This well-corrected accessory lens preserves the high contrast and superb color correction of the main objective. While the telecompressor flattens the field to a certain degree, you may still notice some slightly elongated stars in the corners. This is less of an issue with CCD imaging when the chip size is smaller than a 35mm negative. For the very best edge star images, we recommend the prime focus 2.7" or 4" field flatteners, which have been specifically designed for each focal length of our StarFire refractors. If you own one of our 160, 155 or 140 StarFires and plan to take CCD images, we suggest our dedicated CCD Telecompressors that are optimally corrected for these scopes.

Here are a few examples of images from our gallery that were taken with our telecompressor:

M42, 105mm Traveler at f4.5 taken by Ray Gralak with an SBIG ST8E.
Gamma Cygnus Region, 105mm Traveler at f4.5 taken by Ray Gralak with an SBIG ST8E.
M8, 130mm StarFire EDFS at f4.5 imaged by Loke Tan with an SBIG ST10E.
IC 5070 - The Pelican Nebula, 155mm StarFire EDFS at f5.2 taken by Ray Gralak with SBIG ST-10XE

We designed the telecompressor so that it threads directly into the drawtube, thus placing the optics forward in the optical system. As a result, the telecompressor can only be used with Astro-Physics 2.7" and 4" focusers and Starlight Instruments focusers that have an adapter for Astro-Physics 2.7" accessories. In addition to our refractors, Astro-Physics focusers are featured in several popular Ritchey-Chretiens (the telecompressor produces very fine results with these scopes) and are available for telescope makers (27FOC3E and 27FOC3E-FT).

Two additional adapters released in 2007 and 2008 respectively have greatly increased the versatility of this Photo-Visual Telecompressor. The 2.7" Adapter that Threads onto the 3.25" Rear Cell of Larger Meade SCT's (ADASCTLM27), introduced in July, 2007 now makes this telecompressor available to owners of larger Meade SCT's. The 6x7 Outer Bayonet Adapter (ADA2767), introduced in August, 2008 allows larger imaging platforms like the SBIG STL Series cameras or full frame DSLR's to be attached to the Photo-Visual Telecompressor without the vignetting effects of a 2" nosepiece or a T-ring.

The focal length of the Photo-Visual Telecompressor is 27.6" (700 mm). In order to obtain approximately .75x, please refer to the exploded diagram for various configurations. Although not shown on the diagram, the telecompressor is threaded for 58mm filters. To calculate the compression factor and coverage for your particular setup, please refer to our Telecompressor Spacing, Compression Calculation and Coverage document - PDF format.

The S155EDFFF 4" Prime Focus Field Flattener was originally produced for the 155 f7 StarFire EDF with its 4" focuser and was included with those instruments. It is now available as an accessory for owners of the 155 f7 StarFire EDFS version who have upgraded their 2.7" focusers to the 4" model. It is also the perfect Field Flattener for the 140 f7.5 StarFire EDF when purchased with the optional 4" focuser (140EDF4). These 4" Prime Focus Field Flatteners come with two beautifully machined, felt-lined aluminum covers to protect the valuable optics inside.

This optical marvel was originally designed to take full advantage of the medium format Pentax 6x7 camera, and will provide pinpoint stars all the way to the edge of its field with no vignetting! It is perfect for today's larger CCD cameras as well. We also offer an adapter that allows this Field Flattener to be used with the more conventional SLR's - either 35mm or digital (including a larger clear aperture version for the full format Canon EOS cameras). The S155EDFFF flattens the field across a full 4" circle without significantly changing the native focal ratio of the telescope - The 155 f7 operates at about f7.3 while the 140 f7.5 will operate at f7.8.

In the past, most CCD cameras had to be attached using a 2" adapter and nosepiece - see image below left - but we now have two direct adapters for the larger format STL series of cameras (ADA671 & ADA672) that are similar to the ones available for the 155TCC Telecompressor Corrector, the other outstanding 4" imaging accessory for both the 155 f7 and 140 f7.5 StarFire EDF instruments.

Diagrams and Instruction Sheets:
Astro-Physics Prime Focus Field Flatteners- Exploded diagram showing the field flatteners with a variety of accessories. Note that this is a PDF file. Read hint for viewing this two-page diagram. Installing the CCD Adapter to Use the 2.7" or 4" Field Flatteners with a CCD Camera - Instruction sheet in PDF format.

LEFT - The S155EDFFF in place on a 4" draw tube with the A1261 CCD adapter (sold separately) and ADA2003 2" adapter (included with either telescope).

