Is there a calculator for subject size, distance, focal length, for size in frame?

[FlyingSquirrel]

This is an odd question, but...

Is there a calculator or app that you can type in: Subject size, distance to subject, focal length, sensor (crop etc), and then have it tell you how much of the frame it will fill? I suppose I could do some tests to determine this, and also, experience would give me a second-nature instinct for it, but I thought there might be a tool to calculate it as well.

Thanks for any suggestions

[NorthernFocus]

hi matt. it's a pretty simple calculation. I built a spreadsheet that calcs DOF and FOV(which is what you want). I'm traveling but can send you a copy when I get home. or you can Google the equations and build one.

[Nicks Pics]

Oh the technical tolerance of some folks' minds! I am not sure how you would put it into practice, unless in a controlled invironment, but it might be a good mental practice anyway. I've seen a mathematical attempt at painting correctly, but that's about all it came to.

[george013]

This is an odd question, but...

Is there a calculator or app that you can type in: Subject size, distance to subject, focal length, sensor (crop etc), and then have it tell you how much of the frame it will fill? I suppose I could do some tests to determine this, and also, experience would give me a second-nature instinct for it, but I thought there might be a tool to calculate it as well.

Thanks for any suggestions

Schematic it are 2 lines going through the optical centre of the lens under an angle equal to the angle of view. If you can calculate the distance from the optical centre to the sensor then further it should be a simple relation between the distances.
For the simplicity forgetting the movement of the lens due to sharpening the image. In Dutch it's called the changing image-distance. On the internet in English it's given so many different names.
George

[ajohnw]

http://www.bobatkins.com/photography...d_of_view.html

John
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[Stagecoach]

This one will give you Field of Views and other useful bits Matt.

http://www.tawbaware.com/maxlyons/calc.htm

[chauncey]

Grahame...yours seems ideal except is doesn't include DOF. A non-computer chart would be nice.

[Stagecoach]

Grahame...yours seems ideal except is doesn't include DOF. A non-computer chart would be nice.

Chauncey, you could simply use the top DoF calculator. I have non computer ones as well that you can feed in the ranges you are interested in and print it out as a graph.

[george013]

I think the question was what is the, negative, magnification as product of the distance and focal length. I can't read that out from a DOF-calculator.
George

[Stagecoach]

You are right George, you can't get the info for the OPs question from a DoF calculator but no one has suggested you can.

[george013]

You are right George, you can't get the info for the OPs question from a DoF calculator but no one has suggested you can.

So why those answers?
George

[DanK]

So why those answers?
George

Grahame's and John's posts do answer the question. Once you have the AOV for the combination of focal length and sensor size, you can calculate the dimensions of the field for any given distance. On the other hand, I can't foresee actually doing this. I have been shooting since 1968 and haven't ever done this calculation. I have a rough idea of the needed focal length from experience, and then I just look and see.

[chauncey]

haven't ever done this calculation

I once spent a couple hours running the calculations for numerous lenses>cut appropriate size rectangles in cards
to match my arm length...when all that was finished, I never once used them in the field.

[xpatUSA]

Hello Matt,

I wrote a spread sheet that might be of interest although it has different inputs and outputs than yours. I wanted to start with framing and calculate required distance and DOF. If interested, I can post it on my site for download along with the article I developed it from. It could easily be modified to what you want, I reckon.



Yellow is inputs, green is outputs.

c** is that number found in circle of confusion calcs. It varies by output, pixel pitch and the direction of the wind. Although note for my camera and monitor says 1600, I had entered 1500 for some reason long forgotten.

I use this calculation upon occasion for table top work.

[NorthernFocus]

I once spent a couple hours running the calculations for numerous lenses>cut appropriate size rectangles in cards
to match my arm length...when all that was finished, I never once used them in the field.

Similar to my own experience. But for those technically oriented, and Matt seems to be so, going through the exercise has value and improves one's overall understanding of the geometry etc. Therefore they can be a valuable tools to shorten the learning cycle for some people. We don't all learn the same way. We don't all do things the same way. We don't all have the same opportunities. For someone who benefits from study, understanding these calculations can be beneficial.

While I've never referred to these tools while in the field, I have used them to resolve some shooting issues, to decide what lens to use for certain situations, etc. So one could argue that I have used them "in the field".

[george013]

Similar to my own experience. But for those technically oriented, and Matt seems to be so, going through the exercise has value and improves one's overall understanding of the geometry etc. Therefore they can be a valuable tools to shorten the learning cycle for some people. We don't all learn the same way. We don't all do things the same way. We don't all have the same opportunities. For someone who benefits from study, understanding these calculations can be beneficial.

