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HALOS – viewed without prejudice
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. And every optical system is different because many products from different manufacturers are involved. All optical surfaces interact with each other in some way. One possibility is that coatings of the camera reflect unwanted light back into the telescope and onto all optical elements in front of the filter. If there is no other optical surface that will reflect the light back to the filter a second time, then it is perfect. There are no halos other than residual halos or scattering, which are unavoidable, depending on the filter design. That's what we mean by our slogan "no halos, no ghosting, no reflections" on our product pages. A filter rarely produces halos itself, which are created inside the filter by internal reflections (this happened to us once in 2015, but we replaced all of these filters). Because the moment there are other surfaces near the filter, it is much more likely that light will be reflected from one of those surfaces, creating halos that... -
Using Smaller-Sized Filters with Baader’s Universal Filter Changer (UFC) (Part 8)
It may appear, at first glance, that the Baader Planetarium Universal Filter Changer (UFC) is for use with larger 2″/50mm sized filters. Not so! You can use popular, and more often used smaller 1.25″, 31mm unmounted or 36mm unmounted filters too. So how can the filter slider drawer made for use with larger sized filters be used with smaller filters? Simple – with a step-down adaptor. Baader call these step-down adaptors AUX Filter Holders. Apart from the UFC Base, and the associated telescope- and camera-side adaptors for your telescope/camera combination, you will need Baader UFC D 50.4 Filter Slider (#2459113, € 40,-) . It is to this particular filter slider that any of the AUX step-down adaptors attach to. We offer three AUX step-down filter holder adaptors for use with the D50.4mm slider: Baader UFC 1¼" AUX-Filter-Holder (requires #2459113) (#2459153, € 9,50) : This adaptor is (female) threaded to accept the standard 28.5mm filter cell threads. Baader UFC D 31 mm AUX-Filter-Holder (requires #2459113) (#2459151, € 9,50) : This adaptor comes with three Allen-key socket screws and washers to securely clamp a 31mm unmounted filter in the AUX filter adaptor holder. Baader UFC D 36 mm AUX-Filter-Holder (requires #2459113)... -
Baader Universal Filter Changer (UFC): Simple photographic use example (Part 7)
We've been asked a few times recently on how to set up the Baader UFC for use with a DSLR and a range of wide-field imaging refracting telescopes. So we thought we would write a short blog on some ways this can be done. Let us start from the telescope side first. All the enquiries we have had, the wide field refractors have 2" barrel focusers, so there is our starting point. The telescope side of the UFC Base (to which everything else in the UFC system is connected to) uses Baader's S70 dovetail adaptors to allow the UFC to fit to telescopes. Looking at the UFC main diagram above Baader do a Baader UFC S70 / 2" SC-thread (f) Telescope-Adapter (optical height: 1 mm) (#2459128, € 23,-) that allows 2"/SC male-thread accessories to be used. More about our UFC Telescope Adapters can be found in our blog: The UFC telescope-side adaptors. We offer our Baader 2" Nosepiece with 2" filter thread (#2408155, € 35,-) or our Baader 2" Safety Kerf nosepiece with 2" filter thread (#2408156, € 35,-) . The image below shows the latter 2" nosepiece attached to the UFC S70 2"/SC adaptor. Using one of these will allow... -
Baader Universal Filter Changer (UFC): Visual use example (Part 6)
Now that we have covered the main overview of the Baader UFC system in our previous blogs (parts 1-to-5), we thought it would be appropriate to give some examples of how the UFC system can be used. Firstly, this is not meant to be exhaustive as there are many combinations of telescopes and accessories. In this blog, we will consider an example of the UFC being used visually. One of the simplest ways of using the UFC visually is with 1.25"/2" eyepieces and with a suitable telescope that uses a 1.25"/2" focuser (or 2" focuser with 1.25" adaptor). If we go back to our first blog (Overview of the UFC system), we said that although the UFC system looks complicated, its actually quite simple. At the most basic level, all that is required is a telescope side adaptor, the UFC Base and a camera/eyepiece adaptor. The image below is a simplified diagram showing the UFC system: camera/eyepiece side adaptors on the left; telescope side adaptors on the right, and in the middle is the UFC Base to which the telescope and camera side adaptors are connected. The three main versions of filter slider are also shown below the UFC Base. ... -
Baader Universal Filter Changer (UFC): The UFC telescope-side adaptors (Part 5)
