Bubbles in eyepieces? Plus reticle recommendations

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kwesi
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Joined: Tue Aug 10, 2021 7:08 pm

Bubbles in eyepieces? Plus reticle recommendations

#1 Post by kwesi » Mon Jan 23, 2023 3:37 am

I have these tiny dark dots that appear in my microscope images whenever I capture them through an eyepiece with my phone's camera. Are they bubbles? I don't see them when looking through the microscope with my eyes, maybe because of the different focal lengths or apertures of the eye vs a phone's camera? They rotate with the eyepiece so I know that's where they're originating. They appear in both eyepieces.

I've seen other folks' phone camera pics and they don't seem to have these dots so I'm assuming this isn't standard. So I guess I'm looking for suggestions for affordable eye pieces that don't have these dots? My scope is trinocular so I normally take pics through the photo port, but in certain situations the phone has benefits over the DSLR. I'm also considering getting one eyepiece with a reticle so that when I photograph microbes through the photo port, I can also take a picture through the eyepiece for reference and get an estimate of the size of things. Is it better to get an eyepiece that has a reticle, or buy the reticle separately and set it behind the eyepiece?
Screen Shot 2023-01-22 at 7.33.33 PM.jpg
Screen Shot 2023-01-22 at 7.33.33 PM.jpg (72.75 KiB) Viewed 1258 times
This image is only about 1/6th the FOV - I cropped it so the tiny dots would be easier to see

macnmotion
Posts: 523
Joined: Mon Sep 26, 2022 3:13 am

Re: Bubbles in eyepieces? Plus reticle recommendations

#2 Post by macnmotion » Mon Jan 23, 2023 4:51 am

I just want to make sure we understand what you're describing. You don't see them at all with your eye, only with the phone taking images. And they rotate with the eyepiece. Is the phone attached to the eyepiece, so that it is rotating along with the eyepiece? That would mean that the dots also rotate with the camera, not just with the eyepiece, and that would also explain why you can image the dust through both eyepieces. My guess is that your phone lens (or case if that's outside the lens) is dirty. Have you cleaned that? One way to check that is to use your phone to take a photo of a light colored wall, and see if you see the spots there. Or else, detach the phone from the eyepiece and try holding it manually, then rotate the camera and see if the spots move independently of the eyepiece. Or even try using someone else's phone to image in your system and see if the same spots are there. If they are, then the phone is not the problem.

If none of this helps, please describe better your setup of how you're imaging with your phone.

kwesi
Posts: 28
Joined: Tue Aug 10, 2021 7:08 pm

Re: Bubbles in eyepieces? Plus reticle recommendations

#3 Post by kwesi » Mon Jan 23, 2023 5:24 am

macnmotion wrote:
Mon Jan 23, 2023 4:51 am
And they rotate with the eyepiece. Is the phone attached to the eyepiece, so that it is rotating along with the eyepiece?
Thanks for asking that, I should have specified in my post that the phone is not attached to the eyepiece, just handheld. When I hold the phone and then independently rotate the eyepiece with the other hand, the dots rotate while the phone stays still. I got the same dots with my previous phone which was a different model so I don't think it's the phone.

The other thing that leads me to believe they're bubbles/inclusions in the glass - I don't know if you can make it out from the photo but the dots aren't all uniform, some are sharper and darker, some are slightly more fuzzy and faint. This leads me to believe they're not all sitting on one plane like dust would be. They also cover the entire field of view, edge-to-edge on both eyepieces, and have been there since the microscope was brand new.

Scarodactyl
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Re: Bubbles in eyepieces? Plus reticle recommendations

#4 Post by Scarodactyl » Mon Jan 23, 2023 5:31 am

They are almost certainly dust on multiple surfaces, at least front and back and maybe internal.

Phill Brown
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Location: Devon UK.

Re: Bubbles in eyepieces? Plus reticle recommendations

#5 Post by Phill Brown » Mon Jan 23, 2023 9:00 am

Most likely internal or maybe degraded paint dust but I've had a similar issue with a 2.5x photo eyepiece that is caused by the surface coating on the outer lens.
It isn't visible to the eye but with reflected light and enough magnification there are tiny marks all over.
Good luck with finding the offending surface.
Older optics made from brass that is blacked are very prone to oxides internally.
Reassembly can liberate a new batch of particles also if the threads have oxides.

apochronaut
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Re: Bubbles in eyepieces? Plus reticle recommendations

#6 Post by apochronaut » Mon Jan 23, 2023 2:28 pm

Scarodactyl is correct. Multiple surfaces. I'm pretty sure I am seeing 3. The eyelens of an eyepiece is designed to have a focal plane at the plane of the field stop, so the surface of a lower lens or field lens closest to the field stop will carry debris that is in the sharpest focus or the darkest spots with a little corona around them in the picture. Debris on the other side of that lens surface ; the other side of the same lens and thus farther from the focal point will be fuzzier. The camera lens will also pick up debris spots on the eyelens.
These dust or debris spots can be seen with the eye, if you lower the light level when viewing.

Be careful when cleaning. That stuff can be tenaciously attached and can scratch if moved with force. On old dirty lens surfaces I put each lens in turn into an isopropyl alcohol bath for a minute or so then very lightly drag the corner of a tissue across the surface to collect most of it. Finish with soaked and then dry swabs.

Reticles are placed with the scale, frame or mark right at the focal point or field stop. That means any debris on the reticle glass is in or close to being in focus. Reticles need to be immaculately clean when installed.

I have had the displeasure of having to carefully clean a new microscope that came from the Motic factory. Obviously they probably assemble their apochromats in a clean room but as the price slides down the scale, the specification for assembly in a clean room no doubt does too. The microscope in question was not even that cheap, retailing for about 1000.00 , here in Canada.

kwesi
Posts: 28
Joined: Tue Aug 10, 2021 7:08 pm

Re: Bubbles in eyepieces? Plus reticle recommendations

#7 Post by kwesi » Tue Jan 31, 2023 3:16 am

Thanks everyone, I assumed it would have come from the factory clean but I guess I was wrong! Going to try carefully cleaning the lenses with pieces of cotton ball and isopropyl.

apochronaut
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Joined: Fri May 15, 2015 12:15 am

Re: Bubbles in eyepieces? Plus reticle recommendations

#8 Post by apochronaut » Tue Jan 31, 2023 7:22 am

Cotton ball is very loose and likely will shed lots of fibers. Good quality swabs, although made from the same material are tighter. Swabs also allow more directed control once the surfaces are more or less clean, so you can lightly swipe right across the surface using a small blower bulb to create a tailwind.

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