Trinocular Projection Lenses for DSLRs

[LouiseScot]

Hi
I'm still shopping around for a new (infinity corrected) scope and I'm wondering about the DSLR adapters. I'm assuming the projection lenses in these are apochromatic? Or are they? The adapters are quite expensive - not much change out of £300. I suppose that's life. However, might it be possible to make a cheaper diy one or is that going to be impractical?
I'm interested in others' experiences
Thanks
Louise

[Hobbyst46]

Hi
I'm still shopping around for a new (infinity corrected) scope and I'm wondering about the DSLR adapters. I'm assuming the projection lenses in these are apochromatic? Or are they? The adapters are quite expensive - not much change out of £300. I suppose that's life. However, might it be possible to make a cheaper diy one or is that going to be impractical?
I'm interested in others' experiences
Thanks
Louise

There are definitely cheaper solutions, but it depends on how exactly one wants to install the camera.
Here is just one example
http://www.microscopy-uk.org.uk/mag/ind ... focal.html
Afocal installation. Camera plus camera lens plus an inexpensive (<<300BP) adapter plus ordinary eyepiece. Since you plan on infinity-corrected, the eyepiece may be omitted.

[LouiseScot]

Hi
I'm still shopping around for a new (infinity corrected) scope and I'm wondering about the DSLR adapters. I'm assuming the projection lenses in these are apochromatic? Or are they? The adapters are quite expensive - not much change out of £300. I suppose that's life. However, might it be possible to make a cheaper diy one or is that going to be impractical?
I'm interested in others' experiences
Thanks
Louise

There are definitely cheaper solutions, but it depends on how exactly one wants to install the camera.
Here is just one example
http://www.microscopy-uk.org.uk/mag/ind ... focal.html
Afocal installation. Camera plus camera lens plus an inexpensive (<<300BP) adapter plus ordinary eyepiece. Since you plan on infinity-corrected, the eyepiece may be omitted.

Hi

Thanks for the link but the afocal method looks a bit messy! I see AmScope do what looks like pretty much the same as the Euromex 2x adapter but for only about £100 - including a T-ring and shipping from the States via Ebay! So much more affordable. The question is: 'what is the quality of the projection lens' in each case? I have an ongoing project of a spectrometer for astronomy use which uses achromatic doublets, including one for the (astronomy) camera. It works fine for visible wavelengths in the spectrometer and can be obtained cheaply, so I imagine a similar lens could be used as a projection lens for an infinity-corrected microscope?

Louise

[apochronaut]

Everything depends on whether the optical system employed uses neutral or corrective eyepieces.. You need to know that if you want to d.i.y. an inexpensive solution because you will have to select a tube lens to match if they are corrective. If not , you might be able to do a direct projection.
Worst case scenario would be to use an extra eyepiece as a projection lens, if they are good enough.
What I mean by that is . Photography is a little more demanding than viewing because cameras tend to capture aberrations and defects in the image that the eye might not notice. This is a budget microscope. With microscopes from about 9 companies going back to 1985, the specs. on the lens elements and on barrels could be relied on. Every one of those microscopes would outperform the Oxion optically, so what I would do is trial an eyepiece as a projection lens if one proves necessary but be prepared to up the anti to something a little pricier.
The adapter parts themselves are not expensive but an incorrect tube length or projection length can cause problems.
I would recommend getting a 25 dollar helical focuser as an intermediary tube , start with using an eyepiece as a projection lens so you can sort out your lengths and take it from there.

[LouiseScot]

Hi
I have a helical focuser in my current setup. I think only apo objectives need corrective EPs. Apos are out of my league, unfortunately
Surely the optical quality is down to the objective. There is the option of adding plan fluarex instead of the usual plan achros. Are some plan achros better than others. I suppose you get what you pay for but any achro will only be an achro - it's much the same with refractor telescopes. Apo triplet telescopes can be a lot cheaper than apo objectives! I might get a plan fluarex and try it out... About £300 but cheaper than a whole scope e.g. like the Oxion.
Louise

[deBult]

Louise,

To my understanding nearly all brands of older finite tube length scopes require a matched set of eyepieces and objectives to achieve correct color correction (The older Nikon ones are the only exception to this rule known to me).
This requirement is not limited to Apo objectives but is applicable to all.

