www.photomacrography.net :: View topic - Nikon scope w/ teaching head, afocal micro 4/3 cam, photos
www.photomacrography.net Forum Index
An online community dedicated to the practices of photomacrography, close-up and macro photography, and photomicrography.
Photomacrography Front Page Amateurmicrography Front Page
Old Forums/Galleries
 
 FAQFAQ   SearchSearch   MemberlistMemberlist   UsergroupsUsergroups   RegisterRegister 
 ProfileProfile   Log in to check your private messagesLog in to check your private messages   Log inLog in 
Nikon scope w/ teaching head, afocal micro 4/3 cam, photos

 
Post new topic   Reply to topic    www.photomacrography.net Forum Index -> Equipment Discussions
View previous topic :: View next topic  
Author Message
zzffnn



Joined: 22 May 2014
Posts: 1818
Location: Texas USA

PostPosted: Thu Feb 26, 2015 1:59 pm    Post subject: Nikon scope w/ teaching head, afocal micro 4/3 cam, photos Reply with quote

I know Nikon’s CFWN 10x/20 eyepieces have high eye points that are theoretically better for afocal photomicroscopy than the regular CFW 10x/18 ones. But has anyone compared their real-world photo qualities, or can make an educated guess? Please kindly comment.

I found that my afocal photo rig can resolve fine details of Navicula placenta (diatom) reasonably well, but falls far behind my eyes with Pleurosigma sp. . My eyes can see those tiny dots on Pleurosigma sp. , but my afocal rig cannot capture any (camera live view and photos are both worse than eyes). I understand eyes should be better than cameras without stacking, but I am wondering if using high eye point CFWN eyepieces would produce significantly more details than my current CFWs?

The following are details of my afocal photomicroscopy rig used for Pleurosigma sp.:

1) Nikon Labophot 2 microscope with Leica 0.9/1.25 condenser

2) Labomed LP60x Semi Plan Achro NA 0.85 objective and Nikon E Plan Achro 40x NA 0.65 (also have a NA 1.1 65x LOMO objective with extender being shipped to me from Ukraine - I understand higher NA will help, however my question here is regarding photo quality produced by different eyepieces)

3) Circular oblique, Litonotus’ Gradient Universal Filter, Rheinberg, bright field

4) Micro four third camera (Olympus E-PM2) with Sigma 30mm f/2.8 lens, manual focus, shooting through Nikon CFW eyepieces with Orion SteadyPix Pro camera mount, with or without flash, tried different apertures and shutter speeds (very long or very short w/ flash, vibration is not significant)

5) Klauss Kemp diatom slide

I also noticed that the focus point of afocal camera is slightly different than that of eyes. After I focused with eyes, I still need to turn scope’s focus wheel slightly to get good focus on camera’s live view. But still, even with camera in focus, the image quality of live view and photos are still worse than eyes, especially when we were dealing with Pleurosigma sp.

I know with my afocal photo rig, the actual "tube length" is longer than 160 mm. However I was under the impression that up to NA 1.0-1.1, a tube length variation of 10-20 mm should not degrade image too much (micro 4/3 camera's sensor is not too far back compared to eyes)? I could be wrong, since we are dealing with very fine surface details of Pleurosigma sp.

Thank you very much for you comments.

And sorry for being out of topic here: does camera’s video recording always crop the view slightly (video field area is always less than photo field)? How do I obtain the same view field? I have read my camera’s manual carefully, but could not find a way.


Last edited by zzffnn on Sun Mar 01, 2015 4:44 pm; edited 5 times in total
Back to top
View user's profile Send private message Visit poster's website
solartje



Joined: 11 Feb 2015
Posts: 19
Location: Belgium -Europe

PostPosted: Thu Feb 26, 2015 8:01 pm    Post subject: Reply with quote

I am no expert (by far ! i don't even own a lsr) but i was looking at buying one and looking at specs (especially video), and I read that most camera video's use 95% of the viewfield when on video mode. you can't do anything do anything about it.

about the afocal quality. i'll leave that to the experts.

but REALLY, i know nothing about photomicroscopy so i'm probably all wrong. I'm new on this too, but hey its a start Smile maybe others will answer later
Back to top
View user's profile Send private message
zzffnn



Joined: 22 May 2014
Posts: 1818
Location: Texas USA

PostPosted: Thu Feb 26, 2015 8:13 pm    Post subject: Reply with quote

solartje wrote:
I am no expert (by far ! i don't even own a lsr) but i was looking at buying one and looking at specs (especially video), and I read that most camera video's use 95% of the viewfield when on video mode. you can't do anything do anything about it.

about the afocal quality. i'll leave that to the experts.

