Misconception re: frame lines, DOF, compression

[dpitt]

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19 minutes ago, Anakronox said:

Well, the calculations are helpful to know from a technical perspective. 

However, I’ve never seen a photo and thought “ugh, this sucks because it’s not minimum 95% bokeh.”  Noctilux shooters, come at me.  That’s 95% sarcasm by the way 😜

 

If you have ever used a Digilux 2 with crop factor 4x, you know what we talk about. It was 5MP and basically a ISO 100 JPEG shooter with a crappy EVF, but I could work around that.

It was very hard to get any separation from subject or play with DOF. It was the one thing I craved for when I had it... more play with DOF. So the most important reason to upgrade to a M8 at the time was just that... and later on I moved to the FF M9 which was another little step forward in that area. I am now afraid that moving to MF would be a bit too much of a good thing. I would have to fight the lack of DOF more than anything.

[Ozymandias]

1 hour ago, dpitt said:

Yes it is a simple formula. If you crop by 1,41 then the DOF effect is equivalent to the square of that (i.e. 2x) so cropping from 35 F2.0, by 1,41  results in:

FL : 35 x 1,41 = 49,35 ~ 50
Aperture DOF effect : F 2.0  by half (1,41 x 1,41 = 2) so it becomes F2.8 =  1 stop less than the 35mm has

Mind you, that the exposure needed to take the picture is not influenced, so when you crop it is only the apparent FL and DOF that changes, not the shutter time.

 

Thanks Dirk,

Paul

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[Anakronox]

2 hours ago, dpitt said:

If you have ever used a Digilux 2 with crop factor 4x, you know what we talk about. It was 5MP and basically a ISO 100 JPEG shooter with a crappy EVF, but I could work around that.

It was very hard to get any separation from subject or play with DOF. It was the one thing I craved for when I had it... more play with DOF. So the most important reason to upgrade to a M8 at the time was just that... and later on I moved to the FF M9 which was another little step forward in that area. I am now afraid that moving to MF would be a bit too much of a good thing. I would have to fight the lack of DOF more than anything.

I'm by no means saying that bokeh is a bad thing!  I like it, but I also don't dismiss a good photo or a particular body or lens because there isn't enough of it.

[Mikep996]

"The calculations might be trivial for photography but relevant to understand the concept. "

Well...I'm not sure about that. Looking at "calculations" to evaluate a photograph is like looking at an audio frequency graph to evaluate a recording.  Does it SOUND good or not?  Same as a photo...does it LOOK good or not?  

Edited June 9, 2023 by Mikep996

[MindsEye]

I am loving this discussion. Success in photography, like any artistic endeavor, is the combination of technical expertise and creative prowess. The way I look at these technical issues, such as equivalent depth of field in this discussion, is simply to understand it to the point of it becoming second nature. Then it just becomes a tool without thinking about it, to create meaningful images. Whether those are meaningful just to you or to others is situational/choice. In my case, I have to make a living from my images too.

Side note- I also, wouldn't mind seeing a Q body with a 35mm 1.4 or similar. My very first Leica was a Leitz Minolta CL with a 40mm and 90mm lens. I ended up adding a 28mm Leitz/Leica lens later on. I suppose my attraction to the Q3 is having 2/3 of that kit in one camera plus of course some nostalgia thrown in. I know there is a 90mm crop line but I would only use that in a pinch...but assuming I'm always going to have it with me, still much better than my iPhone. 

[Anakronox]

24 minutes ago, MindsEye said:

The way I look at these technical issues, such as equivalent depth of field in this discussion, is simply to understand it to the point of it becoming second nature. Then it just becomes a tool without thinking about it, to create meaningful images.

100% this right here.  Well said.

[Qwertynm]

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vor einer Stunde schrieb Mikep996:

Looking at "calculations" to evaluate a photograph is like looking at an audio frequency graph to evaluate a recording.

