-II 1¼"

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Baader Calcium GEN-II 1¼"

# 2961590

€ 285.00 Price excl. German VAT tax (19%): € 239.50

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  • Single filter (unstacked!), shows finest solar details in calcium K (Cak) lightFor solar photography only in combination with enclosed AstroSolar photo film ND3.8 or an Herschel prism (sold seperately: Baader Safety CoolCeramic Herschel Prism 2" Photographic (#2956510P , € 645,-) )
  • Enhanced contrast matched to quantum efficiency and s/n ratio of typical CMOS cameras.
  • Reflex-Blocker™ coatings, for maximum immunity to retro-reflection from nearest auxiliary optics, even under the most adverse conditions
  • Identical filter thickness to existing standards, with utmost care for homofocality
  • Reflex-Blocker™ hard coated and planeoptically polished – with sealed coating edges (Life-Coat™)
  • Blackened edges all around, with filter-lead-side-indicator in the form of a telescope-sided black outer rim
  • Supplied with AstroSolar photo film ND 3.8, size: 200 x 290 mm - for pre-filtering sunlight
  • The calcium filter Gen-II must NOT be used in the light path WITHOUT pre-filtering.
  • Visual observation is not possible with the calcium filter, as the eye is practically blind in this part of the spectrum. Never point the telescope directly at the sun with only the calcium filter (without an additional attenuation filter).

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What's the actual size of your 2" filters in "mm" with and without frame/ring? What step down adapter is suggested from a 52 mm to "-- mm"?
Question by: Waqas Ahmad on Oct 10, 2016 7:54:00 PM | 1 Answer(s)

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What are the threads and pitch of your 1.25" and 2" filters?
Question by: Anders G. on Sep 20, 2017 12:55:00 PM | 1 Answer(s)

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Calcium GEN-II Filter 1¼"

The calcium GEN-II filter lets you observe the interesting border region between the photosphere, which is visible in white light, and the chromosphere of the sun, which is reserved for narrow-band H-alpha filters. In addition to the structures known from white light, such as sunspots, you can see the chromospheric network distributed over the entire surface of the sun, which precedes the formation of sunspots, as well as cells of supergranulation and Ellerman Bombs.

The emission line of calcium at 394 nm is already in the near UV. That's why observing the sun at this wavelength is only possible with a camera! Never use this filter for visual observations, as our eye is blind for the harmful UV-radiation, but can be damaged by it.

This filter delivers the best results when used with a monochrome camera (which is more sensitive in this part of the spectrum than a colour camera) and mirror telescopes (because especially refractors with fast f/ratios are not optimized for best sharpness in this part of the spectrum). Nevertheless, many lens telescopes still work fine for calcium observations; unmodified DSLRs may need extremely long exposure times.

All calcium-filters require an additional solar filter in front of them. Part of the Baader GEN-II is a sheet of  AstroSolar Photo Film OD 3.8, 20x30 cm (#2459278 , € 34,-)  to build a solar filter by yourself, so that you can start observing without purchasing any other filters. Of course, you can also use one of the BDSF: Baader Digital Solar Filter OD 3.8 (80mm - 280mm) which are already mounted in a filter cell. On suitable lens telescopes, you can also use a Herschel prism. That way, you can replace the integrated ND3-filter mounted behind the Herschel with a weaker filter to reach shorter exposure times. These filters are already in the scope of delivery of the Baader Safety CoolCeramic Herschel Prism 2" Photographic (#2956510P , € 645,-) .

The calcium GEN-II replaces the older K-Line Filter 1¼" (stacked) # 2458355. Thanks to modern manufacturing techniques, a single filter now achieves a better quality and narrower half-band width (FWHM) of only 5 nm instead of the previous 8 nm; stacking two filters is now no longer necessary. This also makes it possible to use the filter in standard filter wheels/drawers; the low-profile filter mount is only 6 mm high when screwed in.

Baader Kalzium GEN-II Filter: Singlestack und mit moderner CMOS-optimierter Vergütung.
Baader Calcium GEN-II at ED 80/600
Baader Kalzium GEN-II Filter: Singlestack und mit moderner CMOS-optimierter Vergütung.
Baader Calcium GEN-II at 80/910 Fraunhofer

To use the 1¼"-filter at cameras with 2"-nosepiece, you can use either use a filter drawer like the Baader UFC System or a filter wheel. You can always use the filter thread of many barlow lenses as well as 1¼" nose pieces like Baader 1¼" T-2 nosepiece with Safety Kerfs (#2458106 , € 31,-) . You can mount it between two parts with T-2-threads by combining Baader Double T-Filterholder 1¼" (#1508030 , € 33,-) and  Baader T-2 Conversion Ring (#2958110 , € 29,-) ; for cameras with a 2" filter thread, you also need Baader Expanding Ring T-2f / M48m (T-2 part #29) (#2458110 , € 22,-) .

