Chris,
The Olympus NFK's and Nikon CF projection-eyepieces are meant to be used in a trinocular head. Then, the camera body is attached above on a tube of appropriate length. Their primary purpose is to take the (approximately 20mm diameter wide) image formed by the objective in the tube, and enlarge it so that it makes a good "fit" on the sensor/film used. That's why there were different "strengths". A 2.5X made a good "fit" for the 35mm format with it's diagonal of 43.3mm.
(A typical 10X viewing microscope eyepiece looks at a 20mm diameter circle of the image formed by the objective. With a 2.5X photo-eyepiece a 24x36mm sensor will record, across it's diagonal, 17.3mm of that observed image. A nice, "comfortable" fit)
The higher magnification photo-eyepieces were used to provide a fit for larger film formats. Digital sensors are relatively new. So when many of the microscopes we use were made (in the 80's and 90's and much older) 35mm was the "small" format, and that's why there are very few projection type photo-eyepieces with magnifications that provide a good fit on sensors smaller than the 35mm film format. With microscopes in current production there is a wide range of lower powered photo-eyepieces. Even fractional ones to "shrink" the objectives image for a better fit on small sensors.
Check out this page:
http://www.alanwood.net/photography/oly ... ieces.html
Corrective versions, like the NFK's, will provide the needed additional chromatic aberration correction for the objectives they were meant to be used with. Other than that, they do not add anything to the objectives image... they serve to place the image at an appropriate size on the film/sensor. In fact, if you use one that is "stronger" than need be, you are, in a sense just "cropping", and resolution will be less than if a higher powered, higher NA objective were used.
Nikon Projection eyepiece?
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Charles Krebs
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Yes, I do understand that, sorry I must have sent you off at a tangent.
My camera sensor is 24 x 36, which of course most objectives don't cover too well. Hence the interest in projection eyepieces. The one I came across (very cheaply) is "too high" a magnification I know, but the right type I thought, which it turns out was about right.
The gap I'm trying to fill is between that, or its 2.5x brother, and the camera. As you suggested, and I found with the one adaptor I have available, it apparently isn't straightforward.
The Olympus version, being narrower at the top, appears to be easier to handle mechanically. I realise they're for specific Olympus objectives.
Many Olympus objectives, though I haven't delved into precisely which would be appropriate, don't seem particularly expensive, like this one perhaps:
http://cgi.ebay.co.uk/OLYMPUS-MICROSCOP ... 4a9b5ef26d
I already have a few, which came with a part microscope I expect to be sawing up!
Am I making more sense now?!
The link you kindly gave suggests
Some of these "Specialist" adapters can be disproportionately expensive for pretty bits of plumbing though.
Edit - the coupler-finder on that site doesn't seem to find anything for any combination though!
My camera sensor is 24 x 36, which of course most objectives don't cover too well. Hence the interest in projection eyepieces. The one I came across (very cheaply) is "too high" a magnification I know, but the right type I thought, which it turns out was about right.
The gap I'm trying to fill is between that, or its 2.5x brother, and the camera. As you suggested, and I found with the one adaptor I have available, it apparently isn't straightforward.
The Olympus version, being narrower at the top, appears to be easier to handle mechanically. I realise they're for specific Olympus objectives.
Many Olympus objectives, though I haven't delved into precisely which would be appropriate, don't seem particularly expensive, like this one perhaps:
http://cgi.ebay.co.uk/OLYMPUS-MICROSCOP ... 4a9b5ef26d
I already have a few, which came with a part microscope I expect to be sawing up!
Am I making more sense now?!
The link you kindly gave suggests
Which might be a better way to go, but it doesn't mention a projection eyepiece...Alternatives
The Diagnostics Instruments PA1-10A camera adapter fits the Olympus circular dovetail on a trinocular microscope, and takes a T-2 mount at the other end; it can therefore be used with many other SLR cameras, not just Olympus. It is intended to be used with the Olympus PE or NFK 2.5× eyepieces.
Some of these "Specialist" adapters can be disproportionately expensive for pretty bits of plumbing though.
Edit - the coupler-finder on that site doesn't seem to find anything for any combination though!
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Charles Krebs
- Posts: 5865
- Joined: Tue Aug 01, 2006 8:02 pm
- Location: Issaquah, WA USA
- Contact:
Chris,
Diagnostic Instruments Inc and Optem...
http://www.qioptiqlinos.com/Products/CameraCouplers/
...are two companies that offer a variety of "solutions". But as you've noticed, bring your checkbook!
I would only use a projection style photo-eyepiece with a microscope trinocular tube.