This blog continues our series on the Baader Universal Filter Changer (UFC) system, with this one giving an overview of the telescope-side adaptors. Attaching a UFC system to a telescope may be done for example, by using a 1.25" or 2" push-fit nosepiece to go into a focuser drawtube for visual or imaging purposes, or to a focal reducer or field flattener for imaging use. The image below shows the current range of adaptors, as well as the spacers (extensions), that are available that allow you to attach the UFC Filter Base (shown below left in the pink box) to a telescope. There are ten telescope adaptors and four telescope-side UFC extension tubes. Except for the two RASA adaptors, all the other eight telescope adaptor "bodies" are fully anodised matt-black. The two RASA adaptors have their inner central portion anodised black (where the light emanates from the RASA front lens group assembly) to stop any reflections. Looking only at the telescope side adaptors in the green box - see below - the following information given is: Type of fitment that the telescope-side adaptor allows (e.g. T-2, M48 etc). Baader product code. The thickness of the adaptor contributes towards the... -
Baader Universal Filter Changer (UFC): The UFC camera-side adaptors (Part 4)
In this latest blog on the Baader UFC System, we will look at the UFC camera-side adaptors. At present there are nine (9) different adaptors that will allow cameras to be attached to the (camera-side) of the UFC Base unit. These are shown in the image below. The image shows the type of fitment to the camera (e.g. T-2, FLI etc), the product code and also the optical path length (thickness) of the adaptor (which is important when using the UFC system with e.g. focal reducer where the camera sensor needs to be positioned at a particular distance from the reducer - we will cover this in a later post). All of the nine adaptors have the following common features: made of aluminium anodised matt-black have countersunk holes are attached to the UFC-base unit using 8 hex screws supplied with the adaptor for secure fitment (screws are flush fitting when fully tightened) The image below shows the camera side of the UFC Base on which all the UFC camera-side adaptors are fitted. Below is an image of a UFC camera adaptor showing the 8 countersunk holes in which the hex screws are inserted for securely attaching the... -
Baader Universal Filter Changer (UFC): The UFC Filter Slider (Part 3)
In this, our 3rd part of the Baader Universal Filter Changer (UFC) system, we will look a little more closely at the UFC filter sliders. Below is an updated simplified diagram of the Baader UFC system. A general introduction you can find here, and the second part about the UFC Base here. The image below shows the three UFC filter slider models available. More about these are individually discussed later. All the UFC filter sliders feature: a knurled (removable) aluminium handle for holding the slider. This allows the slider to be easily held, inserted and removed from the UFC base. a 4mm long x 3mm diameter brass pin : The brass pin allows the slider to be seated correctly in the UFC Base. Once the filter slider is fully inserted, the brass pin "sticks out" of the locating hole in the UFC Base. The brass pin also serves another main purpose. Rather than pulling on the filter slider handle to remove it, which may potentially disturb the position of your telescope, you gently push on the brass pin to "eject" the slider away from the UFC Base magnet. You then simply, and easily, pull the slider out with the aluminium handle... -
Baader Universal Filter Changer (UFC): The UFC Base (Part 2)
In the first part of this series of blogs about the Baader Universal Filter Changer (UFC), we gave a general introductory overview of the UFC system. In this second part, we will look more closely at the main component of the system - the UFC Base - and outline its features. In the UFC overview diagram below, the UFC Base is the component in the middle (between the two red arrows). The UFC Base is also known as, and sometimes referred to, as the UFC filter chamber. For the purposes of this and future blogs in this series, we will refer to the UFC Base as just the "Base". The Base has a number of functions or purposes. It allows: The range of Baader UFC telescope-side adaptors and spacers to be attached allowing the UFC to be connected to a telescope. The Baader camera-side adaptors to be attached so that cameras can be connected to the filter system. The filter slider, which holds your filters, to be easily inserted and removed, and also to be held securely when in place (thus allowing the filter to be used for its imaging or visual purpose). In the box **Please note: the photographs of the Baader UFC Base... -
Baader-UFC (Universal Filter Changer) – the ever-growing filter chamber (Part 1)
