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Re: Microscope Cameras?

Posted: Tue Jun 25, 2019 7:27 pm
by Dave S
That might indeed be the case, but finding the correct eyepiece could prove to be an expensive exercise.

I have just bought a 10x on Bresser's advice, only to find that it is not correct for use with an APS-C sensor, producing a highly magnified image.

The 10x probably stems from the old 35mm film days, when the 10x was probably correct, but it certainly isn't for an APS-C size sensor.

Having bought the 10x eyepiece from Bresser, based on their advice, I have now 'thrown the ball back into their court', to see what they have to say.

Up to now, they have been nothing but pleasant, and helpful to deal with.

Re: Microscope Cameras?

Posted: Tue Jun 25, 2019 7:31 pm
by Dave S
Hobbyst46 wrote:Your Bresser objectives fit 160mm tube length. Hence, there is a chance that they are corrected to minimize aberrations only with corresponding eyepieces. The 10X Bresser eyepiece that you have experimented with is probably compatible with the objectives. I do not see a 2X relay lens in the Bresser catalogue, although they may have it. Non-brand 2X relay eyepieces are either compatible or not, yet they are fairly cheap.
As I have said in my post above, I have 'thrown the ball back into Bresser's court'.

I have also asked them to confirm whether the objectives, as supplied with the microscope, are of the old 160mm type, or the later infinity corrected type.

Re: Microscope Cameras?

Posted: Tue Jun 25, 2019 7:37 pm
by Hobbyst46
The struggle to get the best image and FOV coverage upon the marriage of a digital camera to microscope has been reflected in many discussions, and is still active. That is why some folks (many IMO) prefer afocal setups. I believe that Bresser and other makers optimize their camera-scope interface for dedicated cameras, not stand alone DSLRs.

Re: Microscope Cameras?

Posted: Tue Jun 25, 2019 8:06 pm
by Dave S
Hobbyst46 wrote:The struggle to get the best image and FOV coverage upon the marriage of a digital camera to microscope has been reflected in many discussions, and is still active. That is why some folks (many IMO) prefer afocal setups. I believe that Bresser and other makers optimize their camera-scope interface for dedicated cameras, not stand alone DSLRs.
As they market a whole range of cameras, all made by Tuopcam, I guess its no surprise that they engineer their microscopes, around these. A good marketing ploy for them.

That said, in principle, there is no reason why a suitable mag relay lens shouldn't work, and I'm guessing that 2x is close enough to 1.6x for most purposes.

Seen plenty of 23mm 2x relay lenses on e-bay, but unfortunately all in China, with delivery times around the middle of July.

Re: Microscope Cameras?

Posted: Tue Jun 25, 2019 8:13 pm
by Scarodactyl
Amscope sells those adapters. A bit more expensively, but if they have a local prrscence they can get it to you quickly. I believe they do not apply any corrections to the image.

Re: Microscope Cameras?

Posted: Tue Jun 25, 2019 8:54 pm
by Dave S
Yes they do, via Amazon UK.

£104 + £29 delivery :o

Aleady have T2 mount to 23.2mm adapter, just need a 2x 23mm relay lens.

Less than £10 from China, via ebay, but delivery mid July.

Re: Microscope Cameras?

Posted: Tue Jun 25, 2019 8:56 pm
by Scarodactyl
Could you link to one of the cheaper Chinese ones? I think yo might be looking at a lens meant for doubling the magnification of a viewing eyepiece. I am not certain if they would work as a relay lens, though I'll admit I'm curious.
The amscope relay is listed cheaper on eBay (as most Amscope things are for whatever reason).

Re: Microscope Cameras?

Posted: Wed Jun 26, 2019 6:56 am
by Roldorf
If you alter the position of the tape wrapped lens inside the tube does it alter the field of view or does it just alter the focus?

Re: Microscope Cameras?

Posted: Wed Jun 26, 2019 7:50 am
by jfiresto
Hobbyst46 wrote:... I believe that Bresser and other makers optimize their camera-scope interface for dedicated cameras, not stand alone DSLRs....
As far as I can tell, Bresser and colleagues are tuning their adapters for cameras with small, inexpensive image sensors and optics. Nothing stops them from offering (or accommodating) cameras with nicely sized, APS-C sensors, with relay lenses to match, but then they would have to charge considerably more.

Re: Microscope Cameras?

Posted: Wed Jun 26, 2019 8:15 am
by Scarodactyl
That is typical for pretty much every microscope maker. The big 4 will certainly have options available for dslrs but the focus always seems to be on small sensor cameras (though I believe this is not just for expense, but also because it is easier to actively cool the smaller sensor? With higher sensitivity and framerates in mind on the higher end?) Leica's dslr options in particular look like afterthoughts.

