What Series IV model do you need?
There are 3 basic Series IV 'Stiletto' packages/models to choose from:
If working at lower f/ratios ( below 10) , consider either the Deluxe or Pro Edition models which include the high-resolution black chrome ronchi screen. This resolution screen will function properly with all telescopes and camera lenses down to below f/3.
If you are very finicky about your imaging, however, you may be more interested in our Pro Edition model. This comes with the 300 LPI screen as well as a Hybrid Knife-edge screen. The edge itself is fifty times finer than a razor blade edge. The Hybrid screen also incorporates a 150 LPI ronchi grid to provide ease in initial focusing. The Hybrid Knife-edge screen and 300 lpi Ronchi screen are also interchangable with no recalibration necessary between swapping the two screens. With the 300 lpi ronchi screen, it is much easier to gage when you are approaching the focal plane since the bars grow larger and fewer in number as you approach focus. A knife-edge is different. This is like a ronchi screen - but basically only has one bar on it! While focusing with a knife-edge is a bit more challenging than with a ronchi screen, with proper guidelines you will be extremely gratified with the results. Click here for our tutorial on knife-edge focusing which details how to use a knife-edge properly.
In general, if you do not know what type of telescope you may have down the line (and all of us are continuously looking for a new scope), it's best to err on the prudent side and choose either a Deluxe or Pro Edition model since they are effective with any scope. Choose the Pro Edition with included knife-edge and ronchi screens depending on your budget and seriousness about astrophotography. A Series IV 'Stiletto' really will last a lifetime, so take this into consideration when choosing a model.
All Series IV 'Stiletto' Standard, Deluxe, or Pro Edition models are complete and come ready-to-use as shown. You simply specify the 'Stiletto' camera mount that matches your camera when you order. One camera mount is included in the prices above. All Series IV models above are identical except for the resolution of the ronchi screen included and accessories.
After you order one of these models and have the Series IV body, you can order Extra 'Stiletto' camera mounts at any time if you would like to use your Series IV with other cameras too. All 'Stiletto' modular mounts are interchangeable on the fly and come pre-calibrated : just unscrew one mount from the Series IV body, and screw another in its place when you like. This way it's easy to go from 35mm to CCD or even to Medium Format in only seconds!
What type of mount do you need ?
35mm Manual and Digital Cameras
You'll find that the wonderful thing about new or old 35mm manual cameras is that they were designed with standards in mind in the first place. This made it relatively easy for manufacturers of astronomy accessories to develop products which were interchangeable between different camera brands, such as t-adapters, t-rings, etc.
At the same time, the major camera manufacturers such as Nikon, Olympus, Canon, Minolta, Pentax, Konica, and Miranda made their different models within their own product lines compatible with each other. This standardization allowed the same interchangeable 35mm lenses to fit and properly reach infinity focus on different models from their own lines.
The result is that a Series IV focuser for Nikon to be used with a Nikon F made in 1965, for example, will also work on all other Nikon (or Nikormat) manual 35mm camera models manufactured after that date, and even the new Nikon DSLRsl. This is necessarily so since all of the Nikkor lenses will fit any Nikon camera body. These camera bodies have the same type of bayonet mount, and therefore, the same film-plane distance. And so, it does not matter if a Nikon body is an F2, F2AS, FM, FT, F3, F4, or whatever. The same Series IV 35mm Nikon focuser will function properly with it. The Series IV 'Stiletto' mount has a bayonet mount to match the camera and the ronchi screen is placed at exactly the same film-plane distance as your camera.
The same is true for all of the other camera brands as well. A Series IV 35mm focuser for an Olympus OM will function with all other Olympus models, a Series IV 35mm for the Canon, will work with all other Canon models, etc.
This same principal holds true for the newer digital cameras made by these manufacturers too. Since a new Nikon D-60 camera, for example, can use the older Nikkor lenses, it necessarily means that the film-plane distance (called backfocus distance in digital designs) is the same.