This is not a good analogy imho. Nobody claimed a E-Piano sounds like a Steinways Grand Piano in a concert hall. An E-Piano can sound like a trumpet or like a Grand Piano but it isn’t either of those things. Knowing the limitations of your equipment and using it to create images or art is what was discussed. 
 

knowing the equivalence aperture number in cropmode can be to your benefit. For example if you take a landscape image in 50mm cropmode on the Q you don’t have to stop down beyond the diffraction limits of your sensor. You can use f/4.5-5.6 to have the same depth of field as if you were shooting f/8.5-11 on a 50mm lens. 
 

if you always shoot wide open these concepts might not interest you. But then why even engage in the conversation? Are you here to learn or something else?

Edited June 9, 2023 by Qwertynm
Typo

[LocalHero1953]

The music director of my choir includes an exercise in auditions consisting of a tricky sequence of five notes played on the piano that the candidate has to sing back. He explained it to me as "it's a good test of musicianship because the only way to get it right is to realise that the first and third intervals are tritones and the others are minor thirds". I didn't reply saying "I just listened to it and repeated it".

The point is that some people gain from a technical analysis of a particular matter, while others gain from an empirical approach.

Edit. I am reading this thread because I find it interesting, even if it is not my approach.

Edited June 9, 2023 by LocalHero1953

[Mikep996]

"Are you here to learn or something else?"

I'm doing the same thing you are doing, providing an OPINION on a subject, worth, as the old saying goes, every penny you paid for it.  

As has often been noted, there are as many ways to approach taking pictures as there are picture takers.  It's interesting to read the various methods/tricks/cameras/accessories some folks swear by...while other folks swear at!  But good pics (and bad) result from pretty much every method...

My point about the audio graph was that looking at the audio graph/frequency response won't tell you if you LIKE the song.

Edited June 9, 2023 by Mikep996

[Qwertynm]

vor 43 Minuten schrieb Mikep996:

I'm doing the same thing you are doing, providing an OPINION on a subject,

I wasn’t giving an opinion but an answer to a question, which was regarding to how to calculate equivalent f stops for the crop modes of the Q3.

No one mentioned anything about how a calculation or knowing about one improves the content of an image. You brought that up and stated your opinion that it‘s irrelevant to you. That’s your right but why bring that up in a technical discussion about equivalence when it’s about a photography concept and not about photography content?

I gave you an example on how this concept can translate to the real world wheras you talk about something else. Maybe that’s why we misunderstand each other?

if it’s no interest for you why talk about it? I still don’t understand

[Mikep996]

"No one mentioned anything about how a calculation or knowing about one improves the content of an image"

 When I read, "...75/28 * f/1.7 = f/4.5 (the lens on the Q is more like a 26mm so it would be more like f/5.0)," I mistakenly took that as "calculating" whether something would work as opposed to cropping/viewing the pic and then deciding if it was good/bad.  I apologize for my misunderstanding.  

 

[Qwertynm]

vor 44 Minuten schrieb Mikep996:

I mistakenly took that as "calculating" whether something would work as opposed to cropping/viewing the pic and then deciding if it was good/bad.

In the context of equivalency that calculation just gives you an idea what kind of lens your Q turns into when engaging the cropmode. Obviously the physical lens itself is not altered but the perceived depth of field changes with the sensor format (all else being equal). I just tried to give factual information without implying whether it’s good or bad. Sorry if that wasn’t clear enough. 

[Olaf_ZG]

You can talk what you want, but still I want a 50mm lens on a Q.

My Q2 is set on 50mm, but precise framing is rather tricky as one loses quite some space within the evf.

So, the Q2 went up for sale, will not buy a Q3 with a 28mm and that’s it for me.

I want to have a Q3-50!

[01af]

Am 8.6.2023 um 21:09 schrieb MindsEye:

Many of you already know this but depth of field does not change with focal length.

What I know is, depth-of-field does change with focal length.

.

Am 8.6.2023 um 21:09 schrieb MindsEye:

The crops for digital zoom in the Q3 (and Q2) will indeed give you the same “compression” and DOF as would those focal length lenses at the same aperture.

Maybe you should actually put your fingers on a Leica Q (or Q2 or Q3). Then you'd stop promoting this nonsense. Glad you captioned this thread 'misconceptions' ...

.

Am 8.6.2023 um 21:09 schrieb MindsEye:

I feel this is important to point out [...] that you have very useable 35 mm and 50 mm “lenses” built in.