While I've never referred to these tools while in the field, I have used them to resolve some shooting issues, to decide what lens to use for certain situations, etc. So one could argue that I have used them "in the field".

I completely agree.

I made some some calculation. I was sure there should be e figure you could use all the way. I think I found it.

Magnifying at 1meter. That's the number I was looking for.
input: Lens 50mm., sensor FF, distance 1m.
output: Horizontal FOV 0.72m

Magnifying factor per meter 0.036/0.72=0.05. Be aware, this is only for this lens.

This is the factor to work with with this lens and sensor.


What is the magnifying at a distance of 59meter?
Answer: 0.05/59=0.000847. So a tower big 85meter at that distance will be 85*0.000847=0.072m. So you will need exactly 2 sensors for that, portrait.

And what if you want that tower exactly 36mm?
Answer: (magn.factor/distance)*height or (0.05/distance)*85=0.036=118m

The main point is to calculate the magnifying factor with help of the calculators, write that down per lens, and the formulas you want to use.

George

I sure hope I didn't make any mistakes.

[Stagecoach]

So why those answers?
George

George,

The link I posted gives a calculator for 'Dimensional Field of View' and whilst this does not allow for an input of 'Subject Size' (lets say height in this case) if your subject height is known you can very easily see the percentage of the Field of View it will take up at any figure of the variable inputs. You can if wanted work backwards from this data to collate the information it will give you.

With regard to DoF you will see that whilst this is not applicable to Matt's initial question Chauncey raised the following;

Grahame...yours seems ideal except is doesn't include DOF. A non-computer chart would be nice.

Hence the reply to him that if DoF is additional info you need whilst the FoV calculator does not have this you do have the required info to simply use a DoF calculator, as also contained in the link.

[FlyingSquirrel]

The link I posted gives a calculator for 'Dimensional Field of View' and whilst this does not allow for an input of 'Subject Size' (lets say height in this case) if your subject height is known you can very easily see the percentage of the Field of View it will take up at any figure of the variable inputs. You can if wanted work backwards from this data to collate the information it will give you.

Ok, wow, this was really great! Thanks to all for your help and input. A couple of the links provided, did, in fact, have the info I was looking for. In particular, Grahame's link to tawbaware is an exciting resource. As he and others mentioned, the Dimensional Field of View Calculator was right on the money for my needs.

Similar to my own experience. But for those technically oriented, and Matt seems to be so, going through the exercise has value and improves one's overall understanding of the geometry etc. Therefore they can be a valuable tools to shorten the learning cycle for some people. We don't all learn the same way. We don't all do things the same way. We don't all have the same opportunities. For someone who benefits from study, understanding these calculations can be beneficial.

Well said! If only they knew that in school and tailored teaching to various learning styles.

...I have used them ... to decide what lens to use for certain situations ...

From what I can tell, I have less years of experience shooting, than many of the regulars on here. So I don't yet have "the intuition" as to what lens to pick up for a certain subject at a certain distance...other than, "it's a bird - grab the biggest lens you have!!" I believe that with increased shooting experience in the field, as well as playing with this calculator a bit, I will start to develop that gut instinct to grab the needed glass.

In this particular case, I am planning to visit a particular "wildlife park" that I've never been to. They have various mammals, medium to large, at various distances. I was trying to decide which lenses to bring. Without knowing the precise distances or sizes of the subjects, I can still generalize, and the calculator has given me what I need. I will most likely bring my 70-200 on my 7D crop sensor, and have a 1.4 in the bag just in case. For this application, I think the 500mm would be overkill, unless I want a shot of just a bear's eyeball.


Thanks again to all! You guys are the best! And I am super excited to go to the wildlife park and bring back some awesome pics to share

[HaseebM]

Maybe one day we will have a camera which will do everything for us as soon as we point it at a subject.

[FlyingSquirrel]

Maybe one day we will have a camera which will do everything for us as soon as we point it at a subject.

Surprisingly, we are getting pretty close to that point already. The newest high end cameras of today have so much technology and data built in, the camera starts to "think" it knows what you want. It is getting closer and closer all the time, though we all know it can never truly "know" what your precise subject is and what your vision for the resulting image would be. But the manufacturers sure are trying hard In terms of photography, I wish I lived in a time where more skill and knowledge were required, which set the pros apart from everyone else. Today, it is easier than ever for the average Joe to buy a nice camera, take some pics, then edit his mediocre photos in some fancy software and have them look amazing. Certainly, those with more skill, experience, and "talent" can produce higher quality, more sensational images, but the gap is being narrowed between that and the software and fancy cameras.