Actually the objectives of a some of the infinite tube length scopes need some correction: this is done via the telan lens in the tube and no longer via the eyepiece.

[LouiseScot]

Hi deBuilt
That might be true of higher quality instruments but it probably doesn't apply to my league of relatively cheap Chinese scopes.
Also, with finite tube lengths with a trinocular tube, there are no lenses between objective and camera yet the camera image is the same as that observed through the eyepiece, so the eyepiece doesn't do anything additional. However, it will be different if I try an infinity corrected plan fluarex objective on my finite scope as I'd have to introduce a projection lens of some sort plus I wouldn't be able to use the eyepieces.
Louise

[MichaelG.]

Surely the optical quality is down to the objective.

.

Louise,

May I suggest that you have a look at the concurrent thread by david_b

viewtopic.php?f=5&t=9968

MichaelG.

[LouiseScot]

Surely the optical quality is down to the objective.

.

Louise,

May I suggest that you have a look at the concurrent thread by david_b

viewtopic.php?f=5&t=9968

MichaelG.

Yes, I've seen that. Obviously with a finite tube the camera sensor and objective have to be aligned and there will be chromatic aberration with an achromat - which is my point. 75RR's diatom image is stunning: viewtopic.php?f=6&t=9889 but at £2k for such an objective, is out of my league! And, as I said, with an infinity tube there are complications since an optical element has to be introduced, plus the camera sensor still always has to be in alignment i.e. no tilt. I'm not totally displeased with my own dslr imaging with my current old finite tube scope but I would like it to be better which is why I was thinking of trying a plan fluor.

Louise

[Adam Long]

A lot of folks over at photomacrography.net use infinity objectives coupled direct to camera (no microscope) via relatively low-cost tube lenses such as Raynox close-up lenses, the Thorlabs ITL200 or telephoto camera lenses. The former two could be an option <£100, though building a rigid connection via extension tubes etc will be a big part of the overall cost, and you'd need to get the tube lens fairly close to the objective. The other caveat is these are typically used at very low mags vs microscopes.

Summary of some of the configurations here: https://www.photomacrography.net/forum/ ... 25&t=37843

[MichaelG.]

Yes, I've seen that. Obviously with a finite tube the camera sensor and objective have to be aligned and there will be chromatic aberration with an achromat - which is my point.

Louise

.

Sorry but I simply don’t understand your comment
... david_b is having problems with an infinity corrected microscope

MichaelG.

[LouiseScot]

A lot of folks over at photomacrography.net use infinity objectives coupled direct to camera (no microscope) via relatively low-cost tube lenses such as Raynox close-up lenses, the Thorlabs ITL200 or telephoto camera lenses. The former two could be an option <£100, though building a rigid connection via extension tubes etc will be a big part of the overall cost, and you'd need to get the tube lens fairly close to the objective. The other caveat is these are typically used at very low mags vs microscopes.

Summary of some of the configurations here: https://www.photomacrography.net/forum/ ... 25&t=37843

Yes, I've seen these and the stuff and the comparisons on closeupphotography.com - very useful!
Louise

[LouiseScot]

Yes, I've seen that. Obviously with a finite tube the camera sensor and objective have to be aligned and there will be chromatic aberration with an achromat - which is my point.

Louise

.

Sorry but I simply don’t understand your comment
... david_b is having problems with an infinity corrected microscope

MichaelG.

I think I was just saying that with a finite tube microscope, and all else being equal, the quality of the image will be mostly determined by the quality of the objective i.e. apo objectives outperform achro ones. It would be strange if they didn't!