For off-brand cameras, the key to choosing the right Series IV model is simple also. Just find out what brand of camera lens is used on the camera. Many of these cameras use a standard Pentax-K mount bayonet, for example. Knowing this assures you that the camera has the same film-plane distance as the true Pentax-K camera. The Russian Kiev 60 camera, another example, uses a Nikon bayonet mount. Thus, a Series IV 35mm for Nikon would match it perfectly.
So, the key to choosing the proper Series IV model is really in knowing what type of bayonet mount is on your camera. Knowing this, it's easy to choose the right Series IV focuser to use with it!
CCD Cameras
Unlike the 35mm world, the CCD camera world is a relative mess as far as standardization goes. The manufacturers are long overdue for a conference call to standardize backfocus distances and the type of mounts used to attach to the telescope, etc. And even within their own camera lines, there is a wide variation in backfocus distances between models. The reason, of course, is that these manufacturers have never really had to consider using camera lenses in the first place! Since a camera lens has an infinity stop position, 35mm manufacturers were actually forced to think about a fixed film-plane distance. No such pressure has come upon the CCD manufacturers, however, since telescopes do not have a set infinity position. The result is that CCD astrophotography is much more difficult than it has to be: a CCD user cannot simply buy any adapter, flip mirror, CFW, or whatever off the shelf and be guaranteed that it will be compatible with his camera. Using the wrong accessory may even result in not being able to reach focus on the chip. What a mess!
To choose the correct Series IV focuser to use with a CCD camera, therefore, requires a bit more understanding of your own camera and set up. The critical specification, of course, is the backfocus distance - how far the chip lies from the front of the attaching mount. We have done considerable research over the years to determine this for you. So, when you order a Series IV for CCD, you must know what specific model you have. You cannot just order a Series IV for SBIG and be done with it. You do need to know what ST- model it is. The same applies to Starlight XPress cameras and what MX or SVX model you have. Knowing this, you will also know which Series IV for CCD model to order.
Another consideration is how you are attaching your CCD camera. Normally, these are attached to the telescope using a 1.25" nosepiece or directly to the M42 threaded ring on the camera. To match a Series IV to your setup, we do need to know how your are attaching it. The reason is that the backfocus distance is significantly affected by the attachment itself. And the killer is that there is no standardization regarding these accessories either. For example, a 1.25" SBIG nosepiece has a flange width of .65mm, a Starlight XPress nosepiece has a flange width of 5mm, and a Meade camera uses a nosepiece with either a 3.75mm or 12mm flange width. A Series IV for CCD is supplied with a nosepiece to match what you are using on your camera. We have already done the homework. But, if you are using a different way of attaching your camera or using any special adapters, we do need to know about these so we can supply the proper attachment device along with the Series IV so that the swap-in, swap-out focusing routine works properly for you.
If you are relatively new to either 35mm or CCD astrophotography, be sure to check out Paul Van Slyke's The Art of Astroimaging: How to Get Started in CCD or 35mm Celestial Photography which offers some excellent guidelines.
In the long run, I have come to the conclusion that the CCD industry will run into some deep trouble and stiff competition if standards are not soon set. The large threat comes from the new standard 35mm digital cameras with interchangeable lenses which are getting better and cheaper everyday. Many of these are now incorporating dark frame compensation and B settings. They allow a means to do prime focus, eyepiece projection, and wide-field astrophotography with standard accessories and lenses - and at prices equivalent or lower than their astronomical CCD counterparts. And these traditional and well-known camera manufacturers all have a long-term vested interest in photography in general.
Other Cameras
Series IV focusers are available for many cameras, even some not listed on our order form. A Series IV for Medium Format cameras is available for popular models from Pentax, Mamiya, Hasselblad, and Kiev. For other models, a Series IV can usually be developed and manufactured from special components. If you think you have a strange camera, it wouldn't hurt to inquire since we have probably developed a focuser for it already!
If you still have any specific questions about what you need, please do not hesitate to email me or give me a call at 1-800-232-9416.
