Something is out of alignment - but what?

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JayAvery
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Something is out of alignment - but what?

#1 Post by JayAvery » Tue Nov 12, 2019 7:25 pm

I'm still getting the hang of my new compound microscope, but I'm confused by two possibly-related problems.

This is the view through the eyepiece, down the 10x objective lens with no slide:

Image

Something is cutting off the edge of the field of view on the right. It's always on the right of the view, and it doesn't move or change at all when rotating the eyepiece all the way round. It seems to be there with all the objective lenses but it's most noticeable with the 10x.

This is the view through the eyepiece down the 4x objective lens, while closing and then opening the condenser aperture: https://i.imgur.com/Cpe1eNt.mp4. The condenser light is clearly not centred in the same place as the objective lens. This is apparent through all the objective lenses (and to the naked eye).

Are these two signs of the same issue, or separate things? What is causing them, and how do I fix it?
Last edited by JayAvery on Tue Nov 12, 2019 8:12 pm, edited 1 time in total.

MicroBob
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Re: Something is out of alignment - but what?

#2 Post by MicroBob » Tue Nov 12, 2019 7:54 pm

Hi Jay,
you must be part of a secret operation, otherwise you would offer us more information about your microscope and adjustments! :lol:
This can be a simple adjustment error. It would be helpful to konow more about your microscope, position and centering of condenser, field aperture, lighting. All preferrable with pictures. You can upload them here directly, up to 1024 pixels anf 500kB.

Bob

JayAvery
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Re: Something is out of alignment - but what?

#3 Post by JayAvery » Tue Nov 12, 2019 8:09 pm

Sorry! :D I have a Brunel SP28 with biological objectives. I'm very much an amateur and this is the first microscope I've ever owned. When I searched about the off-centred condenser there were results suggesting that it can be adjusted. But I'm pretty sure that mine is *not* adjustable? Here is a picture of it from below the stage:
photo_2019-11-12_19-59-53.jpg
photo_2019-11-12_19-59-53.jpg (95.75 KiB) Viewed 2277 times
There's only one hand-adjustable screw on there, and it's just for removing the condenser entirely. The lever adjusts the condenser aperture, but the light source below doesn't have any adjustments:
photo_2019-11-12_20-08-05.jpg
photo_2019-11-12_20-08-05.jpg (69.64 KiB) Viewed 2277 times
(Except for an intensity dial at the side, which has no effect on either of the issues).

PeteM
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Re: Something is out of alignment - but what?

#4 Post by PeteM » Tue Nov 12, 2019 8:21 pm

This could be the condenser, a loose iris leaf in the condenser, the stage, the field assembly, or even the nosepiece not centered -- I'd guess the condenser or the stage it is attached to. There are likely screws attaching the condenser to the stage which allow some degree of centering. Your condenser appears to have a knurled knob holding it, but also two other centering screws that could be adjusted.

If that's not enough, the stage itself may also have some possible adjustment if you loosen the screws holding it, move the stage, and retighten them.

If that's still not enough, consider this a great opportunity to learn how your microscope is built. Follow the path from the light source up through the field lens and condenser, stage, nosepiece, etc. and see where the occlusion seems to be and where you can adjust things.

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Re: Something is out of alignment - but what?

#5 Post by MicroBob » Tue Nov 12, 2019 8:32 pm

Ah - this is better! :D
I don't know this specific microscope but we can check some settings:

- Don't use the 4:1 objective for this test, it probably needs a special condenser setup.
- Under the stage is the condenser - do you know the n.a, (numerical aperture) of it, like 0,6 or 1,2? Does it have a removable top lens? The condenser can probably be adjusted in height.
- I don't think the condenser can be centered. This is not necessarily a problem if it works well.

Please try this setup:
- condenser just below the slide
- condenser aperture wide open
- slide with specimen in place (piece of wet paper on slide is ok)
- 10:1 objective in place
- microscope is focussed on specimen

What do you see?

Bob

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jimur
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Re: Something is out of alignment - but what?

#6 Post by jimur » Tue Nov 12, 2019 8:57 pm

Is that a swing out filter carrier on the bottom of the condenser?
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JayAvery
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Re: Something is out of alignment - but what?

#7 Post by JayAvery » Tue Nov 12, 2019 9:34 pm

Thanks for the responses!
PeteM wrote:
Tue Nov 12, 2019 8:21 pm
This could be the condenser, a loose iris leaf in the condenser, the stage, the field assembly, or even the nosepiece not centered -- I'd guess the condenser or the stage it is attached to. There are likely screws attaching the condenser to the stage which allow some degree of centering. Your condenser appears to have a knurled knob holding it, but also two other centering screws that could be adjusted.

If that's not enough, the stage itself may also have some possible adjustment if you loosen the screws holding it, move the stage, and retighten them.