You can find a first review here:

Baader Blogpost:
First Impression of the new Baader Calcium-Filter

The Baader Calcium GEN-II has got all the advantages of the new generation of CMOS-optimized Baader filters:

  • Increased contrast, matched for typical CMOS quantum efficiency and s/n ratio
  • Reflex-Blocker coatings, for largest ever freedom from halos, even under most adverse conditions concerning aux-optics
  • Identical filter thickness to existing standards, with utmost care for parfocality
  • Blackened edges all around, with filter-lead-side-indicator in the form of a telescope-sided black outer rim, to additionally eliminate any reflection due to light falling onto the edge of a filter
  • Each filter coated individually, with sealed coating edge (NOT cut out of a larger plate with coatings left exposed, read more)
  • Life-Coat™: evermore hard coatings to enable a non-aging coating for life – even in a most adverse environment

Baader Blogpost:
New CMOS-optimized Baader Filters

Related Articles

Additional Information

Manufacturer Baader Planetarium
SKU (#) 2961590
EAN Code 4047825048783
Net weight (kg) 0.108
Transmission Range CaK-II
Filter Thickness (without cell) 2 mm
HBW (Halfbandwidth) 5nm
CWL (Central Wavelength) 394 nm
AR-Coating dielectrically coated, planeoptically polished
Special Features only for photographic use behind another solar filter
Filter size 1 25 inch
Filter Usage Solar
Filter mounted Mounted (LPFC 6mm)
Type of Filter Narrowband
Single or Set? Single Filter
Filter shape round

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Overall Average Rating:
7 reviews
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7 Item(s)

Prasad 293/10/2023 21/10/202322:56
  • Rating:
Great Ca-K filter
I bought this fiklter from Alpine Astro just recently. I used it on my Explore Scientific ES80CF, the carbon fiber 80 mm refractor and Baader OD 3.8 filter. I captured images using ASI178MM camera, initially full frame and then using a PowerMate 2.5X into the imaging train. I am quite pleased to see the results. These are my first exposures with this filter. I hope to get better images as I get to know it better.
  • It delivers what I love to see
  • Nothing much
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FLU 96/04/2023 07/04/202306:39
  • Rating:
Baader CaK Filter Gen II 1 1/4"
Anbei die ersten Ergebnisse mit meinem neuen CaK Filter von Baader, also Ergebnisse des first light.
Die Bedingungen waren eher schlecht, es war starker Wolkenzug und ich musste die Aufnahmen immer wieder unterbrechen. Da ich aber auf die Ergebnisse mit dem CaK Filter sehr gespannt war habe ich trotzdem weiter aufgenommen.
Ich muss sagen: die Produktbeschreibung trifft vollumfänglich zu. Die Fackelgebiete treten kontrastreich hervor, einfach genial. In der Bildbearbeitung steckt noch Potenzial, die Aufnahmen entstanden mit einem APO 72/432, ASI 178MM, Baader CaK Filter mit Sonnenffolie ND3,8. Aufgenommen mit SharpCap, Belichtungszeit um die 1ms, Videos zu 1000 frames davon jeweils 10% gestacket mit Autostakkert. Endbearbeitung mit Photoscape, nur leicht geschärft, Helligkeitskurve etwas angepasst und coloriert, das war es schon. Obwohl die aufgenommene, sehr kurzwellige, Strahlung empfindlicher auf Seeingeinflüsse reagiert waren die Aufnahmen schon im Rohzustand sehr gut, das hat mich schon überrascht, insbesondere weil ich die Sonne immer erst nachmittags ins FOV bekomme und über Hausdächer aufnehmen muss.
  • die Ergebnisse, kontrastreiche Fackelgebiete, selbst weit bis in die Sonnenmitte
  • -
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Bethke Michael 163/06/2023 13/06/202308:54
  • Rating:
Nachtrag zum Kalzium GEN II
Bei meiner ersten Sonnenfotografie wurde nun mein selbstgebaute Sonnenfolienblende mit dem Baader Kalzium Filter eingesetzt.
Ich war begegeistert bei dem Ergebnis ,das ich auch Fotografisch festhalten konnte!
Klare Empfehlung von meiner Seite her !
CS Michael Bethke
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Bethke Michael 36/02/2023 06/02/202319:11
  • Rating:
Baader Kalzium Gen-II mit LPFC
Habe mir den Kalzium Gen-II mit LPFC zugelegt ,weil ich mich in der Sommerzeit mehr der Sonnenfotografie befassen möchte. Bei der beigelegten Folie und der Gebrauchsanweisung baute ich mir eine einige Sonnenblende aus einer GFK Platte. Die Sonnenblende wurde laut beiliegender Anweisung zusammengebaut!
Feldversuche (Sonnenfotografie) wurden noch nicht gemacht aber folgen…weil noch ein Bauteil nicht fertig ist….!
Weil ich einen Quattro 200P Newton habe, der einen Innendurchmesser von 220 mm hat habe ich bei meiner Sonnenblende einen Durchmesser von 160mm fräsen lassen ,weil die Folie alles abgedeckt hätte.
  • Folie etwas zu klein ,
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langlois 277/10/2023 05/10/202304:22
  • Rating:
k line genII
trés bon filtre
le k line gen II est vraiment trés bon , les plages faculaire ressortent bien
  • trés bon filtre solaire
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B. Lindqvist 108/04/2023 19/04/202311:17
  • Rating:
Hervorragender Kalzium Filter
Sehr gute Verarbeitung, seien es die Gewindegänge, die optischen Flächen oder die zusätzliche Folie. Die optische Qualität ist hervorragend, einen guten Himmel vorausgesetzt. Längere Belichtungszeiten sind bei Kalzium grundsätzlich nötig.
  • Sehr gute optische Ergebnisse im Bereich des Möglichen.
  • Die mir zu klein geratene Klappbox für den Filter.
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Váradi Nagy Pál 86/03/2023 28/03/202322:39
  • Rating:
Good, as expected
TLDR: no obvious difference, both the old one (double stacked, high cell) and the new genII (single, standard cell height) are **that good**.

