Optimize image capture by iphone

[smollerthings]

Hi all,

I have a small problem: i need to use a 1.8x magnification on my iphone to get rid of the vignetting, which is detrimental to the image quality. Is there a way to do this optically? Would a Barlow lens or a higher magnification eye piece do the job?

Thanks!

[MicroBob]

Hi,
the angle of the objective has to fit the angle of the eyepiece. Most phones have wide angle objectives so using a wide angle eyepiece would improve usage of the camera pixels. Wide angle eyepieces have a fairly big field size combined with a high magnification:

8x18= image size 144 = not wide
12,5x18= image size 225 = much wider
12,5x20= image size 250 = very wide (probably only small dark corners left)

Or: Use a phone with multiple cameras and choose the tele camera.

Bob

[Javier]

If you want to make the most out of your iPhone, you might want to check the Lab Cam adapter.

https://www.ilabcam.com/

Check on Instagram for Tardibabe. She uses this adapter with an iPhone and a Motic 310, and her imaging is impressive. Check also "My Microscopic" world on YT, I think he uses a very similar setup also with amazing results.

[smollerthings]

Thanks Javier.
This adapter looks impressive but costs 4x the price of my microscope

Actually I think I wouldn't be hard to adapt a 3d printed design to a cheap aliexpress eye piece...

Bob's answer is very enlightening. I am going to buy a cheap 12mm/25x eye piece from Ali and see how it goes. But my Biolam's intermediate image is 13mm down the tube vs 10 mm for DIN. We'll see if this is a big problem...

[Dubious]

LabCam apparently has its own 10x lens that goes in the microscope tube in place of the eyepiece, so would not be a good choice for finite scopes that rely on the eyepiece to correct aberrations of the objective.

[smollerthings]

Indeed. What are the manufacturers that do eye piece correction? I remember I read somewhere that Olympus doesn't and Nikon and Zeiss do? Maybe that was for infinite systems.

[MicroBob]

cheap aliexpress eye piece...

Bob's answer is very enlightening. I am going to buy a cheap 12mm/25x eye piece from Ali and see how it goes.

Sorry, it is a bit more complicated: The 25x/12 eypiece uses only the center 12mm portion of the microscope image and post-magnifies it a lot. This way you would get no black borders but also not the full use of the microscope objectives image, so you can't photograph bigger objects. And: You would only use the resolving power of this small area so waste much of the resolving power of the objective.

From established brands 12,5x /20mm eyepieces were at the very top of the price list, quite impressive things. I don't know whether there is an affordable chinese version.

[Javier]

Could you share a video of the same specimen with and without digital zoom?

If the resolution is much better without zoom, you can always crop the video with edition. That being said, the reduction optics of your phone may prevent you from getting an optimum resolution with your sensor. So, digital zoom might be a necessary evil sometimes to get a bigger image scale.

A combination of digital zoom and cropping might also work.

[Dubious]

Indeed. What are the manufacturers that do eye piece correction? I remember I read somewhere that Olympus doesn't and Nikon and Zeiss do? Maybe that was for infinite systems.

I believe just about all finite microscopes (i.e. 160mm objectives) used the eyepiece to correct aberrations introduced by the objective, with the possible exception of Nikon, but I am far from an expert on the subject. Infinity microscopes generally do the correcting in the objective itself, or in the tube lens, is my understanding.

[MicroBob]

Indeed. What are the manufacturers that do eye piece correction? I remember I read somewhere that Olympus doesn't and Nikon and Zeiss do? Maybe that was for infinite systems.

Your Lomo is Zeiss pre WWII technique. The lower power achromats don't need colour correction, the high power achromats and most Apochromats do. So it will not be possible to find one perfectly fitting eyepeice for all objectives. Some Raw-converters allow for CVD correction, might work in this case. The error shows towards the border when observing colorless objects with high contrast. I wouldn't worry too much for forum pics though.

Zeiss pre war compensation is similar to:
Zeiss Jena: post war e.g. PK 10
Zeiss Oberkochen: Everything with a "k", e.g. KPL 10
and close to
Leitz older eyepieces: e.g. Periplan 10x (here intermediate image 18mm don the tube, use a spacer)
Leitz newer eyepieces e.g. Periplan 10x 18

Eyepieces with intermediate image 10mm down the tube work quite well for objectives designed for 13mm down the tube.

Bob

[smollerthings]

Your Lomo is Zeiss pre WWII technique. The lower power achromats don't need colour correction, the high power achromats and most Apochromats do. So it will not be possible to find one perfectly fitting eyepeice for all objectives. Some Raw-converters allow for CVD correction, might work in this case. The error shows towards the border when observing colorless objects with high contrast. I wouldn't worry too much for forum pics though.

Thanks Microbob, a wealth of knowledge as always. Follow up question: when you say "it will not be possible to find one perfectly fitting eye piece for all objectives", does it mean that my original K7x and K15x are not perfect either for all range of magnification?

Sorry, it is a bit more complicated: The 25x/12 eypiece uses only the center 12mm portion of the microscope image and post-magnifies it a lot. This way you would get no black borders but also not the full use of the microscope objectives image, so you can't photograph bigger objects. And: You would only use the resolving power of this small area so waste much of the resolving power of the objective.

It is funny that things are never as simple as imagined!

If the resolution is much better without zoom, you can always crop the video with edition. That being said, the reduction optics of your phone may prevent you from getting an optimum resolution with your sensor. So, digital zoom might be a necessary evil sometimes to get a bigger image scale.

Yes, indeed. I was trying to not crop in order to get to use the max area of the censor. I saw that you have a peculiar eye piece right? Maybe your crop is smaller. I think it also helps that the iphone 5s camera is not as wide as the 7.

[smollerthings]

Could you share a video of the same specimen with and without digital zoom?

There you go:
Original:


Zoomed in:


Cropped in editing (then rotated for full screen):


Zoomed in is actually not bad because it takes the central part of the image. My objective is not plan anyway. Now, I still think that an optical 2x would be great but it doesn't seem to be that easy to achieve.

One still has to keep in mind that this is my photo setup, so no miracle should be expected But it is frustrating everything looks so good in the eye piece...

IMG_7383.JPG (21.56 KiB) Viewed 3062 times

[MicroBob]

Follow up question: when you say "it will not be possible to find one perfectly fitting eye piece for all objectives", does it mean that my original K7x and K15x are not perfect either for all range of magnification?

K means correction, so they best fit to the strong achromats or apos. Usually these microscopes were sold with K7 and K17 eyepieces not ideal for the weaker objectives. But since phot stacking was unknown the image quality towars the borders was not that important and weaker objectives were maily for seeking, not photography. In visual observation you don't see much of a problem. The field numbers of these eyepices are small so the border where the colour fringing is strongest is excluded anyway.

Bob

[Javier]

Thanks for the comparison. IMHO, the second footage looks fantastic. I wouldn't worry too much about using some digital zoom to eliminate the vignetting.

[MichaelG.]

Thanks for the comparison. IMHO, the second footage looks fantastic. I wouldn't worry too much about using some digital zoom to eliminate the vignetting.

I agree … It looks excellent playing on my iPad
No harm done by digitally zooming … Youtube is only using 720p anyway

MichaelG.