but REALLY, i know nothing about photomicroscopy so i'm probably all wrong. I'm new on this too, but hey its a start Smile maybe others will answer later


Thank you for your comment!
In my case, I am using a micro four third camera (Olympus E-PM2). Its video field is about 85% of its photo view field.
Back to top
View user's profile Send private message Visit poster's website
Pau
Site Admin


Joined: 20 Jan 2010
Posts: 4828
Location: Valencia, Spain

PostPosted: Fri Feb 27, 2015 5:37 am    Post subject: Reply with quote

Quote:
I know Nikon’s CFWN 10x/20 eyepieces have high eye points that are theoretically better for afocal photomicroscopy than the regular CFW 10x/18 ones. But has anyone compared their real-world photo qualities, or can make an educated guess?

Resolution will be the same with both eyepieces. High eyepoint ones are better to avoid vignetting because you are able to put its eyepoint closer to the relay lens front aperture. You also have more flexibility positioning the camera lens. Sometimes they come from higher end series and could be better aberrration corrected, but this isn't a general case.

Quote:
My eyes can see those tiny dots on Pleurosigma sp. , but my afocal rig cannot capture any (camera live view and photos are both worse than eyes). I understand eyes should be better than cameras without stacking, but I am wondering if using high eye point CFWN eyepieces would produce significantly more details than my current CFWs?


Well, the eye/brain team is much more sophisticated than the camera: you're constantly stacking (within some limits), averaging noise, doing true HDR... all automatically at about 25 fps Very Happy
But I think you have an issue maybe optical or maybe from vibration blur. With a 40X objective you can easily resolve Pleurosigma dots, even better with your 60/0.85 (take a look: HERE, 100% crops. Pleurosigma is a classic resolution test subjet for 40X objectives.


Quote:
I know with my afocal photo rig, the actual "tube length" is longer than 160 mm. However I was under the impression that up to NA 1.0-1.1, a tube length variation of 10-20 mm should not degrade image too much (micro 4/3 camera's sensor is not too far back compared to eyes)? I could be wrong, since we are dealing with very fine surface details of Pleurosigma sp.

10-20mm tube length variation can matter a lot with high NA objectives, although I'm not sure if this is enough to explain your issue. Why is your TL longer than the nominal 160mm?. Is your photoeyepiece visually parfocal with your visual ones?.
For "perfect" afocal the eyepiece must be parfocal with the viewing eyepieces and the camera lens focused to infinite.

Quote:
And sorry for being out of topic here: does camera’s video recording always crop the view slightly (video field area is always less than photo field)? How do I obtain the same view field? I have read my camera’s manual carefully, but could not find a way.

This must be a camera design feature. With my Canon both images match, at least to the point to not be a noticable issue if present.
_________________
Pau
Back to top
View user's profile Send private message
zzffnn



Joined: 22 May 2014
Posts: 1818
Location: Texas USA

PostPosted: Fri Feb 27, 2015 7:19 am    Post subject: Reply with quote

Thank you very much Pau. You are always so helpful.

Re vibration blur, I did try 1s long exposure or 1/250s short exposure with electronic flash. I had no improvement. Also my camera was clamped very tightly to the eyepiece and microscope (my Orion camera mount is a lot more stable than tripod).

My loss of resolution can be seen from camera's digital real-time display, even before shutter is released.

Sorry for my poor teminology, what I meant by "actual tube length" is formation of a focused image on sensor: be it my eyes' retina, or camera's sensor. In my case, my retina and camera sensor is NOT parfocal, although eyepieces are (I am using microscope's other teaching head for photos). I think this is because camera sensor always sits further away than my retina ( so when image is in focus at my retina, it is out of focus for camera sensor).

I also tried adding more light with a LED torch light along microscope's optical path. I saw brighter image and lower ISO values, but resolution remain to same.

What do you mean by optical blur? Please forgive my ignorance. Do you mean circle of confusion? If so, what should I do, other than changing to better lens and camera?

Your 40x test shot of Pleurosigma looks great. I assume it is a single shot and not stacked, correct? That may make a difference.

Thank you again!
Back to top
View user's profile Send private message Visit poster's website
Pau
Site Admin


Joined: 20 Jan 2010
Posts: 4828
Location: Valencia, Spain

PostPosted: Fri Feb 27, 2015 8:53 am    Post subject: Reply with quote

With the inespecific expression "optical blur" I just meant any optical issue causing blur (spherical aberration, misfocusing, objective defect, condenser too closed...)

When you shot afocally the position of the camera sensor needs to match with the camera lens to be focused to infinite, not with your retina (your eye has/is a short focal wide angle lens!) To be parfocal what needs to match is the eyepiece used with your camera and the eyepieces used for your eyes.

