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Afocal fail
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dragonblade



Joined: 18 Oct 2014
Posts: 140

PostPosted: Tue Dec 12, 2017 9:29 am    Post subject: Reply with quote

zzffnn wrote:

High eye point is usually indicated by an eyeglasses sign on body of eyepiece.


I have noticed that there are some high eyepoint eyepieces that do use a 'H' though I'm not sure how common they are.

By the way, do eyepiece tubes vary in diameter much? If I bought an eyepiece that was wider than my microscope's tube, I guess I could wrap something around it to keep it in place.
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zzffnn



Joined: 22 May 2014
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Location: Texas USA

PostPosted: Tue Dec 12, 2017 9:50 am    Post subject: Reply with quote

dragonblade wrote:
zzffnn wrote:

High eye point is usually indicated by an eyeglasses sign on body of eyepiece.


I have noticed that there are some high eyepoint eyepieces that do use a 'H' though I'm not sure how common they are.

By the way, do eyepiece tubes vary in diameter much? If I bought an eyepiece that was wider than my microscope's tube, I guess I could wrap something around it to keep it in place.


Super wide diameter eyepiece may not go in at all, though such case is very rare (the standard is 23.2mm, if I remember correctly; but Leitz super wide eyepiece may need a wide tube, for example).

For low power eyepiece at 6x or lower, length may be a problem too (some tubes are not long enough).

Some 'H" in eyepiece names do mean high eye point. Case in point is Nikon HKW10x, which means high eye point compensating wide field 10x. But H may mean different things for different manufacturers. And the same meaning may be represented by different letters, some use C for compensating eyepiece, while some use K, for example.
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dragonblade



Joined: 18 Oct 2014
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PostPosted: Tue Dec 12, 2017 10:15 am    Post subject: Reply with quote

Ive just recently come across the notion of focusing eyepieces. In other words - eyepieces that have their own manual focus rings. I admit I'm puzzled by the reasoning behind this. As if focusing by the objective alone is not sufficient in some cases? I notice those Nikon eyepieces in the ebay link are 'adjustable' and have what look like manual, rotating rings. Would these be focus rings? I'm sure some individuals don't mind but to me, it seems like an extra burden to focus with two different sets of optics.
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Pau
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Joined: 20 Jan 2010
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Location: Valencia, Spain

PostPosted: Tue Dec 12, 2017 10:28 am    Post subject: Reply with quote

There are only two well established standards for eyepiece mounts:
23.2 mm - likely yours
30mm most stereos and true wide field microscopes

but there are out of standard ones in toy microscopes, very old ones and some stereos, the Nikon linked by Fan are 23.2 mount

A focusing eyepiece has most sense in a binocular microscope to set the diopter difference between eyes (and other uses...) but also if you use eyepiece reticles or micrometers, nothing relevant in your case for now.
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Pau
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PostPosted: Tue Dec 12, 2017 11:31 am    Post subject: Reply with quote

dragonblade wrote:
By the way, this is one of the photos I took in my failed afocal attempt.

https://imgur.com/a/ucHi2


As Rik says the culprit is the eyepiece-camera lens combo not playing well together, but in base at your image I think that the main culprit is the camera lens (if it is set at 30mm or higher and really close)...you can even see outside the eyepiece ring!

Quote:
I tried to embed the image but it didn't work out.

Take a look at our image posting guidelines: http://www.photomacrography.net/forum/viewforum.php?f=20
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dragonblade



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PostPosted: Wed Dec 13, 2017 3:41 am    Post subject: Reply with quote

Pau wrote:

It's easy to determine if your eyepiece is compensating (for chromatic aberration) or not:
Take the eyepiece outside the microscope, point it to a white illuminated surface and look through it. If at the round limit you see an orangeish halo it is compensating, if there is a very faint blue halo it is non compensating and it there isn't any halo at all it is a good quality non compensating.


Ive done this test with my current eyepiece. It appears to be non-compensating. I see a very thin blue line around some of the outer edge of the circle. I wish I could grab those second hand Nikon CF eyepieces but money is really tight at the moment. The seller did send me this link to the company's own high eyepoint eyepiece. Do you think this will do a reasonable job with afocal imaging?

http://www.ebay.com.au/itm/Quality-Extra-Wide-Field-EWF-10x-Microscope-Eyepiece-w-FOV-18mm-High-Point-/142486091867

Out of curiosity, would 18mm be the working distance between the eyepiece and the operator's eye?
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enricosavazzi



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PostPosted: Wed Dec 13, 2017 5:48 am    Post subject: Reply with quote

I can confirm that I get no vignetting with a Sigma 30 mm f/2.8 DN on Micro 4/3 on a Zeiss Universal equipped with high eyepoint ("glasses") 10x eyepiece.

