Fluorite Flatfield Converter (FFC) / 3x-8x

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Fluorite Flatfield Converter (FFC) / 3x-8x

# 2458200

€ 730.00 Price excl. German VAT tax (19%): € 613.45

Out of Stock  

  • Apochromatic, multi-coated fluorite lens system
  • 10-times higher line resolution than the world best projection eyepieces
  • The FFC fits on every T-2 thread and in every 2" focuser

Product Questions and Answers

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With a classical Cassegrain such as Orion CC 6 inch Dia 1800 mm focal f12 and focal plane fixed at 6 inch from rear mirror approx would this FFC be practical at all ?
Question by: Sylvain Poudrette on Dec 25, 2020 3:45:00 PM | 1 Answer(s)

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There’re some discussions about FFC on the web, it seems to designed for photography, do you know anyone using it in visual?
Question by: Anonymous on Oct 9, 2017 8:36:39 AM | 1 Answer(s)

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I'm considering Baader FFC for magnifying Venus image through U-Venus filter. Is this better transparency with UV around 350nm wavelength than the other conventional ones such as your VIP 2x barlow.
Question by: Kazuhiro Yamada on Jan 13, 2020 5:29:00 PM | 1 Answer(s)

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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)

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Where can I learn more about the "M 68-System" and how I can connect the FFC via threaded connection to my telescope? Thanks
Question by: Mike Garrett on Nov 21, 2022 4:41:00 PM | 1 Answer(s)

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Could be used with RASA 8"?
Question by: Francisco Javier on Jul 3, 2021 9:30:00 PM | 1 Answer(s)

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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)

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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)

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Can this FFC be used with a SCT such as a Celestron C6 or C8 for imaging in at T2 imaging train?
Question by: David Huff on Aug 15, 2022 4:56:00 PM | 1 Answer(s)

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What happens if i place the fluorite flat field correcter 250mm AFTER the research grade 3x telecentric? Would my telecentric beam become 9x?
Question by: Apollo Lasky on Nov 28, 2018 4:55:00 AM | 1 Answer(s)

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I would like to purchase a focal extender for focal (prime focus) photography. I need a minimum
fully illuminated and corrected APS-C (full-frame welcome as well) format field on the focal plane, as i want to take mosaics of the moon. Let's say the magnification should cover the 2x-4x range, but higher is welcome as well. What kind of options are there ? I tought about zeiss abbe barlow and/or FFC; maybe televue powermates?
In particular, Is the zeiss' barrel form factor enough for my required coverage on the focal plane?
Question by: Simone on Nov 2, 2023 2:14:00 PM | 1 Answer(s)

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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)

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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.
Question by: fabien landrivon on Aug 25, 2020 10:16:00 AM | 1 Answer(s)

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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.
Question by: Jim Lindelien on Mar 25, 2021 1:43:00 AM | 1 Answer(s)

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Is there a mathematical formula for calculating the magnification per distance of F / L?
Question by: Bill on Oct 1, 2022 2:25:00 AM | 1 Answer(s)

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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?
Question by: Alexandros on May 16, 2021 4:09:00 AM | 1 Answer(s)

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If I use the FFC with an F/4.5 Newtonian (16") will I also need a coma corrector for imaging on a full frame sensor or can I use the FFC on its own.
Question by: Roy Foreman on Nov 18, 2019 2:15:00 PM | 1 Answer(s)

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I have a zeiss APQ 150/1200. can I use this together with Zeiss binocular?
Question by: Val A. on Aug 31, 2020 7:39:00 PM | 1 Answer(s)

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On "How to use FFC" it reads: "Do not use it for photographing the sun". If we use FFC for solar imaging after a Baader Herschel Prism, this may still create a problem?
Question by: Alexandros on May 16, 2021 4:01:00 AM | 1 Answer(s)

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Can the FFC be used with a flattener. How would it work since the distance between the flattener and image plane is normally fixed?
Question by: mike on Aug 31, 2019 12:06:00 AM | 1 Answer(s)

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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 Michaelis

How 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 distances

Baader Blogpost:
The camera at the eyepiece

Baader Blogpost:
The eyepiece series from Baader Planetarium

Related Articles

Additional Information

EAN Code 4047825009999
Manufacturer Baader Planetarium
SKU (#) 2458200
Net weight (kg) 0.24
Inner Connection (lens sided) M42 x 0.75 (T-2)
Outer Connection (lens sided) ø 2" (50.8mm)
Outer Connection (eyepiece/-camera-sided) M42 x 0.75 (T-2)
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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2 Item(s)

Joachim D. 323/11/2022 20/11/202210:36
  • Rating:
nicht günstig - aber jeden Cent wert!
Üblicherweise werden mit einer Barlow die Planeten abgelichtet. Leider ist das Wetter sehr unkooperativ und so habe ich seit dem Kauf der FFC nur ein deep sky Bild von M56 bei ziemlich schlechtem seeing aufnehmen können. Dennoch bin ich hellauf begeistert! An meinem FLT 132/925 erreiche ich bei 3x Vergrößerung 2,8m Brennweite. Die DSPro2600C habe ich 2x2 gebinnt und so eine Auflösung von 0,56 artsec/pixel erhalten. Aufnahmedaten: 26x3min, Gain=400, HCG, 2x2bin, 12.9.2022, 40 Flats. Wie man sehen kann, ist das Bild auch an den Rändern wirklich sehr gut geebnet. Bei einer Planetenaufnahme sieht man das in der Regel nicht, da das Planet ja nur im Zentrum abgebildet wird.
Den Sternhaufentest hat mein FFC mit Bravour bestanden und nun muss auch endlich das Wetter wieder besser werden!
  • hervorragende optische Eigenschaften
  • nicht billig, aber seinen Preis wert
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Pete 253/09/2020 10/09/202006:07
  • Rating:
Why did I wait so long?
The Baader FFC received a tortuous series of imaging trials over the weekend. What a magnificent optic to pare with the triplet in the AP130EDFGT! The various 2.7" tubes and A3511 all fit and function flawlessly. Being able to easily adjust the image scale is one thing but the lack of image degradation is another! The crow image was perhaps the most telling image for me. It is perhaps just a mundane snapshot of this bird but the lack of scattering is remarkable. Black and dark blue/purple feathers of these birds under the harsh lighting conditions of that image historically wreak havoc on edges and reflective areas such as the eye. It was a RAW image and subjected to VERY LITTLE image processing. Only white balance and luminance adjustment to dampen some noise of the 7D detector. All aircraft images were far easier to focus even under terrible haze and turbulence.

My only FFC regret at this point is that I waited until now to obtain one. A beautiful compliment to the GT. Find attached some test images (all at stupid long effective focal lengths) and a snapshot of the GT fitted with 2.7" tubes, A3511 with the FFC (inside). My Son's 2017 Mustang GT is in the background. :P

I'll have to acquire a current DSLR with better high ISO capabilities in the near future at help in my wildlife and ISS imaging pursuits.
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