Re: Microscope Cameras?

Posted: Wed Jun 26, 2019 8:52 am
by jfiresto
From what you write and considering the modest numbers of microscope imaging systems compared to mass consumer goods, I wonder if a lot of companies are still amortizing the engineering costs of older designs, or copying designs that someone else paid for long ago.

Re: Microscope Cameras?

Posted: Wed Jun 26, 2019 8:53 am
by Dave S
Roldorf wrote:If you alter the position of the tape wrapped lens inside the tube does it alter the field of view or does it just alter the focus?
I don't know Alan, but I will experiment.

As I said earlier, if I put the third 10x ocular in the photo tube, it is perfectly parfocal with the 10x oculars in the bino head, and has the same field of view. So the addition of the 10x ocular inline with the camera is not the problem, but the image it projects onto the APS-C sensor is.

As I beleive all of the Chinese budget, and mid range cameras follow the same design principles, there must be a logical reason why AMscope offer a T2 to 23mm adapter, which includes a 2x lens, for use with a whole range of APS-C DSLRs.

It would seem that this is something that is missing from Bresser's portfolio.

Re: Microscope Cameras?

Posted: Wed Jun 26, 2019 8:54 am
by Dave S
Duplicate post deleted.

Re: Microscope Cameras?

Posted: Wed Jun 26, 2019 8:57 am
by Dave S
jfiresto wrote:From what you write and considering the modest numbers of microscope imaging systems compared to mass consumer goods, I wonder if a lot of companies are still amortizing the engineering costs of older designs, or copying designs that someone else paid for long ago.
Given that the Chinese are famous for making copies of just about everything, that is a distinct possibility John.

Re: Microscope Cameras?

Posted: Wed Jun 26, 2019 9:26 am
by Roldorf
The term of a patent is 20 years here in Germany and the USA, so I would guess that most of the Chinese microscopes and lenses are produced without breaking any patents.

Re: Microscope Cameras?

Posted: Wed Jun 26, 2019 10:40 am
by Dave S
As usual, a prompt reply from Bresser, which is copied below:

Hello Dave,

the camera does have a smaller depth of field as the eyepieces (and our eyes) have. So it may appear that the sharpness is lower. You could also check if the image is really parfocal or if ther is still a slight defocus. Try to use Live view and zoom in to check this. Also see if your sample is really flat and thin. Please note that the objectives do not have plan correction and the focus is different from the center of the field to the edge.

Also check the condenser setting, centering, height and aperture.  Maybe you can send one of your results so we can check it here and see what is wrong.

A bit of higher magnification is usually no problem as the objectives will work with magnification factors of 10-15x or even 20x for the 4x and 10x objectives. As a rule of thumb you can magnify up to 1000 x NA which is 250x for a 10x objective (NA=0,25).

There are 2,5x photo eyepieces in the market, but these are mostly compensation eyepieces which work only with dedicated lenses as they are correcting some residual color aberration which our objectives do not have. Some model which use this setup is older Nikon, Euromex etc.

The objectives of the Researcher are finite 160mm. Infinity correction does not necessarily give a better quality, only the adaptation of cameras etc. is somewhat easier. We have several infinity corrected microscopes but are in the price range of 1.000€ and above.

Re: Microscope Cameras?

Posted: Wed Jun 26, 2019 10:43 am
by Dave S
My response to Bresser, copied below:

Thank you for your prompt reply, which is much appreciated.

The image at the camera, is not completely parfocal with the eyepiece, and the stage has to be lowered slightly from the visual view, to achieve best focus on the camera's sensor.

The 10x eyepiece installed in the 5942000 adapter, is installed as per your instructions. Would shifting its position in the adapter, that is moving it closer to the sensor. improve or worsen things?.

As an experienced amateur photographer (https://davesimaging.wixsite.com/mysite), I do understand the abberation characteristics of achromatic, and apochromatic lenses, especially related to astro-imaging. Also depth-of-field. and field of view.

Although all of my photographic equipment is hi-end pro-spec (except the EOS 4000d), bought specifically for use with the microscope, microscopy is a new venture, to see if it is something that I would like to pursue, hence at this stage applying a limited budget. 

I note the AMscope offer a T2 to 23mm DSLR adapter which includes 2x ocular, for use with a wide range of EOS APS-C DSLRs. Is this something that is missing from the Bresser portfolio?, and would the AMscope adapter work with the Trino?, albeit further expense!!

