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Two Questions: Will this Barlow be effective at 2X? How can this lens provide up to a 90mm diameter image circle when the lens itself is only 42mm(?) in diameter and the light path is convergent, not divergent, between the lens and the image plane?
Question by: Nick D. on Feb 9, 2018 11:44:00 AM | 1 Answer(s)
Can I use this as an adjustable strength barlow on a refractor that already has be corrected for flat field or a Newtonian that is already coma corrected, or do I need to remove all existing correctors from the optical train ?
Question by: Stuart on Feb 9, 2022 2:05:00 AM | 1 Answer(s)
Two questions: 1. What is the mechanical/optical length of this item, so that I can calculate distances vs. available backfocus of my optic. (I will use an M63-T2 ring of 3mm optical length and the available backfocus is 93.48mm.)
2. I have an APO astrograph (WO Star-71II). Since its field is already flat, is this item suitable or will it over-correct the field flatness?
Thank you.
2. I have an APO astrograph (WO Star-71II). Since its field is already flat, is this item suitable or will it over-correct the field flatness?
Thank you.
Question by: Jim Lindelien on Mar 25, 2021 1:43:00 AM | 1 Answer(s)
What is the Strehl ratio of the FFC at 393nm? I know this is not designed for solar use, but I really need a corrector optic for the calcium k-line wavelength because almost all telescopes have zero correction below 400nm. I would like .95 strehl or greater at 393. anything less than .9 is unacceptable. I do have suitable energy rejection filters and a thermal shield, so there will be no exposure damage thresh hold. You guys make a hydrogen alpha imaging telecentric but do not make a k-line telecentric, and there are none on the market. I must either make one myself or find an optic somewhere.
Question by: apollo lasky on Feb 13, 2018 7:14:00 PM | 1 Answer(s)
In follow-up to my first question, please tell me the mechanical length of this device, really its optical length in mm from mating surface to mating surface excluding the protruding threads. The charts you mentioned do not provide this information, and I need to determine if there is sufficient backfocus distance on my optic to install it.
Question by: James W Lindelien on Apr 12, 2021 9:06:00 PM | 1 Answer(s)
Following my previous question for solar imaging with FFC behind the Baader Herschel prism, can the FFC be used with any of the ND filters available in the photographic version of the Herschel prism, including the 0.6?
Also I see that you have a solar photo of photosphere on the leaflet of FFC. That means it can be used for solar imaging despite the "How to use" instructions below?
Also I see that you have a solar photo of photosphere on the leaflet of FFC. That means it can be used for solar imaging despite the "How to use" instructions below?
Question by: Alexandros on May 16, 2021 4:09:00 AM | 1 Answer(s)
I just bought a Flat Field converter, and I'm trying to understand the drawing, about focusing distances.
I understood that for magnifying 4 times (as exemple), I have to set camera, or his schip, at 150mm from the FFC. this part is ok.
but my question is for the other side. what does that mean "focus of telescope without FFC? the different distances given in the drawings, are they distance I have to put in front of the FFC? between the telescope and the FFC?
Thanks for your help.
I understood that for magnifying 4 times (as exemple), I have to set camera, or his schip, at 150mm from the FFC. this part is ok.
but my question is for the other side. what does that mean "focus of telescope without FFC? the different distances given in the drawings, are they distance I have to put in front of the FFC? between the telescope and the FFC?
Thanks for your help.
Question by: fabien landrivon on Aug 25, 2020 10:16:00 AM | 1 Answer(s)
- Description
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Details
Baader FFC – 2" / T-2 Fluorite Flatfield Converter
The CaF2 Fluorite-Flatfield-Converter can be combined with every optical system for photography and visual observations as best and most sophisticated barlow lens in the world
- apochromatic, fully multi-coated lenses (note: w. multicoated Fluorite-lens faces
- Resolution in lines is 10x higher than that of the best projection eyepieces
- The only barlow lens with two putty elements using genuine calcium fluorite (CaF2). Calculated for a 90 mm image circle, for uncompromising sharpness performance in the days of medium format cameras. Still unsurpassed in imaging performance today.