Louise

[deBult]

Louise... I think you have your facts mixed up: please reread the input of apochromat and others in earlier replies to your posts: for most finite scopes the image quality is the result of the COMBINATION of objective and eyepiece

In addition to your last observation on Apo’s outperforming Achro’s:
Color correction in Apo’s is improved and usually the Apo’s are also having a slightly higher na.
A higher na means LESS depth of field .. so pictures with simple achromats have more depth of field and give an impression of improved sharpness (punch).

In addition to this: the Apo’s have way more lens elements (required for the color correction): net result is a slight loss in contrast (this one is easily remedied - when taking pictures - in post processing)
So “outperform” is a relative qualification.

[LouiseScot]

Again... I think you have your facts mixed up: please reread the input of apochromat in earlier posts: for most finite scopes the image quality is the result of the COMBINATION of objective and eyepiece

In addition to your last observation:
Color correction in Apo’s is improved and usually the Apo’s are having a higher na.
A higher na means LESS depth of field .. so pictures with simple achromats have more depth of field and give an impression of improved sharpness (punch). So what is “better”?

Hi
Um, I'm only talking about imaging via the trinocular tube so no EPs involved for that. As I said my old budget finite tube scope takes ok (plan achromatic) images via the trinocular tube with no other optics involved - just camera sensor and objective. But, I think I said before that with infinity corrected objectives some sort of tube lens would obviously have to be introduced and that will complicate matters. I did also say before that I thought colour correction with EP's was likely only important with apo objectives and/or higher end scopes. I'm not into that price range and probably never will be. I'm really only interested in improving the quality of images I can potentially get - maybe via plan fluor objectives rather than the really expensive proper semi apo or apo objectives. I don't think there is anything to be gained by comparing apo and achro other than figuratively. However, loss of depth of field can be overcome by focus stacking, if needed. I spent many hours operating a laser scanning confocal microscope once upon a time. It takes much more effort to do it manually but it can be done. I presume the budget Chinese infinity corrected microscopes must have some sort of tube lens but it's not clear where it's positioned. They hide all the messy details! It seems like an expensive accessory is required (though costs less than a Thorsons tube lens), and which includes some optics, in order to use the trinocular phototubes on an infinity corrected scope but I have no diagrams or details of either. How good the accessory is when it comes to correcting aberrations, I've no idea. I'm on a learning curve with infinity corrected scopes - never had one. I've had the idea of maybe buying just a fairly cheap infinity objective to have a play with and to learn some things.

Louise

[MichaelG.]

I think I was just saying that with a finite tube microscope, and all else being equal, the quality of the image will be mostly determined by the quality of the objective i.e. apo objectives outperform achro ones. It would be strange if they didn't!

Louise

O.K. I'll buy that ... but look at this way:
The maximum theoretical quality is dictated by the objective, but every additional component modifies that performance.
... and, except for the special case of an appropriately compensating eyepiece, that modification will be detrimental.

Using arbitrary numbers, and assuming that everything else is perfect:
If the objective performance is 90% and the projection eyepiece is 90% the result is 81%
If the objective performance is 90% and the projection eyepiece is 50% the result is 45%

MichaelG.

[LouiseScot]

I think I was just saying that with a finite tube microscope, and all else being equal, the quality of the image will be mostly determined by the quality of the objective i.e. apo objectives outperform achro ones. It would be strange if they didn't!

Louise

O.K. I'll buy that ... but look at this way:
The maximum theoretical quality is dictated by the objective, but every additional component modifies that performance.
... and, except for the special case of an appropriately compensating eyepiece, that modification will be detrimental.

Using arbitrary numbers, and assuming that everything else is perfect:
If the objective performance is 90% and the projection eyepiece is 90% the result is 81%
If the objective performance is 90% and the projection eyepiece is 50% the result is 45%

MichaelG.

