Meet Osram 50035 Ministar Axial-Reflektor

Looking forward to more comments/observations on this bulb.

Actually was fairly easy to insert bulb from inside the reflector. Just wear a soft cotton glove, and I gently let bulb slide down inside of tilted reflector, and lined up bipins with socket, then held gentle pressure on bulb as I uprighted light. Then even inserting it in Modamag's 4" Colossus reflector (0.5" bore) was easy with gentle, straight down pressure. To remove cooled bulb, I got a short length of kite string, tied a single knot making a noose, draped it down over head of bulb, cinched up the loop, then bulb came out with slow, steady pulling on string.

Stefan is right that the bulb then does benefit from focussing. I just tried it with 4s Emoli 18650 cells, using AW's multi-level driver to see that this is a spectacular bulb able to go into a very nice hotspot. I didn't want to push the voltage until I test this 50W in my Destructive bulbs setup to see where it flashes, and what kind of lumens/amps readings I get. I don't have any 35W to test.

Once I know how high it can be cranked up, then I can take some "proper" beam/outdoor shots. There is no question that the 4 x Emoli IMR's were just frolicking with its' filament.

Hey LuxLuthor, I for one cannot wait and am looking forward to see your destructive results on the 50 watt version. I hope it can handle a voltage range similiar to the IRC bulbs.

Does anyone know the bulb lumens for the 35W and 50W bulbs? I noticed on the pdf file from Osram that they are rated at 1,000 cd and 1,400 cd respectively.

Well that is a very good question, and underscores an arguement I have long had when people talk about bulb lumens, especially when the directional effects of a reflector are used.

In reality, there are very strict definitions of lumens and candela, that are rarely understood. Candela underscores the measurement output in a directional cone (called a steradian) which applies more accurately with this type of bulb with a built in reflector coating.

Luckily, we can do an approximate conversion by looking at Osram's site for the 50W Ministar bulb here, which I just finished testing. I will be posting it in my destructive bulb thread shortly.

We see that this bulb puts out 1400 candela with radiation angle of 30° (also has life of 2,000hrs and color temp of 3,000 K). Going back to the WIKI page, there is a conversion table at the bottom if you know the beam angle, which in this case 30° uses 4.67.

So we divide 1400 candela by 4.67 to get approximately 300 lumens.

LuxLuthor: Thanks! I just saw your post in your bulb testing thread and responded there.

This is great work on your part. Moreover, your notes about the candela vs. lumens is helpful to us all. Thanks for doing this.

Regards,

Steve

It looks like the "Sweet Spot" is to drive this bulb and the IRC version at 19-20V. With such low amp's, even AWR's old regulated "Hotdriver" could be used, while we wait for AlanB's project.

So some beamshots using Emoli/A123 cells set at same regulated voltage in same mag setup/reflector should show differences. I think the Ministar will have a better hotspot, but has virtually the same gorgeous color as the IRC.

I found the 35W bulb locally, I'm going to try it with 15 eneloops... And maybe try to squeeze it in my Throwmaster head.

I just came across this bulb while I was in Lux testing thread. I wonder how it would do on 5 or 6 D Li-Ions and my D1 regulator. Runtime would be spectacular.

It is a worthy contender. Only limitation is needing to insert it carefully through a reflector with a 0.5" bore. (See my earlier post, also the tip about using a soft string noose for removal).

I will be setting one of these ministar bulbs up with regulation. So many bulbs can be used now that we have regulation again! I have to get used to this new resource. This larger Ministar bulb is one you want to adjust POT voltage with JimmyM's PhD without head/reflector until you are happy with its output. I'll be starting at 6s2p x 18650 in an elephant.

hey guys... dont really mean to hijack a thread but i finally have my shiny 6D mag IRC with the 64440 bulb on 18 cells.....

this thing is so beautiful.... the predicted 7000lm compared next to the mag 5761 1400lm makes it look like a splash in a bucket....

it completely engulfs the beam....

i 'accidentally' tried a 64447 on 18 cells.... beautiful for a few seconds.... then ill probably try it again on 17 cells

thank you all!

kris23 said:

hey guys... dont really mean to hijack a thread but i finally have my shiny 6D mag IRC with the 64440 bulb on 18 cells.....

this thing is so beautiful.... the predicted 7000lm compared next to the mag 5761 1400lm makes it look like a splash in a bucket....

it completely engulfs the beam....

i 'accidentally' tried a 64447 on 18 cells.... beautiful for a few seconds.... then ill probably try it again on 17 cells

thank you all!

Click to expand...

17 cells is about as much as you can manage without some sort of regulation. I'm not sure a softstart would help. 18 fresh cells is just a tad too much. My 65W IRC ran on 17 NiMH 1/2Ds. Popped on 18.

haha yea im going to try that sometime... dont have any way of regulation so ill just use 17 cells or 16 with the AW soft start

kris23 said:

haha yea im going to try that sometime... dont have any way of regulation so ill just use 17 cells or 16 with the AW soft start

Click to expand...

I HAVE a true RMS regulator that will handle the 64447 or 64458 on 26 cells if you want. See my signature. They come preset to what ever voltage you want and have a low battery warning. You can change setting later on if you want just by turning 2 onboard pots.

yea i noticed that, pretty nice, but i have no money to spend right now...

looks like its only compatible with kiu sockets though...

kris23 said:

yea i noticed that, pretty nice, but i have no money to spend right now...

looks like its only compatible with kiu sockets though...

Click to expand...

It is compatible with the KIU sockets.
What kind of socket are you using?

AW soft start right now, dont plan to spend much more for a long time now...

i has me 2 5761 mags, a 2D, a 6D, the 6D IRC monstrosity, and soon to be a mag85 3D

does that mean i a flashaholic now?

kris23 said:

AW soft start right now, dont plan to spend much more for a long time now...

i has me 2 5761 mags, a 2D, a 6D, the 6D IRC monstrosity, and soon to be a mag85 3D

does that mean i a flashaholic now?

Click to expand...

You had me at "2 5761 mags."

haha there we go....

anyways, i have no money to spend right now..... but for the sake of getting more info on this product...

is it possible to have say.... 6 li-ion D cells in series (22.2v) and lower it down to a more manageable 7.2-7.4v? that may allow the use of a 5761 for well over 3 hours

I wonder what was the design intention of the lamp though...usually integrated reflectors would cover more estate than this