Context: for the past almost two years, I've been doing full disk solar imaging on basically each and every clear day, as a lunch break activity. Full disk, so relatively fast optics to fit onto the sensor, see below. With every filter I have, including deep sky filters, because why not, let me see. I used all kinds of Baader filters at least once, and competitors' dedicated, more expensive solar modules for both Hydrogen Alpha and Calcium K are a regular. I think it is important to mention especially the very narrow, Angstrom-wide CaK, since it kind of brackets the expectations to be realistic here, in concordance with the 5nm specification from Baader. Also, I am familiar with the visibility of the active regions -- the highlight of the Calcium K line -- in basically all wavelengths, also through the Venus U filter (to my surprise, people don't really turn it to the Sun), the nothing-special-about-it dark blue filter, the continuum (both the very old one + an IR cut as it leaks in the IR, and the new 7.5 nm fwhm), and even in deep sky Hydrogen Alpha at 7nm fwhm. The active regions are way less obvious towards the red, but are there and post-processing can emphasize them, and in ultraviolet they are almost comparable-ish to the CaK cells' image.

The first time I used Baader's CaK filter, was back in 2015, and I remember being very happy with what I saw. Then, the filter was one of my favorites during the epic (for me at least) 2020 Venus season. So now there is this second generation filter on the market, I immediately placed the order, and got one.

The above being said, I dedicated two days to testing the genII filter, especially against its predecessor, and also against other filters.

2023-03-19, Romania, UTC+2, local noon give or take, my setup: EQ3-mod, mountpusher, Baader Astrosolar ND3.8 Film (brand new), TS-Optics 76/342 TS76EDPH, automated filter wheel with Solar Continuum 7.5nm, CaK old, CaK gen2, uv/ir cut and Venus U, ASI 178MM (cooled)

First of all, the seeing is a tricky thing in blue/UV, so the first day got dropped. From the second session, the three obvious differences:

(1) the form factor -- the higher filter body means the filter wheel may need a mod, in my case placing a T2 washer to prevent the T2 tube from going deep into the wheel's body and collide with the old CaK's edge
(2) the different focus position -- obviously
(3) and the two times shorter exposure time for the new version -- this doesn't really matter for solar imaging, but for Venus it'l be a competitor to the Venus U, trust me.
(4) uhm, basically no difference.

The result of my test: the image quality is basically the same. I thought, at first, that my filter wheel got stuck or landed on the other filter, as I cycled through, or something, but I inspected the position manually, and also the exposure time was a tell tale sign, not to mention the focusing. Maybe it is the fast optics, and at f/8 it would look different, but again, both filters perform in the very same tube, minutes apart, so for full disk, with this sensor size, let us accept the results. Also, the changes in the seeing can be really weird.

The images I posted here received no aesthetic editing, both are stacks with the same wavelets applied to them.

For further context, do check out the full disk Venus U Sun I posted as a review here

I hope this helps those looking for opinions.

  • It delivers the advertised quality, closer to other filters' usual form factor
  • Realistically, nothing really
Thanks for your review. Here is a link to the mentioned Review on Baader U-Filter.
Furthermore our customer has also published a detailed review on his own website:
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