35mm Equivalent

[cslr_challenge]

I've noticed some pictures are marked with a 35mm equivalent. Ignoring whether this should be included at all (in my opinion, it should not, or should be displayed based upon photographer preference), I notice that some pictures show an erroneous value. For example, take http://www.pbase.com/cslr_challenge/image/65965186 . This picture was taken with a Canon 5D, which is a camera with a full frame sensor. Therefore, the 35mm equivalent should match the actual focal length.

Is this a pbase bug of some kind?

-- Victor

[clarkerobinson]

Seems like images I upload today from my Canon 350D are getting crazy high 35mm equivalent readings, not very useful. Also, when we upload pics from smaller digicams, this info isn't included at all (which could be useful for small digicams).

So, it's not just you.

Clarke

[bobfloyd]

I am not seeing it with my Konica Minolta 7D. Maybe it is something odd that Pbase is picking up in the Canon EXIF? Just a thought.

[marcocelio]

Seems like images I upload today from my Canon 350D are getting crazy high 35mm equivalent readings, not very useful. Also, when we upload pics from smaller digicams, this info isn't included at all (which could be useful for small digicams).

So, it's not just you.

Clarke

same here!

Canon EOS 30D
1/320s f/5.6 at 135.0mm (35mm equivalent: 740mm) iso100

i wish i had that focal!

[nelsonc]

It could be caused by jhead that PBase is using. See this thread for more detail.

http://forum.pbase.com/viewtopic.php?t=23641

This problem seems to only show up for Canon DSLRs. Since the author of jhead is not going to fix it, it should not be too hard for PBase to just filter out those wild focal length equivalent strings for Canon DSLRs.

The following is a list of Canon DSLRs which is not very long.

1.6X bodies: D30, D60, 10D, 20D, 30D, 300D, 350D, 400D
1.3X bodies: 1D, 1D Mark II, 1D Mark II N
FF bodies: 1Ds, 1Ds Mark II, 5D

[boliston]

I'm not sure the "35mm equivalent" would mean much to most people apart from people who have grown up with film.

I only really got interested in photography since digital and am a Nikon user so I tend to think in terms of what a focal length will look like on a 1.5x sensor.

[mfurniss]

This "35mm equivalent" feature is obviously broken and should be removed from pbase. It sucks that I now have to manully edit each upload to fix the info. Pbase, please fix or remove.

[melaniekipp]

Yes, please remove it. My Canon 5D's exif data is now incorrect.

[roamermark]

Clearly this function doesn't work at all. I had no idea that I had a 1600mm lens!!
Fix it or remove it until it is ready as it makes me look foolish

[lightrae]

Don't "fix" it!!!! Dump it fast!!!
This 35mm equilivent is foolishness that marketers use to snare the ignorant, just like the optical/digital zoom crap that caught so many in the early days of digital.
Each lens is marked by the manufacturer with its basic information. Leave at that and save us the annoyance of removing that "equilivent" crap from every image.
Camera sensors are various sizes, so conversion factors vary also. The photogs that want ACCURATE numbers can easily plug in their own calculations, just like you would have to do when using a multiplier.

[ctfchallenge]

I just did a quick series of tests.

Downloaded the Jhead code and looked at the exif from an image straight out of the camera. The 35mm equivalent was correct for the lens and crop sensor.

Then I took that same image, cropped it with PS and saved a new version. Ran Jhead again and got a new 35mm equivalent - which appears to mathematically correlate to the crop of a crop sensor image!

Anyone else try this -- especially with a FF Canon?

[ctfchallenge]

Just did a couple of more tests... changing the resolution of the image will change the 35mm equivalent even without cropping.

[goislands]

Don't "fix" it!!!! Dump it fast!!!
This 35mm equilivent is foolishness that marketers use to snare the ignorant, just like the optical/digital zoom crap that caught so many in the early days of digital.

You are confused!

The 35mm equivalent is one of most useful methods allowing to compare
effective focal length of lenses regardless different sensor sizes. Using a
focal length for a specific size of frame is de facto like obtaining the
same view angle. It is just so, that we are so used to the 35mm focal
length and its view angles attached to the focal length in mm, that we can
keep these values as a reference, at least for the time being. Maybe in the
future the "35mm focal lenght" will lose its usefulness. For now I prefer to use
"400mm" isnstead of (say) "3.135 degree lens" or something like that.

[nickdemarco]

Yes FIX IT or DUMP IT soon. Just uploaded a 5D pic today to be told it's equivilant was over 3 times it's equivilant. Stupid. Was going to make a thread about this but then found this one by accident!

[thejerk]

I am not seeing it with my Konica Minolta 7D. ...

I do not see the problem with my 7D either.

Regards Bill