topic EOS Rebel T7 How to take photos at 300 dpi in EOS DSLR & Mirrorless Cameras

EOS Rebel T7 How to take photos at 300 dpi

Redsed — Sat, 09 Sep 2023 12:11:46 GMT

I am just learning how to take photos of my artwork to post on a marketing site. I am told I have to post a min. 300 DPI photo which means I need to change my settings and photograph all my artwork...again. Can someone give me a simplified explanation about how to do that. Sorry if this sounds a little crazy but I have put myself in a position to learn every. single. thing. about websites and social media and cameras all at once. If I can just take the right pictures I will be miles ahead of where I am now. There are plenty of tutorials about what to put the setting on when you start out but not what any of those settings actually mean. Thank you so much for any information.

Re: Canon EOS Rebel T7 Question

Anonymous — Sat, 09 Sep 2023 01:32:34 GMT

The DPI is only applicable when printing a photo. It is dependent on the resolution of the photo and the size of the print. To assign a minimum DPI to a photograph file that hasn't been printed yet, is meaningless. Typically, Canon cameras put a 72 DPI rating in out of camera files. It means nothing, as it is the DPI value if you printed the image at full size, which would be huge in size. In your printing software, the DPI value will increase with a smaller print size. The smaller the print, the larger the DPI value. If you have your camera set to its highest resolution, you shouldn't have to worry about the DPI value when taking the photo, it is the printing software settings that affect the DPI setting.

Re: Canon EOS Rebel T7 Question

Anonymous — Sat, 09 Sep 2023 01:53:59 GMT

As an example, my camera produces a photo with a resolution of 6720 x 4480 with DPI value of 72. If I print the image at 72 DPI the image size will be 93.33 in. (6720/72 = 93.33) by 62.22 in. (4480/72 = 62.22). If I print the image at 300 DPI the print will be a 22.4 in. by 14.9 in. in size. So you can see the DPI is dependent on the image resolution and the desired size of the print.

Re: Canon EOS Rebel T7 Question

shadowsports — Sat, 09 Sep 2023 01:58:22 GMT

In addition to Bob's detailed explanation 😃, ensure you are shooting in RAW format. This allows the most creative flexibility. You can use Canon's free Digital Photo Professional to edit, correct/enhance your images, and convert them to an easy to print, post format.

Canon Support for EOS Rebel T7 | Canon U.S.A., Inc.

Its available for Windows or Mac OS

We'll be here to help 😃

Re: Canon EOS Rebel T7 Question

rs-eos — Sat, 09 Sep 2023 02:12:00 GMT

The marketing site would need to at least provide one other value. Just providing a 300 DPI value is not enough information. e.g. that value implies you could submit a 300 x 300 pixel image that would print out as 1-inch square.

The site should additionally be providing either a resolution (width and height) or a physical size (width and height in inches).

Once you have the two values, you can then provide the necessary images. e.g. if they want you to submit 8 x 10 inch photos at 300 DPI, that would mean you'd need images with a resolution of 2400 x 3000.

Re: Canon EOS Rebel T7 Question

Waddizzle — Sat, 09 Sep 2023 09:17:02 GMT

I agree with Ricky. They should also define an absolute image size, defined either in pixels or in/mm.. But an overall size specification is independent of a DPI specification.

If you are using a Windows laptop or PC, I suggest downloading Paint Dot Net to adjust the size of JPEG files. You can upsize or downsize canvas size, image size, and DPI or PPI. I do not know if this easy to use app has ever been ported to MacOS.

Paint Dot Net is easy to learn image editor. It is a good introduction to how advanced imaged editors function. It is far more advanced than MS Paint. But nowhere near as complex as GIMP or Photoshop. It is an image editor, not a photo processor.

Re: Canon EOS Rebel T7 Question

johnrmoyer — Sat, 09 Sep 2023 10:33:52 GMT

You have received good information from others here about what DPI means. I am guessing you need to work around the ideas of the marketing site and not do not need to educate the marketing site.

I guess that a clueless marketing site might find it easy to have a computer program look at the image resolution values in the photo meta data. My Canon camera always puts a value of 72 DPI into both the RAW and JPEG files. If I edit the photo with Canon DPP free to download software, then DPP changes that value from 72 to 350. It might be that the only edits one would want to do are to crop, white balance, and digital lens optimizer, but the value would still change from 72 to 350 when a photo is saved. So, an easy way to change this value is to edit the photo, JPG or CR2, in the Canon DPP program and save it.