The eyepiece rim is without a rubber eyecup and only a couple of mm from the front element of the lens. The lens aperture is of course fully open. The lens is focused at infinity and AF is disabled.

Zooms tend to have entrance pupils located more deeply within the lens. A fixed focal length lens usually involves a lower risk of vignetting.
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dragonblade



Joined: 18 Oct 2014
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PostPosted: Wed Dec 13, 2017 6:27 am    Post subject: Reply with quote

enricosavazzi wrote:
I can confirm that I get no vignetting with a Sigma 30 mm f/2.8 DN on Micro 4/3 on a Zeiss Universal equipped with high eyepoint ("glasses") 10x eyepiece.



Yes, I recall your work with the Sigma 30mm lens and Zeiss microscope. Looked like it was an effective combination. I did consider that lens but am probably going to order a Meike 35mm f1.7. According to reports, the Meike lens is intended for mirrorless cameras so it's unlikely to have a retro focus / reverse telephoto design
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Pau
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PostPosted: Wed Dec 13, 2017 10:18 am    Post subject: Reply with quote

Quote:
The seller did send me this link to the company's own high eyepoint eyepiece. Do you think this will do a reasonable job with afocal imaging?

http://www.ebay.com.au/itm/Quality-Extra-Wide-Field-EWF-10x-Microscope-Eyepiece-w-FOV-18mm-High-Point-/142486091867

Out of curiosity, would 18mm be the working distance between the eyepiece and the operator's eye?


Of course I have no idea of the quality of the eyepiece, Extra Wide Field EWF is at least an exaggeration: 18mm is about the most common width for 10X eyepieces (20 or 22mm will be true wide field for 23.2 eyepieces), 18mm is the diameter of the field that sees the eyepiece, in fact the diameter of the internal diameter eyepiece diaphragm or stop, the circle you see, not the eyepoint height.
For its price or less you can buy a Nikon CFW like the one linked by Fan
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soldevilla



Joined: 16 Dec 2010
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PostPosted: Wed Dec 13, 2017 11:53 am    Post subject: Reply with quote

Maybe this can help to search the best set of camera lens and eyepiece, but it is in spanish...

http://pelupolis.blogspot.com.es/2010/04/y-un-poco-mas-de-foto-traves-de.html
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dragonblade



Joined: 18 Oct 2014
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PostPosted: Thu Dec 14, 2017 2:30 am    Post subject: Reply with quote

Pau wrote:

For its price or less you can buy a Nikon CFW like the one linked by Fan


I'm curious about the manual rotating rings on the Nikon CFW. Are they for setting the diopter?
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Pau
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PostPosted: Thu Dec 14, 2017 4:51 am    Post subject: Reply with quote

Yes, they are focusable eyepieces
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dragonblade



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PostPosted: Thu Dec 14, 2017 7:29 am    Post subject: Reply with quote

Is it possible to recommend any other good quality non-compensating high eyepoint eyepieces that are non-focusing? For example, are there any such offerings from Olympus or Zeiss or other companies? I think I'd prefer a more simple approach to afocal imaging where I just focus the objectives and the camera lens.
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enricosavazzi



Joined: 21 Nov 2009
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PostPosted: Thu Dec 14, 2017 9:21 am    Post subject: Reply with quote

dragonblade wrote:
...
I think I'd prefer a more simple approach to afocal imaging where I just focus the objectives and the camera lens.

Just to make sure, the idea is that you don't focus with the camera lens, you just leave the camera focus on infinity and (once you have calibrated the photo tube to be parfocal with the eyepieces) use only the focus rack of the microscope.
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Pau
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PostPosted: Thu Dec 14, 2017 11:06 am    Post subject: Reply with quote

Quote:
...For example, are there any such offerings from Olympus or Zeiss or other companies? I think I'd prefer a more simple approach to afocal imaging where I just focus the objectives and the camera lens.

With a monocular focusing or not eyepiece doesn't matter much, just set it diopter adjustment to zero (and secure it with tape if you want)

Olympus, Zeiss and Leitz (and most others 23.2mm eyepieces from that time) and also older Nikon are compensating, this is why we recommend Nikon CF. Modern Nikon, Olympus and Zeiss are no compensating but usually they are 30mm and much more expensive. I don't know about american AO and B&L
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