By David Haardt:
Note: this text is still an alpha version, can contain mistakes or be incorrect.
You should know that the Fuji GX680 neck strap has a RRP of 300 dollars, the Nikon 4/600 lens shade of 900. So what about you get what you pay for?
You should know that mirror lock-up (MLU) on your 35mm SLR yields you 50-150% sharpness gain at shutter times of 1/15-1/60 with a tele lens, depending on the focal length. Popular Photography, June 1999 http://www.smu.edu/~rmonagha/third/mlu.html
You should know that sharpness is relative. Using the hyperfocal distance of your lens might yield results with a large distance range being acceptably sharp, but if you want best quality, always place sharpness upon the important details of the image. Although this will in most cases cost you depth-of-field.
You should know that 6x6 (over 4.5x6) doesn't only offer you the advantage of not having to turn the camera for portrait format, but also has a built in shift lens effect due to the room for cropping afterwards. Apart from that, many situations almost demand for a square image, and many photographers like that view of the world. The waist-level finder is also a big plus for decentral composing compared to the 4.5x6 eye-level finders you do already know from 35mm.
You should know that Pentax' K bayonet mount and Nikon's F bayonet mount allow you the use of many inexpensive, great, manual focus lenses. Canon switched from FD to EF bayonet mount with the introduction of autofocus, and Minolta from MD to A bayonet mount.
And you should also know that Minolta has created even another bayonet mount for their APS SLR series, while Canon and Nikon use their EF respectively F bayonet mount there too. Pentax don't offer a APS SLR system camera so far.
You should know that plastic construction and electronic circuits make electronic, especially AF, equipment, much more short-lived than manual one. In addition, you're not battery dependent with manual cameras. And your AF equipment will be worthless in five years, whereas your MF equipment will hold its value over the years if properly serviced, or might even increase in.
You should know that the expected life expectancy for LCD displays built into modern cameras is only five years.
You should know that diffraction is the cause for the fact, that a 35mm photo at f/8 will probably have more sharpness than the same photo taken at f/16.
Mathematically, f/8 is the "ideal diaphragm" for 35mm, f/16 for medium format, f/32 for 4x5", f/64 for 8x10". Of course this varies upon the very situation and shouldn't be taken as a law - just like anything in the world.
You should know that a 1964 Pentax Spotmatic with 1.4/50 Spotmatic is equal to a Leica M6 with 2/50 Summicron at f/8 on Kodak T-Max 100 with respect to a 8x12" (20x30cm) enlargement - there might be a difference visible only in an enlargement as large as 16x24" (40x60cm). Maybe.
Popular Photography is known for daring tests. Tests which the photo industry might not want to see. Tests which you probably won't find in German photo magazines. In issue 05/2001, Herbert Keppler found out the above when testing at perfectly equal conditions. Of course there is still the mechanical Leica advantage. But not without cause this test caused angry Leica-owner letters to the editor. It showed that the optical Leica advantage (if it exists) only comes to count at enlargements sized as large that you should be using a medium format camera anyway.
You should know that with an inexpensive 3.5/50 normal lens, you can win 80% of all photo contests - what is called the 80% solution: get the best camera you can afford, and a fine standard lens.
As Sussmann found out in the Amateur Photographer's Handbook, 78% of all contest winning photos were made with a normal lens (focal length being 50mm in 35mm photography). 89% of those photos were made at f/3.5 or slower.
You should know about Bongo's Law: The cost of the lens is inversely proportional to the frequency of its use.
You should know about Rob's Law: Lens cost goes up as the cube (third power) of its diameter...
You should know about Tim Brown's quote that "Excellence in Photography is acquired by Practice, not Purchase". Forget about "You get what you pay for".
A Koni Omega or a Kodak 620 Special, both medium format cameras which cost a few hundred (if) dollars with lens, outperform their Mamiya or even Schneider-Kreuznach counterparts, as you can find out at http://www.smu.edu/~rmonagha/mf/value.html
You should know that almost any b/w film is much sharper than Fuji Velvia, the famous colour chrome film.
You should know that b/w film and b/w prints will last decades, yes centuries, longer than their colour counterparts. Colour film and prints last about 50 years only before serious deterioration starts.
You should know that autofocus restricts your lens' resolution to 50 lpm at average diaphragms. This is a 50% loss of sharpness, which might lead to the case that expensive AF prime focals are as poor as cheap AF zooms.
This is due to the fact that all AF sensors have very large tolerances of what they consider sharp, up to +/-29% in several tests. The poor finders on AF cameras make you don't even notice that while photographing. They are in most cases brighter than MF finders, but much less contrasty, and without any manual focusing aids. So while AF is a necessity for sports and birds/wildlife photography, only MF cameras with MF lenses (which are much better to manually focus, and show much less wear with time, than AF ones) will deliver superior quality in any other field of photography.
You should know that medium format or even large format are not more expensive than 35mm equipment. A top-of-the-line 35mm SLR body costs about 2000 dollars - for this money you can as well get a brand new Western medium format or 4x5" large format camera. The same is valid for lenses. And there are fine medium format and large format cameras out there for a few hundred dollars - outperforming much more expensive equipment.
You should know that medium format photos made with the cheapest equipment (like e.g. with a used uncoated Kodak Ektar lens) are virtually always far superior to 35mm photos made with the finest (read most expensive) equipment. This is simply due to the enormous additional tonality and richness the bigger negative/chrome size provides for.
The difference between medium format and large format is far smaller - you will notice it only in enlargements sized 16x20" (40x50cm) or larger. But large format then allows for contact prints of uncomparable quality, and for many other photographical processes.
You should know that 6x6 is not 60x60mm, but only 56x56mm. 4.5x6 is actually 42x56mm, 6x7 56x70mm, and 6x9 56x83mm.
You should know about bokeh, the Japanese term describing the quality of how a lens depicts objects out of focus. Some lenses have very bad (disturbing) bokeh (also mirror lenses, due to technical reasons), some very nice one, like older uncoated lenses. Unfortunately only very few photo magazines test lenses for their bokeh.
You should know that any "intelligent" metering (multi-zonal) creates photos which are in most cases correctly exposed, but the results can never be repeated, and its errors can never be detected or corrected.
A single metering sensor thinks that everything in the world is 18% grey. So the industry developed multi-zonal metering systems which try to analyse the situation, compare it to saved standard images, and then correct accordingly. Thus, the camera's corrections are fully unpredictable, and uncorrectable. That's why one should use integral averaging metering only, because this is fully correctable with little knowledge. And the results become repeatable with this. More advanced photographers might also use spot metering, but this requires very much knowledge about light, meters, and film.
You should know that the equipment you buy may only improve your photos' technical quality (if), but never your photographical (artistic) one. But of course fine equipment can be a special pleasure to work with, this also shouldn't be neglected.
You should know that not only the Kiev-88 film backs occasionally suffer from light-leaks, but also the Hasselblad ones, which are ten times as expensive as their Eastern copies.