The problem is that the front lens of the scope basically creates an image in a given distance, which is then magnified by the eyepiece. So, you need to get the eyepiece close enough to the front lens. In a spottin scope, the erect-image prism is mounted fix inside of the tube, and you can't get close enough. In a telescope, you can move both prism and eyepiece closer to the front lens.
While a Barlow lense moves the image further to the outside, it has to be even closer to the front lens than an eyepiece - with a refracting spotting scope, you'd have to remove parts of the scope's housing to get into focus. The prism and the internal focusing mechanism are in the way...
So, although you can attach the Barlow mechanically to a spotting scope, you wouldn't be able to reach focus and get a sharp image.
Only if you use a telescope as spotting scope like our C5 Schmidt-Cassegrain spotting scope, you'd be able to use the Barlow - but this only works with a very small number of spotting scopes.
Thanks Jamie Pauley purchasing through Adorama in the US.
To reduce the focal length of your telescope however, in order to increase the field of view (= less magnification) is more difficult. A reducer has to be calculated to optically match your telescope brand and model, otherwise you may not be able to reach focus and the image quality might be horrible, with an enormous amount of field curvature and/or spherical aberration
Unfortunately reducers are not our speciality, since we only offer reducers for very few such special optics. Also please note that the reducers that we do offer (such as the Alan Gee Telecompressor #2454400 - calculated for C8 or higher Schmidt-Cassegrains) are all mainly optimized for photography and cannot be used in combination with prism or mirror diagonals since the optical backfockus just is not enough.
Sorry, this is quite a complex area. For this reason we never offered a "universal" reducer for lowering magnification during visual observation.
The diract link to the PDF is
The calculations are similar for all Barlow lenses.
Instead of using two Barlow lenses, we'd highly recommend to use different glasspath correctors (GPC) to achieve different magnifications with a binoviewer.
You should use a GPC, anyway, to make sure that you reach focus and to eliminate any colour aberrations which might be caused by the prisms inside of the binoviewer. This way, you can also be sure that the image quality is good – if you use two BArlow lenses, both should be made in the same production run to avoid any small differences which are no problem when you use them for mono-viewing, but which become obvious when bino-viewing. That's also why both eyepieces should be bought together.
And an additional bonus, aside of the quality: One GPC is cheaper than two Barlow lenses.
Mirrorless system cameras have a much shorter back focal distance than comparatively large SLR cameras. The available T-adapters are usually for use with telescopes with a moving focuser. Here the shorter back focal distance must be compensated by additional extension sleeves, if a certain distance has to be kept.
The example adaptations in our digiscoping brochure thus apply to all T-adapters that follow the T2 standard and deliver a back focal distance of 55mm.
The indicated distances of
min. 40mm spacer sleeve plus 55mm T-2 flange focal distance for full format
min. 30mm spacer sleeve plus 55mm T-2 flange focal distance for APS-C
min. 15mm spacer sleeve plus 55mm T-2 flange focal distance for MFT
were empirically determined (Canon full format, Nikon APS-C (slightly larger sensor than Canon APS-C), Panasonic MFT) and are the values at which the image looked good, i.e. no (disturbing) distortion could be detected in nature photography. However, only the Hyperion Zoom without Barlow lens was used. For decades, we had in principle recommended the 40mm extension; with the smaller sensors, shorter distances (and less magnification) are also possible. The overall length of an adapter ring from the M43 eyepiece thread to T-2 was neglected, or it was regarded as part of the eyepiece.
With shorter overall distances than indicated above, the sharpness in the edges is catastrophic. Only with these distances the image is enlarged in such a way that the entire sensor can be used.
When working with an additional Barlow lens for even more magnification, the resulting effective focal length increases extremely and the system becomes more difficult to control. The thick stack of lenses does not make the image any better, and the telescope opening must provide sufficient resolution, also in relation to the pixel size of the camera. For highest magnifications we therefore recommend the FFC instead of the eyepiece projection in combination with a barlow lens – more on this below.
What can easily be overlooked is that, depending on the camera type and the telescope aperture ratio, a more or less pronounced vignetting is unavoidable.
