What are the practical differences between trinocular light split settings when imaging? (E.g. 100:0 / 20:80)

[Sir]

My general understanding is that for imaging a 100:0 / 0:100 light split option on a trinocular would be ideal for imaging because there would be no additional prism between the camera and objectives.

I see there has been some discussions in other threads about this, but I'd like to know if there really is a practical difference when it's compared to say a 20:80 light split? Assuming one would use a microscope from a reputable manufacturer, how much degradation in image quality can one expect when comparing these different trinocular settings?

[Scarodactyl]

Air can't get dusty or moldy, which is the biggest advantage in my book.

[MichaelG.]

I am sure your interpretation is correct

... but I doubt there is a useful theoretical analysis available to predict the practical difference.

Quality and cleanliness of the components will over-ride any theory !!

MichaelG.

[MicroBob]

The big practicel difference: When observing and maybe hunting plancton life you may want to release the camera while following your fast moving object. Whith the 100:0 trino you will have to shut off your eyepieces and loose control at the important moment. This can reduce your hit rate dramatically.
Whith an 80/20 trino you will have to make sure that no stray light enters throught the eyepieces when you take you photo, especially when the microscope image is dim and the room in brightly lit.

[jfiresto]

An extra, well-coated, clean prism should have a negligible effect if it still in the collimated (infinity) optical path. On the other hand, the partial mirrored coating that splits the light 80:20 or 50:50, may be only be 90% efficient. To put that in perspective, you could get a similar loss by not coating a lens element or adding an uncoated one.

If you do things right, an 80:20 trinocular port lets you use the eyepiece(s) as the camera's viewfinder, with the microscope as its lens. (Become one with your instrument.)

[mrsonchus]

Well, for what it's worth, as I suspect as with most aspects of our amateur microscopy, meaning in terms of equipment quality, setup, cleanliness etc, I'd say there are few differences. The major difference when using the trinoc in 'split-light' mode, giving camera and eyepieces light simultaneously, is one of light-level.

In the context of my own 'scope, an Olympus BX50 configured for brightfield viewing of mainly permanently-mounted and stained slides, this is a very small difference indeed - the view through the eyepieces is a little darker than without engaging the light-split. As for image quality I can see no difference whatsoever between full-eyepiece, eyepiece-camera split and full-camera position. When I first acquired my Olympus this question quite naturally came to mind, as one usually has an immediate desire to optimise any 'scope being used, especially a new arrival!

Comparing the image quality of the 'full light to camera' and the 'split light to camera and eyepieces' available with the Olympus' trinocular head, I saw no difference in image quality - not even a hint. That done I continued quite happily to use the split-light position during sessions capturing images, finding the ability to view the eyepiece and camera (live-view tethered with Canon's Utility v3 software) views together very convenient indeed.

Incidentally the parfocality of the camera and eyepieces is, with the BX50, perfect - right down to the 'pixel-peeking' fine-focus level when making absolutely certain that desired/best focus is achieved with the camera.... This is my experience with the BX50 and a Canon EOS1200D and now a Canon 200D DSLR, others may of course vary.

[Sir]

Thanks everyone, your responses really helped

[apochronaut]

One of the primary uses for the 20:80 image intensity split was as a patient-practioner or teacher-student tool. It kind of leaped from the use of the dual microscope or teaching microscope to the optical and screen set up to optical and video. In all of these , it really helps to have the illumination level up to a point where the diminution of the intensity is not a hindrance. In my experience , they all benefit from the base unit being capable of supplying high lumens, especially if light absorbing techniques such as DF are used. I'm not sure if a 20:80 split is practical for some techniques with a 20 or 30 watt halogen or equivalent.

[jfiresto]

Equalizing the brightness of the students' screen image and the teacher's eyepiece image may explain an early Wild stereo microscope photo adapter. It directs 100% of the left optical path to the camera and dims the right path at least fourfold.