What's your favorite internet falsehood on photography?

[jnantz]

2. Do not stop down your lens past F8 on 35mm. or F24 (using a 3x rule) or F32 (using 4x rule) on 4x5 to avoid diffraction. Last time I checked, there is always diffraction, and the airy disk is about 10 microns at F8 for green light. This would give about 100 lines/mm resolution. For 35mm 8x print or 4x5 2x print, we would get about 12.5 lines/mm = 317 lines/inch, more than 6x the required 50 lines/inch standard. The airy is always about 10 microns at F8, 20 at F16, and 40 microns, which is linear with respect to F number.

All these details make me tired.

people spend too much time sweating the small stuff and never take the photograph. I mean they are just doing this for fun, as a hobbyist, from what I understand, they are unable to even notice 99.999% of the stuff they sweat most of the time, like people who insist they can tell the difference between ink, FB and RC matted and framed under glass without a magnifying glass .. sorry for my snark but really? I mean who cares.

[AuditorOne]

mark ..

years ago someone posted a calculation device that seemed to work well for him..
it had to do with making believe the MM of hte lens was an Fstop, so a 90mm lens would be f9, extending the bellows to 180mm would be like f16 ( well a little more )
and it's 1(+) "stop" difference. .. seemed a lot easier than multiplication or division to me. I dont' do macro work so I don't know if it is actually as useful as it seems
but for a lot of people the less math the better. LOL

Wait a minute!!

There is math involved??

Oh sh@@@t!

Nobody said anything about math.

[Alan Klein]

KISS...usually one does NOT change the aperture, as that has been decided on because of other factors -- depth of field, etc -- so one just adjusts the exposure time.

In most cases, when using bellows extended beyond the focal length of one's lens and using small apertures to maintain DoF, one's exposure times will be seconds -- easy to adjust exposure without changing the aperture.

That's a good point.

[Alan Klein]

To all, I just remembered two more of these teachings I suspect come from internet laziness.

1. To convert a lens focal length on a 4x5 to 35mm equivalent, multiply by 3. This is reapeat over and over on almost all Youtube videos. I've always used 4, because it's closer than 3 to the actual equivalent, and much easier to calculate. For example, if you are a photographer who has printed 8x10's from 35mm negatives, the factor would be...
35m vertical is 24mm. 4x5 vertical is 3 3/4 inch = 95.25mm. 95.25/24 = 3.97 which is almost exactly 4. In many enlargers, the 4x5 carrier is only 3 1/2 in.tall (in short dimession in landscape mode). When scanning, you have the full frame available. Let's calculate the diagonals. For 35mm, sqrt(24^2+36^2)=sqrt(576+1296)=43.27mm. Same for full frame 4x5 with 1/8 margins all around. sqrt(95.25^2+120.65^2)=sqrt(9072.6+14566)=153.75. 153.75/43.27=3.553 which is slightly closer to 4 than to 3. So why on earth is everyone using a 3x instead of 4x which is much closer and more practical? For example, to get same depth of field on full frame 8x10 prints from both, we convert the F8 on the 35mm X4=F32 on the 4x5.

2. Do not stop down your lens past F8 on 35mm. or F24 (using a 3x rule) or F32 (using 4x rule) on 4x5 to avoid diffraction. Last time I checked, there is always diffraction, and the airy disk is about 10 microns at F8 for green light. This would give about 100 lines/mm resolution. For 35mm 8x print or 4x5 2x print, we would get about 12.5 lines/mm = 317 lines/inch, more than 6x the required 50 lines/inch standard. The airy is always about 10 microns at F8, 20 at F16, and 40 microns, which is linear with respect to F number.

All these details make me tired.

I would use horizontal width for landscape pictures since your height is unimportant when switching formats. You;re concerned about the width the lens will catch. Also, I would ignore diagonals because we don't see that way when composing a picture horizontally or vertically, for the most part. So what would be your calculation/formula based on 5" side? In any case, I use 3.3x 35mm to 4x5 based on a lens angle of view horizontally.

As an aside, wouldn't you compare degrees of angle the lens captures rather than the width or length of the film when switching from one format to the other? What about image circle and the fact different lenses capture different angles for the same focal length?

[linhofbiker]

Years ago, around the time of the early internet (or maybe earlier) I was intrigued by an advert from Olympus about their amazing camera and its exposure system (that obviously everyone needed). It showed models at the beach with all kinds of shutter/aperture combinations. However if you looked closely, they were all exposed at Sunny-22 (for white sand and sunny beach conditions). Ha, I said you are not fooling me! And this was from the company that gave me my Pen-F in 1964. Kodak film came with Sunny-16 and Sunny-22 on/in the box. I still decided to get an exposure meter for those "tricky" exposures when using 4x5 film. But then I usually determined exposure by the incident method for E6 and C41. A box of 4x5 did not have exposure guide with the exception of maybe Fuji 64T etc. Just loved the tungsten film: you were the provider of the sun and had complete control in a darkened environment.

[maltfalc]

1. To convert a lens focal length on a 4x5 to 35mm equivalent, multiply by 3. This is reapeat over and over on almost all Youtube videos. I've always used 4, because it's closer than 3 to the actual equivalent, and much easier to calculate. For example, if you are a photographer who has printed 8x10's from 35mm negatives, the factor would be...
35m vertical is 24mm. 4x5 vertical is 3 3/4 inch = 95.25mm. 95.25/24 = 3.97 which is almost exactly 4. In many enlargers, the 4x5 carrier is only 3 1/2 in.tall (in short dimession in landscape mode). When scanning, you have the full frame available. Let's calculate the diagonals. For 35mm, sqrt(24^2+36^2)=sqrt(576+1296)=43.27mm. Same for full frame 4x5 with 1/8 margins all around. sqrt(95.25^2+120.65^2)=sqrt(9072.6+14566)=153.75. 153.75/43.27=3.553 which is slightly closer to 4 than to 3. So why on earth is everyone using a 3x instead of 4x which is much closer and more practical? For example, to get same depth of field on full frame 8x10 prints from both, we convert the F8 on the 35mm X4=F32 on the 4x5.

you had me at the start, but lost me with the 4x nonsense. it's just as lazy as using 3x. i noticed you calculated the vertical which is closer to 4x but skipped the horizontal which is closer to 3x. not that it matters, since camera manufacturers all use the diagonal for equivalent focal lengths. your calculations for that are close enough, though the numbers vary slightly depending on the brand of film holder. 3.5x works for me.

[MartinP]

It's a fact: there's a direct relationship between the quality of your work and the amount of money you spend!!

That could even be true, or at least have a positive correlation, if one limited the total spending to materials consumed... Maybe?

[Ben Calwell]

That every good black-and-white photograph must — MUST, I tell you — have a good black and a good white. I’ve never agreed with this doctrinaire assertion.

[Vaughn]

That every good black-and-white photograph must — MUST, I tell you — have a good black and a good white. I’ve never agreed with this doctrinaire assertion.

Yep, but ya better have a pretty good reason for not, besides "I can't".

One of my, favorite is not the right word, photo forum falsehoods is that when discussing photography between hobbists, professional photographers and photographic artists, the artist is suppose to not bring up that they are an artist and should keep it hidden until the art fairy blesses them publically somehow. As if, for some strange reason, that bit of information does not add to the discussion...does not help others understand an artist's approach to their photography.

[Jim Noel]

There isn't enough room here, nor do I have the time, to list all of the misinformation which passes through this and other sites. Having been involved with LF photography since 1938 or 39 I have bookcases filled with valuable photo information most of which seems to have been forgotten by today's "experts".
Definition of "expert" - a little squirt away from home.