Substituting LED bulb for incandescent bulb

[jackieone]

Microscope: Bausch & Lomb Academic 255 with Optilume B illumination
Illumination: Has an E26 base 15 Watt 120 Volt bulb, which produces less than 250 lumens. This is uncomfortably orange and dark when viewing specimens.

Question: can I switch to a 6-9 Watt LED bulb, with same E26 base (if they make them with that size base) which would increase lumens to about 450 lumens (lumens equivalent to a 40 watt incandescent)?

Question: would this put any strain on the older wiring - which has a two-prong plug?

Question: is 450 lumens too much for viewing through this microscope?

Question: if able to get a 5 Watt LED with correct E26 base, this would generate about 250 lumens, a bit more than an equivalent 25 watt incandescent bulb. Is this a better choice than a higher wattage LED bulb for viewing through the microscope?

Thank you in advance for your comments and insights.


From the manual for the Bausch & Lomb Academic microscope:

Remove the Lamp from the Optilume and replace it with a new one. The same lamp is used for both Optilume-A and Optilume-B.
It is a 20 watt lamp and should be ordered by Cat. No.31-31-12.
If a lower light level is preferred, for example when examining a thin, transparent specimen, a 15 watt lamp may be substituted. It may be ordered by Cat.No.31-31-15.

[BramHuntingNematodes]

The wiring'll be fine, you already noted that it will pull half the wattage. There are sometimes issues when filament position is critical, but I don't think it's too sensitive with the optilume.

[PeteM]

I've used the LED Edison-base tiny bulb replacements in a few scopes that needed them. The pluses are low cost, less heat, and longer life. However, while adequate, they don't seem much brighter. You do get the higher color temperature.

[jackieone]

OK!
Great information!

So, going for a 6-9 LED wattage, will this be a brighter illumination or will it be too bright?

Any suggestions?

[BramHuntingNematodes]

It's never too bright

[zzffnn]

A very wide controllable brightness range with high color accuracy (high CRI value) would be ideal. If you build only one light, you would want it to be powerful; if you would build two or more lights, then you can do whatever combination that suits you.

My LED is 30w, because I once used it for a very light-hungry Leitz Heine condenser - high magnification darkfield + polarization and recorded images using continuous light videos.

[apochronaut]

Your microscope is an educational microscope that was originally intended to be used with a med. blue filter. The filter increases the resolution and makes the image more like daylight: more pleasing to the eye. In that illuminator the filter is incorporated into the lensing system above the illuminator.There should be two lenses, back to back plano convex and the one closer to the bulb is blue.
It is a simple illuminator with a 15 watt golf ball bulb., however the same illuminator is used with a variable controlled 6 v. 18 watt bulb on the Bactericidal version oof the Balplan microscope, which was a $2000.00 prioessional microscope made by the same mfg. at the same timr as yours.
As Bram pointed out , mis-alignments can happen but in your case I suspect there might be a missing component in the illuminator collimating lens system? I can assure you that microscope engineers prior to the development of the led knew how to engineer optical systems, whether imaging or illuminating.
You might look into whether your microscope is in operating condition before you start messing with the system. Leds can be beneficial in some cases but more often than not they are used like some sort of miracle drug by people who haven't a clue how to assess or adjust an illuminator.

[Chas]

If you havent got any way of regulating the light (beyond an iris ) then it is quite easy to have too much light for your eye.
I think that there is quite a mismatch between what is comfortable to look at with your eye and the sort of of light output you might want to take a video.
It is evening where I am, and I would say that a light output that matches my camera at 1/15 of a second at ISO 100 is the most I am comfortable at looking at.

If the LED bulb that you put in is a bit too bright you can put a neutral density filter over the base (they are not expensive second hand) to throttle down the light output, but it all too easy end up looking down the spout when you take it away

I am surprised that you say that the light is 'too orange and dim' rather than 'too yellow and dim' that might suggest that your bulb isnt running at the right current ... might you have a poor/corroded connection somewhere ? I have seen orangeyness in a simple microscope (that had no diffuser in the light path) where a frosted bulb had been substituted by a non-frosted bulb and one ends up looking at the light from one part of a well spaced out (domestic type) filament .

However as apochronaut pointed out any amount of yellow (actually even orange) can be brought round to white with a light blue filter. Maybe you should post a pic of your microscope base so that apochronaut can take a look at it ?