For almost 20 years (as well as 20 years ago already) our customers had asked again and again: "Do you have a barlow lens or projection eyepiece – but with a flat field – which can be used with medium format (6x7 Pentax) cameras for imaging sun, moon and planets, but without the typical loss of sharpness?"
This bothered us back in those times , and finally one of the designers of the Zeiss APQ lenses calculated the ultimate projection system with a flat image field in 1997. To actually make this design become reality, extreme types of glasses were needed. In this case, two multicoated fluorit-lenses - at that time and until today - a nightmare to produce.
The result was an optical system with an unmatched sharpness, with a ten times higher resolution of line pairs than a Zeiss Abbe eyepiece. Even so the days of emulsion film cameras are long gone, this lens system has persisted to be "the sharpest barlow ever made".
By changing the distance to the camera sensor, you can vary the magnification between 3x and 8x. The optimum line resolution is set at 4x magnification, then you have the full sharpness over an image circle of 90 mm diameter. On the axis, the sharpness is only limited by your telescope – even at a magnification factor of 15x. We have tested this at an AstroPhysics lens telescope. Slowly slowly even the large diffraction limited field of 90 mm will become of importance again - with the advent of ultrafast and giant CMOS-cameras covering a field of 70 mm in diameter.
The FFC can be connected onto every T-2 thread and its 2" main body likewise fits into every 2" eyepiece clamp. With the help of our Astro T2™-System and the M 68-System you can connect it onto a whole world of telescopes.
For best results, you need to keep a certain distance to the original focus point. Please take a look at the PDFs in the Dowmload-section for technical information
Customer statement: The FFC on a Carl Zeiss APQ 130 - Januar 2004
When you are observing and photographing planets, the power and quality of each part in the chain is very important. The result is heavily influenced by design, material, polishing quality of the optical surfaces and the utmost in suppression of straylight. Even small optics can then deliver very good results.
About two years ago I had used the Fluorit-Flatfield-Converter by Baader for the first time ans was positively surprised. I could achieve a better contrast and resolution with the Baader FFC than with normal barlow lenses of good quality.
I use the projection system with up to 8x magnification for taking photos of the planets. This is a rather long setup, and the price seems high, too. But it is well worth the money if you take a look at the build-quality and the achievable results. During the Mars-opposition in 2003 I could take some images with the APQ 130 and the FFC. For such a relatively small telescope, I think they are really pretty good!
Best regards
Dr. Harald MichaelisHow to use CaF2 optical systems. FFC-warning about possible loss of warranty:
The Baader-FFC contains lenses which are made of real Calziumfluorite-crystal. CaF2 has got an impressive refractivity which enables construction of the ultimate lens system that can deliver an incredible amount of sharpness across a very broad spectral range. No other barlow lens design can combine a similar sharpness with such a large image.
Unfortunately, such sophisticated optics are very sensitive to tension caused by temperature differences.
Under no circumstances must CaF2 be exposed to sudden or high changes in temperature. Do not use it for photographing the sun – the fast and high changes in temperature could destroy the Fluorit-lenses. Defects caused by thermal stress can be detected and measured here in house and are explicitly excluded from the warranty.
Also avoid fast changes in temperature during night-observation/imaging. Never use any Fluorite-lenses (especially not in the front lens of a telescope) at -20°C and then all of a sudden put it it into your living room at +20°C or more! In such a case, the resulting severe temperature stress just as well can be detected, when the lenses end up damaged.
Every CaF2 optic needs time to adapt to the surrounding temperature. To do so, for example bring the optical system into the outside in an insulated box and allow it to cool down inside that box over the time of an hour. Keep the box closed but outside. After the imaging session put the FFC back into the same box and allow it to gradually warm up inside that box while bringing it inside the house. Keep it there for at least one hour until you open the box and check that any moisture can dry out.