Hi

Just looking at percentages may be an oversimplification. There are different types of aberration. But, for my purposes, I'm really only interested in improving rather than reaching a theoretical optimum

Louise

[deBult]

I presume the budget Chinese infinity corrected microscopes must have some sort of tube lens but it's not clear where it's positioned. They hide all the messy details! It seems like an expensive accessory is required (though costs less than a Thorsons tube lens), and which includes some optics, in order to use the trinocular phototubes on an infinity corrected scope but I have no diagrams or details of either. How good the accessory is when it comes to correcting aberrations, I've no idea.

Well beginning to get your line of reasoning on the finite Bresser ibjectives.


I have no in depth knowledge on infinity scopes but not only the Chinese are hiding the fine details on the position and correction of the Telan tube lens.

[MichaelG.]

Hi

Just looking at percentages may be an oversimplification. There are different types of aberration. But, for my purposes, I'm really only interested in improving rather than reaching a theoretical optimum

Louise

It's certainly a simplification ...but I thought it might be a good place to start.

Evidently I was wrong.

When you have made your improvement, I look forward to learning how you achieved it.

MichaelG.

[75RR]

I'm on a learning curve with infinity corrected scopes - never had one. I've had the idea of maybe buying just a fairly cheap infinity objective to have a play with and to learn some things.

I don't think you will notice much difference between your finite and an infinity microscope in everyday use.

As far as I am aware there are three main differences to the infinity microscope.

a) It allows the placing of extra components in the light train without having to include costly Telan lenses to maintain the established finite distance.

This is a manufacturing advantage, savings are not necessarily passed on to the customer.

b) Since this is the type of microscope made today by most of the manufactures, the objectives benefit from the latest advances in manufacturing, design, coatings etc...

This is really only noticeable in the very top range objectives costing thousands of pounds - I don't believe there is much difference in the low and intermediate ranges.

c) The corrections take place in the objective and in the internal tube lens, this means that the eyepieces are not corrective.

This is an advantage, as it means that when attaching a camera to the microscope one should in theory not have to worry about the corrections that finite microscopes include in their eyepieces.

[MichaelG.]

... images via the trinocular tube with no other optics involved - just camera sensor and objective.

Louise

I can't leave this discussion without mentioning: That is a very bad place to start.
You are effectively using the objective as a 'macro' lens
This is only viable with a few [typically simple, low power] objectives, or something like the fully corrected '160mm tube-length' Nikon objectives shown here: http://www.krebsmicro.com/Nikon_CF.pdf

MichaelG.

[Hobbyst46]

... I'm on a learning curve with infinity corrected scopes - never had one....

I believe that confocal microscopes are infinity-corrected optics microscopes. Truly not all confocal microscopes are equipped with cameras in addition to the PMT sensors.
One more comment: you brought as an example the stunning (agreed on that!!) diatom image posted by 75RR. That image was created with a finite optics (160mm TL) objective, not infinity corrected. Some asking prices for such (used) objectives are in the hundreds (<500 BP I believe), whereas ~2K BP prices are typical for (used) infinity corrected objectives from either Zeiss or Olympus. I would add that the image is an example of excellent creative photomicrography, more than a specific advantage of the planapo objective.

[LouiseScot]

... images via the trinocular tube with no other optics involved - just camera sensor and objective.

Louise

I can't leave this discussion without mentioning: That is a very bad place to start.
You are effectively using the objective as a 'macro' lens
This is only viable with a few [typically simple, low power] objectives, or something like the fully corrected '160mm tube-length' Nikon objectives shown here: http://www.krebsmicro.com/Nikon_CF.pdf

MichaelG.

I'm afraid you're confusing me - I've always imaged on my old finite scope with a camera, trinocular tube and plan achro objectives up to 60x. There was never any other option. What are you saying I'm missing with my current setup?
Louise

[viktor j nilsson]

You are missing an eyepiece that would complete the optical corrections intended by the lens designer. Nearly all finite microscope manufacturers relied on this system: you design objectives that intentionally produce an image with some optical aberrations, and then design "compensating" eyepieces with opposite, matching, aberrations. Put them together and you get a final image that is as good as intended.

