Afocal imaging with m 4/3 camera through microscope eyepiece

zzffnn · Post by **zzffnn** » Mon Oct 06, 2014 9:30 pm

Hello fellow members,

I am enjoying the informative discussions and fascinating images of this great forum.

Inspired by you, I just bought a Nikon Labophot 2 microscope with teaching head for my kids and myself. I will use one of its 4 eyepieces for videotaping / photographing pond life (at 100-400x under bright/ darkfield and oblique illumination).

Please kindly advise me on afocal imaging with micro four thirds camera through microscope eyepiece. I have done research in this forum but was not able to get a definitive answer, partially due to my lack of knowledge of photography.

My Olympus E-PM2 (micro four thirds 4/3) camera currently has a kit zoom 12-42mm lens (which I heard is not good for photo microscopy). Camera suspension will be done by an Orion telescope/camera adapter.

Which of the following will give the best afocal image?

1) Sigma 30 mm f/2.8 lens for micro 4/3 (this option is a bit pricy though)
http://www.bhphotovideo.com/bnh/control ... &A=details

2) Olympus 50 mm f/1.8 (I like the low price on this lens and it also seems to be direct mount for micro 4/3?)

http://www.mir.com.my/rb/photography/ha ... 50mm1a.htm

3) An ultra slim point and shoot camera Panasonic TS20 (if chosen, this camera will work by itself instead of the Olympus E-PM2 micro 4/3):
http://www.amazon.com/gp/aw/d/B00728ZC1 ... ot_redir=1

The above options 1) and 2) were obtained from my search/research in this forum, though in original context they seemed to be recommended for APSC cameras.

I know my smartphone camera (Sony Exmor IMX214) can also produce decent afocal image with same magnification and field of view as seen by eyes.But I am wondering if the above options 1) to 3) will produce better image, and will they change magnification an field of view?

Electronic flash (per Mr. Chales Krebs) may be used (to "freeze" motions of pond life). Speedlite is usable when my smartphone camera is set to 2 second slow shutter, though I am not sure if external flash can be used with the Panasonic point and shoot mentioned in option 3.

Sorry for my long post.

Thank you so much!

Pau · Post by **Pau** » Tue Oct 07, 2014 7:38 am

All the linked options will work for afocal, but the best one is very likely the m4/3 camera with the Sigma 30mm lens coupled to a high 10X eyepiece. Take a look:
http://savazzi.net/photography/zeissadapter.html

To calculate the relay magnification the formula is:

eyepiece mag X camera lens FL / 250,

In your case 10 X 30 /250 = 1.2X, ideal to cover the 4/3 sensor with a field similar to the viewing eyepieces.
The Oly OM 50mm will provide 2X, so the image will still be good but too much cropped (you can't use it directly on m4/3, you need an adapter)

But already having a short zoom covering this focal lenght I would test it first at 30mm, the geometry will likely be inferior, but often this is not important depending of the subject. Some short kit zooms can work nicely, some others not because vignette or aberrations.

Hope ths could help

rjlittlefield · Post by **rjlittlefield** » Tue Oct 07, 2014 8:34 am

One thing more: be sure to set your camera so that the aperture stays wide open when the picture is taken. If the camera lens stops down, you will almost certainly get vignetting.

--Rik

zzffnn · Post by **zzffnn** » Tue Oct 07, 2014 10:09 am

Thank you very much guys.

I will try the Olympus m 4/3 camera with kit lens again on my Nikon Labophot 2, once the scope is back from service.

Before I accquired the Labophot scope though, I had a cheap $80 compound scope and did try the Olympus m4/3 with it in two ways:

1) afocally (through microscope 10x eyepiece with kit zoom lens at 50mm and tripod), and
2) via a 0.75x OMAX relay lens without 10x eyepiece or camera lens

Images from both methods were inferior to an afocal smartphone camera (which revealed bright, bigger and sharper image close to that saw by eyes).
I guess 2) failed because of lack of aberration correction by eyepiece; and 1) failed because the kit zoom lens does not mate well with microscope?

Alternatively, it may be the cheap scope being the limiting factor (no condenser and poor optics), though it is still puzzling why smartphone camera did much better.

Maybe smartphone camera (f/2.0 Sony Exmor IMX214) did better because of wider aperture (than the f/3.5 kit lens in the Olympus m4/3), as Rik pointed out.

I will see if testing with Labophot's Kohler illumination change that dynamics - I will report back.

What f stop is wide enough for afocal imaging with Nikon Labophot scope though (darkiest scenario would be darkfield at 400x)? This will be done with a Nikon turret phase condenser slider without darkfield objective and using one eyepiece from the scope's teaching head.

Thanks again!!