The Baader Universal Filter Changer (or UFC for short) is a very versatile simple system for using, mounting and changing (or swapping) filters in and out of a light path. The UFC can be used for imaging where you may want to swap different filters (e.g. LRGB) between a camera and a telescope but do not want the bulk, or expense, of a filter wheel. The UFC can be used between a camera and a Celestron RASA 11/14(36) or a Starizona Hyperstar system where the overall size and shape of a filterwheel causes issues. You can also use the UFC for visual purposes where you can easily switch between different colour filters between a telescope and an eyepiece. The image below shows the standard "exploded" diagram of the parts that make up the Baader UFC. We've colour-coded it to highlight the main different parts (see below). At present there are 30+ parts to the whole UFC system in total. The large number of components may seem somewhat overwhelming at first glance, and can lead to some confusion, and that the system is complicated. However, we hope this series of blogs will help show how simple, and effective, the UFC is.... -
Baader's RASA 8" UFC telescope-side adaptor (Part 9)
It may only be an adaptor but this little piece of anodised metal will let you use a range of popular astroimaging cameras with Baader Universal Filter Changer (UFC) on Celestron's RASA 8 telescope thus allowing you to swap filters quickly and easily. Unlike the Baader UFC telescope adaptors for the 11″ RASA and RASA 36 that are mated to the corrector lens group cell face-plate and secured with the knurled retaining ring, this adaptor screws onto the male outer threads of the lens group housing itself. So you would remove the RASA 8’s retaining, the T-2 or C camera adaptor and then the clear filter, and then attach the UFC Base with its RASA 8 UFC adaptor in place. The adaptor has female M84 threads on the telescope side and uses Baader’s S70 dovetail on the UFC/camera side for secure fitment to both the RASA and the UFC Base. This S70 UFC adaptor itself only adds a minuscule 1.4mm to the optical path, but what is the overall optical length with the rest of UFC system in place? The UFC base is 13mm thick, and with the typical types of UFC camera adaptors (T-2/M48 etc) used being 2mm, the... -
Why choose UFC Quickchange-Frontfilters with DSLR-Cameras?
Info about using quickchange-frontfilters with the UFC in combination with DSLR-cameras There are no monochrome DSLR-cameras on the market, so a filter holder (e.g. the Baader-UFC) may seem quite useless for DSLR imaging, but if you take a closer look, there are indeed some interesting use-cases. Many owners of DSLR-cameras remove the complete UV/IR-blocking filter and use this simple way to improve the sensitivity especially for H-alpha – but because of the costs, they decide not to add a new blocking filter with increased H-alpha-transmission. But as a result, you have to find another way to block the IR- and UV-parts of the spectrum so that they will not decrease the image quality. You can use the UFC to mount such a UV/IR-cut filter in front of the camera - and to quickly replace it with another filter, without touching the camera. Narrowband filters are not perfectly suited for a DSLR because of the Bayer-matrix, but especially a 35 nm H-alpha filter will show the emission nebulae better. Especially in light-polluted areas the UHC-S-filter is very helpful. You can use the Baader-UFC to switch between several filters fast and easy. This way you can see which filter is the best for... -
Free Download: 3D-printable UFC-Case for filter sliders
You are the owner of one or more UFC filter sliders and are looking for a way to safely store the filter sliders with mounted filter? Then we have the solution for you: our 3D-printable UFC-Case for filter sliders. This box with hinged lid holds all UFC filter sliders. We offer you the STL files (consisting of two parts) as free download, you only need to login with your customer account or register on our website. Below is the download link (which will only work when you're logged in). Please also note the information below about the Creative Commons License. The file is optimized for printers according to the FDM procedure. Ideal would be a heated pressure bed. Material with little warping or heated space. Preferably PLA. As a primer we recommend Bluetape. Case for UFC filter slider as 3D-printable .STL file * (Size: 644.2 KB) Downloads: 150 * You have to Login or Register to download this file The download file is licensed under the Creative Commons License CC BY-NC-SA 4.0. You may pass on the file under Attribution © Baader Planetarium GmbH as well as linking the license and indicating any changes. The file may not be used... -
Testreport ATT 1/2018 Baader-UFC - the Swiss Army Knife of filter technology
The current issue of Astronomy Technology Today introduces the UFC System - the tester was impressed: What do you get if you cross an Erector Set with some giant metal washers, a plethora of variously-sized openings, a filter tray that slots in like a clip in a Glock, and, well, all sorts of other stuff? The Baader Universal Filter Changer, or UFC for short. And when Baader says “universal,” they mean it. Read the Testreport ATT 1/2018 Baader-UFC . Mark Zaslove shows all wonderful things you can do with the Baader UFC (Universal Filter Changer).
