Ysarex Loc: St. Louis

Wanting to understand how things work is normal human behavior.

How about a story: About 40 years ago I worked behind the counter of a camera store. I sold the pro-gear, mostly medium format cameras to the wedding/portrait photographers. My photo education to that point was reading popular books/magazines and talking to the rest of the crew at the shop.

I had been taught the erroneous rule of thumb that DOF distributed 1/3 front and 2/3 back around the plane of focus. One day I was showing a customer a camera lens and explaining the DOF scale on the lens and in looking at the scale I realized; "hey, that's not 1/3 -- 2/3, not even close." So after the customer left I asked Bob (manager) about that and Bob reached around to his bookcase and pulled down an old 1940s vintage copy of The Leica Manual. He said, you'll find the answer in here -- make sure and do the math." When I was finished I understood DOF.

Some months later one of the wedding/portrait shooters came in the store and he had a print with him of open end wrenches in a nice design against a dark textured background. He was showing off and told me he was working on his portfolio because he wanted to move up into some product work. He was shooting the wrenches at a 45 degree angle and not getting the DOF he wanted. So he asked me to go in the back and get a 50mm lens for his camera. He wanted to see one and consider it. The normal lens on his 6x6 camera was 80mm. He told me he planned to solve his DOF problem with a wider lens. I asked him if when he switched to the 50mm lens wouldn't he just move in closer to frame the image the same as with the 80? He said yes and with my new knowledge I told him that the DOF would be the same. The only thing he could really do was back off, which he could do with the 80, and then crop.

Even back 40 years ago a 50mm lens for a medium format camera was serious $$$$. And it wasn't going to solve his problem. But he was the pro and I was just the lowly clerk behind the counter. He put me in my place with his "pro-level photo knowledge" and I smiled and sold him that lens.

Moral -- if you don't want the shop help laughing at you behind your back it helps to understand how things work.

BushDog Loc: San Antonio, TX

Thank you for the input. I also think this thread has been an interesting discussion. I do think there are circumstances where some might consider it more than just academic. I’ll explain my thinking.

I posed the original question to satisfy my own (academic) curiosity and to help me decide what lenses to take on an upcoming trip to the mountains. For my wide to normal photos, I like to use primes. I am taking multiple primes including a recently released 35mm f1.4. There is also a newly released 50mm f/1.2 lens I plan to buy but I missed out on the few days it was available. Now I have to wait for it to become available again. So, my posed question was to help me decide whether I’d be happy using that new 35mm or to also take another lens that covers 50mm. So, I consider that to be non-academic. Like you, I’m fortunate to buy what I want (when it’s available).

Another situation I consider non-academic is for those many less fortunate photographers to be able to intelligently know what they could do with a prime lens and cropping the image to mimic a longer focal length and to know what may be lost or gained in the process.

Some of the things I have gleaned from this thread - based on the very specific criteria I posed and may need to be referenced - are:
1) the perspective is the same - note the two images posted by Ysarex.
2) cropping the 35mm image is going to reduce the file size by eliminating pixels outside the selected crop size. This decreases the resolution of the final cropped image. The 50mm image is using all those pixels in the final image; the cropped 35mm image is not.
3) the 35mm lens, by the nature of wide angle lenses, is going to have a greater depth of field. Note again the two images posted by Ysarex. Thank you Ysarex. 👍🏽

There may also be some other differences such as vignetting but those are likely to be negligible differences.

Thank you everyone for your valued input. I feel like my question has been answered quite thoroughly.

Architect1776 Loc: In my mind

5 pages of pontification.

srt101fan

In an earlier post you called it an "interesting discussion"....

selmslie Loc: Fernandina Beach, FL, USA

There are two ways to view resolution:

- Area resolution is measured in digital megapixels and it directly affects the file size. It drops as the square of the crop factor - a 1.5x crop reduces it by 1/2.25.

- Linear resolution is measured in lines or line pairs per millimeter or per picture height. It is reduced in direct proportion to the crop factor - a 1.5x crop reduces it by 2/3. With film this was the only way to think about it. Cropping also increases the effect of diffraction.

We use multiple prime lenses because a wide angle lens is not likely to make up the difference in linear resolution lost with cropping.

