If you click that link I provided in my first reply, that will explain and even show you all that. Nevertheless, that T-Ring attaches to the camera in place of the cameras lens, then the T-Adapter threads onto the T-Adapter. T-Adapters come in a variety of styles, and they do come in either a 1.25" or a 2" focuser insert/barrel. You can even get a barlowed 1.25" T-adapter to double the magnification of your camera. You can get a Universal Eyepiece Projection Adapter which has a detacheable 1.25" T-Adapter that will thread into the T-Ring also.
Most reflectors require both the T-Ring and T-Adapter because they don't have a threaded focuser. Many Refractors and Cassegrain don't require the T-Adapter because you can thread the T-Ring directly onto the focuser or visual back.
Orion Sells a Zero Profile T-Adapter made specifically for DSLR's. Most often you can't reach focus because there isn't enough inward focuser travel. I falls just a little shortt of being in focus with a regular T-Adapter.
A Low Profile Crayford style focuser and the Zero Profile Adapter would be more than enough extra inward focus travel, unfortunately the zero profile only comes in the 2" size.
I don't want to discourage you from your attempts at astrophotography, however you really need to take it one easy step at a time.. Read and learn as much as you can about the equipment requirements and photography in general and astrophotography with a DSLR..
Before you start cutting on your Optical Tube, you must know and understand your equipment first. You start messing around with the focal length you could easily mess something up and ruin it.
Meade has been selling a lot of these lower end reflector telescopes using a design that can prove to be difficult even for visual use let alone imaging.
I don't know about your telescope since I don't have the spec nor have seen it. Do you have the correct nomenclature of the Telescope listed in your above post. Is it an ETX DS 114mm reflector.. The Reason I ask is because the ETX series telescope are completely different from their DS series telescopes.
Is it what is called a short tube reflector and does yours have a small corrector/relay lens inserted into the focuser draw tube? If it is this telescope>> o not Mess with the focal length. If it is the Meade DS-2114ATS-TC, Do Not Mess with the Focal Length.. These are both Jones-Bird design optical tubes.. Cutting the tube shorter to move the mirror foreward will ruin the telescope. You can't even change the focuser on those telescopes because they also have a corrector built into the draw tubes.
Both those telescopes are on less than stable Alt_Az mounts that would make prime focus Deep Sky photography all but impossible with most any camera.
If what you have is one of the EQ Mounted 114mm reflectors, then your chances for long exposure photography has a better chance provided you can get motor drives for it. Neither of the EQ mounted 114mm telescopes have motors for them. And if it is the ATS version that is the Jones-Bird design reflector and again you wouldn't want to mess with the focal length..
From my own personal experience with that particular mount of Meade's I can tell you that it is less than desireable for any kind of photography. That is an EQ-2 type mount that will shake, wobble and vibrate with any amount of breeze or the slightest touch. It takes too much time to settle down for most astophotography and would cause smeared and blurred images. One of my telescopes is what is now the Meade 114 EQ-A.
The first steps you want to take into astrophotography should be learning and getting familiar with the equipment.
Second: with that telescope and mount, if you want to take images start with Web cam images of the moon and planets. Or Afocal Planetary and Lunar photography. This way you won't have to make any modifications to the telescope, and since those objects require only short exposures you can do that with that telescope and get some good results.
With a DSLR your first night sky shots should be with the camera on a simple camera tripod. Start with short exposures (20 0r 30 seconds) of the constellations. Then work up to long exposure star trail images.
Third: if you're really set on getting into Prime focus imaging, then the above still applies first, then think about the equipment requirements for nice DSO images.
Although astrophotography of one method or another is possible with almost any telescope and mount; Not all methods of astrophotography are possible with just any telescope and mount. Everything has its limitations. Even people do when it comes to astrophotography.
Click that link I provided in my first reply, That will explain a lot of what you need to know. If that isn't enough follow the links at the bottom of that post..
I don't want seem as though I am trying to discourage you. I feel it better that you get into something new armed with a little information so your expectation won't exceed the reality of what you have at hand. You get into this with high expectation it will be you that discourages yourself..
Have A Nice __________