For imaging you would either use a matching photo eyepiece, or use afocal imaging with a normal visual eyepiece + camera lens.

The only exception to this that I know of is the Nikon CF system which put all optical corrections into the objectives (and used optically neutral eyepieces) and some low power objectives from other makers (Lomo and Zeiss Jena comes to mind). These are the only ones I would ever use for direct projection (objective straight to sensor). For all other finite systems, you really need a matching eyepiece between objective and sensor.

[LouiseScot]

You are missing an eyepiece that would complete the optical corrections intended by the lens designer. Nearly all finite microscope manufacturers relied on this system: you design objectives that intentionally produce an image with some optical aberrations, and then design "compensating" eyepieces with opposite, matching, aberrations. Put them together and you get a final image that is as good as intended.

For imaging you would either use a matching photo eyepiece, or use afocal imaging with a normal visual eyepiece + camera lens.

The only exception to this that I know of is the Nikon CF system which put all optical corrections into the objectives (and used optically neutral eyepieces) and some low power objectives from other makers (Lomo and Zeiss Jena comes to mind). These are the only ones I would ever use for direct projection (objective straight to sensor). For all other finite systems, you really need a matching eyepiece between objective and sensor.

Um, I think you guys are operating on a different plane to me! I'm 100% sure this need for compensation only applies to high end scopes, not to relatively cheap Chinese finite ones (like my 30 year-old Brunel trinocular!) with cheap, generic achro objectives, and generic eyepieces too.
I realise it changes with infinite systems with the need for a tube lens which I guess may or may not do some corrections as well as projecting the image, depending on the design/maker. I think even the Olympus infinity uis/uis2 system does its imaging with the objectives, an adapter - the UTLU singtle port tube lens - plus a camera plus possibly a second adapter (https://www.edmundoptics.co.uk/p/olympu ... gth/29244/). So you can image with just the objectives plus the U-TLU (which is quite expensive new), but you don't need eyepieces in the mix in order to image. Well, that's what I've ascertained - correct me if I'm wrong!

Louise

[Hobbyst46]

You are missing an eyepiece that would complete the optical corrections intended by the lens designer. Nearly all finite microscope manufacturers relied on this system: you design objectives that intentionally produce an image with some optical aberrations, and then design "compensating" eyepieces with opposite, matching, aberrations. Put them together and you get a final image that is as good as intended.

For imaging you would either use a matching photo eyepiece, or use afocal imaging with a normal visual eyepiece + camera lens.

The only exception to this that I know of is the Nikon CF system which put all optical corrections into the objectives (and used optically neutral eyepieces) and some low power objectives from other makers (Lomo and Zeiss Jena comes to mind). These are the only ones I would ever use for direct projection (objective straight to sensor). For all other finite systems, you really need a matching eyepiece between objective and sensor.

Um, I think you guys are operating on a different plane to me! I'm 100% sure this need for compensation only applies to high end scopes, not to relatively cheap Chinese finite ones (like my 30 year-old Brunel trinocular!) with cheap, generic achro objectives, and generic eyepieces too.
I realise it changes with infinite systems with the need for a tube lens which I guess may or may not do some corrections as well as projecting the image, depending on the design/maker. I think even the Olympus infinity uis/uis2 system does its imaging with the objectives, an adapter - the UTLU singtle port tube lens - plus a camera plus possibly a second adapter (https://www.edmundoptics.co.uk/p/olympu ... gth/29244/). So you can image with just the objectives plus the U-TLU (which is quite expensive new), but you don't need eyepieces in the mix in order to image. Well, that's what I've ascertained - correct me if I'm wrong!

Louise

The Olympus camera that fits onto the Olympus infinity does not need an eyepiece but it comes with a lens: either a 1X or a 0.63 or 0.5X.

[MichaelG.]