Please do not use the FFC, if you can not supply the environment and time, to treat this high-end optical system in the way it demands.
The Baader Barlow lenses at a glance
With currently five different barlow lenses in Baader Planetarium's product range, it is not easy to keep track of which model fulfils which function best.
Fluorite Flatfield Converter (FFC) / 3x-8x
(#2458200 , € 730)
90mm field of view also for medium format cameras - uncompromising quality even for extreme enlargements.
Focus gain: depending on configuration about 1.5-2.6cm
Carl Zeiss 1¼" Abbe Barlow lens 2x
(#1603321 , € 477)
Legendary Zeiss quality for the common magnification range between 2x and 3x (with additional T-2 extensions). With T-2 connection for cameras or eyepiece clamps. The qualitatively equivalent solution to the Fluorite FFC when smaller field size and smaller post-magnification are desired.
Focus gain: About 3 cm
VIP 2x modular barlow lens, visual and photographic
(#2406101 , € 228)
Versatile barlow lens for magnifications from 2x, for use with cameras (via T-2 thread) and eyepieces. Calculated for 35mm image diagonal (full format). With additional T-2 extensions it can also be used for slightly higher magnification factors.
Focus gain at 2x: Approx. 3.3 cm
Baader Q-Barlow 1.3x/ 2.25x
(#2956185 , € 55)
Inexpensive and amazingly high quality Barlow lens for the lower magnification range: In addition to being used as a normal Barlow lens with eyepiece clamp (with factor 2.25x), the Barlow element can also be used as a negative lens group when screwed directly into (almost) all eyepiece sleeves or directly in front of a camera with 1.25" filter thread and then provides a lower magnification of approximately 1.3x. Ideal for adapting a modern planetary camera to the resolution of an already long focal length telescope. Prerequisite: There must be no other elements in the nose piece that would prevent the approximeately 13 mm long Q-Barlow lens group from being screwed in.
Focus gain at 2.25x: About 0.4 cm
Hyperion Zoom 2.25x Barlow lens
(#2956180 , € 133)
Specially designed for the Hyperion Zoom eyepiece, also fits the filter thread of other eyepieces. With the included T-2 adapter, it can also be used directly on cameras; provides about 2.7x at 55mm working distance and about 2.3x at 25mm.
Focus gain: About 1.1 cm
More information, images results...
... can be found on our detailed Blogpost:
Baader Blogpost:
Barlow lenses, their magnification factors and working distancesThis entry was posted on October 17, 2022
Baader Blogpost:
The camera at the eyepieceThis entry was posted on October 17, 2022 Last modified on March 14, 2023.
Baader Blogpost:
The eyepiece series from Baader PlanetariumThis entry was posted on October 17, 2022
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The camera at the eyepiece
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Eyepiece Projection - How good can it get?
Question: With eyepiece projection, the image at the edge is extremely blurred. What could be the reason for this? For eyepiece projection with our Morpheus and Hyperion (zoom) eyepieces, we recommend a distance between eyepiece and T-ring of 40 mm on full-frame cameras, in addition to the 55 mm that were the flange focal distance of all "SLR" and DSLR camera bodies for decades when a T-ring was placed in front. Only with a T-ring that maintains this distance can old lenses with a T-thread deliver sharp images. Therefore, it has been tried to take this distance into account in all designs, because this is the only way to ensure that the sharpness performance is optimal. Of course, all this is only valid to a limited extent today - because the DSLR standard is losing it importance and the term „T-ring“ is all too often reduced to the mechanical thread and not the correct distances. In our brochure on digiscopy, we have therefore stated the back focal distance of 55mm. With a DSLR (full frame or APS-C), this distance is also maintained in good approximation with modern, narrow T-rings, which are intended for use on telescopes, where every millimetre often...