The free software exiftool program will display or change the value in the metadata. Changing the DPI value will not change the image, but in ancient times it would have changed how some web browsers displayed the image and how some programs printed it. https://exiftool.org/

exiftool -G0:2 -xresolution -yresolution -resolutionunit IMG_6277*
======== IMG_6277c.JPG
[EXIF:Image]    X Resolution                    : 350
[EXIF:Image]    Y Resolution                    : 350
[EXIF:Image]    Resolution Unit                 : inches
======== IMG_6277.CR3
[QuickTime:Image] X Resolution                  : 72
[QuickTime:Image] Y Resolution                  : 72
[EXIF:Image]    Resolution Unit                 : inches
======== IMG_6277cs.JPG
[EXIF:Image]    X Resolution                    : 350
[EXIF:Image]    Y Resolution                    : 350
[EXIF:Image]    Resolution Unit                 : inches
======== IMG_6277.dr4
======== IMG_6277.JPG
[EXIF:Image]    X Resolution                    : 72
[EXIF:Image]    Y Resolution                    : 72
[EXIF:Image]    Resolution Unit                 : inches

Re: Canon EOS Rebel T7 Question

johnrmoyer — Sat, 09 Sep 2023 11:43:39 GMT

I re-read your question. I hope some of this might be helpful.

It is not clear to me whether you are selling the original art or are selling prints. I had previously guessed you were selling prints and the marketing site was doing the printing.

If selling the original art, then if the work is 20 inches by 30 inches, the photo would need to be 6000 pixels by 9000 pixels to have a 300 dpi digital copy of the original. Depending upon the marketing software, then one might be able to zoom in on the digital image to see brush strokes.

Since the Rebel T7i can produce an image of 6000x4000, if you had no margins this could sample an original art work at 300 dpi for a size up to 20 inches by 13.33 inches in a single image. If cropping margins from the photo or if the original is larger, then it would be necessary to stitch multiple photos together.

One could create a 6000x9000 digital image from photos made by a camera that has less resolution by stitching together multiple photos. I use the free hugin software to stitch images together.

Re: Canon EOS Rebel T7 Question

Waddizzle — Sat, 09 Sep 2023 13:24:41 GMT

“ The free software exiftool program will display or change the value in the metadata. Changing the DPI value will not change the image, but in ancient times it would have changed how some web browsers displayed the image and how some programs printed it. https://exiftool.org/ “

Changing DPI should change how an image is displayed on a monitor. Displaying an image on a monitor mean you use a different device Type. Printers and Monitors have the same base class and share the same interfaces.

Re: Canon EOS Rebel T7 Question

Waddizzle — Sat, 09 Sep 2023 15:57:23 GMT

This is what "Image Resize" dialog box looks like in Paint Dot Net.

Thre is a siimilar dialog box for "Canvas Resize".

Re: Canon EOS Rebel T7 Question

johnrmoyer — Sat, 09 Sep 2023 16:00:19 GMT

In ancient times, changing the DPI in the metadata would for some software change how the image is displayed on the screen. I cannot think of any software that would do that now. Do you have an example?

It has been over 30 years since I wrote a printer driver and I do not know much about modern software for printing. I might guess that modern software might look at paper size and pixel resolution before resizing the image for print and ignore the DPI in the meta data. Is that not the case?

Re: Canon EOS Rebel T7 Question

rs-eos — Sat, 09 Sep 2023 16:49:34 GMT

macOS to this day (ever since Mac retina displays existed).

All screenshots captured on my Mac prior to having a retina display (that I still have stored) display as having 72 DPI when looking at properties within the Preview application. All screenshots taken though when you have a retina display will be marked with 144 DPI.

So when displaying screenshots now on my Mac with 5K display (retina) in Preview:

If the image was older (2560 x 1440 at 72 dpi), when viewed at 100% it fills my entire screen. Each pixel in the image is backed by four physical pixels on the display.
If the image was newer (5120 x 2280 at 144 dpi), when viewed at 100% it also fills my entire screen. Each pixel in the image is backed by a single pixel on the display.
If modifying the DPI in a new screenshot to be 72 dpi, then viewing that at 100%, only a 25% area section can be viewed at any given time on my display. Each pixel in the image is now backed by four pixels on the display.

Re: Canon EOS Rebel T7 Question

rs-eos — Sat, 09 Sep 2023 17:00:31 GMT

While not specifically tied to DPI values in images, other examples of where DPI values of your display are used:

When doing Apple device development and running things in simulators (e.g. iPhone simulator), there are now three different modes to have the virtual device displayed on your Mac. Some of the modes take not only the DPI value of the simulated hardware, but the actual DPI value of your display:

Physical size. The simulator window would match a real-world device size (e.g. iPhone 14 Pro)
Point accurate. This gets complex as on a retina Mac display (@2x display), you can have simulated @1x, @2x and @3x devices. It's easiest to understand when both the Mac's display and simulated device are both the same scale (e.g. @2x). So each "point" on both will be the same exact quantity.
Pixel accurate. Each pixel on the simulated device is backed by a single pixel on the Mac display.