In principle you've done the standard trics to avoid vibration blur, so I lean towards an optical issue.

If you post (or refresh my memory if already posted) detailed pictures and written details of your photo setup this could help to understand the problem.

-Yes, my Pleurosigma test shots aren't stacked
_________________
Pau
Back to top
View user's profile Send private message
zzffnn



Joined: 22 May 2014
Posts: 1818
Location: Texas USA

PostPosted: Fri Feb 27, 2015 1:09 pm    Post subject: Reply with quote

Thanks so much Pau.

Regarding your comments: all my 4 eyepieces are/were parfocal and exactly the same Nikon CFW10s. All objectives are/were parfocal as well. Condenser NA was set to 85% of that of objective. When used with 60x objective, condenser was at its highest position and sub-stage aperture was fully opened.

I did test again today and have resolved the problem without knowing exactly why. My new set of Pleurosigma shots are still not as good as Pau's, but I am happy enough with them considering the compromises that I have accepted (Labomed non--Nikon-corrected 60x air objective, lesser camera, less skills and non-optimal set-up such as light-splitting by teaching heads).

I probably had brain farts in previous trials and did not focus well. My camera's LCD screen resolution is pretty bad - camera sensor actually IS parfocal with my eyes, but camera's LCD might give the wrong impression that it was not parfocal. I also cleaned most lens, tightened some joints and made better alignments yesterday, so that might help as well.

So today I shot Pleurosigma diatom with many combinations of shutter speed (1.3'', 1/3, 1/250, ect.), aperture, lighting (stock halogen, halogen+ LED torch light or flash) and filters (circular oblique [COL] or Litonotus’ Gradient Universal Filter [GUF]).


My favorite single shot, shown below, was taken using GUF with LED torch (1000 lumens) + halogen. Shutter speed 1.3'' + automatic aperture (F/2.8, probably not necessary). I focused onto the area circled in red (other areas of Pleurosigma [note this diatom is not flat and has a raised middle portion] or other diatoms are not in focus). Please feel free to comment on or modify this photo.



GUF +flash ( 1/8 ) +1/250 shutter speed, or
GUF +stock halogen +1.3'' shutter speed is close though slight worse.

GUF +stock halogen can shoot at 1/3 shutter speed without much image degradation - in this condition without flash, I did not test faster shutter speed than 1/3.

GUF + shutter speed slower that 1.6'' produced vignetting.

In general, GUF performs visibly better than COL in my system.


My rig with teaching head / 4 eyepieces (the LED torch shines into light path of the stock halogen light source, flash can be place at the same location as well, stock halogen bulb does not need to be removed):


Camera coupling with eyepiece is very tight with the Orion mount:
Back to top
View user's profile Send private message Visit poster's website
Ichthyophthirius



Joined: 07 Mar 2013
Posts: 883

PostPosted: Fri Feb 27, 2015 3:27 pm    Post subject: Reply with quote

Hi,

I was under the impression that all CF eyepieces are high-eyepoint eyepieces. Even the simple CFW 10x.

The aperture of the camera objective isn't effective when using it in an afocal set-up. If you stop down a lot, the iris sometimes shows up as vignetting.

However, depending on how your camera works, if the iris moves just before taking the image, it might introduce vibrations. In that case, best to disable it.
Back to top
View user's profile Send private message
zzffnn



Joined: 22 May 2014
Posts: 1818
Location: Texas USA

PostPosted: Fri Feb 27, 2015 3:50 pm    Post subject: Reply with quote

Ichthyophthirius wrote:
Hi,
I was under the impression that all CF eyepieces are high-eyepoint eyepieces. Even the simple CFW 10x.


The CFW10s do have higher eye point than my other non-Nikon eyepieces. I wear eyeglasses myself and feel that CFWs are very comfortable to use. I was just wondering if CFWNs would produce significantly better image - my guest was that they won't - as Pau confirmed, chances are high that they won't make a big difference.

Ichthyophthirius wrote:
The aperture of the camera objective isn't effective when using it in an afocal set-up. If you stop down a lot, the iris sometimes shows up as vignetting.


Thank you! Understood. Pau taught me about that before and I also read about it elsewhere. If I remember correctly, stopping camera down to F/5.6 should help more than hurt, the lower limit is around F/8. In reality, I didn't stop down to more than F/4 - my lens is sharp enough around that point.

Ichthyophthirius wrote:
However, depending on how your camera works, if the iris moves just before taking the image, it might introduce vibrations. In that case, best to disable it.