I will experiment with adjusting the position of the condenser, but am not expecting this to improve the focus/sharpness of the sensor captured image.

While understand that attempting to fill the APS-C sensor could introduce chromatic aberration, edge distortion, and vignetting, this could be cropped out in processing. That said, ignoring the focus/sharpness issue, the magnification provided by the 10x ocular in the 5942000 adapter is excessive.

I had dealt with Broadhurst, Clarkson, and Fuller (Bresser UK) over many years for astronomy related equipment, hence choosing to opt for the Bresser microscope, as opposed to one of the many other re-badged Chinese microscopes (e.g. AMscope, Omax, and APEX etc). Given the price bracket of the Trino, I am pleased with the mechanical, and optical performance of the microscope. However, having bought a new EOS 4000d specifically for micro photography, I am disappointed at the problems I am encountering with the Bresser Trino. Especially having now bought two T2 to 23mm adapters, and an extra 10x ocular.

I do hope a satisfactory solution can be found.

Re: Microscope Cameras?

Posted: Wed Jun 26, 2019 11:40 am
by Dave S
I have just tried moving the 10x eyepiece to the other end of the T2 adapter (nearer to the sensor), and while this gives a small increase in the field of view, it introduced severe vignetting.

I have updated Bresser on this finding.

I should add that images taken with my iPhone at the bino head, are fine in terms of the visual field of view, and sharpness. The problem exists only when using the photo tube, and the EOS4000d without its lens.

Basically, the 10x eyepiece placed in the T2 adapter produces comparatively excessive magnification, and the inability to give sharp focus.

Re: Microscope Cameras?

Posted: Wed Jun 26, 2019 1:57 pm
by Hobbyst46
Dave S wrote:I have just tried moving the 10x eyepiece to the other end of the T2 adapter (nearer to the sensor), and while this gives a small increase in the field of view, it introduced severe vignetting.

I have updated Bresser on this finding.

I should add that images taken with my iPhone at the bino head, are fine in terms of the visual field of view, and sharpness. The problem exists only when using the photo tube, and the EOS4000d without its lens.

Basically, the 10x eyepiece placed in the T2 adapter produces comparatively excessive magnification, and the inability to give sharp focus.
If, as Bresser state, their objectives do not need any compenstion, there is some chance that even a non-branded 2x relay lens will yield a decent image.
The iphone method is an example of afocal, the same can be done with a DSLR, using a viewing eyepiece. As an alternative.

Re: Microscope Cameras?

Posted: Wed Jun 26, 2019 2:25 pm
by MichaelG.
Dave S wrote:I should add that images taken with my iPhone at the bino head, are fine in terms of the visual field of view, and sharpness. The problem exists only when using the photo tube, and the EOS4000d without its lens.

Basically, the 10x eyepiece placed in the T2 adapter produces comparatively excessive magnification, and the inability to give sharp focus.
It might provide a useful 'sanity check' if you try using the iPhone at the eyepiece in the photo tube.
... The result should obviously match that obtained at the binocular.
... If it does not, then something needs to be investigated.

Assuming a successful result, it is safe to look at the photo tube situation:
If Bresser has delivered a standard 10x eyepiece, then it is 'intended' to produce a virtual image at infinity; and will probably need raising by a few mm to perform best as a projective.
Try lifting it by about 5mm, and then check at what distance the sharp image is formed.
This is where your camera sensor needs to be placed for 'direct projection' [and you will probably need to add an extension tube].

As you have aready noted ... This will inevitably mean that the sensor crops the projected image from a 10x eyepiece.

Some options to consider:
a) use a lower power eyepiece
b) add a reducing lens to the system
c) add a lens to the camera, and adopt 'afocal' technique

There are Pros & Cons to all of these ... but any one of them is probably more practical than moving to large-format film or plates !!

MichaelG.

.

Note: Hobbyst46 posted whilst I was drafting this

Re: Microscope Cameras?

Posted: Wed Jun 26, 2019 2:57 pm
by Hobbyst46
Michael, I am guessing that the trick suggested by Bresser to shift the position of the 10X eyepiece with the aid of the sticky band, is effectively the same as raising the objective above the photo tube rim. Likely it is an ordinary high eyepoint eyepiece, not a projection.

Re: Microscope Cameras?

Posted: Wed Jun 26, 2019 3:00 pm
by Dave S
I am now fairly confident that the problem is Bresser's suggestion of using a 10x eyepiece between the photo tube, and the camera, which then adds significant magnification of the image as produced by the APS-C sensor.

I can see where Bresser's 10x eyepiece idea comes from, as when the eyepiece is placed in the photo tube, it is perfectly parfocal with the 10x eyepieces in the bino head.

