What use is EXIF?
 

From time to time I get asked questions like: There is no EXIF data with the file what exposure did you use?

Its a question I don't really understand. I mean even if I tell you that a particular shot was taken at 1/100 sec at f8.0 what useful information does that convey? Similarly if one knows that an image in the gallery was taken with a Dodo 100-300 zoom XT lens, what use is that?

My personal opinion is that, despite the fact that such data gets pasted by rote into all photographic books and magazines, it is for the most part useless noise.

Can anyone tell me what practical use it actually has.

EXIF is data tagged to the image file. Data recorded is mostly about the camera settings that were used to take the picture, hence the question you quoted. 'There is no EXIF data with the file what exposure did you use?'

I think this site sums the EXIF situation quite well.

http://www.exif.org/

a joy of WPF is learning from other people wiling to share their knowledge rather than keep it close to their chests. I have found it very useful knowing what camera, speeds etc have been used and what proportion of the frame is actually represented. I hope it shows in what I see as a huge improvement in my pics since I joined, and now helps in passing on what I have learnt to newcomers who one recognises as taking the earlier steps on the path.

I also post occasionally on WildAboutBritain where the exif is jumbled and that is one of the reasons I have gradually spent less time there and more here :)

Perhaps I wasn't clear, but I do know what EXIF is. What I don't understand is how it can be considered useful to anyone? What use can the exposure data for this

http://www.fotograffiti.it/albums/An..._Mountains.jpg

or any other photo be put to?

Seems Chris posted while I was typing so I'll go with what I have written. Sorry if I repeat anything Chris.

On the forum I find them interesting. It is not that I intend to memorise and copy them for a given situation. However I did use some as a starting point for my first moon shots.

Examples :

I always read Foxy's and have come to greatly admire the capabilities of his D2Hs. Now is there any benefit in that. YES. If I contemplated getting that camera, and I very nearly did but opted for the D2X instead. Once again Foxy's images amongst others helped sway that decision.

Similarly Leifs images. Leif is a Nikon man the same as me. I looked at his pics taken with the Nikkor 200mm macro and have compared bokeh with shots posted with the 105mm VR macro. If I was in the market for an upgrade of my macro then his pics would probably swing me towards the 200mm.

If I was thinking of attending an airshow, and we have talked prop blurr in posts before, then I would do a trawl through the gallery to check out approprite shutter speeds. I could say the same for blurring water over a fall. These are things I do not have in my head. Give me a subject and a flashgun or two and I don't even have to think about anything. Others however may.

Generally creative use of focal length, shutter speed or aperture is something that the exif can show up. Some of Robs images to name but one of several fit that bill.

On the fun side how will I know someone is posting images with an undeclared new toy.

Outside of the forum then I am helping Ros. She is currently using the camera in simple program mode until she can digest and make sense of info on the relationship between shutter speed, aperture and ISO. Without the exif to refer to on pics she e-mails me then I would have no idea what shutter speed and aperture settings the program selected to be able to offer advice. So if the picture is blurred, was it incorrect point of focus, or too low a shutter speed for the focal length used, possibly agravated by a low an ISO setting. All info in the Exif. Without going through the Critique Forum I am sure there are pics posted where that same info has been helpful in someone providing reasoned help.

Don

It is very useful to learn from. Say I take a macro shot but there is not enough depth of field I can look at the data and know that next time what f stop would be better at that distance and with that lens or perhaps I want to know what shutter speed I used on that pan shot that worked so well. A helpful tool to build up experience and knowledge with.

No exif in that, but as its Ansel Adams then he was probably using a 10 x 8. A google of Ansel throws up thee images at the top of the page. Now if you look at the middle image aperture would certainly be interesting and that would probably be f64. So I have guessed at 10 x 8 camera and an aperture of f64 but if you were into that format then the lens used might also be of interest. Also dare I mention film type.

No exifs in those days. You had to buy his books and I did. Did I learn anything ............. I hope so. ;)

Don

Don,

The problem though is that if he took the photograph 10 minutes later or earlier the exposure would have been different. In addition we're not seeing the PP work that went into producing the image, the time the plate spent in the developer, the type of developer, or the dodging and masking involved in the printing. In addition to exposure being situational and transitory, we have no idea where he took the reading from, nor whether he overrode what the meter told him.

