250W Vs 400W MH setup??

[declined]

Hello!
I'm FINALLY about to start the building phase of my PJ project.
The only thing I really cannot decide is wether to invest in a 400W MH or go for the 250W...

Is there a great chance that 250W won't be enough?
Or: Could 400W be overkill?

Is there a big difference in heat?

-> I found nice a 250W bulb + ballast after a long search, but I need to be *absolutely* 100% certain that the lamp is OK to use. I really can't afford to buy another one because in Belgium, these bulbs are very expensive!

Who has had good results with 250?
and also: who has had BAD experiences using 250W/400W bulbs?

[18wheeler]

Hello!
I'm FINALLY about to start the building phase of my PJ project.
The only thing I really cannot decide is wether to invest in a 400W MH or go for the 250W...

Is there a great chance that 250W won't be enough?
Or: Could 400W be overkill?

250w will be enough for some people. and 400w will not be enough for some others. it depends on your favor. but lots of people succeed with both.

Is there a big difference in heat?

400:250 = 60% more heat, roughly.

-> I found nice a 250W bulb + ballast after a long search, but I need to be *absolutely* 100% certain that the lamp is OK to use. I really can't afford to buy another one because in Belgium, these bulbs are very expensive!

post some spec.

Who has had good results with 250?
and also: who has had BAD experiences using 250W/400W bulbs?

search for the posts by cruser. he used 250w HQI for quite a few good projectors.

[declined]

I'll go check soon to get the full specs of the 250W.

The heat of the 400W might be a problem, since I also can't seem to find any low-E glass here in Belgium. Why don't people know this type of glass?? (it -does- also mean Low-dispersion, right?)

---> Anyway: I want to use it in my room, lights out, with *just* enough brightness to be able to walk around without bumping into everything. (=very dim room)
BUT I dont want the image it to be "almost bright enough", I want it to be bright enough to really enjoy a movie without constantly thinking "hmm i guess it would be better if the image was brighter", because thats what i think every single second i use my "test-pj" with a 50W 30° angle halogen bulb (even in a 100% DARK room)

I'll be using the usual 15" flatscreen lcd, 250W (400W??) bulb, customised OHP optics, about 4 cooling fans and some other stuff

-> with such a setup/conditions, you think I could go for the 250W?
Cruser's results seem pretty acceptable
I just wanna prevent disappointment...

[moltenrock]

I'm using a 250 Watt MH bulb with a 15" lcd monitor and some OHP optics, and I must say that I am quite pleased with the results from my setup. In a room with no ambient light, my projection looks outstanding, but as ambient light enters the room then you may become disappointed.

[moltenrock]

But, I do have a 400Watt MH kit that I would sell you if you decide to go that route. Best of luck.

[declined]

I'm absolutely interested in the 400W kit, but I'm from Belgium... won't that be a major problem? (shipment & shipping costs)

If it's possible without problems (or very high costs) , I'd be interested in the kit!

What's your price?

PS: do you have anyy experiences or something about shipping stuff to Europe? (& getting paid)

[bfourcade]

Hi guys

I´m using a 400w MH with excellents results.

Now I want to improve my reflector in order to really use the most light from this bulb.
Anyone can help me to calculate the radius or diameter of an semispherical reflector ?

My bulb is a tubular type one 26cm long and 5 cm diameter so the arc is at 25 mm from the tube glass edge.
My condenser lens is 60mm in diameter.
So, how can I calculate the diameter of the semisphere and the distance to the arc in order to get the most out of the arc ?


In the atached graphic I need to calculate X and Y distances.

Anyone can help me ?

Bernardo.

[moltenrock]

Declined,

No, I don't have any experience shipping anything to Belgium, but I have received things from Europe if that helps. LOL. And I have no idea what shipping costs would be for this deal. The payment method that I really prefer is paypal. It's quick easy and safe. I would accept $60 for the whole kit (socket, bulb, ballast). Let me know what you think.



To Bernardo,

I have modified your picture. The arc of your bulb should be placed at the plane of the hemisphere which is the radius of the reflector. You can measure D with a tape measure and then use the formulas that I wrote down on the picture.

[declined]

moltenrock,

60$ really is a great deal... prices here in Belgium are EASILY triple that...

But I'm gonna wait for a little while because just now I met someone from this forum that lives "just around the corner"
He can help me with fairly cheap kits so I'm going to go for that...

But thanks a lot for the offer anyway!


-DeclineD

[bfourcade]

Thankyou for your response.

One last question.

How can I calculate the correct diameter of the reflector ? Is it
related to the diameter of the condenser lens ?

or is a matter of just picking a semispherical reflector a little bigger than the bulb and putting the source point of the lamp in the center of the sphere ?

If is just that, I think my current soup ladle reflector is doing his job.

thank you !!