DIY T5 reflectors?
- Thread starter Aqua Keepers
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BeanAnimal
Premium Member
Your English is just fine Firochromis 
hahnmeister
In Memoriam
I do not believe it is impossible, nor do you need a special computer to design a T5 reflector, since its just a 2D reflector (it doesnt change along its length). But you REALLY need to know what you are doing. Or, there are some reflector design programs that are available for free on the net... not that you really need them.
You would be shocked to know how many companies actually design/make their reflectors. With a good break and sense of design... you could DIY some.
The problem is that the better reflectors have ALOT of facets/bends, or they have none at all (they are a continuous curve)... the less 'flat surfaces' a reflector has, the less space it can take up and still be just as effective.
I am writing the 'T5 shootout part 2' article right now (lots of diagrams/pics to process besides just 'raw data' from grid tests), and I plan on including some simple design pointers and considerations so that some common myths get cleared up, and so without me or Sanjay having to test a reflector, a person can look at one and tell on their own if they are likely to be a good design or not.
The main idea to consider is to try to make every possible angle from the bulb reflect away from the bulb. Just being 'parabolic' doesnt mean much... in fact, you could make a parabolic that is WORSE than a flat piece of reflective material... by having most/all of the surfaces pointing right back at the bulb.
You would be shocked to know how many companies actually design/make their reflectors. With a good break and sense of design... you could DIY some.
The problem is that the better reflectors have ALOT of facets/bends, or they have none at all (they are a continuous curve)... the less 'flat surfaces' a reflector has, the less space it can take up and still be just as effective.
I am writing the 'T5 shootout part 2' article right now (lots of diagrams/pics to process besides just 'raw data' from grid tests), and I plan on including some simple design pointers and considerations so that some common myths get cleared up, and so without me or Sanjay having to test a reflector, a person can look at one and tell on their own if they are likely to be a good design or not.
The main idea to consider is to try to make every possible angle from the bulb reflect away from the bulb. Just being 'parabolic' doesnt mean much... in fact, you could make a parabolic that is WORSE than a flat piece of reflective material... by having most/all of the surfaces pointing right back at the bulb.
BeanAnimal
Premium Member
I think if you read what you wrote a few times, you have contradicted your own point
Of course it is not impossible, but the fact is that the well engineered SLR is going to spank the DIY SLR every time. To argue any differently is to ignore the basic science of how light behaves.
I would be interested to see you test a few DIY models in your shootout.
Of course it is not impossible, but the fact is that the well engineered SLR is going to spank the DIY SLR every time. To argue any differently is to ignore the basic science of how light behaves.
I would be interested to see you test a few DIY models in your shootout.
tarzan
New member
I wouldn't agree with you BeanAnimal, he made a clear point that it's possible and i would hae to agree with him. It's true that it's not so easy, but it can be done. I guess there are also some people that go ahead and buy the fanciest SLR reflectors out there and by mounting them too close or too far from the tube they do even worse than they would do making their own reflectors from scratch.
About basic science of how light behaves: i don't get it. What did you mean with it? The light doesn't mind you using different reflectors, and it doesn't get cranky if you have ugly reflector. There are many different reflectors for different final effects. Yes, correct shape is very important, if you look at this diagrams you can see what difference does the reflector make. Who says that only one is good? Perhaps you would want to have inner reflectors wider and the one next to front and rear glass to be more focused.
Hahn - you would have to "close" the reflector completely on the bottom part to get worse results than with a flat reflective material. I guess nobody is THAT stupid....
About basic science of how light behaves: i don't get it. What did you mean with it? The light doesn't mind you using different reflectors, and it doesn't get cranky if you have ugly reflector. There are many different reflectors for different final effects. Yes, correct shape is very important, if you look at this diagrams you can see what difference does the reflector make. Who says that only one is good? Perhaps you would want to have inner reflectors wider and the one next to front and rear glass to be more focused.
Hahn - you would have to "close" the reflector completely on the bottom part to get worse results than with a flat reflective material. I guess nobody is THAT stupid....
BeanAnimal
Premium Member
It is possible to make a backyard pulse-jet engine out of some copper pipe and a propane tank as well. The point is that the average DIYer is not going to be able to build an efficient design with any reasonable savings or benefit.
Exactly, even the DIYer with above average skills and a sheet metal break are not going to do a very good job. There are 3 areas for errors to be introduced. 1) Design 2) Final Shape 3) Material. Even if you end up 15% less efficient, how much money are you saving in the end and what benefit is the DIY?
We are quibbling semantics here. Hahn contradicted himself and you are basically doing the same. You both are saying it can be done but, the shape is important. The average DIYer has no chance in hell of easily coming up with AND bending an efficient shape.
That is a straw argument. User error has nothing to do with the fact that bending a proper SLR is not an easy or reasonable task for a DIYer. Furthermore, most quality SLRs come with bulb clips that are designed to position the bulbs correctly in the reflector.
Nice diversion. You know exactly what I meant. The path of light is predictable and reliant onthe shape of the reflector. A poor shape means poor efficiency with regard to the desired focus. Errors in the design and final shape mean more scattered light and less light in the desired focus. The differences between well designed reflectors can be different, let alone the differences between a well designed reflector and a back yard special.
You are assuming that ALL of the light from the bulb makes it into the overall footprint cast by each reflector of a different shape. That is not at all the case. The most efficient design moves the most light with as few surface contacts as possible and little or no restrike. Poor designs cause more surface contacts and restrike and therefore more scattering and absorption (as heat). The losses due to each contact are significant. When over 65% of the light cast by the lamp MUST be reflected to reach the tank, SHAPE and MATERIAL are extremely important. Errors in shape are extremely significant. There is simply no way around it.
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