Correct distance to subject for 1:1 print out

Hi all,

I could only find the question posed on 1 other forum and it descended into lots of arguing.

I've been tasked to shoot details of a big mural (they don't need a stitched image) and for the details to be printed out at 1:1 scale to the real thing.

I'm planning on using a prime lens and then using a ruler or stick (it doesn't have to be exact to the mm - just to the nearest 1 cm or 2) and just keeping the lens at the same distance from the wall for each shot.

If I was using a 50mm lens (Sigma Art Lens to be precise) what distance do I need to be for the print out to be 1:1?

The image will be printed at 300dpi

I have a Canon R5: 8192 x 5464pixels

which means that the print out at 300dpi is 463mm x 694mm

If the 50mm is not suitable I could rent a 100mm RF macro lens or another lens etc

Basically how do i calculate the distance from lens or sensor etc to the wall to give 1:1 print outs at 300dpi?

Wouldn't part of the answer be determined by how large you made the final prints, or to what extent you cropped your original capture?

D Saul said:

Wouldn't part of the answer be determined by how large you made the final prints, or to what extent you cropped your original capture?

Click to expand...

For this workflow, I was planning on working to the max printable size of the R5 at 300dpi so making prints at 463mm x 694mm.

I would supply these images to the designers.

The final outputted print will be A2 (it's for a book), which is just slightly smaller than full resolution of the R5.

And then they can chose how to trim the image down slightly to A2, BUT not shrinking or scaling the image to A2. Only trimming off the edges if you see what I mean and using a little bit needed for bleed.

Steve BB said:

D Saul said:

Wouldn't part of the answer be determined by how large you made the final prints, or to what extent you cropped your original capture?

Click to expand...

For this workflow, I was planning on working to the max printable size of the R5 at 300dpi so making prints at 463mm x 694mm.

Click to expand...

The R5 is a camera, not a printer, right? So max printable size of the R5 does not compute. You mean, if you output at 300 ppi (I'm distinguishing here because the printer likely uses smaller dots than the pixel size), given the full resolution of your camera, 463mm x 694mm is the size print you would get, right?

In that case, you just need to do some geometry, if you know the field of view, but it's actually simpler than that. You need not do any math. Just take a sheet of A2 paper and photograph it, making sure the center of the lens is perpendicular to the sheet and in the center. Just move the camera until it fills the portion of the frame you want (looks like A2 is smaller than the max print size, so your A2 image should not fill the frame).
If you don't know how much of the frame, then approximate it, take a shot, count the pixels across and compare it to A2 size. Make any distance adjustment accordingly. For small adjustments like this, the linear approximation will be good enough. Shoot another photo to confirm your adjustment is right. If not, repeat. If so, measure the distance to the camera. Done.

P.S. I've been wanting to do something similar with this mosaic. https://goo.gl/maps/waHkbreJzgDgqAQ77

I gave a test run using a 400mm lens from across the street, but I think I really need to do it more carefully with my 24mm TS-E lens. Lighting may be tricky. What are you doing about lighting in your situation?

EDIT: Victor beat me to it with a very similar answer, but I'll leave this here anyhow.

Steve BB said:

D Saul said:

Wouldn't part of the answer be determined by how large you made the final prints, or to what extent you cropped your original capture?

Click to expand...

For this workflow, I was planning on working to the max printable size of the R5 at 300dpi so making prints at 463mm x 694mm.

Click to expand...

It seems to me your answer is hidden here -- you need to cover 463mm x 694mm on the mural so you can figure your distance by marking off the image width on a wall and checking camera position to cover that distance. That should get you within your tolerances.

If you want to 'do the math' I'm sure someone here can give you a formula, but to be exact you need to know the actual focal length of your lens at your working distance and aperture -- which could vary a few mm from the marked focal length.

But the more important question to me is how big an area do your clients want in the photo? Can you better serve them by shooting tighter?

Unless they want to show the mural life-size on the printed page

Gato

--
Portraits, fantasy, cosplay and such (mildly NSFW)
https://www.instagram.com/jrsprawlsphoto/
.
Personal pictures, road trips, rural nostalgia, and kitty cats:
https://www.instagram.com/j.r.sprawls/

Victor Engel said:

Steve BB said:

For this workflow, I was planning on working to the max printable size of the R5 at 300dpi so making prints at 463mm x 694mm.

