Comparing Zeiss PMIII internal camera to a Canon AE-1 and Sony a6000

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cmtalb01
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Joined: Tue Nov 15, 2016 4:55 am

Comparing Zeiss PMIII internal camera to a Canon AE-1 and Sony a6000

#1 Post by cmtalb01 » Sat Mar 24, 2018 10:41 pm

In recent attempts to achieve theoretical resolution on the microscope, all aspects of the microscope subsystems are being tested and optimized. This optimization has also included the best possible camera setup to image what is seen in the binoc eyepiece. It was of interest to compare the acquisition properties of the PMIII internal camera with other afocal cameras PMIII photo tube option.

Little comparison info was found on the internet, so this endeavor wamay be interesting to some. Testing was performed using ISO200 35mm film in both the PMIII 35mm camera and the Canon AE-1 camera, and similarly, the Sony a6000 was set to ISO200. A halogen source (running at 12V) was used and a blue conversion filter for the internal camera and the AE-1. No filter was used for the Sony but an auto white balance setting was used instead. In hindsight, it may have been better to set the white balance specifically for the source illumination. A Canon Photomicro Unit F camera adapter attached to the Zeiss 473024 camera port was used in the focal setup

Various considerations were tested including:

PMIII mask image of full binoc FOV
PMIII internal 35mm camera capture are of the PMIII mask
Best eyepiece to mimic the PMIII mask and internal PMIII camera fiew
Camera Port image comparison to the PMIII 35mm camera
Eyepiece lift testing
Comparison of images taken between the PMIII camera and a photoport camera in brightfield and with various enhancement techniques

Results Summary:

The PMIII only sees 38% of the full binoc FOV. Is this choice by Zeiss related to the film area or could it also be influenced by the understanding that in the wide FOV of the human lens, a similar portion is actually only in "brain" focus at one type; equivalent to what a 50mm lens might seen on a full frame camera? Furthermore, the PMIII camera only captures 92% of this masked area, even further reducing what image is acquired from the original binoc FOV. Interestingly, a camera using the photo port camera with 2.5X eyepiece actually captures a bit more of the binoc field of view (actually 23.3% more area) than did the PMIII internal camera.

Testing showed that the 2.5X and 5X eyepieces to more accurately mimic the view obtained through the PMIII camera system. Similarly a Zeiss Beam splitter system 47 60 10 also using the 2.5X or 5X eyepiece also gave similar results to the PMIII mask. The outer mask through the beam splitter view port
appears to match the same area as does the PMIII mask. It is noted that the Olympus NFK 2.5X L.D. eyepiece as well as the Zeiss C5X eyepiece did show significant chromatic aberration in other testing. However, in this study, that aberration did not play a significant or perceptible role. The KPL eyepieces are far superior, however, I am not aware that a KPL 2.5X eyepiece was ever made?

Finally, in comparison the PMIII camera appeared to provide images with greater hue and saturation, however the image quality of the Sony far exceeded that obtained with 35mm film in both the PMIII camera and the external Canon AE-1. Comparisons were not only made in bright field, but also phase, Hoffman Modulation, and DIC - images attached.

Hopefully, this information might be of interest or use to someone else.

Note in picture 5, it did not copy that the middle row center is 40X phase with green, and outer is 40X phase without a green filter. The bottom row is a 40X phase with a dark field stop.
Attachments
PMIII mask and internal camera areas versus Sony a6000 and view through binoc eyepiece
PMIII mask and internal camera areas versus Sony a6000 and view through binoc eyepiece
1 PMIII Mask Area_B_s.jpg (149.38 KiB) Viewed 4613 times
PMIII and Sony a6000 bright field comparison images
PMIII and Sony a6000 bright field comparison images
2 Comp image using PMIII camera images_s.jpg (190.21 KiB) Viewed 4613 times
Selecting best eyepiece to mimic the PMIII mask and internal camera image
Selecting best eyepiece to mimic the PMIII mask and internal camera image
3 Eyepiece Comp Test on PMII_sI.png (414.42 KiB) Viewed 4613 times
PMIII versus Sony a6000 DIC images printed circuit board - reflected light DIC
PMIII versus Sony a6000 DIC images printed circuit board - reflected light DIC
5 PMIII Camera Test DIC_s.jpg (165.97 KiB) Viewed 4613 times
PMIII versus Sony a6000 enhancements
PMIII versus Sony a6000 enhancements
6 PMIII Camera Test Enhanc_s.jpg (147.11 KiB) Viewed 4613 times

Hobbyst46
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Re: Comparing Zeiss PMIII internal camera to a Canon AE-1 and Sony a6000

#2 Post by Hobbyst46 » Sun Mar 25, 2018 7:54 am

Thanks for posting this comparison.
1. What are "6x" eyepieces? are they KPL?
2. About the diatom photos - were the settings on the a6000 camera optimized?
3. I think there is some inconsistency in the diatom photos, as follows. Refer to the photos by row and column, as follows:
row 1- a,b,c,d
row 2- a,b,c,d
row3- a,b
IMO the modulation "relief" effects in 1b vs 1c (PMIII vs a6000, respectively) are the reverse of the effects in 3a and 3b (again, PMIII vs a6000).
4. I can hardly identify chromatic aberrations in your photos of the stage micrometer, even after high zoom-in (must be me). Can we conclude that the Olympus NFK2.5X combines very well with the Zeiss Neofluar objective?
5. Was any of the photos taken on a real film? because film hues and color rendition varied greatly among brands and types.