RIGHT - The S155EDFFF shown with its beautifully machined covers.

The most discriminating CCD imagers with large chips may wish to use our field flatteners for the best possible results at the edge of the field. These adapters will preserve the correct spacing from the field flattener to the focal plane of your CCD camera. Choose the correct length for your system. For owners of the SBIG STL Series of large format CCD cameras, we suggest the special STL Series adapters (ADA671 & ADA672) below for both perfect spacing and minimal vignetting.

Important: There are now a huge variety of CCD cameras, filter wheels and other accessories on the market, and all of them have different dimensions in terms of their optical backfocus or light path distance. Even different filter choices will affect the optical distance because of the indexing effect of the filter itself. It is important that you know the specifications of your own particular equipment before deciding on an adapter. The information below provides guidelines - NOT inviolable laws.

Diagrams and Instruction Sheets:

Astro-Physics Prime Focus Field Flatteners
- Exploded diagram showing these CCD adapters with the field flatteners and a variety of other accessories. Note that this is a PDF file. Read hint for viewing this two-page diagram.

Installing the CCD Adapter to Use the 2.7" or 4" Field Flatteners with a CCD Camera
- Instruction sheet in PDF format.

The design allows full corner-to-corner illumination of the ST10E chip with most catadioptric telescopes. This design does not add coma to the wavefront, and thus can be used with all flat-field and coma-free telescopes such as Maksutov-Cassegrains, Schmidt-Cassegrains, Ritchey-Chretiens and refractors. The inherent resolution of the telescope is not compromised when using this compressor.

Please review the exploded diagram to see how this item will fit into your imaging system. If you want a higher compression ratio, but do not use the color filter wheel, you can add two T-2 extension rings that we offer from Baader Planetarium. Thread both the 15mm T-2 Extension Ring (part # BP25A) and 7.5mm Extension Ring (part # BP25C) between the CCD camera and the nosepiece. This will approximate the length of the color filter wheel. You can also experiment with a single extension or other combinations. Although it may be possible to use additional T-2 extensions (there is also a 40mm version, part # BP25B) to gain even further compression, you may not have enough backfocus to do so. Also please note that as you increase compression, you decrease the size of the fully illuminated circle at the focus point. At 0.67x, the CCDT67 will cover the chip of the ST10E. It can never cover the chip of an STL series camera or the newer large size digital SLR chips, because its clear aperture is no larger than their CCD chips.

• Clear aperture is 1.75", designed to screw into our 2” Tapered Nosepiece (AP16T) or any other 2" nosepiece with 48mm threads that is designed for CCD cameras. It will not thread all the way into the nosepiece provided with SBIG cameras since the threads of that nosepiece are not deep enough.
• 0.67x Compression ratio for SBIG ST7/8/10 + Color Filter Wheel, when used with refractors. Fully illuminated circle: 30mm
• 0.75x Compression ratio for SBIG ST7/8/10 (without Color Filter Wheel or T-2 extensions), when used with refractors. Fully illuminated circle: 34mm
• Approximately 5 inches of back focus is needed to achieve focus on the CCD chip. It will not work with the AO7.
• The focal length of the CDD Telecompressor is 12" (305 mm)

To calculate the compression factor and coverage for your particular setup, please refer to our Telecompressor Spacing, Compression Calculation and Coverage document (PDF).

This image of the Ring Nebula was taken with the Astro-Physics 10" f14.6 Maksutov-Cassegrain and the CCD Telecompressor using an ST10E with the color filter wheel. Once you receive your CCD Telecompressor, we invite you to submit your images so that they can be featured here, all scopes will be welcome.

We highly recommend our 2" Tapered Nosepiece (AP16T) for your CCD camera. When used with the brass locking ring of most of our adapters, this unique barrel will seat your valuable CCD camera squarely and solidly into place. Even a single thumbscrew interface will be improved. If you are using the older style thin 2" adapter (part # ADA2013) or the 2" adapter of the 92mm f5 or f7 Stowaways, we suggest that you use the 2" nosepiece that came with your camera or the 2" nosepice from Baader Planetarium (we offer as part #BP16). The current style 2" Thin Adapter (ADA20132) works perfectly with the AP16T.

(67RT - - -, last 3 letters indicate t-ring)

Use this adapter with the 2.7" or 4" Prime Focus Field Flatteners to obtain the best possile results with your 35mm camera - pinpoint from edge to edge. I.D. painted flat and threaded for 48mm filters. See how this part fits into your photographic system in the exploded diagram (PDF file). Read hint for viewing this two-page diagram.

