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Old May 30, 2015, 2:53 AM   #1
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Hi everyone! I am a complete newbie. I have been wanting to start getting my feet wet for quite a few years in photography, and only recently have been able to. Any suggestions on books, learning materials, etc. would be greatly appreciated. I am working with a Canon EOS Rebel T5 1200D with 18-55mm f4.5 kit lense and a 75-300mm f4.0 telephoto lens. (Hopefully I put all of that the correct way. I am still learning!) I look forward to reading the different forums, and learning from everyone!
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Old May 30, 2015, 3:54 PM   #2
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I see you're already off to a good start and sharing images in the forums. So, we hope to see you here often.

As for the descriptions of your lenses, almost... It looks you're shooting with an 18-55mm f/3.5-5.6 lens (likely an EF-S 18-55mm f/3.5-5.6 IS STM lens if you purchased a kit), and an EF 75-300mm f/4.5-5.6 lens.

The first aperture number (for example, f/4.5 with your telephoto lens) is the widest available aperture on the wide end of the lens (for example, at 75mm with your 75-300mm), and the second number is the widest available aperture on the long end of the lens (for example, f/5.6 at 300mm with your 75-300mm lens).

IOW, as you zoom in more, the widest available aperture (and wider apertures are represented by smaller f/stop numbers) becomes narrower, letting in less light with those lenses. That's why the f/stop numbers are higher at the telephoto (longer) end (less light gets in, requiring a faster shutter speed for correct exposure with the same lighting and ISO speed).

Some higher lenses can maintain the same aperture throughout their focal range. For example, something like a Canon 24-70mm f/2.8 or 70-200mm f/2.8 (and they have various versions of them without and without IS, etc.).

But, when you see two numbers, they're representing the widest available aperture on the wide end, and on the long end. When you're zoomed in between the widest and longest zoom setting (smallest and highest focal length in mm), then the widest available aperture (represented by a smaller f/stop number) will be somewhere in between the two f/stops you see for a given lens.

BTW, Welcome to Steve's
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Old Jun 3, 2015, 1:48 AM   #3
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Thank you so much for that explanation JimC. That was a BIG help for me in understanding the aperture numbers for the different lenses out there. I have already learned a great deal being apart of this forum, and people are so kind here! I am grateful to have found you all.
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