TRBenjeski Loc: Rochester, New York

Greetings...

My sincere interest in photography includes both the artistic and technical aspects. After undergraduate studies at the Rochester Institute of Technology, I spent nearly 15 years as a Research Laboratory Technician at the Eastman Kodak Research Laboratories on multiple interesting and exciting projects during the 70's and 80's.

Enough about me – now for my digital photography questions that I hope you can help with.

While I continue to have a strong interest in photography, unfortunately, my knowledge and expertise is associated with “analog” photography – silver halide, wet chemistry photography – and not with digital photography technology. However, I would very much like to better understand the digital photography technology, especially regarding digital image quality – how it is achieved, what factors affect it.

Although I have conducted some personal research into better understanding digital image quality, the texts that I have reviewed have not contained the answers or detail that I seek. For one example of what I mean by “digital image quality”, I have viewed multiple digital image files of the same subject, with each digital image file consisting of increasing quality – sharpness, resolution, color rendition, etc. I would very much like to understand how this is achieved.

I understand that the digital camera’s imaging sensor size significantly contributes to the digital image quality, as well as megapixel quantity of the camera. But, I believe that there are additional factors that affect digital image quality, including megabyte size of the digital image file itself.

If you might be able to recommend one or more texts that could answer these and other questions I have regarding digital image quality, how it is achived, and what factors affect it, I would sincerely appreciate it.

Additionally, I would like to try to “connect the dots” between analog and digital photography, wherever possible. Basically, I would like to identify the technical aspects in digital photography that have a corresponding technical aspect in analog photography.

Please accept my sincere appreciation for your time in reading this message, and for any assistance you can provide. Thank you very much!

nervous2 Loc: Provo, Utah

Unfortunately I have no answers for you but I am fascinated by what you are seeking to learn. I will be eager to see what our fellow Hedgehoggers come up with. I never cease to be amazed by the depth of knowledge some have. Thank you for your inquiry. Looking forward to substantive responses.

Bobspez Loc: Southern NJ, USA

Several here shoot both digital and film as I have. If you shoot in manual mode and set your own iso, shutter speed and aperture, both types of photography are quite similar. In terms of getting sharp and high quality images, the focus, and lens are important just like in film. The advantage of digital is you can view your results beforehand in live view and after you take the shot on your lcd screen and to a much greater extent on your computer screen.

In terms of sensor size, I have FF, DX, CX (1" sensor), and 1/2.3" sensor cameras. For Color rendition and sharpness the 1" sensor is about the smallest to achieve high quality. However, for many things I use the bridge cameras with the 1/2.3" sensors for convenience, even though the images don't stand up to pixel peeking (blowing the image up to 100% resolution on the computer monitor, where 1 pixel of image equals 1 pixel of monitor).

The other issue is film doesn't look quite like digital. Images taken with digital lenses don't look quite like film lenses on a digital camera. This is subjective so hard to quantify. The same discussions are held about digital vs. analog music, or film vs. video movies.

I have been in this hobby for several years now and have accumulated a bunch of dslr and film bodies. lenses, and bridge cameras (cameras with a built in zoom lens). To me they are all tools and have their use. They all have their strengths and weaknesses depending on what you are shooting. There's no best camera.

hipines Loc: Prescott, AZ

There is a free class by John Greengo on Creative Live titled "How to Choose Your First DSLR Camera". I haven't watched this class, but I have purchased other classes of his and I find him to be a very effective instructor. Although the class appears to be aimed at beginners, you can review the chapters and possibly find some subjects that would apply to your interests. Good luck!

https://www.creativelive.com/class/how-choose-your-first-dslr-camera-for-beginners

Ysarex Loc: St. Louis

Start here and then see if you have more specific questions.

https://sites.google.com/site/marclevoylectures/

Joe

cascoly Loc: seattle

the MB size per se doesnt affect quality -- a 20MP camera could produce similar quality JPG images with sizes from 2 - 10+ MB. this is a function of the compression - eg, pictures with clear blue sky will have significantly smaller sizes than those with clouds

srt101fan

I have no direct responses or insights with regard to the questions you raise. However, you should keep in mind that, particularly if you are saving RAW files, you are now including computer processing as an element that affects digital image quality.

Strodav Loc: Houston, Tx

I worked for a very large commercial printer and visited RIT and the Kodak R&D facility many, many times around the years you were there. I was part of an R&D team that successfully moved our company from film to digital and the rest of the industry eventually followed.

The great thing with the new technology is that the cost of taking a picture is virtually nothing after the initial capital investment and the processing time has been reduced by orders of magnitude. I can take some shots at the bird feeder in the back yard and see the results a few minutes later and have 13" x 19" high quality color prints hanging on the wall within an hour. The human vision system has not changed. Color theory has not changed, but the computer tools we have to manipulate digital images far exceeds what I could do in the darkroom, but the concepts haven't changed much. For example, you can still perform good old USM on your images and dodge and burn is still there. The technique for taking a good picture has not changed much, but what I really like is being able to go into manual mode on my cameras, set shutter speed and aperture and let ISO auto range. OMG, what a luxury! AF, what a luxury! Of course, the creative side has not changed much. Understanding, seeing and manipulating light has not changed, but I think IQ has improved significantly when you get much over 16MB sensors. Photographic vision has not changed. Anyway, I find some of the best materials available are here: https://www.cambridgeincolour.com/ . Especially look in the tutorials -> Concepts and Terminology. You will find many of the tutorials do not change whether you are using an slr or a dslr. You can apply your fundamental knowledge and skills, just using updated tools.

rjaywallace Loc: Wisconsin

When you learned about analog photography, you were in an outstanding Kodak Rochester center to do so. How did you accomplish that learning? That’s right, you studied it. Is there a public library in your area or a community college? You need to study digital photography just like you did analog. Amazon has literally thousands of books on the subject. YouTube has literally thousands of videos on every aspect. You seem insulted that you are being asked to start anew. Sorry, you learned Greek but details of digital gear is often written in Gaelic or Portuguese so time to go back to school.