Click to expand...

The R5 is a camera, not a printer, right? So max printable size of the R5 does not compute. You mean, if you output at 300 ppi (I'm distinguishing here because the printer likely uses smaller dots than the pixel size), given the full resolution of your camera, 463mm x 694mm is the size print you would get, right?

Click to expand...

You've literally just told me I'm wrong but then explained the exact same result as I already had to me.

Victor Engel said:

In that case, you just need to do some geometry, if you know the field of view, but it's actually simpler than that. You need not do any math. Just take a sheet of A2 paper and photograph it, making sure the center of the lens is perpendicular to the sheet and in the center. Just move the camera until it fills the portion of the frame you want (looks like A2 is smaller than the max print size, so your A2 image should not fill the frame).
If you don't know how much of the frame, then approximate it, take a shot, count the pixels across and compare it to A2 size.

Click to expand...

But I'm not shooting A2 size. I'm shooting full resolution of the R5.

Gato Amarillo said:

EDIT: Victor beat me to it with a very similar answer, but I'll leave this here anyhow.

Steve BB said:

D Saul said:

Wouldn't part of the answer be determined by how large you made the final prints, or to what extent you cropped your original capture?

Click to expand...

For this workflow, I was planning on working to the max printable size of the R5 at 300dpi so making prints at 463mm x 694mm.

Click to expand...

It seems to me your answer is hidden here -- you need to cover 463mm x 694mm on the mural so you can figure your distance by marking off the image width on a wall and checking camera position to cover that distance. That should get you within your tolerances.

Click to expand...

Thanks - this sounds like a very simple method to work this out. Thank you.

Gato Amarillo said:

But the more important question to me is how big an area do your clients want in the photo? Can you better serve them by shooting tighter?

Click to expand...

They are very specific in wanting 1:1 size between the subject and the printed outcome.

Steve BB said:

They are very specific in wanting 1:1 size between the subject and the printed outcome.

Click to expand...

In that case for each setup do a shot with a ruler included. Often in this kind of work a photographer will include a ruler or scale in the margin of the photo, and also a color control target. These will serve as a guide to the printers putting together the book.

And, of course, be sure the camera is square to the work.

Gato

--
Portraits, fantasy, cosplay and such (mildly NSFW)
https://www.instagram.com/jrsprawlsphoto/
.
Personal pictures, road trips, rural nostalgia, and kitty cats:
https://www.instagram.com/j.r.sprawls/

Steve BB said:

Victor Engel said:

Steve BB said:

For this workflow, I was planning on working to the max printable size of the R5 at 300dpi so making prints at 463mm x 694mm.

Click to expand...

The R5 is a camera, not a printer, right? So max printable size of the R5 does not compute. You mean, if you output at 300 ppi (I'm distinguishing here because the printer likely uses smaller dots than the pixel size), given the full resolution of your camera, 463mm x 694mm is the size print you would get, right?

Click to expand...

You've literally just told me I'm wrong but then explained the exact same result as I already had to me.

Click to expand...

No. There is a difference. But no matter. I just wanted to be sure I understood your intention.

Steve BB said:

Steve BB said:

In that case, you just need to do some geometry, if you know the field of view, but it's actually simpler than that. You need not do any math. Just take a sheet of A2 paper and photograph it, making sure the center of the lens is perpendicular to the sheet and in the center. Just move the camera until it fills the portion of the frame you want (looks like A2 is smaller than the max print size, so your A2 image should not fill the frame).
If you don't know how much of the frame, then approximate it, take a shot, count the pixels across and compare it to A2 size.

Click to expand...

But I'm not shooting A2 size. I'm shooting full resolution of the R5.

Click to expand...

Sure, but you're printing on A2, right? That means you will be printing a crop of the full image.

Steve BB said:

They are very specific in wanting 1:1 size between the subject and the printed outcome.

Click to expand...

Depending on the lens, there may be some distortion you need to correct. I don't know the distortion this particular lens presents, but perhaps it's insignificant. If you do need to correct distortion, be aware that Canon's lens correction parameters are not worked out for third party lenses, so you'll need to work that out yourself. If you do need to do any correction, you'll want to take measurements after the correction operation.