But linear resolution is not the same from corner to corner. As with vignetting, the fall-off in sharpness can be reduced by stopping down. A cropped wide angle image may be more uniform in sharpness but that is going to be a lower sharpness than an image shot with a longer lens. And a lens with the widest maximum aperture may be less sharp than one that is 1 stop darker. For example, an f/2 lens is usually sharper than an f/1.4 or f/1.2 from the same source.

If you are shooting landscapes with prime lenses the difference is not academic.

Architect1776 Loc: In my mind

Pontification does not mean not interesting.
Get a dictionary.

Bill_de Loc: US

These examples have been automatically selected and may contain sensitive content.Read more…

Most of the filler is writerly pontification.
Times, Sunday Times (2015)

But beyond that we are into the realm of pontification and digression.
Times, Sunday Times (2015)

Other stars without specific policy portfolios have not let ignorance stand in the way of pontification.
Times, Sunday Times (2009)

If only there were a collective noun for poets: a poverty of poets, perhaps, or a pontification.
Times, Sunday Times (2018)

Pontification will become grounds for disqualification.
The Scientist (2000)

https://www.collinsdictionary.com/us/dictionary/english/pontification#:~:text=pontification%20in%20British%20English,the%20act%20of%20pontificating

---

Architect1776 Loc: In my mind

Gee glad you proved my point.

Bill_de Loc: US

That was my intention.

UHH would be very boring if everyone just regurgitated the same facts over and over again. Actually, many folks do just that, but not everybody.

---

User ID

I worked a very similar job. When it came to successful working photographers I found that the least technically advanced were the top journalists. They are not inept, but not overly knowledgeable cuz their “job one” is not technique. They keep to the crude-but-effective rule on technique and on gear.

Their real “job one” is not related to film, nor gear, nor process. “Job one” is hustle, access, connections, organization, etc. The weight of all that left no room for any “photo-geekiness”.

I should point out that their version of crude-but-effective is actually more knowledge and refinement than the typical Hogster brings to their own work. But *compared* to most other fields of professional photography the journalists technique ranks as crude-but-effective.

The “1/3 2/3” rule of DoF does work, just not perfectly or universally. For crude-but-effective it really is a perfect tool. Works perfectly for riots, sports, politics, etc etc. The true and perfect DoF math would slow things down for no visible benefit. For a more critical DoF result, just fudge the DoF scale by one f/stop. Practicality 101.

I remember when the Nikon F2 arrived. Dilettantes were trading up from their barely used F cameras and journalists were on waiting lists to buy the trade-ins.

They were fearful and distrustful of the F2 for the understandable reasons: newer, later tech and the downsides of progress. They were hoarding back-up F bodies cuz they were crude-but-effective ... effective at taking a licking and keeping on ticking. THAT was the machine’s “job one”, not metering, not ergonomics, not useless conveniences.

Convenience is eye level viewing, quick return mirror, auto iris, and combined film wind with shutter cocking. Thaz all ! “Viewfinder information“ is focusing and framing. Zooms are off the table: bigger, slower, more moving parts.

selmslie Loc: Fernandina Beach, FL, USA

It doesn't work at all unless the lens is focused at 1/3 of the hyperfocal distance.

As you move from there up to the hyperfocal distance it approaches 1:∞ (infinity). As you move in closer it approaches 1:1.

A practical photographer would have used the DoF markings engraved on the lens barrel. That was a lot easier than trying to calculate it.

This assumes that they cared at all, which was unlikely

User ID

Your “solution” is actually the problem.
You didn’t reeeeeally read my post. You just scan it and use it as a launch pad to spout geek speak. You claim something “doesn’t work”. Thaz your claim versus world wide results to the contrary.

Your value as entertainment vastly outweighs your value as advisor. But thank you for that much, anywho.

selmslie Loc: Fernandina Beach, FL, USA

I think you miss my point.

Fretting over DoF is something you might do when have too much time on your hands,

An experienced photographer understands when they need to worry about it which is seldom. They just use a wide aperture or a small aperture for the effect and focus on something they want to look sharp.

User ID

Thank you, Captain Redundancy ! And give my regards to Captain Obvious !

I know I wrote “crude-but-effective” several times in that post, plus a clear mention of quick use the on-lens scale complete with fudge factor.

And yes I do get your point. Your point, as always, is to watch for key words or phrases as plausible excuses for your pontifications. Verrrrry transparent.

imagemeister Loc: mid east Florida