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Additional Information
Manufacturer | Baader Planetarium |
---|---|
SKU (#) | 2459120 |
Optical length (mm) | 2 |
Inner Diameter / Clear Aperture (mm) | 47 |
Outer Diameter | 89 |
Outer Connection (eyepiece/-camera-sided) | Thread, 2" (50,8mm) |
Type of Adapter | Camera Adapter, Changer Adapter |
FAQ
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HALOS – viewed without prejudice
Halos - no problem!
A tutorial by Andreas Bringmann on how to remove halos around bright stars using Photoshop image editing – if desired.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. And every optical system is different because many products from different manufacturers are involved. All optical surfaces interact with each other in some way. One possibility is that coatings of the camera reflect unwanted light back into the telescope and onto all optical elements in front of the filter.
If there is no other optical surface that will reflect the light back to the filter a second time, then it is perfect. There are no halos other than residual halos or scattering, which are unavoidable, depending on the filter design. That's what we mean by our slogan "no halos, no ghosting, no reflections" on our product pages. A filter rarely produces halos itself, which are created inside the filter by internal reflections (this happened to us once in 2015, but we replaced all of these filters). Because the moment there are other surfaces near the filter, it is much more likely that light will be reflected from one of those surfaces, creating halos that may not be removable.
There are so many combinations of camera (windows), field flatteners, correctors, etc., that it is common for "halo-free" filters to be involved in halo production in some unfortunate cases - but not guilty themselves. The RASA optics set a good example.
Small cause - big effect The anti-reflective coatings of the camera windows of different manufacturers differ slightly. Shown here are two cameras from different manufacturers, the left one reflects more in the green spectral range, the right one more in the blue spectral range. These small differences are responsible for the fact that the photos taken with the left camera in combination with OIII filters show strong halos, while with the right camera and the same filter halos will appear hardly noticeable.
In contrast to broadband RGB filters, narrowband filters reflect much more of the relevant spectral wavelengths near the emission lines. At the same time they produce a much darker sky background. Therefore, they are much more involved when halos occur. It is also no contradiction that cheaper, wider band filters show less halos. Because the narrower the filter, the longer the exposure time, the better the contrast. And all this increases the chances of stronger halos around more stars in the field.
We know from customers that the windows in front of the chips of certain camera models are more likely to produce halos than other cameras. And some more inexpensive flattener/reducer/correctors are also more often involved in the problem. A third problem is the lack of space to adjust the distances between the optical elements only slightly - as is the case with almost all primary-focus mirror systems. RASA and Hyperstar are also good examples here.
To find the source of the reflections, you can try turning the filter around so that the (more reflective) front is no longer facing the light source, but the camera sensor. It can help by chance that the reflection of another wavelength range from the other filter surface simultaneously reduces the halo appearance. Try this with unmounted filters. Very large overlapping halos are indications of reflections from distant surfaces. If the halos are closer to the edge of the image and eccentric to the star, they are likely caused by a curved surface such as a lens, e.g. from a flattener in front of the filter.[br]
C11 Hyperstar + ASI 1600 mm w/o filter, 60s exposure| © A. Bringmann.
Veil Nebula NGC 6960 with bright star Cyg52, single subframeBut: Are Halos really terrible? We notice that at the time of the Culimation of certain objects such as the Horsehead Nebula IC 434 or the Veil Nebula NGC 6960, there are especially many "Halo Complaints". The reason is quite simple: it is impossible to extract the image information of the nebula without halos if there is a bright star in the field that produces a strong halo even without a filter.