Victor Engel said:

Steve BB said:

Victor Engel said:

Steve BB said:

For this workflow, I was planning on working to the max printable size of the R5 at 300dpi so making prints at 463mm x 694mm.

Click to expand...

The R5 is a camera, not a printer, right? So max printable size of the R5 does not compute. You mean, if you output at 300 ppi (I'm distinguishing here because the printer likely uses smaller dots than the pixel size), given the full resolution of your camera, 463mm x 694mm is the size print you would get, right?

Click to expand...

You've literally just told me I'm wrong but then explained the exact same result as I already had to me.

Click to expand...

No. There is a difference. But no matter. I just wanted to be sure I understood your intention.

Click to expand...

You perfectly understood me otherwise how else were you able to re-explain my own information back to me exactly as I had stated it? By the way 'no matter' doesn't compute. It's not correct grammar. Just pointing that out, as I want to be sure I understood your intention.

Victor Engel said:

Victor Engel said:

Victor Engel said:

In that case, you just need to do some geometry, if you know the field of view, but it's actually simpler than that. You need not do any math. Just take a sheet of A2 paper and photograph it, making sure the center of the lens is perpendicular to the sheet and in the center. Just move the camera until it fills the portion of the frame you want (looks like A2 is smaller than the max print size, so your A2 image should not fill the frame).
If you don't know how much of the frame, then approximate it, take a shot, count the pixels across and compare it to A2 size.

Click to expand...

But I'm not shooting A2 size. I'm shooting full resolution of the R5.

Click to expand...

Sure, but you're printing on A2, right? That means you will be printing a crop of the full image.

Click to expand...

Yes I have said I will be cropping to A2 down from the 1:1 full frame resolution image. The method you've put above - I don't see how it would give a reliable result. It looks like it involves guessing the difference between 463mm x 694mm and 420 x 594 mm through the view finder?

Victor Engel said:

Steve BB said:

They are very specific in wanting 1:1 size between the subject and the printed outcome.

Click to expand...

Depending on the lens, there may be some distortion you need to correct. I don't know the distortion this particular lens presents, but perhaps it's insignificant. If you do need to correct distortion, be aware that Canon's lens correction parameters are not worked out for third party lenses, so you'll need to work that out yourself. If you do need to do any correction, you'll want to take measurements after the correction operation.

Click to expand...

Lightroom works this out for you automatically.

Steve BB said:

Victor Engel said:

Steve BB said:

Victor Engel said:

Steve BB said:

For this workflow, I was planning on working to the max printable size of the R5 at 300dpi so making prints at 463mm x 694mm.

Click to expand...

The R5 is a camera, not a printer, right? So max printable size of the R5 does not compute. You mean, if you output at 300 ppi (I'm distinguishing here because the printer likely uses smaller dots than the pixel size), given the full resolution of your camera, 463mm x 694mm is the size print you would get, right?

Click to expand...

You've literally just told me I'm wrong but then explained the exact same result as I already had to me.

Click to expand...

No. There is a difference. But no matter. I just wanted to be sure I understood your intention.

Click to expand...

You perfectly understood me otherwise how else were you able to re-explain my own information back to me exactly as I had stated it? By the way 'no matter' doesn't compute. It's not correct grammar. Just pointing that out, as I want to be sure I understood your intention.

Click to expand...

OK. Since you apparently are more interested in sparring than getting a solution to your issue, I'll leave you to your own devices now.

Steve BB said:

Hi all,

I could only find the question posed on 1 other forum and it descended into lots of arguing.

I've been tasked to shoot details of a big mural (they don't need a stitched image) and for the details to be printed out at 1:1 scale to the real thing.

I'm planning on using a prime lens and then using a ruler or stick (it doesn't have to be exact to the mm - just to the nearest 1 cm or 2) and just keeping the lens at the same distance from the wall for each shot.

If I was using a 50mm lens (Sigma Art Lens to be precise) what distance do I need to be for the print out to be 1:1?

The image will be printed at 300dpi

I have a Canon R5: 8192 x 5464pixels

which means that the print out at 300dpi is 463mm x 694mm

If the 50mm is not suitable I could rent a 100mm RF macro lens or another lens etc

Basically how do i calculate the distance from lens or sensor etc to the wall to give 1:1 print outs at 300dpi?