What you say is absolutely correct but... even without the exif we can say that he used a small aperture (because of the depth of field) and slow shutter speed (because of the movement in the cloud). If his intention was depth of field, then an exposure 10 minutes earlier or later would have had the same aperture but a different exposure time. Conversly, if his intention was a certain degree of movement in the clouds then his exposure time would be fixed and nthe aperture varied.

If someone wanted to take a shot similar to the one I posted of water moving over rocks the exif tells us that this was taken at 1/13 sec. OK some rivers move faster or slower but it gives someone else a starting point. Similarly to freeze the action at the Appleby horse fair I used a 1/500 and to get this perspective in Victoria Square I used a 10mm lens on a 1.6 crop factor body.

I cant remember all that sort of information but the exif records it for me so I can learn for the future, and help others. Now OK Ansel Adams didn't have the luxury of cameras that encoded the exposure info into his negatives, but I wouldn't mind betting the he, and other greats of the times, kept records of how their images were captured.

Post processing, whether it be in the dark room or digital, can affect things like the brightness, or contrast the image, but they cant change perspective (lens choice) or depth of field (aperture - unless focus stacking is employed) of freezing of action (shutter speed)

At the back of my mind (from some 25 years ago) I recall blurry water 1/4 second. But as you say it all depends on the rate of flow, and the amount of blur required. Go back a month later and the flow rate will have changed, the light and mood will be different and a different length of time will be optimal for the moment. So you bracket on length of time, you're not going to set up camera and tripod dial in 1/13 second press the shutter and pack up.

I don't know, perhaps there are novices that look at EXIF data to use as a starting point, but I suspect they're more likely to have got a book on photographic technique out of the library, which has told them: blurry water long shutter speed.

I suspect they are also more likely to read "landscape photography: set white-balance to cloudy" than to ascertain that from EXIF data.

We appear to be discussing two different aspects of photography here, firstly the whole creative process, including post-processing as suggested by walwyn's Ansel Adams example, and secondly, the usefulness of basic capture information that can be used as a learning tool by the amateur and beginner.

Certainly I used to keep records in a notebook of settings used for a specific reel of film if I was trying to learn a particular technique or effect. It was the only way I could really learn about how much impact the settings had on the final image when I got the film back from the lab, I had to be very careful that the prints stayed in order until I'd annotated the settings on the back of the prints. This wasn't the norm for me, I used it to help my learning process. If I change the aperture by one stop, really, how much impact does that have on the DoF for that particualr focal length? Likewise, how slow do I need to set the shutter to freeze the motion of a particular subject?

This is the great benefit of EXIF, all the information I need is readily to hand. Certainly, as Mrs Y has taken up the camera again after a break of a few years, it has helped her learn about the effect of the basic settings used.

So, you can dial in the same camera settings, take two identical captures, post process (film or digital) to your heart's content, and produce two very different pictures with identical EXIF (or notes in film photographers notebook). In this case, the settings may not be of much value - though Clive's excellent reply shows that regardless of post processing, it is of some value.

It's an excellent resource for learning the craft, I'd hate to be without it.

Regards,

Duncan

Perhaps we should have a poll on who takes any notice of EXIF data. I must admit that I've never keep any records of shots. The only time I have look at other peoples EXIF data is when considering a new lens purchase.

Unfortunately Neat Image strips out the EXIT data as part of it's file size reduction process.

Huh? What version of Neat Image are you using? Must be right out of the Stone Age., Robski, as Neat Image has preserved EXIF info intact for ages - long as I can remember, in fact.

Back to the original topic: agreeing with pretty much everyone in this thread (except Walwyn), shooting info is not just of practical use from time to time, but of genuine interest a lot of the time too.

My free version of Neat Image strips EXIF data.

It was one of the reason's I paid for a copy of NeatImage, the other being the tiff output. Unfortunately some other piece of software I use also strips the EXIF when saving to tiff, which is normally the first thing I do. Oh well.

