If you have been around photography for just a little while, you will have heard at least one of those comments that are (to the maker of the statement) cast in concrete and indisputable.
Usually based on the statement makers own loyalty to some brand or process, they often do more harm than their intended good.
Black and white is better than colour
Lets face it, some photos are better in mono and some are better in colour. Few photos are great in both forms, and fewer still are restricted totally from one form or the other. At the time of composing, the photographer will usually have one in mind, so it stands to reason that an image taken to be black and white or colour will be best reproduced that way. There is no doubt that an image changes "shape" when converted from one to other as the depth preceptors and focus triggers change. Colours draw the eye and create mood using colour intensity, temperature and placement where mono relies on tone and texture and can be more two dimensional and intimate. Notice the effect of red shoulder and shoes and the warm yellow road markers as focus indicators, the colder, deeper looking background forming two planes of composition and the effect of soft pink for contrast to the harder colours in the image below, compared to the placement of the less dominant two other women and the glowing tones in the dress and umbrella in the mono image.
Very few photographers are good at both, but I believe no one should shut any doors unless they have given both a try.
Film is better than digital (Nikon is better than Canon etc.).
Who cares. Any photo taken well and with feeling is a winner, from a digital compact, mobile phone, ancient film camera or state of the art camera. Have you ever noticed that any photographer who has the talent to take a good photo does not have to limit themselves to "The one and only" camera or format that works, for them anything will work. For every successful exponent of one format or brand there is an equally successful contradiction (and plenty of us capable of taking rubbish no matter what we are using). Use what you want, it does not matter as long as it works for you and the process gives you satisfaction. If you need validation for any argument, it won't be hard to find.
What is Bokeh and who cares.
Bokeh is a thing, but it's a bit misunderstood, it's as real as lens sharpness and megapixels, but is more subjective and a bit of a support player. There is no way to measure Bokeh, although the Japanese have various names for the Aji or flavour of different blur. Every lens, at every focus distance and aperture combination is different. One persons' smooth and creamy will be another's mushy. I find it frustrating when a reviewer reacts overly to the Bokeh of any lens, especially based on tests, as the viewer of the end image can really be the only judge.
Bokeh is not just a 300 f2.8 or a 50 f1.4 wide open shooting out of focus night lights! Bokeh is the quantity, quality and form of the transition from the in focus to out of focus zones of a photo. This happens at nearly any aperture on any lens, so telephoto lenses at their widest aperture are an exaggeration of a normal phenomena, but it is present in nearly any photo (indeed, an image fully in sharp focus from front to back is technically difficult). Mike Johnson and John Kennerdell, who between them revealed and coined the term Boke-Aji or "Flavour of blur" * in the May/June 1997 issue of Photo Techniques (a real photo mag), actually cited wide angle lenses at smaller to middle apertures in their articles and focussed more on lens personality than just sheer blur. Getting really close or using long lenses will always give you lots of out of focus blur, but Bokeh is a term for the look of it not just the quantity. The article on The Online Photographer blog called "In defence of depth" is the best I have seen at explaining this.
Getting to know your lenses or learning to recognise what it is you are probably already responding to, is the key. Some lenses can actually look more or less sharp because of their Bokeh rendering (an old Leica trick) and some blur is so "busy" that it can be a distraction to the main point of focus. Some lens Bokeh is so unusual it actually becomes much sought after such as the old Jupiter lenses. Do you have a lens that should be the ultimate portrait lens but leaves you cold, or a zoom that does not have the credentials to impress, but produces images you really like? It's probably the combination of the Bokeh and sharpness rendering of the lens. In the old days, aficionados would state confidently that they could pick lens "X" from lens "Y" just by looking at otherwise identical photos. The giveaway was in the sharpness rendering or Bokeh. You may never use it intentionally as a creative tool or even care, but it is there, like it or not and can be made as relevant as any other part of photography.
*Pronunciation is "Bo" as in bone and "ke" as in kettle, the "h" was added to help with correct pronunciation and the Aji dropped.
Street (landscape, sports, portrait etc.) photography should to be done (this) one way.
Do what ever works for you. Look to your mentors for ideas and tips, but never limit yourself just because someone else says there is "only one true way". Most photography evolves from the limitations of equipment, social constraints and fashions, but new rules are made by those who power on regardless of convention and learn to reinvent. If you spend more time trying to do as do or others say, you are not being true to yourself and will never grow.
Mirrorless beats SLR's or SLR's beat mirrorless.