This fact and this appearance of the object is widely accepted - and it doesn't look any worse than the spikes on the photos taken with Newton reflectors. Some APO photographers even add artificial spikes to their photos.
From his 2.6M Private Observatory Andreas Bringmann is creating stunning deep sky images
Even photos from professional observatories show halos because they are unavoidable (not of concern) when a big field is main emphasis - and nobody hides the haloed results. More information can also be found in the document: Problems with filters can have the strangest Causes
If you send us your photo with a halo and give us detailed information about the optical setup (camera, reducer, flattener, corrector, filter, telescope with aperture ratio and all their manufacturers and positions) we might find a clue to find the source for the halo. But most likely you can't get rid of it - unless you are using an extensive image processing like our customer Andreas Bringmann, as described in the PDF Halos - no problem!
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Off-standard single filter sizes from Baader - why not:
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:
Sorry (we know it would be so very much cheaper in production - and we would be so much more flexible to fill special requests) - but we have decided long ago to not cut or saw our filters from large plates because this would leave the coating stack open and mutilated (with microscopic cracks) all around, prone to aging and peeling.
Many times we had the chance to inspect our competitors filters after several years of use (due to our 30+years of servicing SBIG-CCD-cameras/and filter wheels) and we realized already 15 years ago how moisture and heat stress can deteriorate even most modern hard coatings, slowly peeling off from the carrying substrate over time, unless the coating stack is sealed all around the filter stack.
As a consequence - in order to create our filters to remain impermeable - we only offer all filter substrates already cut to final shape and run each substrate on an double deck auto-polisher to achieve perfect optical flatness and freedom from cone errors.
Then we do individually coat these substrates in 500 pc per run as minimum to fill a complete coating chamber, in a way that the coating stack (many times 50+ layers) applied onto each filter won't reach to the very edge of the round or square substrate, so that the coating stack remains completely sealed from all sides. In this way we can ensure that our filters will not age at all.The sad effect is that we cannot offer other sizes unless the inquired production quantity were in the range of 250 to 500 pc (depending on size) and the tooling rings or square holders will be paid for, which serve to precisely center each individual filter substrate within the rotating calotte inside the coating chamber. Sorry - as explained above - we just will not coat onto large plates and cut any shape from them, also because such large plates cannot be polished optically flat in the same way we do it.
For your most urgent need and for single piece solutions we can only recommend to order the next larger size of our respective filter and have that cut to shape by an ophtalmologist locally. We can supply the round filters without the metal cell in such cases; square filters come without cell in any case.
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Unmounted Filters – which side should face the telescope?
Question in Detail:
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"?
Answer:
Always put the more reflective side towards the telescope side. To guide you we already put a small arrow on the filter rim, on those filters were the position matters. This arrow indicates which face of the filter should be directed towards the sky (telescope-sided). All cell-mounted filters are already oriented in a way that the most appropriate filter face is facing the sky when the filter would be mounted directly onto the front end of the nosepiece of a camera.
If you mount your filter the other way, any reflected light would have a short way to the camera sensor, resulting in a higher risk of getting some kind of back-reflections inside the camera field. Many sensors have highly reflective areas near to the light sensitive area, also the area with the bonding contacts is sometimes highly reflective.But: this is true only for instruments without optical elements near to the focal plane. If you have f.e. a coma corrector, field flattener, focal reducer, focal extender (to a lower degree due to concave surface), or in extreme cases a whole lens group for more complex field corrections a few centimeters in front of the filter it could be useful to flip the filter against the rule from above (thus having the arrow pointing away from the telescope). Cause in such cases the likelihood of reflections from the sensor could be lesser then fort- and back- reflections from such glass-surfaces. If in doubt, it helps to make some test images from a star field with bright stars, using the filter in both ways for comparison.
Should you really have some reflections with both positions it can be more effective to add a spacer between filter and camera, eventually shifting the reflection out of the image field. With focal correctors having curved surfaces changing the filter-lens distance could help also.