MicroBob
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Joined: Sun Dec 25, 2016 9:11 am
Location: Northern Germany

Re: Comparing Zeiss PMIII internal camera to a Canon AE-1 and Sony a6000

#3 Post by MicroBob » Sun Mar 25, 2018 2:27 pm

Thank you for posting this interesting comparison! This is equipment from several decades in direct comparison.
I have no experience with the photomicroscope so I have no answers why the field of view is so restricted - may be a mismatch of components?
It is not unexpected for me that the Canon AE1 can't compete with the Sony A6000s electronic first shutter curtain.

The colours in the analog images result from how the film interprets them and how the lab reproduces them. Today the usually scan the film and print from a digital image.
The Sony can be set to different colour modes like "neutral" of "vivd". These modes also can be tweaked to your personal preferences. When you take the images in raw - format you are completely free to set the colours after the shot when developing the raw image.

cmtalb01
Posts: 27
Joined: Tue Nov 15, 2016 4:55 am

Re: Comparing Zeiss PMIII internal camera to a Canon AE-1 and Sony a6000

#4 Post by cmtalb01 » Sun Mar 25, 2018 11:41 pm

Thank you MicroBob, I was very curious about the hue differences on the actual photos versus Sony. I was curious how the printing process now works particularly how you also received a CD with the photos. Your explanation answers many of my questions.

I did go back and scan the photos that came with the CD and the comparison between CD images and scanned photos shows no hue difference. I've included a photo of those.

Thanks also Hobbyst46 for your comments. I was also curious about the "relief" differences noted. In some photos, in particular the Hoffman modulation and arguably even the phase contrast with green filter, it appears that the film captures details that the Sony camera did not. However, in other images, the Sony appears to better capture details. At this point, I can only assume it has to do with the wavelength sensitivity of the film versus the same for the camera detector? I double checked before submitting and the images as shown are correctly labeled - but granted are very curious.

The 6X eyepiece was not KPL, nor as far as I know had any correction included. It was a no-name brand, I have a similar 6.4X that was tested as well, but not data not shown. The 6X was used to help narrow down the best eyepiece magnification to math the photomic camera mask.

In other testing, it was surprising to see the actual amount of chromatic aberration observed with the Zeiss C5X eyepiece. Zeiss literature indicates that this eyepiece should not be used with the more highly corrected objectives, but in other testing it was found that even with acrhomats (which is what Zeiss recommends it to be used for), the aberration was significant. Included is a photo that was posted in a previous forum post showing the observed chromatic aberration for several objective-eyepiece combinations.

The film used for the PMIII internal camera was Fuji brand ISO200. Admittedly the film had been stored in a refrigerator for about 2 years. The film used in the Canon AE-1 was Kodak ISO400 and had been in the camera the same period of time. That said other pictures developed from the Canon camera did not show any unrealistic issues with color matching to the original subjects photographed, and the film age was deemed to not be a problem. That said, your comment about different film types may also be at play.

Earlier testing with the Sony had demonstrated that for most applications the Auto White Balance setting of the camera worked very well for a variety of applications. Just to verify this was re-tested and the results are also included. The results show that using the cameras white balance measurement function, the same result is obtained halogen source with no filter, and halogen source with blue correction filter. That said, when auto white balance is used, it appears to do an excellent job with the blue filter inserted and with no blue filter but a neutral density filter (med). Where the AWB seems to wobble a bit is when there is no filter, there is a slight difference in hue observed. This may very well be due to the internal algorythm working against the very strong lamp intensity - of course this is only a guess.

Thank you all for your comments and help!
Attachments
Auto white balance testing of the Sony camera in various microscope brightfield settings
Auto white balance testing of the Sony camera in various microscope brightfield settings
9 White balance test of sony_s.jpg (123.81 KiB) Viewed 4539 times
Comparison of photos (scanned) and CD images obtained development of film from the PMIII internal camera
Comparison of photos (scanned) and CD images obtained development of film from the PMIII internal camera
35mm film vs CD images.jpg (182.89 KiB) Viewed 4539 times
Objective-eyepiece for correction of chromatic abberation
Objective-eyepiece for correction of chromatic abberation
8 objective-eyepiece correction testing_b_s.jpg (125.34 KiB) Viewed 4540 times

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