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For adapting any cell mounted Baader 2 inch Filter onto a camera lens with 52mm front filter thread you will need:
#2408166 Baader DSLR 2" Filter-Holder M48 / SP54: https://www.baader-planetarium.com/en/baader-dslr-2%22-filter-holder-m48sp54.html
#2958052 Baader Lens-Adapter-Ring SP54 / M52: https://www.baader-planetarium.com/en/baader-hyperion-dt-ring-sp54m52-for-dtadapter-iiandiii-and-hyperion-eyepieces.html
Based on the SP54 thread, we offer many more adapters for various camera threads, our so-called Hyperion DT-rings. https://www.baader-planetarium.com/en/catalogsearch/result/?q=sp54
Both thread sizes come with our proprietary pitch - which is not the same for the female and male threads.
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. 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.
For 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. It is a mixture of a queer pitch and under-/over-dimensioning . We will not want to declare this as a standard and get bashed up for it. It works for us and is a result of 20 years adaptation to fit our filters onto all crazy threads we have seen. And inspite of this - every now and then there comes another "dragonboat-eyepiece" were even our filters may not fit...
2. because the filter cell would need to be ~ 12 mm high - a killer criterium for most users as there is not enough space in the optical train.
3. since lucky imaging cameras have small chips - not needing larger filterrs than 1 1/4"
4. BECAUSE WE ÀBSOLUTELY DO NOT WANT TO SUPPORT LOOKING AT THE SUN IN UV-LIGHT !!!
You can't combine K-Line and Solar continuum, as one filter only lets green light pass, and the other one only deepest blue.
You can replace the Solar Continuum with the K-Line-filter, but the image will probably still be too dark - and it will almost certainly be much too bright if you remove the ND3-filter, too. This depends on the sensitivity of your camera and on the f/ratio of the telescope, so we can't say which filter will be the right one.
The photographic version of the Herschel wedge contains three 2" ND-filters. If you do not have the photo-version of the Herschel, you can also buy them seperately at
As the K-Line-filter is only 1.25", you can also buy only the 1,25"-filters for photography.
You may need more than one filter, if you use e.g. a Barlow lens for higher magnifications - then you need a stronger filter like ND1.8 for lower magnifications and e.g. ND0.9 or even N.0.6 for those times when the seeing permits highest magnifications.
Even the small 1.25" CaK-version does require 8 mm cell length û and the demand is always so low that K-line filters are somehow far from making commercial sense...
So we will continue to offer the 1.25" K-line – and we are working on a new generation of these – but there will be no 2" ones, sorry to say.
And BTW: we had experimented extensively with single substrate CaK-filters, but solar work is entirely different to DeepSky in terms of energy throughput. We found it impossible to achieve deep enough off-band OD – other than using four full coating stacks
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|Net weight (kg)||0.01|
|Filter Thickness (without cell)||2 mm|
|CWL (Central Wavelength)||394 nm|
|AR-Coating||dielectrically coated, planeoptically polished|
|Special Features||doube stacked|
|Filter size||1 25 inch|
|Filter mounted||Mounted (classic 8mm)|
|Type of Filter||Narrowband|
|Single or Set?||Single Filter|