We regret that we can’t give a binding (or universal) recommendation for an eyepiece-Barlow-lens-combination - for no single eyepiece on the market - where vignetting does not occur. Eyepiece projection is basically a compromise and has been "invented" for planetary photography since the beginning of all photography in order to be able to image a small object in the center of the image with excellent sharpness and very long focal length. The further development of the eyepiece also made it possible to enlarge the usable image area - however, this method is still a compromise. We therefore do not claim that you can achieve perfect sharpness over the entire image field with an eyepiece and a Barlow lens. We also do not claim that you can achieve a completely unvignetted image field!
For exactly this reason - because there has been no solution from anyone in the world (and still is not) - we asked Carl Zeiss-Jena in 1990 to calculate for us a plano barlow lens of any complexity for medium format cameras. Ultimately, this was only possible with two additional crystal substrates made of genuine calcium fluorite (not comparable to simple ED glass). For the Baader Fluorite Flatfield Converter (FFC) Barlow - which can produce an image circle of 90 mm from 4x to 8x - an aperture ratio of 1:10 - as is the case with many refractors - was the basis for calculation at that time. The 90 mm image circle was due to the fact that the famous "PENTAX 6x7" medium format camera was available at the time - with a 90 mm image diagonal.
To this day, this FFC converter lens system is "the sharpest of all Barlow lenses" in the world. And since the full 42mm format uses less than half of the FFC’s 90mm image circle, the FFC works so well even at an aperture ratio of f/5 that it delivers diffraction-limited sharpness even with CMOS chips with ~ 4my pixel size (if the telescope optics and seeing are good enough). However, this only works so well due to the large image distance. If you are looking at the "Baader FFC-Barlow", you will see that the image distance has to be varied between 80 and 150 mm (or even more). So you pay for the excellent optical performance with a very long mechanical construction. Without an excellently stable focuser, this can only cause frustration. Anyhow - You will surely find enough judgments which testify that there is no other projection lens system with sharper - and not vignetting - imaging.
So if photography with very long focal lengths is your main focus, then you would have to replace the combination of the eyepiece with a 2.25x Barlow for a FFC - in addition to the armada of extension rings, which are necessary if you want to use this projection method without mechanical distortion.
Please note that you will achieve a very high magnification and a low f-stop with the Barlow; you can find the formulas for calculating the effective magnifications in this PDF: https://www.baader-planetarium.com/en/downloads/dl/file/id/444/product/3117/digiscoping_camera_adaptations_for_afocal_photography_and_eyepiece_projection.pdf
Bundle: MARK IV Hyperion Universal Zoom 8-24 mm eyepiece & Baader Hyperion Zoom Barlow lens 2.25x mag
The set consisting of the MARK IV Hyperion 8-24 mm Universal wide angle Zoom eyepiece (#2454826) and the Hyperion zoom Barlow 2.25x (#2454654) results in combination in a zoom eyepiece with a large focal length range. The set covers all eyepiece focal length from 3.6-24 mm.
This set can only be used on all astronomical telescopes; use with tripods is only possible without the Barlow lens.
MARK IV Bundle contains the following items:
1) 1x Hyperion Universal Zoom MARK IV, 8-24 mm eyepiece with ClickStop Action (#2454826)
Versatile wide-angle zoom eyepiece with connection option for cameras.
- 2 "(left illustration) and 1¼" (right illustration) barrel
- 2" SC thread and 1 3/8" thread for spotting scopes
- Eyepiece holster with belt-strap, which fastens onto many tripod legs just as well, to serve as a bin for all dustcaps that may go astray otherwise
- Height-adjustable eyecup as well as a standard non-foldable and a winged rubber eyecup
- three dustcaps
2) 1x Hyperion Barlow Lens 2.25x (#2956180)The Barlow lens with T-2 adapter (above) and Hyperion zoom adapter 1.25 "(Center).
Increases the focal length of your telescope by a factor of 2.25, with docking adapters for camera (T2-system) and zoom eyepiece.
- T2 Photo-Adapter
- Zoom-Eyepiece Adapter
The Hyperion ClickStop Zoom Eyepiece with 1¼" and 2" Connector
There is an old saying that there is nothing like an eyepiece with fixed Focal length, if it should be the highest image quality. But this zoom eyepiece is second to none fixed focal length eyepieces, saving especially during mobile use so you don't have to carry many eyepieces around.