Back on topic. I can see how the EXIF data might be useful in controlled situations. Back in the early days I sort of took notes too, because that is what you were supposed to do. But I never found it that useful when you were out in the 'wild' what was best last week in the Mendips isn't necessarily true this week on the Norfolk Broads. That's why you'd bracket the exposures, back home you may find that the 'over exposed' shot was better than the others, perhaps it was the 'under exposed' one, or the 'correct' one, but damned if a day or two later I could ever remember what the exact circumstance might have been that made one better than the others. You can see the same thing happening in Clive's Appleby photos, some are at 1/800 some at 1/500, whether its done manually or automatically by the camera, there is a degree of bracketing occurring on shutter speed. Which I think is the most important thing of note, but nothing in the EXIF for an individual photo tells you that.


I have photographic books and magazines on my selves, underneath each photo is stuff like 1/100 f16, and I've always felt so what? What if it had been taken at 1/200 f16, perhaps that would have made a better image, or perhaps if he was better at panning he'd have been able to use 1/250 instead of 1/500.

A lot has been made in the thread about novices being able to work out how to do things by examining someone's EXIF data. Which presupposes that the novice knows how to read the EXIF and what it is telling them. I'm pretty sure that if one of my non-photographic savvy coleagues asked me how do you get blurry flowing water and I replied 'Look at the EXIF in this photo.' I'd get a pretty sharp response.

Quite so, Walwyn. I think the info for novices theme in this thread is overdone - though there is some point to it. For me at least, it's more about interesting (but admittedly non-vital) info for people with some experience. I'm not sure what proportion of shots I want to see the EXIF info for, it's maybe one time in three that I ask myself the what camera, what exposure settings, what lens questions.

Actually, now that I think about it, the pictures I most often want to see the shooting data for are the bad ones! As Tolstoy observed (well, about families rather than photographs, but same thing) in a way good pictures are all alike - but bad pictures all have their own particular problems.

Edit: from EXIF data to Tolstoy in a single post. Dear or dear - I think I should get out more.

Edit #2: I forgot to mention Neat Image. And I forgot that the demo version doesn't save EXIF - well, it doesn't save TIFFS either, both of which are fair enough given that it costs you nothing. Can't give away the crown jewels.

where can i get a demo for this neat image malarky. evenry one seems to go on about it? is it better than photoshop or is it the poor mans Ps?

http://www.neatimage.com/

It just does digital noise reduction and sharpening. But it does it very, very, well.

My procedure is:

1) read data from camera.
2) delete stuff I don't want to keep.
3) repeat 2
4) Load image into editing software.
5) Save a copy as tiff.
6) Process tiff in neatimage and save result under different name.
7) Back in editing software crop, alter levels, contrast, saturation.
8) Save result
9) Resize for web and save again as jpg.

cheers matey

I don't look at the EXIF for other people's shots very often but lately I have been looking a bit more. I've been trying to get good shots of hummingbirds and having poor success. The ruby colour of the males is coming out black and the overall colour is not what it should be. Then there is the issue of whether the freeze the wings or not. A very specific issue, so I've been looking at the EXIF data of hummingbird pictures that I feel are very good to get a clue as to where I'm going wrong.
I also find it useful to look at the data for my own stuff just to try and work out where I went wrong (or right0 for a specific picture.

looking at the EXIF info, I see Jamie uses a D50 and probably doesn't need the NeatImage software for noise reduction (in fact from his last pic, maybe he needs a noise-inducer ;) ), whereas Walwyn uses a Pana FZ30 and maybe sometimes does.

NeatImage is as useful for sharpening, which it does more subtly than 'unsharp mask' and can be used for that with noise reduction sliders left zeroed. It is a complement to PS not substitute, in fact often as not the layer it is used in can be pulled back to say 60% opacity to just give a slight 'edge' but avoid halo etc.

Of course, if you really want to go overboard with EXIF data, there is this utility. It even tells me what temperature my camera was at when I took the picture, what date my camera was manufactured, and a whole load of other stuff (apparently).
http://www.photome.de/home_eng.html

That looks like an great program for getting more information from the camera, I will download and have a nosy. Thanks Duncan.