If that's still not enough, consider this a great opportunity to learn how your microscope is built. Follow the path from the light source up through the field lens and condenser, stage, nosepiece, etc. and see where the occlusion seems to be and where you can adjust things.
There's definitely no loose leaf in the condenser - here are photos of it open and closed:
20191112_211305.jpg
20191112_211305.jpg (120.43 KiB) Viewed 2254 times
20191112_211258.jpg
20191112_211258.jpg (123.02 KiB) Viewed 2254 times
I don't think those are centering screws - there are three of them equally spaced around the ring that holds the condenser in place and seem to just be part of the construction of the ring. They're tiny and very difficult to get to, and when I tried loosening the front one it seems ready to just drop out, with no sign of movement from the condenser itself.
MicroBob wrote:
Tue Nov 12, 2019 8:32 pm
Ah - this is better! :D
I don't know this specific microscope but we can check some settings:

- Don't use the 4:1 objective for this test, it probably needs a special condenser setup.
- Under the stage is the condenser - do you know the n.a, (numerical aperture) of it, like 0,6 or 1,2? Does it have a removable top lens? The condenser can probably be adjusted in height.
- I don't think the condenser can be centered. This is not necessarily a problem if it works well.

Please try this setup:
- condenser just below the slide
- condenser aperture wide open
- slide with specimen in place (piece of wet paper on slide is ok)
- 10:1 objective in place
- microscope is focussed on specimen

What do you see?

Bob
How come a 4x lens needs a special condenser setup? :O

I don't know the numerical aperture of the condenser, and there doesn't seem to be any writing on it. It doesn't look like the top lens is removable. The iris part unscrews from the part with the lenses, but that all seems to be one solid piece. Here are pictures of the top and bottom:
20191112_210415.jpg
20191112_210415.jpg (119.28 KiB) Viewed 2254 times
20191112_210404.jpg
20191112_210404.jpg (129.94 KiB) Viewed 2254 times
It does have a height adjustment, but no apparent centering adjustment. I followed your setup: condenser at its highest position, aperture wide open, focused on a slide of wet paper with the 10x objective. The result is like my first picture in the original post, with a straight dark edge along the right side of the field of view (but with a close up view of wet paper instead of the blank background!).

Here is an artist's impression of the results of the same setup cycling through each of the objectives:
photo_2019-11-12_21-29-20.jpg
photo_2019-11-12_21-29-20.jpg (60.3 KiB) Viewed 2254 times
This makes me think that obstruction must be in the turret or eyepiece somehow - because if it was to do with the stage or condenser then it would surely get less visible at greater magnifications? This *also* makes me think that the obstruction is a completely separate problem from the off-centred condenser! Because that *does* get less obvious at greater magnifications. 🤔
jimur wrote:
Tue Nov 12, 2019 8:57 pm
Is that a swing out filter carrier on the bottom of the condenser?
Yep! You can see it in the pictures above. Swinging it in and out doesn't make any difference to the problems that I can see.

Hobbyst46
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Re: Something is out of alignment - but what?

#8 Post by Hobbyst46 » Tue Nov 12, 2019 10:28 pm

To verify that the problem does not arise from the condenser OR light source (lamp and collector optics if any) you might try this: choose the 4X objective, remove the condenser altogether, turn off the scope lamp, place a small mirror on the base (actually, on a thin plate laid on the field lens) inclined at 45 degrees, and shine light with a flashlight or a focused desk goose-neck lamp into the mirror; such that the specimen is illuminated by reflection from the mirror. Try a wide beam source to get uniform brightness, and check if the shadow is still there.
Note: often the 4X can be used (not ideally) without any condenser.
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JayAvery
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Re: Something is out of alignment - but what?

#9 Post by JayAvery » Tue Nov 12, 2019 10:44 pm

Hobbyst46 wrote:
Tue Nov 12, 2019 10:28 pm
To verify that the problem does not arise from the condenser OR light source (lamp and collector optics if any) you might try this: choose the 4X objective, remove the condenser altogether, turn off the scope lamp, place a small mirror on the base (actually, on a thin plate laid on the field lens) inclined at 45 degrees, and shine light with a flashlight or a focused desk goose-neck lamp into the mirror; such that the specimen is illuminated by reflection from the mirror. Try a wide beam source to get uniform brightness, and check if the shadow is still there.
Note: often the 4X can be used (not ideally) without any condenser.
Good idea! I didn't manage the delicate operation with the angled mirror. But just shining light in from the side below the stage illuminated the slide enough to verify that the shadow *was* still there.

So, there's definitely something going on in the turret or eyepiece. With that information, I'm guessing that the seemingly mis-aligned condenser is actually just a symptom of that. If the eyepiece is somehow pointing off-centre (??), then it makes sense it would also not be centred on the condenser light correctly. Now I just need to.. find out what exactly is going on higher up, and how to fix it. Maybe it's actually just a manufacturing fault with the microscope? I was assuming user error but that seems less likely after all this investigation. 🤔

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mrsonchus
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Re: Something is out of alignment - but what?