As for the "geometry"....
The "shoulder" of the photo-eyepiece should be about 160mm from the shoulder of the objective (or 210mm for a finite 210 tube length objective). The camera film plane should be about 125mm from the shoulder of the photo-eyepiece (at least with the NFK's). Shouldn't really be too hard to cobble together.
Before I tackled that project, I would first try the CF M Plans on the full frame camera. First with a "standard" 210mm extension, and then perhaps with slightly more. I've heard a couple reports from people very satisfied with their full frame results. (Personally I've not tried it with my full frame body). I always feel obliged to inform people that these microscope objectives are normally used to produce an image circle of 28-30mm max. I'm not aware of any microscope that used larger than 30mm eyepiece/trinoc tubes. (... and that way they can't beat me up if they get lousy corners on a full frame body
). At the NA's we're working with the tube length is not that critical. So even if the corners were a little soft at the marked magnification it's very possible some additional extension (and thus magnification) would improve the edges. I would anticipate better overall results this way than with a 2.5X photo-eyepiece added to the mix.
Diagnostic Instruments Inc and Optem...
http://www.qioptiqlinos.com/Products/CameraCouplers/
...are two companies that offer a variety of "solutions". But as you've noticed, bring your checkbook!
I would only use a projection style photo-eyepiece with a microscope trinocular tube.
As for the "geometry"....
The "shoulder" of the photo-eyepiece should be about 160mm from the shoulder of the objective (or 210mm for a finite 210 tube length objective). The camera film plane should be about 125mm from the shoulder of the photo-eyepiece (at least with the NFK's). Shouldn't really be too hard to cobble together.
Before I tackled that project, I would first try the CF M Plans on the full frame camera. First with a "standard" 210mm extension, and then perhaps with slightly more. I've heard a couple reports from people very satisfied with their full frame results. (Personally I've not tried it with my full frame body). I always feel obliged to inform people that these microscope objectives are normally used to produce an image circle of 28-30mm max. I'm not aware of any microscope that used larger than 30mm eyepiece/trinoc tubes. (... and that way they can't beat me up if they get lousy corners on a full frame body
). At the NA's we're working with the tube length is not that critical. So even if the corners were a little soft at the marked magnification it's very possible some additional extension (and thus magnification) would improve the edges. I would anticipate better overall results this way than with a 2.5X photo-eyepiece added to the mix.Thanks Charles
>> the CF M Plans on the full frame camera.
They vary quite a lot. a 23mm tube of course gets in the way completely.
One thing I need to try is a teleconverter at the camera end. I have a 1.6 or is it 1.7, with that in mind. That of course is a negative lens.
I find it slightly odd that the x5 is FL a couple of centimeters positive, but if I sketch the rays, I can make it sort of make sense.
I thought these were supposed to work with infinity objectives as well. Er, the mirror's in the way...
>> the CF M Plans on the full frame camera.
They vary quite a lot. a 23mm tube of course gets in the way completely.
One thing I need to try is a teleconverter at the camera end. I have a 1.6 or is it 1.7, with that in mind. That of course is a negative lens.
I find it slightly odd that the x5 is FL a couple of centimeters positive, but if I sketch the rays, I can make it sort of make sense.
I thought these were supposed to work with infinity objectives as well. Er, the mirror's in the way...
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Charles Krebs
- Posts: 5865
- Joined: Tue Aug 01, 2006 8:02 pm
- Location: Issaquah, WA USA
- Contact:
Chris, 
I think I started wandering about aimlessly when you asked:
Whaa??
a 23mm tube of course gets in the way completely
Yeah... I guess I'm not really sure what you are trying to dosorry I must have sent you off at a tangent.
I think I started wandering about aimlessly when you asked:
So are you trying to set up a bellows type arrangement, or use a microscope stand (without a trinoc head), or something else entirely?SO how does an NFK fit on to an Om body?
They will. (Although newer versions are made for the "infinity" objectives... the Nikons are "CFI" and I think the Olympus designation is "PE". Both infinity microscopes and finite microscopes form a "real" image that is positioned at the plane of the eyepiece aperture. This is called the "intermediate" image. The finite objectives form it directly, the infinity via a tube (or "telan") lens. These photo-eyepieces are designed to take the intermediate image in the trinocular tube and project onto film/sensor. So they would do the same job with either finite or infinity systems. As always, it's a good idea to use the ones made by a manufacturer for the objectives being used. Mix and match may work great but who knows?I thought these were supposed to work with infinity objectives as well.
Er, the mirror's in the way...
Whaa??