Baader Planetarium

Fluorite Flatfield Converter Barlow (BPFFC) and Related Accessories in the FFC System

Baader Fluorite Flatfield Converter Barlow (BPFFC)
FFC Basic Set - Recommended
Baader FFC System, a.k.a. Baader Astro T-2 System®
A3511 Robust FFC Attachment System
Achieving Various Powers with the FFC
Tips for Using the FFC System with Various Telescopes
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Baader Fluorite Flatfield Converter Barlow (BPFFC)

The Baader Fluorite Flatfield Converter was designed by a top German optical inventor to cover up to a 6x7 cm format at magnifications up to 8x. The 4-element fluorite design provides a diffraction-limited, apochromatic flat field over a 90 mm image circle. It produces a sharp, color-free image for any projection photography need. It can be coupled to 35 mm cameras, 6x7 cameras (adapters are available for various camera models), as well as any CCD camera using 1.25" or 2" nosepieces or threaded custom adapters. The BPFFC also can be used visually for critical high-power lunar/planetary/double star viewing.

The fluorite lenses do not add any chromatic aberrations or other optical defects to the image. The lenses are corrected from deep violet to the IR regions, and present an excellent match to the new extended-wavelength CCD cameras.

The BPFFC is fully multi-coated with a hard 7-layer design, each layer exactly matched to the material index. The result is very high transmission while suppressing stray light. Looking into the front of the lenses shows a black tube with the elements barely visible as shown in the photo. All optical surfaces are polished to the highest optical standards of 1/10 wave accuracy, in order not to disturb the incoming wavefront from your telescope's optics.

For projection photography, the BPFFC is unmatched for image fidelity. Unlike eyepiece projection systems, the BPFFC is free of the common defects such as chromatic aberration, pincushion/barrel distortion, astigmatism, coma, and vignetting of the light cone.

This design works equally well on all optical systems - be it Newtonians, apochromatic refractors, Schmidt-Cassegrains, Ritchey-Chretiens, etc.
BPFFC$793.00 in stockAdd BPFFC To My Cart

FFC Basic Set and Extensions
The FFC System (also known as the Astro T-2 System) offers a wide array of adapters to suit a variety of needs. We have also manufactured a 2"/T-2 Adapter with brass locking ring (ADAT2) to simplify the system (it takes the place of several components). The Basic Set couples the 2"/T2 Tapered Nosepiece (AP16T) to the front of the BPFFC optic and the 2"/T2 Adapter with brass locking ring (ADAT2) to the back, allowing a simple method for using visual and photographic accessories.
Shown from left to right:
AP16T - 2"/T-2 Tapered Nosepiece (fits into 2" openings). This item helps you to come to focus when the FFC is inserted directly into your refractor or SCT (not used for Newtonians).
BPFFC - Fluorite Flatfield Converter Barlow
ADAT2 - 2"/T-2 Adapter with brass locking ring (manufactured by Astro-Physics, not shown on FFC System diagrams)

Assembled unit: ADAT2, BPFFC, AP16T. Shown with the following three extension tubes threaded together on the right:

BP25A - T-2 Extension Tube, 15 mm long
BP25B - T-2 Extension Tube, 40 mm long
BP25C - T-2 Extension Tube, 7.5 mm long

AP16T$45.00 in stockAdd AP16T To My Cart
BPFFC$793.00 in stockAdd BPFFC To My Cart
ADAT2$40.00 in stockAdd ADAT2 To My Cart
BP25A$27.00 in stockAdd BP25A To My Cart
BP25B$30.00 in stockAdd BP25B To My Cart
BP25C$25.00 in stockAdd BP25C To My Cart

Baader FFC System, a.k.a. Baader Astro T-2 System®
Please link to the PDF diagrams below for a complete listing of all available accessories. With these items, you have complete freedom to configure your FFC system for almost any application.

The FFC System - PDF document from Baader Planetarium
This is an exploded diagram of the various parts in the FFC System and their relationship to one another. Pertinent notes:

  • The numbers beneath the extension tubes indicate their length in mm.
  • Our part numbers are derived from the numbers in the circles. Simply add the letters BP to the circled number, i.e. the circled part 1 is our part number BP1.
  • Part number 3 is now included with part number 1, so it should not be ordered separately when used with the prism star diagonal (order as BP1 to receive both components).
Standard FFC Combinations - PDF document from Baader Planetarium
This diagram shows the following:
  • Basic Configuration for 4x Focal Extension
  • Visual use with 2" Diagonal and 2" or 1.25" Eyepieces
  • Visual use with 1.25" Eyepieces and T-2 (Zeiss) Star Diagonal
A3511 Robust FFC Attachment System

Realize the full potential of the Baader FFC (or Astro-Physics 2" Convertible Barlow, part # BARCON) when imaging by using the A3511 Extension. The internal T-thread on this extension allows you to attach your BPFFC, BARCON or other accessory with male T-threads INSIDE the 2.7" extension tube. In this way, the camera, filter wheel, off-axis guider, and/or other accessories are all supported by the much more robust and rigid 2.7" tube system, and the Barlow only needs to support its own weight inside the extension tube.

This is particularly important when imaging at some of the higher magnifications achievable with the BPFFC where over a foot of extension may be used between the Barlow optic and the focal plane. The maximum OD of the T-thread accessory is 2.5". Please see this A3511 System Chart for component options.

