Eyepiece for Smartphone Camera Mount

[bsat6815]

Hi all,

I am just getting started with a Swift SW380T trinocular compound scope and Swift SPA-E28 smartphone adapter. I kinda didn't realize when I ordered that I also needed an eyepiece to mount on the trinocular eyepiece adapter, in addition to the smartphone adapter to enable use of my smartphone on the trinocular port. I am using the WF10x (DIN 18 mm) stereo eyepieces to begin with, given that I am looking at large specimens. So upon discovering that the smartphone setup required an eyepiece, I attempted to use one of the two WF25x eyepieces that also came with the scope for the smartphone setup. I quickly learned that the 25x eyepiece creates an image field on the smartphone that is way too small to be useful. So I had to temporarily steal one of the x10 eyepieces from the binocular ports for the trinocular port; that creates a correctly-sized image field on the smartphone (Samsung Galaxy S5).

So, it appears that I will need to order an eyepiece for the smartphone camera setup. Is there some x10 eyepiece that would be better than others for this purpose? The eyepiece barrels for this scope mic out at just over 23 mm o.d.

The Galaxy S5 smartphone appears not to be a great fit for this application. Samsung cheapened out on this model by choosing a "camera on the processor SoC" design instead of separate camera silicon. The result is almost complete lack of manual control of basic functions such as focus. I also have an old original Samsung Galaxy phone that I might try. I would appreciate any other suggestions for camera solutions with this setup. The USB microscope sensors seem to be quite expensive relative to the available resolution.

Also related to the camera portion of my microscope setup, parafocality at the trinocular port is adjusted by screwing the trinocular port eyepiece adapter in further to shorten the distance to the eyepiece or out to lengthen the distance to the eyepiece. Then there is a locking nut on the eyepiece adapter to tighten down onto the trinocular port to prevent the parafocal distance from changing. Is there a preferred way of calibrating this distance, other than by trial and error to bring an image prefocused at the binocular ports into best focus with a given eyepiece at the trinocular port? My eyesight is not great; and it seems to me that I must adjust the barrel of the eyepiece adapter many turns to make any difference in the apparent focus/fuzziness of an image on a slide. Maybe there is some "calibration" slide with a fine cross-hatch pattern for this purpose? Or some other magic method for this adjustment?

Many thanks for any guidance that you can provide to this newbie.

[Greg Howald]

Hi Bruce.
I have used both a 10x and a 16x eyepiece with my phone and have had good success.
I never use the 25x Eyepieces for anything. They are just too difficult for me to work with. Remember that the objective should do the mainstay of the optical work. The eyepiece should be comfortable for you to use.
Greg

[bsat6815]

Thanks Greg. I can see from my experiments with x10 vs x25 eyepieces that x10 provides the proper size field of view on the smartphone screen. I just wondered, since I will be ordering a x10 eyepiece, whether any old x10 with a 23 mm barrel will do or whether I should be looking for some brand, type, quality etc. for the particular function of collecting light into a smartphone camera at the trinocular port.

[Greg Howald]

Just about anything will do.
Greg

[MicroBob]

Smartphone cameras have fairly wideangled lenses. When you use an eyepiece with a narrower field of view you only get a circular image in the middle of the rectangular frame. Good are eyepieces with a wide viewing angle. The viewing angle depends on magnification and field size. A 10x 18mm eyepiece has a smaller view angle than a 12,5x 18mm. Since smartphone cameras are built flat it doesn't have to be a "for glasses" eyepiece. For optimal image quality the eyepiece should be compatible to the objectives in the way it corrects residual chromatic errors.

[Roldorf]

Calibration slide for microscope:

https://www.amazon.com/AmScope-MR095-Mi ... B00GGY3IGC
There are many others. Just search the net for 'microscope calibration slide'.