A quick explanation:
The three OHPs from left to right are
1. Geha 575HMI with singlet objective lens, condenser lens, bottom bulb design, Manufacturer claims 12000 lumens
2. Nobo 699, again, 575HMI with triplet objective lens, side bulb design, with plane mirror at 45 degrees, no condensor, Manufacturer claims 5500 lumens
3. Leisegang 400w/36v Halogen (EVD bulbs), triplet lens, condensor lens, bottom bulb, Manufacturer claims 4000 lumens
Room conditions are large hall 30mx22m in size, well lit - you can see two windows letting sunlight pour in. As you will have noticed, one pic was taken with the flash on, the other with it off.
Don't know about bulb condition / life expectancy in each OHP, but have no reason to think they aren't all about half way through their respective lifespans.
The picture with coloured transparencies are revealing - supporting a view on another thread that too many lumens might be a bad thing - on the two MH ohps, the Reds look distinctly pink!, whilst on the halogen it looks a truer red.
I am suprised however by the similarity in performance by all three, once the transparencies are in place - not indicative of their respective lumens ratings at all!!
What do you all think??
The three OHPs from left to right are
1. Geha 575HMI with singlet objective lens, condenser lens, bottom bulb design, Manufacturer claims 12000 lumens
2. Nobo 699, again, 575HMI with triplet objective lens, side bulb design, with plane mirror at 45 degrees, no condensor, Manufacturer claims 5500 lumens
3. Leisegang 400w/36v Halogen (EVD bulbs), triplet lens, condensor lens, bottom bulb, Manufacturer claims 4000 lumens
Room conditions are large hall 30mx22m in size, well lit - you can see two windows letting sunlight pour in. As you will have noticed, one pic was taken with the flash on, the other with it off.
Don't know about bulb condition / life expectancy in each OHP, but have no reason to think they aren't all about half way through their respective lifespans.
The picture with coloured transparencies are revealing - supporting a view on another thread that too many lumens might be a bad thing - on the two MH ohps, the Reds look distinctly pink!, whilst on the halogen it looks a truer red.
I am suprised however by the similarity in performance by all three, once the transparencies are in place - not indicative of their respective lumens ratings at all!!
What do you all think??
To me the first one looks the brightest and the 2nd one has a wierd green tint and the 3rd just looks brown. So I have a question when A lcd panel is on the geha and the rooms windows are open can you project a good Image while the room is not tatally dark? thats what Im looking for at the moment a projector that can be used as a TV( ie not pitch black in the room) cool pics tho finally someone did the comparison. Where did you get all 3? do you own them all? do you have a source for the geha's? LOL
More tests to be done...
I just acquired the Geha, but had the Nobo a few months back, and was very disappointed with it. I expected it to be the Holy Grail of OHPs. I am however, a little more encouraged by the performance of the Geha (so far!)
I work for a conference centre, so they bought the Nobo off me, as they were short of them themselves! The third (Leisegang halogen) is one of their stock OHP's, but a similar spec to my GBI5000, which also uses EVD bulbs.
As far as doing a test with a panel goes, what I guess I need to do is take three separate photos and perhaps paste them together side by side - perhaps a paused DVD image, such as the Paramount, or Universal welcome screens, that are images familiar to everyone + then also find a "dark" scene in a movie, pause that, and run the test on all three again.
I also want to do the test with a triplet lens in the Geha, and swap the Nobo and Geha bulbs over, as the "bubble" part of the bulb in the Geha also looks a bit cloudy - so it might be quite old.
I'll also get a 250W halogen OHP out of the storeroom, and set that up, as a fourth comparison for those the benefit of those forum members who are still using this type of OHPs.
What comes through for me from tests so far is the integrity and cripsness of the MH's. The Halogen is reasonably bright, but just looks yellowish and a bit whimpy.....
watch this space - hopefully I'll have more pics up in the next couple of days.
I just acquired the Geha, but had the Nobo a few months back, and was very disappointed with it. I expected it to be the Holy Grail of OHPs. I am however, a little more encouraged by the performance of the Geha (so far!)
I work for a conference centre, so they bought the Nobo off me, as they were short of them themselves! The third (Leisegang halogen) is one of their stock OHP's, but a similar spec to my GBI5000, which also uses EVD bulbs.
As far as doing a test with a panel goes, what I guess I need to do is take three separate photos and perhaps paste them together side by side - perhaps a paused DVD image, such as the Paramount, or Universal welcome screens, that are images familiar to everyone + then also find a "dark" scene in a movie, pause that, and run the test on all three again.
I also want to do the test with a triplet lens in the Geha, and swap the Nobo and Geha bulbs over, as the "bubble" part of the bulb in the Geha also looks a bit cloudy - so it might be quite old.