Click to expand...

It's not possible to calculate the distance but it should be quite straightforward to determine it.

Simply create a test target that has a 694x463mm rectangle and position the camera so that it fills your image. If the viewfinder is not 100% then this might take a little trial and error to get "right".

Based on your requirement actual magnification is about 36mm/694mm ~ 24mm/463mm ~ 1/19.28

Based on optics an estimated distance from sensor to subject is (2+19.28) *f ~21*f where f is the focal length; so about 1 meter.

Probably a bit closer since that lens is probably less than 50mm when focused close.

Thanks Bill, very informative and useful answer!

bclaff said:

Steve BB said:

Hi all,

I could only find the question posed on 1 other forum and it descended into lots of arguing.

I've been tasked to shoot details of a big mural (they don't need a stitched image) and for the details to be printed out at 1:1 scale to the real thing.

I'm planning on using a prime lens and then using a ruler or stick (it doesn't have to be exact to the mm - just to the nearest 1 cm or 2) and just keeping the lens at the same distance from the wall for each shot.

If I was using a 50mm lens (Sigma Art Lens to be precise) what distance do I need to be for the print out to be 1:1?

The image will be printed at 300dpi

I have a Canon R5: 8192 x 5464pixels

which means that the print out at 300dpi is 463mm x 694mm

If the 50mm is not suitable I could rent a 100mm RF macro lens or another lens etc

Basically how do i calculate the distance from lens or sensor etc to the wall to give 1:1 print outs at 300dpi?

Click to expand...

It's not possible to calculate the distance but it should be quite straightforward to determine it.

Simply create a test target that has a 694x463mm rectangle and position the camera so that it fills your image. If the viewfinder is not 100% then this might take a little trial and error to get "right".

Based on your requirement actual magnification is about 36mm/694mm ~ 24mm/463mm ~ 1/19.28

Based on optics an estimated distance from sensor to subject is (2+19.28) *f ~21*f where f is the focal length; so about 1 meter.

Probably a bit closer since that lens is probably less than 50mm when focused close.

Click to expand...

Another calculation:

Diagonal angle of view is 46.8 so horizontal angle of view is 38.9. Width is 694mm, so half width is 347mm. Half angle of horizontal angle of view is 19.45. Now we just use some trig to get the distance. Distance = 347 / tan(19.45) = 983mm

Victor Engel said:

bclaff said:

Steve BB said:

Hi all,

I could only find the question posed on 1 other forum and it descended into lots of arguing.

I've been tasked to shoot details of a big mural (they don't need a stitched image) and for the details to be printed out at 1:1 scale to the real thing.

I'm planning on using a prime lens and then using a ruler or stick (it doesn't have to be exact to the mm - just to the nearest 1 cm or 2) and just keeping the lens at the same distance from the wall for each shot.

If I was using a 50mm lens (Sigma Art Lens to be precise) what distance do I need to be for the print out to be 1:1?

The image will be printed at 300dpi

I have a Canon R5: 8192 x 5464pixels

which means that the print out at 300dpi is 463mm x 694mm

If the 50mm is not suitable I could rent a 100mm RF macro lens or another lens etc

Basically how do i calculate the distance from lens or sensor etc to the wall to give 1:1 print outs at 300dpi?

Click to expand...

It's not possible to calculate the distance but it should be quite straightforward to determine it.

Simply create a test target that has a 694x463mm rectangle and position the camera so that it fills your image. If the viewfinder is not 100% then this might take a little trial and error to get "right".

Based on your requirement actual magnification is about 36mm/694mm ~ 24mm/463mm ~ 1/19.28

Based on optics an estimated distance from sensor to subject is (2+19.28) *f ~21*f where f is the focal length; so about 1 meter.

Probably a bit closer since that lens is probably less than 50mm when focused close.

Click to expand...

Another calculation:
Diagonal angle of view is 46.8 so horizontal angle of view is 38.9. Width is 694mm, so half width is 347mm. Half angle of horizontal angle of view is 19.45. Now we just use some trig to get the distance. Distance = 347 / tan(19.45) = 983mm

Click to expand...