A3511$50.00 in stockAdd A3511 To My Cart

Achieving Various Powers with the BPFFC

The power of the BPFFC will vary depending on the distance to the focal plane behind the Barlow. As the spacing increases, so does the magnification. However, remember that as you increase the spacing (magnification) you also will need to shift the BPFFC forward in the focuser. The amount of in-travel available becomes a consideration as you reach towards the higher magnifications. The following is a list of the magnifications and the distances required: 2x = 42 mm, 3x = 96.2 mm, 4x = 150 mm, 5x = 206.4 mm, 6x = 259 mm, 7x = 314 mm, 8x = 368 mm.

When using the Astro-Physics Maxbright Diagonal, we suggest one of the following configurations:

  • Basic Set: ADAT2 (Astro-Physics 2"/T2 adapter) + BPFFC (FFC) + AP16T (2"/T-2 nosepiece)
  • FFC system components: BP17 (2" adapter) + BP28 (expanding ring) + BP6/7 (T-2 changer system) + BPFFC (FFC) + BP16 (T-2 nosepiece)
    BP17$64.00 in stockAdd BP17 To My Cart
    BP28$45.00 in stockAdd BP28 To My Cart
    BP6/7$88.00 in stockAdd BP6/7 To My Cart

Using either the "Basic Set" or the "FFC System Components" in front of the AP Maxbright Diagonal, the eyepiece focal plane will be effectively 152 mm (+/-10% depending on the style of the eyepiece) behind the BPFFC for an approximate 4x magnification. To get an exact measure of power requires the exact position of the eyepiece field stop with respect to the rear flange of the BPFFC. Using various extension tubes, the power can be increased to 8x, assuming that your telescope focuser has sufficient in-travel to allow this configuration to come to focus.

Lower powers can be achieved by placing either the “Basic Set” or the “FFC System Components” into the AP Maxbright Diagonal and then adding the eyepiece. This setup will place the focal plane approximately 50 mm behind the BPFFC, yielding about 2x magnification. The magnification will vary somewhat with eyepiece design.

35 mm Camera
35 mm SLR and DSLR cameras have a 55 mm spacing distance to the film/sensor plane when using a T-ring system. The lowest magnification of 2x is achieved by threading a standard T-ring directly to the back of the BPFFC body (without a 2" adapter).

3x to 8x magnifications are achieved by adding 50 mm - 320 mm of extension tube(s).

If you use the 2" Astro-Physics Adapter (ADAT2) and a 2" Astro-Physics Prime Focus Camera Adapter (part # starting with PFC or PFCT), the distance to the film plane will be 140 mm for 3.7x magnification.
ADAT2$40.00 in stockAdd ADAT2 To My Cart
BPFFC$793.00 in stockAdd BPFFC To My Cart
PFCT$50.00 in stockAdd PFCT To My Cart
PFCTCAN$70.00 in stockAdd PFCTCAN To My Cart

PFCTKON$70.00 in stockAdd PFCTKON To My Cart
PFCTMAF$70.00 in stockAdd PFCTMAF To My Cart

PFCTMIN$70.00 in stockAdd PFCTMIN To My Cart
PFCTNIK$70.00 in stockAdd PFCTNIK To My Cart
PFCTOLY$70.00 in stockAdd PFCTOLY To My Cart

PFCTPTS$70.00 in stockAdd PFCTPTS To My Cart

6x7 Camera
To use a medium format camera requires the Baader M68 Quick Change System and the appropriate adapters and extension tubes. The lowest power without extension tubes will be between 3x and 3.3x depending on camera type: Hasselblad: 74.9 mm and Pentax 67: 84.95 mm.

CCD Camera
The FFC system allows you to achieve various powers with your CCD Cameras (such as the
ST-7/8/9/10 or the STL-11000). If you thread the BPFFC directly into your camera (without the 2" nosepiece or with a custom low profile adapter) the lowest possible magnification will be approximately 2x. By inserting the 2" nosepiece of your CCD Camera (with color filter wheel closely coupled) directly into the Astro-Physics 2"/T2 Adapter (ADAT2), which you have attached to the back of the BPFFC, the power will be approximately 3x. This will increase with the addition of extensions or other intermediate accessories.

Tips for Using the FFC System with Various Telescopes

There are several options for attaching the BPFFC to your telescope.

  • Basic Set: If you have an 8 or 9.25" SCT, use our ADASCT, which was designed for 2" slip-in accessories and features our brass locking ring. We have also developed the ADASCTLC and ADASCTLM, which are larger versions designed for SCTs that are 10" or larger. This adapter takes advantage of the 3.25" opening of these scopes.
    ADASCT$40.00 in stockAdd ADASCT To My Cart
    ADASCTLC$60.00 in stockAdd ADASCTLC To My Cart
    ADASCTLM$60.00 in stockAdd ADASCTLM To My Cart
  • FFC System: If you prefer to thread the FFC System components directly onto your visual back, you can use BP21 (2" SCT Short T-adapter for the standard visual back) or BP18 (adapter for the larger SCTs).
    BP18$55.00 in stockAdd BP18 To My Cart
    BP21$57.00 in stockAdd BP21 To My Cart

When inserted into a 2" focuser on a Newtonian telescope, the Baader FFC Barlow will require an additional 1 inch of in-travel to allow focus at 2x magnification. More travel is required for higher powers. To use, slip the FFC directly into your focuser. Tighten the focuser screw on the smooth surface of the FFC between the ridges. You will also need our ADAT2 (and possibly a 1.25" adapter) for your eyepiece.
ADAT2$40.00 in stockAdd ADAT2 To My Cart
BPFFC$793.00 in stockAdd BPFFC To My Cart

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This page was last modified: June 16, 2011

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Phone: 815-282-1513   Fax: 815-282-9847