To answer your question, may I suggest you find a copy of “Understanding Exposure” by Bryan Peterson, now in its 4th edition. In well-printed paperback, it is not expensive and well worth it. Peterson has other books on gear and digital topics as well. Best wishes, Ralph.

Bobspez Loc: Southern NJ, USA

The great thing about digital is you can shoot all the pics you want for free, and get immediate results, so you can easily compare settings, bodies, lenses, lighting, etc. in your own home or backyard. I've never gotten much out of books, even ones written by the great Ansel Adams. I'm not particularly interested in theories of how things work. I use the manuals and Youtube videos like a dictionary or encyclopedia, just look up what I don't know how to do. I did the same working my last 20 years as a sys admin and dba. Just learned what I had to know to get the results I wanted.

burkphoto Loc: High Point, NC

The combination of sensor surface area and sensel density together determine the dynamic range (photon sucking potential) of a camera. The bigger the sensels (sensor elements), the more light each of them can turn into electrons. So both the "chip" size and the "megapixel density" of the sensor affect dynamic range, color depth, and low light performance.

Sensors are analog. Their output is optionally amplified, then digitized with an analog-to-digital converter, and then either saved into a raw file, or converted in the camera to a JPEG image. (Actually, the JPEG conversion ALWAYS happens, because a small JPEG preview image is stuffed into every raw file's "wrapper" format.)

Different cameras perform both of these operations differently! So the processing design engineered into the camera can have a profound effect on the appearance of the output. Two sensors of the same size with 16 MP output will produce different results due to different sensor design, and different processing. Two 16 MP sensors of different size, will have those differences, plus the inherent differences in signal-to-noise ratio caused by the size difference of their sensels.

At this point I want to make a very important distinction between a sensor element and a pixel. If you always think of pixels as NUMBERS, numbers that have no associated physical properties, you will understand digital photography much better!

A sensor element by itself (except in the Foveon sensor) is not a pixel, because it cannot represent more than one color. The sensor elements on the sensor are covered with red, or green, or blue filters. Their output is stored in an array. Data from several to many adjacent sensor elements is processed into pixel data with very complex algorithms. So a pixel is really a calculation of a point of color and brightness based on SEVERAL points of filtered light.

If raw data is processed into an image file in post production software on a computer, we have an analogy to color negative film. The raw file is likened to exposed film that has not been developed, but that can be developed in an infinite number of ways, both now, and in the future. It includes everything that the sensor recorded that the A/D converter could turn into numbers. But it is NOT an image.

If raw data is processed to an 8-bit JPEG in the camera, we have an analogy to color slide film. The image quality is highly dependent upon camera menu settings, especially white balance and exposure. Most of the raw data is discarded during this processing. What remains has limited latitude for adjustment later.

The BIT DEPTH of the data in the raw file determines potential dynamic range of the file. The physical properties of the sensor limit the actual dynamic range recorded. Bit depth is how many binary digits are used to store each value... 8 bits is 256 bits per color, 12 bits is 4096 bits per color, 14 bits is 16,384 bits per color. Better digital cameras record 12 to 14 stops of dynamic range in raw... But a JPEG contains roughly six stops of data, and you can only fit about 5.5 stops onto most photo papers.

Resolution is affected by many factors, but the basic one is *image dimensions in pixels*. A 6000 pixel by 4000 pixel image (24 Megapixels) is a relatively high resolution file. It can make a very nice 20" by 13.333" print at 300 INPUT Pixels Per Inch (NOT dpi, which is an output device (printer) resolution measurement, or a scanner input resolution measurement. DOTS have dimensions. PIXELS have ONLY VALUES that can be represented by dots.)

You can scale pixels to any size, with or without interpolation. Maintaining the same pixel count changes the resolution. Interpolation modifies the pixel count, either "faking data" (enlargement) or discarding data (reduction).

It is best to forget about megabyte sizes of files. Various file compression schemes (especially JPEG) render file size useless as a guide to image quality. Pixel dimensions are really the only accurate indicator. Divide each dimension by your intended "output resolution input" (how many pixels from the original, uninterpolated file you will convert to each inch of printed or displayed output) to get the optimal maximum size. In the example above, 6000x4000 at 300PPI yields 20"x13.333" on paper. Each of those pixels may be reproduced by a varying number of dots, depending on the output device.

Of course, most of the same things from analog photography affect digital image quality, too. Factors such as lens performance (MTF performance, coma, astigmatism, distortion, chromatic aberrations...) play a similar, if even more critical role. Light is light, although the linearity of digital camera response means you may prefer much less specularity, greater fill light in shadows, and lower overall lighting ratios. The S-curve of the H&D plots we had for film must be simulated in post-production from raw files — if you prefer a more film-like look.

That's all for now... food for thought. WELCOME TO THE 'HOG.

traderjohn Loc: New York City

Gee....Do you ever wonder why cell phones are so popular?

David Taylor

LOL.

Peterfiore Loc: Where DR goes south

This has been my journey for the last 17 years or so...I have enjoyed every moment of it. Much reading and just and getting lost researching ways of replicating the work I always did in my darkroom days. Implementing the old with new tech has been an exciting trip.

mizzee Loc: Boston,Ma

In addition to equipment being far advanced, the darkroom has gone digital with post processing programs such as Lightroom and Photoshop. Dodging and burning, exposure, sharpening and softening, etc. can be accomplished with sliders and buttons. I can’t give you a technical discussion except for the results you see.