Finally, Adobe Illustrator has a "Display Print Size at 100% Zoom" setting. When enabled, any document viewed at 100% size on your display will also be the real world size. e.g. for US Letter, I can hold up a US letter sheet to my display and it matches perfectly.

Re: Canon EOS Rebel T7 Question

johnrmoyer — Sat, 09 Sep 2023 21:01:50 GMT

I do not think I understand what you are saying about macOS. Maybe I have changed some settings?

I have a 2019 iMac with a 5120x2880 display. The same JPEG will display the same in Preview.app whether the meta data says 72dpi or says 350dpi when I select view actual size.

When I view an image on my iMac in Chrome, Firefox, or gimp and zoom to 100%, it is displayed pixel for pixel with no reference to dpi. First image is coyote face screen shot from preview displaying out of camera JPG with 72 dpi in the metadata.

Second image is same photo and has been edited in Canon DPP and saved as a JPG with 350 dpi in the meta data, a screenshot viewed in preview at actual size.

I conclude that the value in the meta data is ignored. There is apparently the same number of pixels on the coyote face if I had cropped the screen shot the same. (I remember software in the 1990s that would use a bad algorithm to scale any image that was not 72dpi before displaying it)

Re: Canon EOS Rebel T7 Question

johnrmoyer — Sat, 09 Sep 2023 21:20:14 GMT

@rs-eos wrote:
While not specifically tied to DPI values in images, other examples of where DPI values of your display are used:
When doing Apple device development and running things in simulators (e.g. iPhone simulator), there are now three different modes to have the virtual device displayed on your Mac. Some of the modes take not only the DPI value of the simulated hardware, but the actual DPI value of your display:
Physical size. The simulator window would match a real-world device size (e.g. iPhone 14 Pro)
Point accurate. This gets complex as on a retina Mac display (@2x display), you can have simulated @1x, @2x and @3x devices. It's easiest to understand when both the Mac's display and simulated device are both the same scale (e.g. @2x). So each "point" on both will be the same exact quantity.
Pixel accurate. Each pixel on the simulated device is backed by a single pixel on the Mac display.
Finally, Adobe Illustrator has a "Display Print Size at 100% Zoom" setting. When enabled, any document viewed at 100% size on your display will also be the real world size. e.g. for US Letter, I can hold up a US letter sheet to my display and it matches perfectly.

It has been a very long time since I used any Adobe software, but I remember specifying DPI when writing a PDF. I understand scaling to display the entire image, but I do not expect that scaling to depend upon the dpi number recorded in the meta data. I understand print preview showing the paper size, but the paper size does not depend upon the dpi value in the image meta data. The dpi is either set by the printer and the image is scaled to that value, or the image is cropped or the image does not fill the paper. I understand the need to know the dpi of the display or the DPI used by the printer when choosing elements like fonts or icons along with an assumption of viewing distance.

At some point in the past, I also understood image handling in CSS and HTML ( https://drafts.csswg.org/css-values/#resolution ) where assumed viewing distance is considered ( https://www.w3.org/TR/css-values-4/#reference-pixel ) .

Re: Canon EOS Rebel T7 Question

rs-eos — Sat, 09 Sep 2023 21:34:22 GMT

It's probably because you chose an arbitrary 350 value. I provided the full details regarding 72 vs 144 values which indeed drive different results.

Re: Canon EOS Rebel T7 Question

Redsed — Sun, 10 Sep 2023 19:11:38 GMT

This is what I'm looking at from my marketing company.

Re: Canon EOS Rebel T7 Question

Redsed — Sun, 10 Sep 2023 19:17:17 GMT

Wouldn't let me copy/paste but here's what they said. If you're Starting with photographs of your art, you can determine roughly how large you can print your images using this chart. Just find the resolution of your image , then compare it with the height and width to get a rough estimate of the print size at 300 dpi.

My problem is that I cannot find the settings for my camera to shoot at 300dpi.

Re: Canon EOS Rebel T7 Question

Redsed — Sun, 10 Sep 2023 19:19:21 GMT

But how do I set my camera to get that resolution? They want me to have every photo at 300dpi to be able tto print several different sizes of prints.

Re: Canon EOS Rebel T7 Question

Anonymous — Sun, 10 Sep 2023 20:01:57 GMT

There are no settings in the camera to shoot at 300 DPI. Your camera can record up to 6000 x 4000 pixels in L JPEG or L RAW. That is the highest resolution that your camera can provide. There is no DPI setting in the camera. The largest photo that you can print at 300 DPI is 6000/300 = 20 inches by 4000/300 = 13.3 inches. How large of a print in inches do you require? That will tell you the DPI of your print, by using the formula below.

Pixels divided by inches = DPI
or
Pixels divided by DPI = inches

So you can see it is dependent on the number of pixels and the desired print size. The only setting in the camera that affects DPI is the resolution that you select in your camera's settings. Choose Large (L) JPEG or (L) RAW to allow for the largest prints.