Pau · Post by **Pau** » Tue Oct 07, 2014 11:34 am

Fan,
when you try it, post your images to figure what could be wrong. Today phone cameras may be wonderful, but the image quality of a big sensor camera when well coupled to the microscope must be superior (but not necesary easier)

About f stop, as Rik said first try wide open, just because a too closed diaphragm will vignette the image. In fact what is stopping down the system is the microscope optics, not the camera lens aperture, you get no benefit from a faster camera lens nor closing the aperture, you just need an aperture wide enough to not vignette.

zzffnn · Post by **zzffnn** » Tue Oct 07, 2014 11:39 am

Got it. Thank you so much Pau.
I will try something and also look into that Sigma pancake lens (it looks quite good to me).

zzffnn · Post by **zzffnn** » Thu Oct 09, 2014 1:42 pm

My Nikon Labophot 2 microscope is still waiting at service shop for its parts (darkfield stops, condenser, ect.) and won’t get back to me till next Friday.

So just for fun, I took some photos with my cheap toy scope (which has no condenser, http://www.carolina.com/compound-cordle ... /597100.pr) just to compare photo quality of my cell phone camera vs. Olympus camera.

First photo was taken from cell phone and second one was take from Olympus camera.

Sorry for the horrible image quality. But since I am newbie please don’t spank me

Photo shoot conditions are:
1) 100x brightfield, Daphnia premade slide, afocal through 10X eyepiece,

2) On cell phone camera (Sony Exmor IMX214):
HDR mode (stack of multiple exposures), stabilizing adapter (Orion SteadyPix Pro).

3) On Olympus camera (E-PM2, micro 4/3 with 12-42mm kit zoom lens):
Best photo picked from various shooting setting (Manual aperture and manual shutter, auto or high key), tripod aligned with scope eyepiece the best that I could. Please note my camera lens, when set at 30 mm, can only go down to aperture F/4.5. Many shutter speed have been tried.

My own analysis is:

The camera lens/tripod/microscope combination did not mate well (vignetting, overall darker and less contrast than phone camera). My (kit) camera lens may be the cause for vignetting, partially because it is too long to fit onto my scope adapter to get perfect the alignment that cell phone achieved. The Sigma 30 mm f 2.8 lens should fit my scope adapter.

Once fitted on the scope adapter, my cell phone camera was less fuzzy than the Olympus camera. It either did not produce full image at all, or produced bright full images (while I could not seem to eliminate vignetting with the Olympus mounted on tripod). The poor light source of the toy scope may also favor cell phone camera and its HDR mode for some reason.

Comments are welcome!

I will upload more photos when my Labophot 2 comes back.

Pau · Post by **Pau** » Thu Oct 09, 2014 3:00 pm

About vignette: It may be very likely due to the eyepiece. For good afocal imaging without dedicated lenses you need a high eyepoint tipe one (those adequate for eyeglasses use, sometimes marked an eyeglasses symbol or with H. I don't think that your cheap microscope will have h.e. eyepiece, although the image corner seems to show the limit of the actual eyepiece field, but it also can be a small field, perhaps smaller than the ccommon 18 or 20mm found in 10X eyepiecxes of most microscopes
I you still get vignette when you have the real microscope, try just zooming a bit more.
I don't understand why you have cropped the images, to evaluate them is better to have them complete. You can post images upt to 1024 X1024, see the forum guidelines
At the posted size I don't see better qualilty with the phone, just more contrast, and the camera image allows for many improvements in post processing as most of us do with microscope images. The raw format is specially useful for that.

Again don't worry about the maximum f4.5 aperture, with my OM 50mm setup I can close it up to f8 without vignette, but maybe it will be better to wait to the Labophot.

zzffnn · Post by **zzffnn** » Thu Oct 09, 2014 3:20 pm

Thanks Pau.

My bad, I cropped photos to similar size to compare quality.

My toy scope eyepiece is at around 18-20 mm dia. Will find out if my Labophot has high eye point eyepieces.

Indeed, phone camera only provided more brightness and contrast, not more detail/resolution.

I need to learn how to process RAW photos. What free software do you recommend? I don't think I will stack much.

The following are 1024 crop of the photos, again first is phone camera and second is Olympus.

Pau · Post by **Pau** » Fri Oct 10, 2014 4:24 am

zzffnn wrote:My toy scope eyepiece is at around 18-20 mm dia. Will find out if my Labophot has high eye point eyepieces.

Indeed, phone camera only provided more brightness and contrast, not more detail/resolution.

What really matters is the field number of the eypiece (the diameter of its internal aperture circle in mm), not the external diameter that will be almost for sure 23mm.