I'll also get a 250W halogen OHP out of the storeroom, and set that up, as a fourth comparison for those the benefit of those forum members who are still using this type of OHPs.
What comes through for me from tests so far is the integrity and cripsness of the MH's. The Halogen is reasonably bright, but just looks yellowish and a bit whimpy.....
watch this space - hopefully I'll have more pics up in the next couple of days.
Okay, I'm really going to say something contentious now!
Well, well.
I've done some preliminary side by side testing with panels on four different OHP's - and yes pictures are coming.
First, VF's hope that he will be able to use this equipment as a TV, in a fully ambiently lit room is not really feasible, unless he's happy with a barely watchable image.
The only three qualifications of this are:
(i) Image is quite good if you wait until late afternoon - room is still lit by daylight, but the sun is not so strong
(ii) Draw the blinds, but feel free to use almost as much artificial lighting as you want. In my living room I'm using 120Watt domestic ceiling lights, and the projected image is still good.
(iii) The only possible way to use OHP+panel in a fully sunlit room would be using rear projection. My panel (and most others) have a rear projection switch, so its just a case of buying some rear projection cloth from someone like Dazian in the U.S.
A lot of this won't be new to anyone....however my (possibly) contentious points are that, when using my Powerview panel in my tests:
The HMI 575W Metal Halide OHP produced an image that is ONLY MARGINALLY BRIGHTER than my 400W halogen (with virtually identical optics in each machine). This point has also been established by someone else on another thread.
It seems the main reason for little difference in performance is the fairly mediocre CR of my panel (100:1). Bright scenes look (just!) noticeably brighter, but dark scenes look pretty much the same with both OHPs - lacking visible detail & definition.
The only real benefit is that colours seem to be rendered a little more faithfully with MH because the light is white where as halogen light tends to be yellowish.
IMHO, its only worth getting a MH ohp if you alreadu have, or intend to get, a panel with a much higher CR (maybe 250:1 or above)
Although running costs for both types are about the same (75hr halogen = £8.50, 750hr HMI = £86.00), the initial outlay to buy a MH ohp is considerably more....and if the ballast goes, you're up the creek without a paddle!!
Why does the halogen on its economy setting (2500 lumens) still give a 12,000 lumens OHP a run for its money - surely the halogen should be blown out of the water!
Is it to do with the wavelength of the light produced by the two different sources - does halogen-light have an easier time getting through the polarizers and TFT?The HMI 575W Metal Halide OHP produced an image that is ONLY MARGINALLY BRIGHTER than my 400W halogen (with virtually identical optics in each machine). This point has also been established by someone else on another thread.
Well, well.
I've done some preliminary side by side testing with panels on four different OHP's - and yes pictures are coming.
First, VF's hope that he will be able to use this equipment as a TV, in a fully ambiently lit room is not really feasible, unless he's happy with a barely watchable image.
The only three qualifications of this are:
(i) Image is quite good if you wait until late afternoon - room is still lit by daylight, but the sun is not so strong
(ii) Draw the blinds, but feel free to use almost as much artificial lighting as you want. In my living room I'm using 120Watt domestic ceiling lights, and the projected image is still good.
(iii) The only possible way to use OHP+panel in a fully sunlit room would be using rear projection. My panel (and most others) have a rear projection switch, so its just a case of buying some rear projection cloth from someone like Dazian in the U.S.
A lot of this won't be new to anyone....however my (possibly) contentious points are that, when using my Powerview panel in my tests:
The HMI 575W Metal Halide OHP produced an image that is ONLY MARGINALLY BRIGHTER than my 400W halogen (with virtually identical optics in each machine). This point has also been established by someone else on another thread.
It seems the main reason for little difference in performance is the fairly mediocre CR of my panel (100:1). Bright scenes look (just!) noticeably brighter, but dark scenes look pretty much the same with both OHPs - lacking visible detail & definition.
The only real benefit is that colours seem to be rendered a little more faithfully with MH because the light is white where as halogen light tends to be yellowish.
IMHO, its only worth getting a MH ohp if you alreadu have, or intend to get, a panel with a much higher CR (maybe 250:1 or above)
Although running costs for both types are about the same (75hr halogen = £8.50, 750hr HMI = £86.00), the initial outlay to buy a MH ohp is considerably more....and if the ballast goes, you're up the creek without a paddle!!
Why does the halogen on its economy setting (2500 lumens) still give a 12,000 lumens OHP a run for its money - surely the halogen should be blown out of the water!
Is it to do with the wavelength of the light produced by the two different sources - does halogen-light have an easier time getting through the polarizers and TFT?The HMI 575W Metal Halide OHP produced an image that is ONLY MARGINALLY BRIGHTER than my 400W halogen (with virtually identical optics in each machine). This point has also been established by someone else on another thread.
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