Nope, they are similar but different. SLR cameras are still generally better at tracking focus (for now) and their view finders are clear glass, which some prefer. Mirrorless on the other hand can be quicker, smarter and lighter and can be reinvented to get around some technical limitations (face detection, video and electronic shutters etc.). SLR's have the two biggest names in photography behind them and the tradition and history that entails. Mirrorless are more innovative and interesting, but can be a bit thin in options. Time will only blur the differences more until it matters not at all what you choose, and that time is close.
You need full frame to be a professional.
This one is just crap. Lets look at it logically. The cheapest SLR on the marked today takes a better image than the best pro camera of 5-6 years ago. Each generation of cameras adds more of everything, but few in the industry want to ask, or answer the question "how much is enough?" as this will stunt sales. If you go back to the release of the D3X Nikon a few years ago, people paid $10,000+ for a full frame 24mp camera that did not even have a sensor cleaner! The current base model D3300 can match that camera for pixels, come close in low light performance, cleans it's own sensor and shoots video. Don't even get me started on print requirements! Ok, so while we are here. In a recent test a photographer showed two large (A1?) prints to a number of passers by (remember 95% of the people looking at your work are not photographers, but "passersby"). One was printed at 72 dpi and the other at 300 dpi. (industry standards suggest that if you do not print at 240 dpi+ you will not get gallery quality images). Nobody, not even an actual teacher of photography picked the difference between the two images. Luminous Landscape has a revealing article comparing the 50mp 5DS to the old 8mp 1DS in direct print comparisons, they are not as different as you might think. Ming Thein tried on the other hand to produce a print that held more detail than the human eye could see without assistance. He hired an industrial scale printer to do multiple, micro fine passes over the carefully selected paper to max out the resolution of a D800. He could only manage 11x14" paper before the test ran out of steam. The prints sold for many $100's to cover costs and in his words the whole exercise was pretty pointless, but revealing. Finally Pekka Podka has an interesting article on his blog comparing the OMD to the D800. So, to create gallery quality images at a reasonable size, you need...... a crop sensor camera of about 10-12 mp. We know this because people used to do it and still do.
What makes a pro photographer is actually pretty simple, know your process and HAVE A BACKUP!
More pixels make a better camera.
As above, the evidence says otherwise. Sharpness, light and composition are not controlled by pixels. More pixels technically make a bigger file and that should allow a bigger print, but that is only if the above considerations are met. Colour depth and "lushness" can be improved with more pixels, but so can detail smearing and image "noise". For more resolution to be achieved better technique and lenses are required and remember, resolution is not the same as perceived sharpness.
When a mobile phone has more pixels packed onto its tiny sensor, the pixels get smaller, gather less light, resolve less real detail and produce more noise through pixel failure, but still produce bigger files! The most important feature of a camera is the size of the sensor as this determines the size and density of the pixels and their effectiveness.
There is a reason that full frame sensors are just hitting the 40+ mp mark when phones have been offering this for a while. That reason is marketing. The marketing people control the sales of phones and small digicams and have two weapons; zoom ratio and pixels. These are easy numbers to identify with and the industry has trained us all well to respond to them. Better cameras are controlled by marketing also, but photographers know that balance is far more important, so the marketing/camera design appeals to other needs.
For a serious photographer there is no point in having a small sensor/high pixel/long zoom camera if the thing becomes useless in poor lighting and does not produce the images it promises. Most top of the line pro cameras are full frame with less than 20mp (the flagship 20mp D5 Nikon has just been announced). This is because if you want the very best performance in all other important areas (low light noise/grain control, processing speed, accuracy, image quality), the number of pixels still have to be controlled. So if you put pixels first, what is being compromised?
You need to cover "all the bases".
In the "5 stages of the photographer" the third stage (?) is collecting all the gear you can carry. No one is good at everything. Work out what you are interested in, get good at it and produce work. This will save you a lot of time, money and frustration. I know this because I have been down this road many a time. What you actually need is usually not much, what you think you need is probably more. I carried a macro lens around in my kit bag(s) for years. Switch brand or format, better get that macro. Turns out I hardly ever used them, so "just in case" did not ever really happen. My father in law on the other hand would use a macro or similar more often than not (the man actually likes spiders). Any reasonable close focus lens would do enough for me. I learned that one 6 lenses too late (bit slow, but I get there). By the same token, don't cut out lenses just to go with convention. Many landscapers use longer lenses and sports shooters find a use for wide angles and some dog photographers even use a fish eye lens. If you look in camera bag of most experienced photographers you will usually find only a couple of favourite lenses in preferred focal lengths, often specialist lenses and primes not zooms. They have worked out over time what works for them and that's all they carry. Try a day out with just one non zoom lens, surprise yourself.
Maybe this one is true;
No method, camera brand, opinion, technique or personal vision is better than another unless it pertains to you and your needs only. Be your own mentor, make your own rules.