Sure. Agrees with my estimate.
FWIW, that's from the entrance pupil who's location is unknown but almost certainly at least one focal length in front of the sensor.
And .. that diagonal angle of view is only good at infinity

bclaff said:

Victor Engel said:

bclaff said:

Steve BB said:

Hi all,

I could only find the question posed on 1 other forum and it descended into lots of arguing.

I've been tasked to shoot details of a big mural (they don't need a stitched image) and for the details to be printed out at 1:1 scale to the real thing.

I'm planning on using a prime lens and then using a ruler or stick (it doesn't have to be exact to the mm - just to the nearest 1 cm or 2) and just keeping the lens at the same distance from the wall for each shot.

If I was using a 50mm lens (Sigma Art Lens to be precise) what distance do I need to be for the print out to be 1:1?

The image will be printed at 300dpi

I have a Canon R5: 8192 x 5464pixels

which means that the print out at 300dpi is 463mm x 694mm

If the 50mm is not suitable I could rent a 100mm RF macro lens or another lens etc

Basically how do i calculate the distance from lens or sensor etc to the wall to give 1:1 print outs at 300dpi?

Click to expand...

It's not possible to calculate the distance but it should be quite straightforward to determine it.

Simply create a test target that has a 694x463mm rectangle and position the camera so that it fills your image. If the viewfinder is not 100% then this might take a little trial and error to get "right".

Based on your requirement actual magnification is about 36mm/694mm ~ 24mm/463mm ~ 1/19.28

Based on optics an estimated distance from sensor to subject is (2+19.28) *f ~21*f where f is the focal length; so about 1 meter.

Probably a bit closer since that lens is probably less than 50mm when focused close.

Click to expand...

Another calculation:
Diagonal angle of view is 46.8 so horizontal angle of view is 38.9. Width is 694mm, so half width is 347mm. Half angle of horizontal angle of view is 19.45. Now we just use some trig to get the distance. Distance = 347 / tan(19.45) = 983mm

Click to expand...

Sure. Agrees with my estimate.
FWIW, that's from the entrance pupil who's location is unknown but almost certainly at least one focal length in front of the sensor.
And .. that diagonal angle of view is only good at infinity

Click to expand...

Right - that's why taking a shot and scrutinizing the image is better. Plus you don't need to do as much math.

Steve BB said:

Hi all,

I could only find the question posed on 1 other forum and it descended into lots of arguing.

I've been tasked to shoot details of a big mural (they don't need a stitched image) and for the details to be printed out at 1:1 scale to the real thing.

I'm planning on using a prime lens and then using a ruler or stick (it doesn't have to be exact to the mm - just to the nearest 1 cm or 2) and just keeping the lens at the same distance from the wall for each shot.

If I was using a 50mm lens (Sigma Art Lens to be precise) what distance do I need to be for the print out to be 1:1?

The image will be printed at 300dpi

I have a Canon R5: 8192 x 5464pixels

which means that the print out at 300dpi is 463mm x 694mm

If the 50mm is not suitable I could rent a 100mm RF macro lens or another lens etc

Basically how do i calculate the distance from lens or sensor etc to the wall to give 1:1 print outs at 300dpi?

Click to expand...

If I understand you correctly, your question is what distance should the lens by from the artwork, in order to capture a 463mm by 694mm section of the artwork.

According to the field of view calculator at https://www.pointsinfocus.com/tools/depth-of-field-and-equivalent-lens-calculator/ , with a 50 mm lens on a full frame camera, the distance from the artwork to the sensor should be about 1 meter. For a 100mm lens you would want a subject distance of twice that.

Keep in mind that you may be better off capturing at a higher resolution than you print. The pixels on the sensor are unlikely to line up one-to-one with the pixels in the printer driver.

Remember, lenses tend to have some barrel or pincushion distortion, you will need to correct for this if you want the images to match when you stitch them together. That software correction moves the image around in ways that doesn't increase sharpness.

The preferred type of lens for this sort of work is a macro prime lens. These lenses tend to have low distortion, flat planes of focus, and tend to be very sharp.

Lighting will be critical (and don't change it between captures or the images may not stitch well). I find that polarizing filters on the lights, and a polarizing filter on the camera are the best way to reduce glare and capture the best colors.

You should also profile the camera, and use that profile when processing the raw files.