I'm afraid you're confusing me - I've always imaged on my old finite scope with a camera, trinocular tube and plan achro objectives up to 60x. There was never any other option. What are you saying I'm missing with my current setup?
Louise

You are possibly/probably missing the performance that comes from using an objective within its design envelope.
The image from the objective in a 160mm tube-length microscope lies about 10mm down the tube ...
Does your set-up put the DSLR sensor at an equivalent position ??
Are your objectives fully colour corrected, or would they be better used with a compensating eyepiece ??

I don't know, because I haven't seen the specification of what you are using.

MichaelG.

[viktor j nilsson]

You are missing an eyepiece that would complete the optical corrections intended by the lens designer. Nearly all finite microscope manufacturers relied on this system: you design objectives that intentionally produce an image with some optical aberrations, and then design "compensating" eyepieces with opposite, matching, aberrations. Put them together and you get a final image that is as good as intended.

For imaging you would either use a matching photo eyepiece, or use afocal imaging with a normal visual eyepiece + camera lens.

The only exception to this that I know of is the Nikon CF system which put all optical corrections into the objectives (and used optically neutral eyepieces) and some low power objectives from other makers (Lomo and Zeiss Jena comes to mind). These are the only ones I would ever use for direct projection (objective straight to sensor). For all other finite systems, you really need a matching eyepiece between objective and sensor.

Um, I think you guys are operating on a different plane to me! I'm 100% sure this need for compensation only applies to high end scopes, not to relatively cheap Chinese finite ones (like my 30 year-old Brunel trinocular!) with cheap, generic achro objectives, and generic eyepieces too.
I realise it changes with infinite systems with the need for a tube lens which I guess may or may not do some corrections as well as projecting the image, depending on the design/maker. I think even the Olympus infinity uis/uis2 system does its imaging with the objectives, an adapter - the UTLU singtle port tube lens - plus a camera plus possibly a second adapter (https://www.edmundoptics.co.uk/p/olympu ... gth/29244/). So you can image with just the objectives plus the U-TLU (which is quite expensive new), but you don't need eyepieces in the mix in order to image. Well, that's what I've ascertained - correct me if I'm wrong!

Louise

You are correct that many modern infinity systems make the final optical corrections in the tube lens, and thus use neutral (non-compensating) eyepieces.

Regarding the need for compensating eyepieces on your
microscope, I don't know the generic Chinese scopes well enough to say for sure. I would assume that your Brunel objectives are a clone of some other manufacturer's objectives, and would thus benefit from having matching eyepieces. But maybe the manufacturer didn't even bother to copy the corresponding eyepiece design.

If that's the case, I think it is better to say that your objectives NEED compensating eyepieces - the manufacturer just didn't provide any.

I would be very surprised if the Chinese objectives were a copy of Nikon's CF objective line.

[viktor j nilsson]

I'm afraid you're confusing me - I've always imaged on my old finite scope with a camera, trinocular tube and plan achro objectives up to 60x. There was never any other option. What are you saying I'm missing with my current setup?
Louise

You are possibly/probably missing the performance that comes from using an objective within its design envelope.
The image from the objective in a 160mm tube-length microscope lies about 10mm down the tube ...
Does your set-up put the DSLR sensor at an equivalent position ??
Are your objectives fully colour corrected, or would they be better used with a compensating eyepiece ??

I don't know, because I haven't seen the specification of what you are using.

MichaelG.

Some trinocular heads do allow you to place the intermediate image directly onto the sensor. But most of them don't. You will be able to get an image anyway, but as Michael points out, this will mean that your objectives will work outside their intended optical configuration. The working distance will change, and you will introduce unwanted optical aberrations.

A good way of seeing if your sensor is where it should be is to see if your objectives are parfocal. Do you need to refocus more than a slight turn of the fine focus knob when you change objectives? If you do, your sensor is not where it should be.

[viktor j nilsson]

What I'm trying to say is that any properly setup 160mm finite microscope with a matching set of objectives and eyepieces from one of the major producers is likely going to be a massive upgrade for you. I don't really understand why you are looking for a new infinity microscope.