#10 Post by mrsonchus » Tue Nov 12, 2019 11:11 pm

Hi, this has the look of a nosepiece that isn't locating or isn't mounted properly, stopping with each objective misaligned from the 'scope's optical axis.
John B

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Re: Something is out of alignment - but what?

#11 Post by PeteM » Wed Nov 13, 2019 4:41 am

You might try rotating the lens turret left and right of it's detent, while looking through.

Don't have a picture of this area on your scope to see how yours work. Sometimes it's external to the turret (your case?) and held by a couple screws. Sometimes internal to the nosepiece.

Could also be a misaligned tube, displaced prism inside the monocular head, etc.

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75RR
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Re: Something is out of alignment - but what?

#12 Post by 75RR » Wed Nov 13, 2019 7:28 am

Here is a photo of the complete microscope + a link to the Brunel page which might help in the diagnosis

Brunel page shows an alternative head with webcam incorporated so it would seem that the head is removable and perhaps misaligned. I wonder if some of those screws are for centering the head?

The other candidate as mentioned would be the rotating nosepiece.

http://www.brunelmicroscopes.co.uk/univ ... scope.html

Image
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MicroBob
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Re: Something is out of alignment - but what?

#13 Post by MicroBob » Wed Nov 13, 2019 10:38 am

Hi Jay,
you problem is already nicely narrowed down.
One additional point to check is wheter the black eyepiece tube sits straight in the head. It protudes and might have been damaged in shipping.
These tubes are usually screwed in, so you might try to unscrew it with moderate force and look whether it turns without wobbling.
Your condenser will have a medium n.a. (ca. 0,6-0,9). In the correct position it may not fully light the image when using the 4:1 objective. For this reason the condenser is often set up differently or even removed. That was the reason for my recommendation to not test with the 4:1 objective. But the condenser and light are already ruled out as a cause for the problem by now.
100:1 objectives are usually oil immersion objectives - is this the case with your objective? An oil immersion objective gives only a clouded image when used dry.

Bob

JayAvery
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Re: Something is out of alignment - but what?

#14 Post by JayAvery » Wed Nov 13, 2019 12:13 pm

Thanks again for all the responses! After narrowing the problem down thanks to all your help, I contacted the manufacturer. They agree it sounds like the monocular head got shifted in transit somehow, so they're going to fix it up for me. I really appreciate all the advice - I've also learned a lot about how microscopes work :D

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Re: Something is out of alignment - but what?

#15 Post by MicroBob » Thu Nov 14, 2019 8:13 am

Hi Jay,
please report how the repair by the manufacturer / dealer worked. When they offer good service this will be interesting for many others who prefer to buy new chinese microscopes.
With chinese quality control, low prices and overseas shipping there is always a risk of malfunctions and a knowledgable and service oriented dealer can make a big difference and would be worth a recommendation.

Bob

JayAvery
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Re: Something is out of alignment - but what?

#16 Post by JayAvery » Thu Nov 14, 2019 9:32 am

I definitely will! They've already arranged to collect it today and return it when it's fixed, with no mention of me paying for anything. I'm already convinced of their good service because there was also a problem when I first ordered it (came with the wrong set of objectives) and they handled it very quickly with no trouble.

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Re: Something is out of alignment - but what?

#17 Post by mrsonchus » Thu Nov 14, 2019 2:53 pm

Hi, have you had a look while rotating the nosepiece a touch either way, in case it's the set-point (where each objective 'clicks-into-place' when rotated to select) of the nosepiece causing this?
John B

JayAvery
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Re: Something is out of alignment - but what?

#18 Post by JayAvery » Tue Nov 19, 2019 11:48 am

Update: I just got the microscope back from the manufacturer, and the problem is completely fixed! The shadow on the right of the field of view is gone, and the condenser light is centred in the view too. They didn't charge me anything, and they were very quick and arranged collection and delivery according to my availability. I definitely recommend Brunel Microscopes and I'm not being paid to say so. :D

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Re: Something is out of alignment - but what?

#19 Post by mrsonchus » Tue Nov 19, 2019 1:44 pm

Great news.
Yes, I've been a customer of Brunel since I first started in 2015. I bought a new infinity 'scope (SP200) from them then later progressed to a used Leitz Orthoplan - also from them. A reliable and honest source for certain.

What was the problem with the 'scope?
John B

JayAvery
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Re: Something is out of alignment - but what?

#20 Post by JayAvery » Tue Nov 19, 2019 5:54 pm

Actually they didn't reply directly to say what problem they found. But when I initially contacted them they said it sounded like the nosepiece had been knocked out of alignment, so I'm guessing if it had turned out to be something different they probably would have told me!

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Re: Something is out of alignment - but what?

#21 Post by mrsonchus » Tue Nov 19, 2019 7:44 pm

A good job done!
Time to get down to business!

Enjoy your new 'scope, and keep us posted on what you get up to! :D :D
John B

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