F-Stop vs Aperture??

[Steve Kendrot]

I was reviewing some disappointing sunset photos I took with my Canon 10D/28-105 1:3.5-4.5 II USM the other night.  I mostly underexposed the shots, but I was hoping to get some nice crisp shots of pines silhouetted against the setting sun. In trying to figure out why my shots were fuzzy (not out of focus per say, just not crisp...is that soft?)I looked at the EXIF file info to check shutter speed and aperture. The data file lists F-stop and Aperture value seperately. I always thought these terms were interchangeable, but the F-stop value was 22 and the aperture value was 8.9. What's the difference between the two values? I did notice that the difference between the two values was greater with more underexposed images.

So Here's one of the pictures, I'd appreciate some critical feedback...I'm not pleased with it composition or exposure wise so don't be afraid of hurting my feelings here.

 


The setting were as follows:ISO 100. Shutter speed 1/60 (on a tripod)Aperture 6.5 (F-stop 9.5)

As far as the fuzzyness of the  shot goes, what is most likely the root cause? I figure it could be one of (but not limited to) the following:
- Lens quality/poor performance at low light
- Camera shake (not likely with self timer and tripod)
- Wind movement of trees.
- wide aperture/low depth of field
- ISO too slow?
- Focus (shouldn't be as trees were well past infinity)

I'm just learning this digital thing and this series of photos was an experiment in exposures etc.. I'd appreciate feedback, especially from those reluctant to give it after the other thread on Critiquing (Thats you Sackett and Weasel!).

   

[Phil Magistro]

I'm not sure what information Canon provides but my photos, taken with a Nikon camera, show the Exposure - speed and f-stop, and the Max Aperture Value.  But the numbers you posted don't make sense for that.

About the fuzziness, as far as I can tell from the photo, the water in the middle of the photo looks pretty sharp.  What you see as softness could be caused by any of the things you listed but it shouldn't be the aperture at the distance you took the photo and the ISO you used shouldn't have anything to do with it.  You also mentioned wind - that could have moved the camera slightly.  

The lens quality may cause softness but you're not at maximum aperture and most lenses perform better stopped down a bit.  Did you shoot any at other exposures?

Phil

[Weasel]

What focal length was the lens set at?  With the camera on a tripod (and cable release), I probably would have gone f11 or f16.  

Did you sharpen the image in Photoshop? With 72 dpi resolution for web purposes I generally use the UnSharp Mask (USM) settings at 250, .2, and 0. Twice.

[Chad Edgar]

I would guess that you depth of field was limited.  I have seen some f/6.5 with really out of focus backgrounds.  Something I asked a week ago really pointed it out to me.  Different focal lengths will change the depth of field for the same f/.  With your 28-105 lens if you were "zoomed in" creating a longer focal length, you would limit your depth of field.  I THINK!!!  Where's J.G.?

Edit: Well, guess I should have just waited for the Weasel in the first place.

[Weasel]

Does this look better?

[Steve Kendrot]

Heck Yeah Jerry! That looks a lot better. I've not even scratched the surface of photoshop. I find it pretty intimidating and I don't have a good idea of what's wrong with the image and what tools address what issues. Flow of work is another issue. I wind up making willy nilly adjustments just to see what happens and I'm seldom pleased with the results. I'm awaiting CS2 in the mail so can't delay much longer.

I've loked at some of the web tutorials, but most assume a base level of knowledge that I don't seem to have. Any suggested ready on digital processing?

That picture was taken on the wide side of the range. I zoomed slightly to get rid of some foreground clutter. I did take other exposures, but most were more underexposed than this one.

I'll try a higher aperture next time. I was shooting with a higher shutter spead so if any birds flew by they wouldn't be a blob... Too bad you only get about 20 minutes a day to get it right!

Thanks all for taking the time to review my post/picture!

Steve

[Weasel]

Unless you set the in-camera sharpening on high (not recommended) you will always have to sharpen the image in PS.  That's just the nature of the DSLR beast.

I would suggest a basic Photoshop night course at the local community college.  It's usually a one night a week affair for 6 to 8 weeks.  Probably money well spent and something I wish I would have done instead of a couple years of trial and error and picking up bits and pieces of info here and there.

[IB]

Damm... Jerry what can you do with an UGLY WOMAN          

  UPS or Fed-X

[Weasel]

quote:Originally posted by Iron Bull:
Damm... Jerry what can you do with an UGLY WOMAN        :D

[Steve Kendrot]

Dang....I started laughin....til I realized I shoulda been insulted!  LOL

[IB]

Steve.....Weez just made a good shot better        

 I fought that very thing till I got a grasp of PHOTO make it look better stuff also, Still have miles to go but it's sure great when something works.
 Jerry is doing a great job splaining, but we can't tell him, or he'll want to go to moving on us        So we'll just have to whisper about how much help he is .........vance

[paleFace]

steve, if you are using photoshop CS or CS2 go to the bookstore and pick up the book photoshop for digital photographers by Scott Kelby
 http://www.amazon.com/gp/product/0735714118/104-3910457-4884747?v=glance&n=283155.

the latest version is for CS2 but will help you out regardless which version you have.  it gives you step by step instructions on how to do many of the basics that you will need to use on just about all of your images.  also what Jerry said about taking a class at the local CC in photoshop will really get you headed in the right direction.  the class i took was called "digital darkroom".

Rob

[ks chas]

Also F-stop is the shutter speed it determines how long you allow light to go into the camera. Aperture is the size of hole that you allow the light to go through. If you use a slow shutter speed you need a small aperture. With fast shutter you need a large aperture. You adjust depth of field by adjusting shutter and aperture.

[Phil Magistro]

Actually f-stop is the aperture.  If you have a f2.8 lens, the minimum aperture is f2.8,an f4 lens is f4, etc.  Shutter speed is measured in  seconds to fractions of a second - 1 sec., 1/8 sec., 1/15 sec., etc.

The realtionship between shutter speed and f-stop (aperture) depends on variables and what the photographer is trying to do.  I like shooting early and late in the day.  Using  available light quite often I shoot as wide open as reasonable, even to f2.8 with a slow shutter speed. I like to stay in the f5.6-f8 range which means I may have a 10 second or more exposure.

Depth of field is dependent upon the f-stop, not shutter speed.  The only relationship shutter speed plays is if you choose to shoot in shutter priority where the camera would then change the f-stop (and change the depth of field) depending on the speed you choose and the light avialable.  If you shoot in manual or aperture priority you can select the f-stop (aperture). If you shoot in program mode the camera makes both selections - speed and aperture.

Phil