Why no Focal Length? - DPChallenge Forums

Canon EF 70-300mm f/4.5-5.6 DO IS USM

07/14/2005 10:29:52 AM · #1

Ok, we now have lenses and I love that feature (hoping everyone starts using it!).

At least one piece of EXIF info is missing from the metadata we store with our photos on DPC: focal length. When using a zoom lens, what focal length were you set to?

I know it can be put in the comments, but, for example, when I see a photo listed from a 100-400mm lens, I'd like to know the focal length along with the other broken out data about the equipment.

cpanaioti

Canon EOS-40D

07/14/2005 10:33:17 AM · #2

I second that idea.

EddyG

Canon EOS-1D Mark II

Canon EF 70-200mm f/2.8L IS USM

07/14/2005 10:36:26 AM · #3

The focal length is only meaningful if the image is uncropped.

Someone listing the focal length as "50mm" and then cropping the image tightly could end up with an image that represent the equivalent FoV of a 200mm focal length...

Canon EF 70-300mm f/4.5-5.6 DO IS USM

07/14/2005 10:39:29 AM · #4

Originally posted by EddyG:

I am not trying to "replicate" their shot, but it helps to see what focal length the lens was set to from a performance standpoint. A 70-300mm at 300mm performs quite differently than it does at 150mm.

Message edited by author 2005-07-14 10:39:54.

cpanaioti

Canon EOS-40D

07/14/2005 10:40:57 AM · #5

Originally posted by EddyG:

Very true, you can't trust people to only enter the focal length if they didn't crop the original image. (I still would like to see it)

pawdrix

Nikon D700

Nikon AF Nikkor 85mm f/1.4D IF

07/14/2005 10:42:59 AM · #6

I've been very curious, many times to see or get an idea, how much an image was cropped.

This image has that information and I was surprised to find out that it wasn't a taken with a macro lens.

Message edited by author 2005-07-14 10:43:16.

EddyG

Canon EOS-1D Mark II

Canon EF 70-200mm f/2.8L IS USM

07/14/2005 10:46:10 AM · #7

Originally posted by nshapiro:

it helps to see what focal length the lens was set to from a performance standpoint. A 70-300mm at 300mm performs quite differently than it does at 150mm.

Of course, I feel compelled to point out the silliness in evaluating any sort of "performance" data (camera or lens) from a 640px (maximum) image, which could have been significantly processed -- via in-camera settings, post-shot editing, or both. With your Rebel XT, a 640px shot represents about 20% of the pixels in the source image. That is a LOT of data to disregard in terms of "performance evaluation", and that's just raw pixels, not even talking about all the pixel-pushing that could have occurred to "enhance" the image...

Message edited by author 2005-07-14 10:49:10.

Panasonic Lumix G 14mm F2.5 ASPH

07/14/2005 10:50:36 AM · #8

Originally posted by EddyG:

Originally posted by nshapiro:
it helps to see what focal length the lens was set to from a performance standpoint. A 70-300mm at 300mm performs quite differently than it does at 150mm.

Of course, I feel compelled to point out the silliness in evaluating any sort of "performance" data (camera or lens) from a 640px (maximum) image, which could have been significantly processed -- via in-camera settings, post-shot editing, or both.

Yes, I knew you were going to say that :-), but the same is true for ISO, aperture, and to a lesser extent, shutter speed, at least (or especially) for advanced editing where aspects affected by these can pretty easily be altered.

So I'll just say, from my point of view, it's just more information about the photo parameters, and it's of interest to me. Anyone else who would like to see it, just chime in.

Olyuzi

Panasonic Lumix DMC-GX7

07/14/2005 10:51:06 AM · #9

I'm all for seeing the focal length used as it helps me to confirm the perspective distortion that I see in the image.

EddyG

Canon EOS-1D Mark II

Canon EF 70-200mm f/2.8L IS USM

07/14/2005 10:56:10 AM · #10

Originally posted by nshapiro:

I should have made it clear that I would also like to see the focal length as part of the "shooting data" -- just that its use as a "performance evaluation" datapoint would be limited.

That being said, I'd actually like to see the ISO, aperture and shutter speed data be required for all images uploaded to DPC, challenge or not. There are far, far too many pictures where this data is not entered by the photographer. (There could be a checkbox labeled "Data not applicable to this non-photographic image" for times when you want to upload a chart, screen shot, etc.)

Message edited by author 2005-07-14 10:59:05.

hopper

Canon EOS-80D

Canon EF 35mm f/2 IS USM

07/14/2005 10:57:54 AM · #11

i don't remember exactly, and i'm at work so i can't check - but I know that i never crop smaller than twice the allowable pixels for this site - so this shot has at least (and probably exactly) 1300 pixels across before resizing - so you're only looking at 43% of the image.

...roughly

looks cool though :)

Originally posted by pawdrix:

I've been very curious, many times to see or get an idea, how much an image was cropped.

This image has that information and I was surprised to find out that it wasn't a taken with a macro lens.

strangeghost

Canon EOS-7D

Tamron SP AF 28-75mm f/2.8 XR Di for Canon

07/14/2005 11:13:30 AM · #12

How about just a drop-down that asks for crop info:

Crop:
None
Very minor crop
Significant crop (~50%)
Major crop

Or something similar. I like it when people post their original after the challenge. You can see the impact of their post processing and how much of the original was removed.

coolhar

Canon PowerShot Pro 90 IS

07/14/2005 11:19:30 AM · #13

Originally posted by EddyG:

... That being said, I'd actually like to see the ISO, aperture and shutter speed data be required for all images uploaded to DPC, challenge or not. There are far, far too many pictures where this data is not entered by the photographer. (There could be a checkbox labeled "Data not applicable to this non-photographic image" for times when you want to upload a chart, screen shot, etc.)

I wish they would adopt this idea.

It really irks me when people put images into the forums asking for feedback but are too lazy to include the exposure data with their upload.

I would even go so far as to say that it would help people to become better photographers if they were forced to go back to their original image files and see what settings they used.

mcrochip

Pentax K20D

Tokina AF 28-80mm f/2.8 AT-X 280AF Pro for Pentax

07/14/2005 11:20:37 AM · #14

I like this idea, if for no other reason than learning about DOF and such. On the other hand, not all cameras/lenses report this information. I have a Pentax SMC-A 50mm Lens... so yes, the length is always 50mm in this case. However, this is a manual lens and does not report the focal length; I am looking at other used lenses, as some of those have far better optics than many of the new lenses available. Making the information available would be great. Making it a requirement, maybe not so much.

I do agree, however, that ISO,f/xx,shutter should be required information. If nothing else, it reminds the submitter to read/confirm their EXIF information.

-Steve

Keith Maniac

Canon EOS-350D Rebel XT

Sigma 30mm f/1.4 EX DC HSM for Canon

07/14/2005 11:25:19 AM · #15

I would love to see focal length info. added! I think it would be very useful/helpful. I sometimes add it to my pictures under "photographer's comments", but it would be nice to have an "actual focal length" field with all the other info (aperture, shutter speed, etc.)