Weird ring patterns when imaging

[CorrectHorseBattery]

Hi, when I'm imaging through my microscope, I get weird bright patterns, even when I'm not looking at anything. When I rotate the camera, the pattern rotates too so I don't think it's a problem with the camera. The pattern can be seen at any level of brightness of the illumination and when I move the focus knob, the pattern changes in sharpness. It also happens with every objective. I'm using a compound microscope and a Canon 600D. Any advice on how to fix this?

[CorrectHorseBattery]

Here are the pictures since it seems like they aren't loading:
https://flic.kr/p/2mJJYXT
https://flic.kr/p/2mJJXN8

[smollerthings]

You may be looking at the lamp filament. Can you post a picture of you setup, your condenser placement and your illumination?

[patta]

try put a piece of white paper in front of the lamp, as improvised diffuser.
If the rings disappear, then post #3 (or other sharp reflections in the lamphouse)

[CorrectHorseBattery]

The paper only seems to dim the entire thing and the pattern is still there.
https://flic.kr/p/2mJG9DR
https://flic.kr/p/2mJG9DL
That's my setup. The microscope was the same as it was out of the box, the only differences are I removed the stage from the original to hold the slide in place and replaced them with these ones, and I bought the adapter for my camera separately. I used the new stage on another microscope and it worked fine. It seemed identical to the other one except for the part on top to hold the slide in place

[patta]

Let's have a look at the "condenser":
the little lens that maybe is there in the hole of the stage
it may be the culprit too
if it has some bright metal rings... that reflect...

[CorrectHorseBattery]

I can't see any metal rings or anything reflective, only the plastic. I've tried swapping out the entire stage also. The pattern is there with the original stage, the new stage, and no stage at all. Also, about it being the filament, I tried using the light on my phone with the illumination off and it still showed the pattern. Could it be the nosepiece or the tube?

[patta]

one more try
remove the camera only
look in the adapter hole with your eye
if you see some weird reflection from the tube walls... try to understand where it is

[smollerthings]

Try turn things to see where the artifact comes from. Not sure you have access to the below on your microscope

1/ Eye piece
2/ Objective Lens
3/ Condenser lens
4/ Collector lens
5/ Light source

[CorrectHorseBattery]

This is what it looks like through the tube:
https://flic.kr/p/2mJGHQf
I've tried rotating every piece I can, those being the objectives, the camera, the tube, the illumination, the head part the tube extends out of, and the stage, and the only one where it changes is the tube. When I rotate the tube, the pattern stays the same but the lines making up the rings rotate around.

[smollerthings]

Well, I think it is the tube then. Do you have the artifacts when using the eyepiece vs camera?

[CorrectHorseBattery]

It's every time when using the camera but through the eyepiece I only see it when I'm looking at certain angles, it's not visible when looking straight on

[smollerthings]

What are those bright cercles in your tube? That can't be good...

[CorrectHorseBattery]

It seems like they're what is causing the weird pattern. They seem to be where light is reflecting off the sides of the tube at points and maybe somewhere further down the optical train in the head or the objective lens, although I'm not sure what I can do if that's the case

[Chas]

I have an adapter that looks much like that attached to a 600d, but note that mine doesnt have any lens in it. if your adapter also has then no lens inside , then:
I am pretty sure that you have two problems:
Prob1] The inside of the adapter, even though it is black, is reflecting light , so roll up some matt-black material inside the adapters tube, I have seen black paper suggested but I havent tried it.
Prob2] The same situation with the eyepeice tube ( a lot of similar long-tubed microscopes have the issue)
If you want to locate the predominant fault you could try lifting off the angled head (it looks like there is a knurled bolt holding it on) and then place a wider tube on top of the body and then rest the cannon with the eyepeice adapter on top of that (it looks as if a lavatory-roll tube might work/fit).

[CorrectHorseBattery]

Thanks, I tried 1 and it partially worked. Putting matte black paper into the tube got rid of the central two semicircles but unfortunately, it seems like the reflections causing the other rings are further down maybe in the head or objectives, at least too far to reach so I'll have to settle for a few rings.

[patta]

Fine! and settle, is a good idea, as those little improvements to the microscope easily get out of hand, always want a little better

[PeteM]

Does your microscope have field and condenser irises?

Normal practice would be to get everything centered. Then close down the field iris (or one of your own devising) so the illuminated area is just outside the objective's field. A different adjustment for each objective. Finally, close down the condenser iris a bit to get some optimum trade-off between contrast, depth of field, and resolution.

Main point - some of the artifacts you're seeing might be due to peripheral illumination you just don't need to properly illuminate your specimens.

[Chas]

You could try and see if putting a diaphragm near the bottom of the microscope's eypiece tubing helps;
[This should be non-destructive and reversible ]:

Get a spare eyepiece, remove the top cap and remove the bottom lens.
You will be left with just its body which should have a diaphragm in the middle of it.
This can be lowered down the microscope's tube.( Attach a cable-tie or something similarly fexible to the inside of the eypiece's body with a peel-off glue such as hot melt).

My guess is that will be able to get it all the way to the bottom, but it might be better a little bit further up.
....go gingerly when lowering it into the tube!

I used self adhesive telescope flocking, in the end, inside the camera adapter tube. I have spare, so if you would like some, PM me and I will put some in an envelope.

[smollerthings]

I was wondering, how does closing down the condenser aperture impact the rings?