As a matter of fact, you have nothing but a 28 mm lens built in.

.

Am 8.6.2023 um 21:09 schrieb MindsEye:

Then import and crop the wide-angle to the same framing as the telephoto shot and voilà, you will see they look the same.

No, they won't. They will look very similar—but not the same.

.

Am 8.6.2023 um 21:09 schrieb MindsEye:

The only difference will be the number of pixels.

... aaand the depth-of-field (wider in the cropped pictures).

[MindsEye]

2 hours ago, 01af said:

What I know is, depth-of-field does change with focal length.

Incorrect. Aperture changes DOF, but not focal length unless you also change aperture. I provided both a link with an explanation for those not aware of this and an experiment you can try yourself.

Maybe you should actually put your fingers on a Leica Q (or Q2 or Q3). Then you'd stop promoting this nonsense. Glad you captioned this thread 'misconceptions' ...

How did you come to this conclusion? I don't know you and I'm pretty sure you weren't with me when I was using a Q3 recently

As a matter of fact, you have nothing but a 28 mm lens built in.

I think you know that my use of quote marks around the word lenses indicates a virtual lens. But perhaps you are not aware of this feature on the Q3?

No, they won't. They will look very similar—but not the same.

This contradicts your first, rather adamant, comment that depth of field changes with focal length. Seems like picking nits here. No, not exactly the same because they are separate exposures at different times, perhaps even seconds apart.But to put it on your level- two exposures will never be exactly the same.

... aaand the depth-of-field (wider in the cropped pictures).

If by "wider" you mean greater DOF for smaller crops at a specific aperture, that is one of the points of this discussion. Look back at all the f/stop equivalents originally pointed out by @Qwertynm along with subsequent discussion, especially DOF for f/1.7.

If you don't want to contribute something constructive to this discussion because it challenges your assumptions, then please just avoid it. I'm trying to be polite here but as my mother used to say "If you can't say something constructive, say nothing at all"

 

 

Edited June 9, 2023 by MindsEye
typos

[Qwertynm]

vor 8 Stunden schrieb 01af:

What I know is, depth-of-field does change with focal length.

Because the Q has only one focal lenght the lens will behave like a wide angle lens in regards to DoF. As you crop in, you will simulate longer lenses eg 35,50 but with more depth of field at the same aperture compared to real 35 or 50mm lenses. 
 

see my photos on page one of this thread. Q3 shot at f/1.7 and Canon R5 with 50 1.2 shot at f/3.2. the DoF is the same or indistinguishable to my eyes. Formula to calculate the equivalent aperture for a cropped Q shot is 50/26 * f/1.7 = f/3.2. The aperture is obviously not changed in the cropped shot but gives the equivalent DoF as you‘d stop down the 50mm lens.

So at the same aperture you are right, the physical 50mm lens will have less DoF compared to the wide angle Q.

[01af]

11 hours ago, MindsEye said:

Incorrect. Aperture changes DOF, but not focal length unless you also 

Depth-of-field basically depends on four factors: Format size, focal length, distance, and aperture. Increase focal length (while keeping the other three parameters constant), and DOF will decrease. Decrease effective format size (while keeping the other three parameters constant), and DOF will also decrease.

Sheesh, why do we have to discuss this elementary stuff over and over ...!?

[Qwertynm]

2 hours ago, 01af said:

2 hours ago, 01af said:

Decrease effective format size (while keeping the other three parameters constant), and DOF will also decrease.

That’s where you’re wrong. Look at the two images on page 1 of this thread. 50mm @ f/3.2 vs Q3 at 50mm f/1.7. DoF is the same. Decreasing sensor size increases DoF at the same FoV. Or did your ever hear somebody say I need to shoot micro 4/3 to get a shallower DoF?

[jaapv]

Cropping in-camera is exactly the same as reducing sensor size. And yes, this affects DOF.  Perspective remains unchanged, aperture remains unchanged. It has been explained with examples multiple times on this forum  DOF is a function of magnification throughout the chain once aperture is set. DOF falloff is a characteristic of the lens and to a minor extent of sensor resolution. All this assuming the same camera position. 01AF is right. 

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[LocalHero1953]

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