Your Oly zoom seems working nicely for afocal, just try it at a bit longer FL to avoid vignette, as the vignette you're showing in both pictures is the eyepiece aperture, not due to the camera lens. The image periphery is not good but this is due to the cheap optics, will be much better with the Nikon if bundled with Plan objectives

About the image quality, the camera now seems clearly better. Please allow me posting a reworked image: just a bit of brightness/contrast adjustements in Photoshop to match your phone camera:

You are only using a small part of a small sensor of your phone vs most of a big sensor!.

For simple RAW adjustements I just use the camera supplied converter (Canon DPP in my case), do you had got one with your camera?. There are also several free converters. For more critical work I use Photoshop ACR but not very often

zzffnn · Post by **zzffnn** » Fri Oct 10, 2014 1:10 pm

Pau wrote:
.......as the vignette you're showing in both pictures is the eyepiece aperture, not due to the camera lens. The image periphery is not good but this is due to the cheap optics, will be much better with the Nikon if bundled with Plan objectives ........

Thank you so much Pau. Please let me know if I can do anything for you as appreciation of your kind help (I will PM you).

I appreciate your referring me to the toy scope's terrible eyepiece. I tried direct projection instead (from 10X objective direct to camera sensor, without eyepiece or camera lens in between) and got a better image. I had to removed the entire eyepiece tube, as the tube causes some light reflection in photo (may need additional coating?).

This image is resized to 900x863 pixel to make it less than 300 kb:

As with my Labophot 2, I know it comes with 40x E Plan achromat objective and 10x achromat objective, both of which have some aberration correction built in. So I will give them a try with the direct projection method and comapre it to afocal relay lens method. I remember its eyepieces are labeled as "CFW10X" and there is no indication of high eye point.

The Sigma 30 mm f 2.8 lens is good for family portraits, correct? I think I will still get that lens if it is good for portrait. Since that Sigma lens is shorter, lighter and of better optical quality than my current kit lens.

Sorry for my incorrect terminology. I meant to say that my toy scope's effective field of view is much smaller than my Labophot 2, even though they have the same external diameter.

I will look into RAW converter software - I don't even know if my Olympus camera came with one.

I also realized that I re-sized yesterday's photos incorrectly and lost comparatively more resolution in camera's photo, thus favoring phone camera. I did it again and can tell by myself that phone camera's image is
inferior.

For others interested on the topic of direction projection onto a micro four thirds camera, Charles Krebs provided some expert comments in the following thread:
http://www.photomacrography.net/forum/v ... rd&start=0[/u]

Comments are very welcome.

zzffnn · Post by **zzffnn** » Mon Oct 20, 2014 1:54 pm

My Nikon Labophot 2 and Sigma 30mm f2.8 lens have arrived. I tried them with afocal imgaing under oblique lighting:

1. With oblique lighting using strong halogen alone:

2. With oblique lighting using electronic flash (exposure) and weakest halogen (focus):

With this rig, I am looking into stacking. Do most people here use Stackshot tied to microscope's fine focus knob (like Mr. Rik did there: http://www.photomacrography.net/forum/v ... hp?t=11008), or do they just use hand and eyes?

I don't know what Mr. Charles Krebs use, though reading from his web site I am guessing that he is using hand and eyes. It seems difficult for moving (not drunk) pond critters though.

For those interested, I used a Orion SteadyPix adapter to connect camera to microscope's eyepiece. Oblique lighting was done by using a Leica condenser with darkfield/brightfield slider (oblique = brightfield off center . I swapped out the original Nikon condenser, as I do not have $300 for Nikon's turret phase condenser).

My darkfield under 10x objective kind of works, but I will try more stop diameters based on http://micro.magnet.fsu.edu/primer/tech ... field.html

I will also try direct focus with a m 4/3 to T mount and a T to microscope adapter.

Pau · Post by **Pau** » Mon Oct 20, 2014 2:43 pm

Good optics with a good condenser... a big difference! This images look of very good quality. I see you've cropped again the images, this can be of course adequate for the subjet but is all the frame up to the corners good?. If yes you've found your right setup.

About stacking of course it is rarely doable with moving subjets. An automated stacking device will be very nice but you can stack very well with the fine focus by hand with some patience.

zzffnn · Post by **zzffnn** » Mon Oct 20, 2014 3:03 pm

Thank you very much Pau.

Corners look good to my eyes/needs and there is no obvious deterioration (photos were taken with NIkon CFW10X eyepieces and Nikon regular 10x Achromat objective - it is not even an E Plan or CF Plan - which I think would be even better especially at 40x or up).

I only changed maximum pixel to 1024 to comply with forum rules.

I will do manual stacking then. Thanks for saving me $350 :-) That Stackshot rig is kind of expensive.