EF 75-300mm f/4-5.6 IS USM

[bigchef920]

I just bought this lens from B&H. I haven't had the opportunity to really use it though. I have been working a lot & the weather down here in FL has been pretty rainy. I did mess around with it the other night at my apartment complex & took this shot of the fountain out back. I am very new to SLR photography & have been learning a lot very fast. This shot was taken with a 30 sec. exposure at f/20; ISO100;120mm. I love the exposure effect on the fountain & the clarity of the background.

Could someone please explain ISO to me. I am using the Rebel XT which can be set from ISO 100 - 1600. I would really appreciate some teaching. Thanx.

Rob

[sparker1]

Very nice shot. Where are you chef? I grew up in Jacksonville, go back occasionally.

[bigchef920]

I work at a hotel on Amelia Island. I checked out your gallery. Awesome!!! Love the pics of the Main Street Bridge.

Rob

[bikerider]

Very nice photo and particularly since you stated you're new to your equipment, keep up the good work.
Roger.

[Music to my eyes]

With respect to ISO.......I can give you a non-technical explanation - ISO in a camera is like a rating of how sensitive the film/sensor is to light. The low numbers (50, 100 for example) require a lot of light to expose the image. So normally those ISO's are used in bright conditions - eg., daytime. Usually at low ISO's, the noise/graininess of an image is very low, so you get better picture quality (smoother)......but the trade off is that you need slower shutter speeds or wider apertures to allow more light to expose the image properly. This explains why you needed 30 seconds to expose the fountain and houses correctly....OK for still objects, but obviously a lot of blur for moving ones. If you increased the ISO to 200, you could reduce the exposure to 15 secs. If you increased ISO to 400 the shutter speed would drop to 7 secs......and so on
(At least, that's my understanding of it..........)
High ISOs like 1600 and 3200 means it's much more sensitive to light. It requires much less light to expose the image correctly - so these are usually used at night or in low-light conditions - eg., indoors. The trade off is you get more noise at higher ISO's. So pictures look more grainy/less smooth. The benefit is that you can have much faster shutter speeds - so better for moving subjects, for example. And also better when using longer lenses which accentuate the need for faster shutter speeds. (Rule of thumb: 1/focal length of lens= shutterspeed - to obtain shake free handheld pics)
A good way to learn about all this is to put your camera into manual mode and play with the settings.......ISO, shutter speed and aperture. As you increase one value, you will need to reduce another to compensate to maintain correct metering. eg - meter an object in your lounge room in P mode (program.) Note the settings. Then change your camera to manual mode. Choose the same aperture and shutter speed as what it did, but then change the ISO value - watch the picture get lighter or darker as you change the ISO and take the shot. If you are getting to much shake/blurring in the image, you'll either need to up the shutter speed, the ISO or open up the aperture (lower number value)....... But changing each one has a slightly different effect......
eg., INcreasing ISO may produce more noise, increasing aperture reduces depth of field......etc...
Hope that helps, rather than confusing you!
It would appear you understand quite a bit already from the shot you took. Nice long exposure.
Look forward to seeing more!

(-And if I'm spouting nonsense, someone please correct me! Haven't tried to explain this to someone before))

[bigchef920]

That was a very, very, very helpful explanation. Thank you sooooooooo much for taking the time to type all of that for me. I got the chance to do some real shooting today with the new lens, as it was my day off & the weather down here in Jacksonville, FL was pretty nice, and HOT! Here are a couple of my favs from Guana River State Park, FL. I hope I don't offend anyone by them not being landscape photos. Sorry if I do!!!

[Music to my eyes]

No worries at all. Glad it helped.
Those 2 nature pics are excellent. I especially like the bee!
Looks like the lens is a good investment - which lenses are you shooting with??
edit: Never mind - just saw your post in another thread.
I have the 75-300 IS as well.......not a bad allrounder, but most feel it is pretty soft compared to lenses like the 70-200 f4l. But the reach is nice. And the IS lets you pull off shots you never thought you'd get.... :)

[bigchef920]

Very nice photo and particularly since you stated you're new to your equipment, keep up the good work.
Roger.
Thanks Roger!!!

[jfrancho]

I believe each stop of increasing ISO, buys you one stop of light. For example, if you are shooting at ISO 100, at a certain aperture, but do not have enough shutterspeed for the focal length, or subject movement, you can open the aperture one stop, which change your depth of field, or increase the ISO by one stop to 200, without changing the DOF. Basically, ISO, shutterspeed, and aperture are the "trinity" of proper exposure.

[bigchef920]

I believe each stop of increasing ISO, buys you one stop of light. For example, if you are shooting at ISO 100, at a certain aperture, but do not have enough shutterspeed for the focal length, or subject movement, you can open the aperture one stop, which change your depth of field, or increase the ISO by one stop to 200, without changing the DOF. Basically, ISO, shutterspeed, and aperture are the "trinity" of proper exposure.
Thanx JF.

[bigchef920]

I had to get this before the 3 fountains in the middle of the lake get turned on, usually around 7:30am. I really like the clarity of the reflection.

[bigchef920]

Here a 2 of the fountains I mentioned previously.