It is the magnification factor added to the image by the crop sensor, that pushes things beyond sensible limits, and degrades the image sharpness. Not by much, but noticeable. As a photographer, I am a 'stickler' for sharp images.

I made up a crude adapter to place the 18-55 lens on the eos4000d against the 10x eyepiece in the photo tube (afocal), and the image was not as that seen visually, but quite magnified by the sensor.

As such I really do think that a 2x eyepiece would bring the image down to a sensible size, by counteracting the magnification produced by the sensor.

I just have to locate a 23mm 2x eyepiece, that's not going to take until the middle of July to arrive from China.

At this stage, it would not pay to gamble £103 on AMscope's T2 to 23mm adapter, with built in 2x relay lens, in case it isn't the answer.

Re: Microscope Cameras?

Posted: Wed Jun 26, 2019 3:09 pm
by Roldorf
Is it available in Amazon? If so you could send it back if it didn't work

Re: Microscope Cameras?

Posted: Wed Jun 26, 2019 3:15 pm
by MichaelG.
Hobbyst46 wrote:Michael, I am guessing that the trick suggested by Bresser to shift the position of the 10X eyepiece with the aid of the sticky band, is effectively the same as raising the objective above the photo tube rim. Likely it is an ordinary high eyepoint eyepiece, not a projection.
Agreed ... Thanks for reminding me

MichaelG.

Re: Microscope Cameras?

Posted: Wed Jun 26, 2019 3:40 pm
by MichaelG.
Dave S wrote: As such I really do think that a 2x eyepiece would bring the image down to a sensible size, by counteracting the magnification produced by the sensor.

I just have to locate a 23mm 2x eyepiece, that's not going to take until the middle of July to arrive from China.
Have a look at this, Dave ... quoted from a 2016 thread on this forum:
.... Nikon CF objectives. They are excellent and can be found in (very good) Plan Achromat types as well as Plan Apo types (not cheap!). These are finite type, 160mm tube length, and 45mm parfocal (DIN). They do not require chromatically corrective eyepieces.

You can find a brochure of what I believe was the last incarnation (before the change to "infinity") of this type objective here. It is dated February 1989:

http://www.krebsmicro.com/Nikon_CF.pdf
I have emboldened the really important sentence

The implication being that any Nikon eyepiece that is suitable for use with the CF objectives should do the job on your Bresser.

Hopefully this will allow you to broaden your search

MichaelG.

Re: Microscope Cameras?

Posted: Wed Jun 26, 2019 3:51 pm
by Roldorf
Two images 1st is from the 4000d on the photo tube scaled to 900x600 to fit here but not cropped.
Last is through the eyepiece with a sony dsc rx100 again scaled 900x600 but not cropped.
4000d no crop.JPG
4000d no crop.JPG (142.22 KiB) Viewed 2962 times
Sony RX 100 Eyepiece.JPG
Sony RX 100 Eyepiece.JPG (79.59 KiB) Viewed 2962 times
Field of view about the same

Re: Microscope Cameras?

Posted: Wed Jun 26, 2019 4:00 pm
by MichaelG.
The blue fringes on that first image are worrying :o
... Something is obviously not as Bresser imagines it to be.

MichaelG.

Re: Microscope Cameras?

Posted: Wed Jun 26, 2019 4:27 pm
by Roldorf
I think that's my fault as I was only trying to show the f.o.v and didn't try to focus the image, so I think it may just be a focusing error, as I haven't had that in any of the other images I have taken with the setup.
I also wasn't paying attention to any of the settings on the camera, just switched it to manual and clicked.

Re: Microscope Cameras?

Posted: Wed Jun 26, 2019 4:35 pm
by Hobbyst46
Dave S wrote:I made up a crude adapter to place the 18-55 lens on the eos4000d against the 10x eyepiece in the photo tube (afocal), and the image was not as that seen visually, but quite magnified by the sensor.
Dave, for afocal setup, the appropriate focal length of the canera lens, for an APSC sensor, when the eyepiece is 10X, is 40mm. The zoom should be set at 40mm and pre-focused at infinity. Both settings can be mechanically fixed on the zoom lens by means of a turn of cellotape wrap.

Re: Microscope Cameras?

Posted: Wed Jun 26, 2019 6:16 pm
by Scarodactyl
If they do not require corrections, one of those 2x chinese relay lenses (like the amscope) should be fine, or perhaps better a nikon 2.5x cf relay. The nikon ones are very nice, and available used cheaper than the 2x. In either case you will not need any intermediate optics, just straight to the sensor.