Hi Pau,
Thank you for the detailed questions and instructions. Very helpful!
Pau wrote:Kai,
I want to add some other suggestions and comments:
- Is the camera port itself parfocal with the viewing ones? . To test it, cancel any posible diopter correction in the viewing eyepieces, focus with one eye to one single small point like a dust spot with the 10X objective, remove one eyepiece and put it at the camera port and look trough it with the same eye.
Not quite, but almost. Assuming the information about the fine adjustment on the stage is correct, the difference is about 0.8mm. Easily corrected if needed.
- when doing the former test, is the image quality, is special out of the center equally good than through the normal viewing tubes?. I ask to test this because I vaguely recall a post from another Amscope user and his main problem was in the trinocular port itself, maybe at the prism that directs the light to the photoport or at any internal lens in the microscope head.(but from your test this isn't likely the issue)
Very little difference. If anything, slightly less contrast when using the eyepiece on the camera port. In any case the difference is not significant.
- Also compare the field of view of the camera and viewing tubes with the same eyepiece, are they equal?
Yes, practically the same. I'm not saying "100% the same" because exact comparision is impossible when moving eye from one tube to another, but within my capabilities of looking at the details and remembering them, yes, they are the same.
- Compare the visual field with viewing eyepiece and with the 2X adapter and the camera. If well matched, the fisual field will be larger than the camera's one, being the picture rectangle fully circunscripted inside the visual circle. In your sample pictures it seems very different but I think that the vignette is due to your 100mm macro, not a well matched relay lens)
Visual field using the eyepiece is slightly larger. If you look at the image taken with the camera adapter, horizontally the field is the same as with the eyepiece, reaching all the way to the edge seen in the camera adapter photo. Vertically it is larger with the eyepiece, covering all the way to the circle of the vignetting that is cut off by the edge of the camera sensor.
Put another way, the field is the same, it just does not fit completely on the camera sensor as it is not square.
If all the former tests end positive, your camera adapter is true rubbish. Return it as you plan.
Yup, rubbish it is
Thank you for helping me confirm that.
The standard relay magnification with FF cameras is 2.5X. 2X in your adapter seems too low, in special with achromat objectives not well corrected for the image periphery.
To get that 2.5X relay magnification with an afocal setup you need a 63 mm lens over a 10X eyepiece or a 50mm lens over a 12.5X eyepiece. (i know that those are not very usual numbers, although they were in older systems from Zeiss or Leitz like the stuff I use)
With a 50mm lens over a 10X eyepiece you again will get 2X relay magnification but maybe with a better quality. With your 100mm you get 4X, too high and so too cropped, apart of the vignette issue.
Got it. After your message I did some more reading around how the optics work in different situations and I think I now understand it. This is brand new field for me, but degree in mathematics and physics (long time ago!) helps a bit
I've found few candidates for 50mm relay lenses. 63mm (or thereabouts) is harder, but I can live with the 2x relay magnification and the need to crop the image to get rid of vignetting. Canon 5D Mark III has 22+ megapixel sensor so I can spare a few for cropping
Of course with simple achromat objectives you can't expect good quality outside the image center, but may be acceptable if the slide sample is not thin or if you do some focus stacking. For good quality you need at least plan achromat objectives (much better with plan fluorite and plan apos, but you would need to buy used old models from the best makers and spend much more money that your microscope full price.
That is another discussion. In principle I'd be happy to use more $$ to get better image quality. But I'm realistic, and until I prove to myself that I will stick with this hobby I don't want to spend any more money than necessary. I believe I'll get "good enough" results with the afocal approach, for now. I got a good deal on the scope I have, so I'll use it until I hit some concrete limitations with it.
Thank you again for your help!
// Kai