The Hyperion Universal Zoom is a perfect solution for all hunter, birdwatchers and astronomers alike, it brings a whole range with focal lengths from 8 to 24mm in a single high-quality eyepiece! It lets you continuously zoom with Clickstops at 8, 12, 16, 20 and 24mm. The only difference to the fixed focal length is that the field also varies from 53 Degrees at 24mm focal length up to 68 degrees at 8mm. This eyepiece was "Reverse" constructed unlike most other zoom eyepieces: largest field of view and the sharpest image at the highest magnification.
See a more detailed description of the eyepiece and its possibilities at the individual product page
Caution: On spotting scopes you can use the Hyperion zoom eyepiece only without the Barlow lens!The Hyperion Barlow lensHyperion Barlow threaded on the discontinued Mark III Hyperion zoom eyepiece in 1.25"(left) and 2" configuration (on the right)
Hyperion zoom Barlow lens - 2.25x
The 2.25x Baader Hyperion Zoom Barlow lens was designed especially to complement the Hyperion Zoom eyepiece. It converts the regular focal lengths of 8 to 24 mm to a range of focal lengths between 3,6 and 10,7 mm, while retaining the outstanding image quality for observing sun, moon, planets and double stars with high resolution.
The Mark IV Zoom, in conjunction with or without the Hyperion Barlow, covers all focal lengths between 3.6 to 24 mm.
The Hyperion Barlow works with every Hyperion 8-24 mm Zoom eyepiece ever produced. The barlow is attached onto the 1¼"-nosepiece. Because of the dual nosepiece of the Mark IV, it can be used at telescopes with 1¼" or 2" eyepiece clamps.
The Hyperion Barlow comes with a T-2 thread-adapter, to mount the Barlow in front of any camera or other accessories with T-2-threads. Combine it e.g. with a DSLR-camera – in this way the camera body will be equipped with a 1 ¼" nosepiece. The camera body just needs a standard T-ring to fit it onto any 1 ¼” eyepiece holder.
Attach the lens unit without the Barlow-adapter (A) directly onto many 1¼" eyepieces, whenever they do not already have an integrated barlow element. The result is a 2x Barlow with very good optical properties (see left image).Also included is an adapter on T2-thread. Thus, the Barlow can be used - for example, on a DSLR with T-Ring
Some highlights of the Hyperion Zoom Barlow Lens
- Triplet lens design for highest optical quality
- Anastigmatic Flatfield Design for high sharpness all over the field of view
- Baader Phantom CoatingTM Group for highest contrast and light transmission
Connections Eyepiece side
- Direct connection to any Hyperion Zoom with Barlow-adapter A
- T-2 (M42x0.75 mm) thread with Barlow-adapter B
- 1¼" filter thread without additional Adapter
Attention: The Barlow lens is only suitable for use in astronomical telescopes; the use of spotting scopes is not possible.
|Focal Length||3,6 - 24 mm|
|Apparent Field of View||48° - 68°|
|AR-Coating||Phantom Coating® Group|
|Barrel Size (in)||1¼", 2"|
|Speciality||Eyepiece projection: classical|
|Number of Lens Elements||7|
|Number of Groups||4|
|Slip Protect Safety||Safety Kerfs|
|Eyepiece Body above Reference Plane (mm)||81 mm|
|Length of 1¼" barrel (mm)||24,5 mm|
|Length of 2" barrel (mm)||27 mm|
|Outer Diameter||55 mm|
|Outer Connection (eyepiece/-camera-sided)||Thread, M43|
|Inner Connection (lens sided)||Thread, 1 3/8", 2" (50,8mm)|
|Outer Connection (lens sided)||Barrel, 1¼", 2" (50,8mm)|
|Threaded for filters||Yes|
|Dustcaps||1¼" dustcap (31,8mm), 2" dustcap (45mm), 2" dustcap (46.5mm - fits over eyecup)|
|Eyecups||large height adjustable eyecup (M43), small eyecup (M43), winged eyecup (M43)|