Great point. I am guessing my 1st shutter may introduce some vibration. I don't think my camera allows disabling 1st shutter, but I could try second curtain sync flash (also known as slow sync flash) to dampen its vibration.
Back to top
View user's profile Send private message Visit poster's website
zzffnn



Joined: 22 May 2014
Posts: 1818
Location: Texas USA

PostPosted: Fri Feb 27, 2015 6:02 pm    Post subject: Reply with quote

My LOMO water immersion 65x NA 1.1 objective came in just now and I did a test. As expected, on 12 mm extender, it is about 70x and produces a brighter image than the Labomed air 60x NA 0.85 objective.

However, looking at Pleurosigma diatom and the diatom above it, LOMO's apparent resolution does not seem to be significantly higher than the Labomed. I guess that means all resolvable details on those two diatoms have been captured by Labomed (NA 0.85 seems enough for the smallest details on those two diatoms, NA 1.1 seems overkill concerning resolving power)?

I am still happy with the LOMO though :-)


Last edited by zzffnn on Tue Mar 03, 2015 10:56 pm; edited 3 times in total
Back to top
View user's profile Send private message Visit poster's website
Pau
Site Admin


Joined: 20 Jan 2010
Posts: 4828
Location: Valencia, Spain

PostPosted: Sun Mar 01, 2015 5:43 am    Post subject: Reply with quote

Hi Fan,

You have a nice scope and an original photo adaptation: it's logical but I've never seen a teaching head used for this purpose. The only caveat I can guess is that you only can send about 1/4 of the light to the camera
I'll post a link in my afocal tread.

Some further comments:
- The image quality is good: just what you can expect with achromat objectives in bright field with no processing nor stacking, nothing to worry about

- The pictured lower diatom isn't Pleurosigma (maybe Gyrosigma)

- If your objectives are parfocal and as it seems you're useing the microscope parts as designed you have the right tube length (forget about the external impression, this is corrected optically inside the binocular heads, optical and mechanical TL only really match in simple monocular tubes)

- About parfocality, if your eyepieces are focusable you can fine tune it.
If you can send the camera live image to the computer or tv, set the camera eyepiece to "0", focus the camera image with the fine focus knob and then focus the visual eyepieces with their own focus rings.
If you can't have a reliable camera live image, follow one of the methods posted at http://krebsmicro.com/parfocal/index.html

In both cases use a 10X objective and a high contrast flat detail to do the critical focus. In my experience often a small dust particle can be better than a actual interesting micro subject.

Quote:
However, looking at Pleurosigma diatom and the diatom above it, LOMO's apparent resolution does not seem to be significantly higher than the Labomed. I guess that means all resolvable details on those two diatoms have been captured by Labomed (NA 0.85 seems enough for the smallest details on those two diatoms, NA 1.1 seems overkill concerning resolving power)?

Very likely you're right, but even without more detail it would look sharper
_________________
Pau


Last edited by Pau on Sun Mar 01, 2015 8:46 am; edited 1 time in total
Back to top
View user's profile Send private message
zzffnn



Joined: 22 May 2014
Posts: 1818
Location: Texas USA

PostPosted: Sun Mar 01, 2015 7:45 am    Post subject: Reply with quote

Thank you so much Pau.

You are exactly right. Teaching head takes lots of light. However, the scope's primary duty is teaching my sons, so I will have to keep it that way for a while. For photos, I have a spare eyepiece attached to camera mount (see photo #3 above), so I can switch between eyes and camera in a minute.

The teaching head can be removed in a few minutes leaving only the bino head (to get more light), when necessary. Photographing through trinoc is more complex and expensive (for me) involving more lens and adapters.

In my current rig, photos are decent with falsh or long exposure, though videos (GUF w/eaching head) are a little dark and need higher ISO. Fiber optic light may help, especially if I can get a surgical arc lamp. High power LED may work as well.

When I have more toy funds, I may buy a fiber optic (FO) or LED light and point it down the optical path of the original halogen bulb. I have read almost all discussions re FO or LED in this forum and read expert comments from you, Gene and Charles.

That diatom is probably not Pleurosigma :-) I found that its fine surface details are quite different than yours. Edit: I think you are right - mine is a Gyrosigma.

I was able to get real-time 720p image/video onto my TV and used focusable eyepiece along with camera's manual focus ring.

Thanks again!
_________________
Selling my Canon FD 200mm F/2.8 lens
Back to top
View user's profile Send private message Visit poster's website
Display posts from previous:   
Post new topic   Reply to topic    www.photomacrography.net Forum Index -> Equipment Discussions All times are GMT - 7 Hours
Page 1 of 1

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum


Powered by phpBB © 2001, 2005 phpBB Group