Sharper Image Portable Key Finder
Zee Petty
Your EOS R camera has a tiny black thumbwheel just to the right of the top right corner of the viewfinder eyepiece. That is the dioptre adjustment, it's for adjusting the viewfinder optics to match your individual eyesight.
If you wear spectacles, you need to decide whether you're going to look through the viewfinder while wearing your glasses, or will remove them. Some people find it difficult to see though a viewfinder eyepiece while wearing specs,but your EOS R is particularly good and I can see fine through my viewfinder with my specs on. While looking through the viewfinder, operate the autofocus (with the camera switched on, take up the first pressure on the shutter button to make the lens snap into focus) and then rotate the above mentioned thumbwheel and note that the image becomes sharper or less sharp. Turn it appropriately forwards or backwards until you have a nice sharp image.
Oops - as glimpsed in the video linked above by Stephen, I note that the dioptre adjustment thumwheel on your EOS R camera is actually lower left of your eyepiece, not as on my R6mkII and I think most other Canon cameras, upper right. Sorry about that! I hope otherwise what I've suggested proves useful.
This makes sense if your microAF calibration is off or if your lens' tolerance range is beyond those of your lens mount. There is after all a tolerance value for both the lens mounts (lens itself and on the body).
The Live View uses Contrast Detect AF while the AF module in the viewfinder uses Phase Detect. If your AF calibration is off then the Contrast Detect of the LiveView would always be sharper.
Originally posted 48 months ago. (permalink)
Zeroneg1 (a group admin) edited this topic 48 months ago.
Out of tolerance cannot be simply done with looking at an image. It simply means that say if your lens needs say a -20 change and the micro AF only goes to -10 then it is out of tolerance. If Nikon says it is good it means they have checked the mirror box and the viewfinder and the AF module. Does it happen to all your lenses?
Originally posted 48 months ago. (permalink)
Zeroneg1 (a group admin) edited this topic 48 months ago.
Hi there
Thank you for your time.
you will need to copy the blue link and paste it on your browser to download the zip folder from drop box
No, I dont really find it happen to all my lens. I find it abit off after I sent in for the advisory replacement. I feel that it is not having the consistency which it should have before sending in.
From the test images, I find the camera and all lens are somewhat at my tolerance range. But once in the field, it may not be so consistently performing.
Some friends were saying, the focusing may not be so accurate if I am shooting with in door lighting.
Or is it just my mind playing tricks on me?
Regards
Originally posted 48 months ago. (permalink)
kwchiang001 edited this topic 48 months ago.
Ideally when you send it to Nikon for this you also include your lenses so if they need to adjust the mirror box assembly to change the tolerance range for your lenses, they can. However they will only accept Nikon lenses and no gray-market lenses either.
If you are using Sigma, you can use the DOCK USB for microcalibrate your AF. For Tamron you need the TAP-In Console.
Also keep in mind that NOT all zoom lenses are 'parfocal' (meaning their focus stays if you zoom in and out) and most lenses are 'varifocal' (focus changes as you zoom in and out). So if you lens is varifocal you will need to refocus once you zoom in or zoom out.
www.nikonimgsupport.com/ni/NI_article?articleNo=000004089...
BTW the newer models have micro AF calibration which compares the focus from the LiveView and adjusts the micro AF calibration accordingly.
Also why were you in Aperture Priority mode? Your ISO, Shutter speed and Aperture should all be locked for a test like this. Also the most sensitive AF point is always on the center. ISO's above 100 will reduce acutance (edge contrast) hence the image would look less sharp because:
sharpness=resolution+acutance
PS: More realistically, if you need more adjustment beyond the +20 or -20 range that's available in the micro AF calibration adjustment then your lens is out of tolerance for your lens mount.
Originally posted 48 months ago. (permalink)
Zeroneg1 (a group admin) edited this topic 48 months ago.
Like the title says, how can one tell if an image is well focused? We are here studying image processing/analysis. But we need a good image to begin with. While a good image needs to be taken from microscope well focused. Human eyes may be able to tell if an image is well focused. But is there a computational criteria/algorithm to tell?
Adding to @Research_Associate you can use the Normalized variance to find the in focus plane of multiple images for example.
Here is a imagej macro with the implementation to determine image focal quality image-wide (not ROI-wide)
There are a variety of metrics that can be used to compare images to see which one is better in focus. For the most part, these metrics quantify the presence of sharp features relative to blurry features (or equivalently, assess the magnitude of high vs low spatial frequencies in the image). This supplementary information has a lengthy description of various metrics used.
In order to estimate focus from a single image, you need to include some prior information about the class of objects being imaged. For example, it would be hard to tell whether a blurry-looking image comes from a smooth object with few high spatial frequency details vs an object with sharp details that are lost due to the low-pass filtering of a defocused imaging system. But if you have some idea of what an in focus object should look like, you can disambiguate these cases. Sometimes you can use an algorithm that learns this information from data, and use it to build a single-image focus detector. For example, this.
The ImageJ wiki is a community-edited knowledge base on topics relating to ImageJ, a public domain program for processing and analyzing scientific images, and its ecosystem of derivatives and variants, including ImageJ2, Fiji, and others.
There have been some great answers already but wanted to add this in here too. Whilst this blog post is about general photography, the principles would be the same for digital pathology and a blurred image should have a distinctly different value from a sharper image. A laplacian is convolved with the image and the sum taken, the higher the result the sharper the image. Laplacian blur detector
An alternative to the F3 is the Pentax LX. In many ways superior to the Nikon, the body should be cheaper and the lenses certainly so. Optical and mechanical quality are fairly equal. It also has interchangable finders, including a wlf and meters with them all.
However - after 15 years of street photography I'd go for a rangefinder every time. They are quieter, smaller and quicker to focus - big pro SLR's will get you noticed and make it harder to get candid shots.
IMHO the Leica CL rules the roost for street work, I use it with its 40mm f2, an (older) Leica 90mm f2.8 and a voightlander 25mm f4 with finder. The CL is almost silent and small enough to be unobtrusive. However they are expensive and can be a bit flakey. I imagine the Bessa R or R2 would be almost as good in this role.
If you want to try waist level on a budget, why not look out for an Exacta? They're tough old cameras and are generally quite cheap. There was also an autofocus Yashica with a built in WLF, the T4 I think. I've often thought of looking out one of those myself.
There is much to favour an SLR for this kind of work; personally, I use a Contax S2(b) with a pancake lens and a right-angle adapter. The set up is very small, and portable. I believe you can acquire a quality second-hand one for around $300-500. The Nikon system is probably as good a choice, particularly with the waistlevel facility (but their manual lenses are probably no longer produced).
As you are still at high school, it may be in your interests to have a camera which can adapt to many different forms of photography (macro? telephoto? nature? landscape?) even if you do not try these other forms at the moment. SLRs also advantages precise composition and through the lens metering, if you use filters, often with complex flash facilities if you ever go down that route. You have a choice of focusing techniques as well as screens; waist-level, or eye-level; split image on the screen, horizontal or diagonal, or a matt-grid. This flexibility is unrivalled by the rangefinder group, which condemns the photographer to focus on the subject foremost, and then compose, since the focusing is done within a tiny central double-image area. In contrast, an SLR enables you to focus manually at any point in the screen, if you use a matt-grid; I find this enables me to work faster.
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