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Barlow lenses, their magnification factors and working distances
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Mars Opposition 2020 –The Return of the Red Planet
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Additional Information
| EAN Code | 4047825009999 |
|---|---|
| Manufacturer | Baader Planetarium |
| SKU (#) | 2458200 |
| Net weight (kg) | 0.24 |
| Inner Connection (lens sided) | Thread, T-2 (M42 x 0,75) |
| Outer Connection (lens sided) | Barrel, 2" (50,8mm) |
| Outer Connection (eyepiece/-camera-sided) | Thread, T-2 (M42 x 0,75) |
| Magnification (x) | 3x - 8x |
| AR-Coating | High transmission multi-coated (HT-MC) |
| Optical Design | Barlow, Field Flattener |
| Speciality | Barlow lens, Field Flattener |
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Eyepiece Projection - How good can it get?
The "copper moon" in all its glory. Mars can be seen above the windmill. © Michael Risch. More impressions of the lunar eclipse 2018 can be found here
Do you still remember the lunar eclipse two years ago? At that time the moon was not the only orange-reddish celestial object. Nearby – next to Jupiter – there was Mars in the sky, too. For many people, this was the first time they saw the two planets knowingly "live" – thanks to the attention that the lunar eclipse generated. Unfortunately, the Moon will not give us such a show again this year, but Mars is coming back. As since the beginning of mankind, it can be seen brightly shining in the sky every two years. That's because two Earth years are almost exactly as long as one Mars year, i.e. the time Mars needs for one orbit around the Sun. Only then will it shine again as a bright "star" in our night sky.
THE WARRIOR IN THE SKY, OUR FUTURE HOME?
What impression did a biennial, particularly bright, orange-reddish celestial body, which returns every two years, make on our ancestors? 5,000 or even 10,000 years ago, when humans did not yet live in light-flooded cities that outshine the starry sky, Mars must have been very striking. Every culture has located its gods in the sky and seen their images in the stars. The Greeks connected the red colour of Mars to the blood that is shed in wars. Such a bright, reddish star, which returned again and again, could only be the god of war.
Since those days, our view of Mars has changed, and the significance of our neighboring planet has changed as well, but it has not diminished. Mars is no longer a divine symbol, yet it holds a promise: The journey of mankind to the stars shall find its first goal there, and mankind itself may even find a second home. Our closest neighbour, the moon, was the first celestial body to receive a human visit almost 50 years ago. However, it orbits the Earth and is almost a part of it (in a cosmic sense) – but Mars is a completely different planet! It is a celestial body that orbits the Sun on its own, completely independent of the Earth-Moon-system. If we set foot on it, we have reached a new level of the adventure of space travel, only then will we really have left the sphere of influence of our home planet. This could allow our species to survive even if our ancestral home is destroyed by a cosmic accident or by ourselves, or if the number of people has become so large that the Earth's resources are not sufficient. All this hope is hidden in the orange-red dot in the sky. It is currently enlivened especially by the company SpaceX. Its founder, Elon Musk, has set himself the goal of developing a spacecraft that could fly people and material to Mars in sufficient quantity and in a reasonable time to allow for colonization.
ROBOTIC SCOUTS
Before humans can land on our neighbouring planet, every two years robotic missions dominate the headlines of the media. This is because a period of good visibility of Mars also means that it is particularly close to us, which has a positive effect on flight time and fuel consumption. Since the first successful landings of robots with the two Viking probes in the 1970s, Mars has been the target of many space missions. This year, several robotic scouts of mankind will set out to further unlock the secrets of Mars. Here is a brief overview: Mars missions planned for 2020.
For the fourth time, the USA is sending a "rover", a travelling science laboratory, which will be accompanied by a mini helicopter for the first time. This small drone will explore the path for the rover. In addition, the carbon dioxide in the Martian atmosphere will be used for the first time to produce oxygen, an important experiment before astronauts can visit the planet. China and the United Arab Emirates are each sending an "orbiter"; i.e. a satellite that orbits Mars, takes photos and acquires measurement data. Although the Chinese orbiter also includes a lander and a rover, they are mainly used to test technologies and promise few scientific results. The European-Russian contribution, a rover called Exo-Mars, unfortunately had to be postponed to the next launch date in two years due to technical difficulties. It was to search for traces of earlier life - just like the US rover "Perseverance" which is now starting.