This part can also be used with the 2.7" to 6x7 Outer Bayonet Adapter (ADA2767) if you wish to do so, although the required T-ring for camera attachment will not maintain the ADA2767's wide open light path.

Owners of Canon EOS auto-focus 35mm and digital SLR's may wish to consider the larger, 1.875" clear aperture adapter below. (67RLEOS)

Purchase the adapter with or without the t-ring. T-rings thread easily into place. If you order your camera adapter with a t-ring, the three dashes in the part number will be replaced by three letters, i.e. 67RTNIK if a Nikon t-ring in included. Please specify the t-ring that you wish to use. Order an extra t-ring if you have two cameras. This part can be used with 2.7" field flatteners shipped after May 1994 and 4" field flatteners from any year.

If you have a field flattener that is an earlier model, please call.

This SLR Camera Adapter for Canon auto-focus 35mm and digital EOS SLR cameras with its large 1.875" (47.6 mm) inside diameter EOS bayonet minimizes vignetting on full frame chips and on 35 mm film by eliminating the restrictive 1.5” (38 mm) diameter standard T-thread interface. Since the introduction of Canon’s full 35 mm frame digital SLR’s, people have been asking for a solution to the vignetting caused by the small clear aperture of the standard T-ring interface that is universally used to connect telescopes to SLR cameras. This was especially true for Astro-Physics telescope owners who also had either our 2.7” or 4” Field Flatteners. What good were pinpoint stars to the edge of a wide field when the edge of that field was darkened by the T-ring’s vignetting effect? So, in keeping with our commitment to imagers, we introduced a solution!

The adapter body is precision-machined aluminum and is anodized black. The bayonet is machined stainless steel, and both the body and the bayonet are baffled and painted flat black on the inside. The adapter was originally developed to be used exclusively with Astro-Physics 2.7" and 4" Prime Focus Field Flatteners (except the 160FF - Please note that the 160 Field Flattener has its own large diameter EOS Adapter, the ADATCCEOS). The 67RLEOS will position the chip (or film) at the correct distance from the Field Flattener optics for pinpoint stars. If you received your 2.7" Field Flattener prior to May 1994, you will need new aluminum parts to use this adapter. Please call Astro-Physics for details.

The versatility of this adapter took a quantum leap forward with the introduction of the 2.7" to 6x7 Outer Bayonet Adapter (ADA2767). With the 67RLEOS and the ADA2767 together, full frame Canon EOS SLR's can produce unvignetted, easily framed images with a wide variety of configurations.

Thread this adapter into place, then use use the ring shown on the right-hand side of the adapter to lock your camera into position after you have framed your image. This allows you to rotate the camera to achieve your desired composition.

Applications:
Telecompressor - This adapter allows you to use the Telecompressor (27TVPH) with your Pentax 6x7 camera. Your image circle will be approximately 2" fully illuminated. We suggest that you review the exploded diagram (PDF file) showing the telecompressor with a variety of accessories. Read hint for viewing this two-page diagram.

To couple scopes that don't need a field flattener to the Pentax 6x7 - Thread directly onto your Astro-Physics 2.7" focuser, 4" focuser, or any focuser drawtube that measures 2.740" I.D. with 24 TPI in order to use a Pentax 6x7 without a field flattener. This is appropriate for our older 6"f9 and 6"f12 scopes, however, a field flattener is needed for the shorter focal lengths to obtain the best results.

Please note: This adapter uses the Pentax 6x7 INNER bayonet and will only attach to a Pentax 6x7 camera. This adapter can NOT be used with our CCD adapters (A1260, A1261 & A1262); with our STL series adapters (ADA671 & ADDA672); or with our SLR camera adapters for the field flatteners (67RLEOS, 67RTxxx etc.).

The unique micro-adjust knobs allow you to frame star fields easily in 2 axes. The camera bracket comes with a flat base and screws that enable you to attach it to the holes on the top of our mounting rings. Attach your favorite 35mm camera with wide-field lens and take some terrific Milky Way shots.

Please note that your telescope rings must be tapped with two 10-32 holes spaced 3" apart to accommodate this bracket. Some of our earliest rings were produced before we included this set of holes in our standard hole pattern. To confirm that your rings are appropriately tapped, please refer to our Astro-Physics Mounting Ring Hole Pattern document.