MARS IN THE TELESCOPE
Until the 90s, amateur drawings showed more details than photos, here an example with a 114mm Newton, © Michael Risch
© Michael Risch
Mars is a worthwhile destination not only for space probes, but also for eartbound observation and photography. For centuries, the eye was the sharpest detector of (amateur) astronomers. Drawings of the planet were made, internationally compared and evaluated. When there was no Hubble telescope and no satellites constantly orbiting Mars, this work had scientific value.
Even today it is still a very special personal experience to see the solid surface and the weather on the probably most Earth-like planet in the solar system with your own eyes. Orange-coloured to dark-black desert areas, white ice pole caps, clouds and yellowish dust storms can be discovered on our neighbouring planet. Already with small telescopes from about 100mm aperture and about 200x magnification this can be achieved. But since a few years much more detail can be gained with new photographic detectors, CCD and CMOS cameras, and the so-called "Lucky Imaging", which almost eliminates the disturbing effects of the earth's atmosphere.
The photographs by Sebastian Voltmer (weltraum.com) show the view of Mars from July to September 2003.
THE TELESCOPE EQUIPMENT FOR THE OBSERVATION OF MARS
In April 2014 Mario Weigand (Skytrip.de) took this close-up of Mars – with a C14 and the Baader FFC.
In general a telescope should have at least 100mm aperture – more is better, because the planets are small and the highest useful magnification depends on the diameter of the telescope. As a guideline, the highest useful magnification is twice the aperture in millimetres.
Magnifications of 200x to 300x are worthwhile when observing Mars.
If our own Earth's atmosphere allows it, it is also possible to increase the magnification even further. The larger the aperture of a telescope is, the more details can be resolved. No wonder then that Schmidt-Cassegrains are so popular with planetary photographers: They combine a large aperture and focal length with a compact design, so that no extremely heavy and expensive mount is necessary to carry the telescope stably.
Azimuthal mount or equatorial mount
Whether you use an azimuthal mount, which can be set up in no time, or an equatorial mount, which is optimal for photography, remains a matter of taste on Mars – for planetary photography you can even use an azimuthal mount. The only important thing is that it has a tracking system: Then the planet remains in the field of view even at the highest magnification, and you can observe with complete relaxation.
High magnifications can be achieved with short focal length eyepieces
Orthoscopic eyepieces ("Orthos") are still the first choice for planetary observers because they need just a few lenses to show a bright, high-contrast image; modern wide-angle eyepieces such as the Morpheus eyepieces are not inferior to them and at the same time offer a more comfortable view with a larger field of view – but they also cost much more. With a good Barlow lens, the magnification can be further increased or brought to a value that matches the pixel size of a video module for planetary photography. For highest demands and magnifications you should use the Fluorite Flatfield Converter (FFC) / 3x-8x (#2458200 , € 730) .
Colour filters help to better highlight delicate details
For surface details on Mars, red and orange filters have proven their worth. A green filter helps in the hunt for fog fields and CO2 rime, while a blue filter shows surface details and the violet clearing. Changing the filter is particularly convenient with a filter slider or wheel.
The Baader FlipMirror II star diagonal with its two M48/T-2 connectors is ideal for making planet photography easier. Learn more about planetary photography with the Baader FlipMirror II.
Relaxed observation with binoculars
Relaxed observation is possible with a binoviewer (for example with our Baader MaxBright® II binoviewer). We use two eyes during the day, why should we do without them in the night sky?
Remember the Star Diagonal
Often a bad image is not due to the telescope, but to the simple star diagonal that is included. We offer a range of mirror and prism diagonals. There is also an especially interesting option if you are doing both photography and visual observations: With the Baader FlipMirror II Star Diagonal (#2458055 , € 228) you can switch from eyepiece to camera in seconds, and of course it can be combined with filter sliders / wheels.
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