Newbie here

[Burnings]

HI gurus,

I have just purchase a 500D and exploring around. Previously was using a couple of PnS and a Lumix Prosumer.

I have some questions out here relating to lens. The kit lens is 18-200mm F3.5-5.6. I was wondering what kinda difference does it have from 24-70mm F2? WHen the spec is F2 does it means that the aperture is fixed at f2?

 

[MrKami]

Hihi Burning! A very warm welcome to you

18-200 f3.5-5.6 is not a constant aperture. So when u zoom in to the max it will be f5.6

Unlike for 24-70 even if u zoom in or out it will still be constant aperture f2.8

 

[limwhow]

Burnings, a very warm welcome to you.
I guess you must have meant 24-70mm f/2.8 right? (Because I am not sure if I have seen a 24-70mm f/2.0... )
So yes, it's a constant aperture at f/2.8 no matter what focal length (wide angle of 24mm or tele at 70mm) you are at.
The 18-200mm has an advantage of a higher tele at 200mm, which on your cropped APS-C body, would give you an effective zoom of 320mm. The only issue is at this maximum tele, the widest aperture can only be f/5.6. So you would lose out a little in situations of low lighting.
That said, the 18-200mm is still, in my opinion, a very good lens that can take you for many many months and years.

 

[Burnings]

Hihi Burning! A very warm welcome to you

18-200 f3.5-5.6 is not a constant aperture. So when u zoom in to the max it will be f5.6

Unlike for 24-70 even if u zoom in or out it will still be constant aperture f2.8

Ok, that means that it is irrelevant to what is shown on my camera settings? eg I can set f4 on my camera and it will still take at f2?

 

[Burnings]

Burnings, a very warm welcome to you.
I guess you must have meant 24-70mm f/2.8 right? (Because I am not sure if I have seen a 24-70mm f/2.0... )
So yes, it's a constant aperture at f/2.8 no matter what focal length (wide angle of 24mm or tele at 70mm) you are at.
The 18-200mm has an advantage of a higher tele at 200mm, which on your cropped APS-C body, would give you an effective zoom of 320mm. The only issue is at this maximum tele, the widest aperture can only be f/5.6. So you would lose out a little in situations of low lighting.
That said, the 18-200mm is still, in my opinion, a very good lens that can take you for many many months and years.

Yes it is f2.8 my bad hehehe.. I read the reviews on 18-200mm and it is consider ok as a general use and travel len where you dun have to constantly change lens. I asked abt the 24-70 is because I am thinking it can give me better IQ over the kit lens when I am not travelling and I should not be taking landscape shots in Singapore I think so tele is not an issue to me. Street ,portrait and macro is more for me...

 

[mimik07]

Ok, that means that it is irrelevant to what is shown on my camera settings? eg I can set f4 on my camera and it will still take at f2?

If you are referring to the 24-70 f/2.8, then my answer will be no. When you set the aperture to f/4, the shot will be captured at f/4 regardless of how far you zoom.

If you are using the 18-200 and you have set the aperture at f/4, the aperture will automatically be set to f/5.6 because that is the widest aperture at 200mm.

 

[MrKami]

24-70 The IQ Is great!

 

[limwhow]

Yes it is f2.8 my bad hehehe.. I read the reviews on 18-200mm and it is consider ok as a general use and travel len where you dun have to constantly change lens. I asked abt the 24-70 is because I am thinking it can give me better IQ over the kit lens when I am not travelling and I should not be taking landscape shots in Singapore I think so tele is not an issue to me. Street ,portrait and macro is more for me...

Sure, Burnings.
Yes, with constant aperture lenses, you can adjust the aperture to anything smaller than the stated f/2.8 at any focal length.
And seeing your genre of interest, I would proceed to say that the 18-200mm can certainly accomplish what you like to shoot.
Of course the 24-70mmf/2.8 can too. A quality lens at a premium price it is. If cost is not too much of a consideration, it will definitely give you the best, if not one of the best.

 

[Burnings]

Sure, Burnings.
Yes, with constant aperture lenses, you can adjust the aperture to anything smaller than the stated f/2.8 at any focal length.
And seeing your genre of interest, I would proceed to say that the 18-200mm can certainly accomplish what you like to shoot.
Of course the 24-70mmf/2.8 can too. A quality lens at a premium price it is. If cost is not too much of a consideration, it will definitely give you the best, if not one of the best.

Well... I just find that sometimes when I already set the aperture in M mode and ready to take the shot, the camera tends to change it after the AF kicks in. No luck with MF either. Is this something to do with the lens? Sometimes it is frustrating because I wanted a lower aperture than what is "recommeded" by the camera.

 

[Rashkae]

Well... I just find that sometimes when I already set the aperture in M mode and ready to take the shot, the camera tends to change it after the AF kicks in. No luck with MF either. Is this something to do with the lens? Sometimes it is frustrating because I wanted a lower aperture than what is "recommeded" by the camera.

If you are in M mode then there's nothing the camera will "recommend".

Are you sure it's only after the AF kicks in? Or do you zoom into the subject as well? AF will not change the aperture in M or Av mode.

 

[Burnings]

If you are in M mode then there's nothing the camera will "recommend".

Are you sure it's only after the AF kicks in? Or do you zoom into the subject as well? AF will not change the aperture in M or Av mode.

COme to think of it, I think it changes after I zoomed in but if I am in M mode, it should'n change rite?

 

[Rashkae]

COme to think of it, I think it changes after I zoomed in but if I am in M mode, it should'n change rite?

That's your problem right there. Of course it will still adjust if you zoom to a point where the maximum aperture of the lens changes. If you set it at 3.5 at 18mm, it CANNOT stay at 3.5 if you zoom to 200mm. As stated in the lens specs, the largest aperture at 200mm is 5.6. It' snot the camera recommending anything; it's the camera being FORCED to change it because you change the focal length of your lens and the lens had to compensate the aperture.

Limwhow and Mimik17 already gave you the answer.

I do suggest learning more about the basics of your equipment.

 

[madmartian]

Welcome to CS Pls read up your manual & also google some search. That will help you understand the specs of different lenses

 

[Burnings]

That's your problem right there. Of course it will still adjust if you zoom to a point where the maximum aperture of the lens changes. If you set it at 3.5 at 18mm, it CANNOT stay at 3.5 if you zoom to 200mm. As stated in the lens specs, the largest aperture at 200mm is 5.6. It' snot the camera recommending anything; it's the camera being FORCED to change it because you change the focal length of your lens and the lens had to compensate the aperture.

Limwhow and Mimik17 already gave you the answer.

I do suggest learning more about the basics of your equipment.

So with a constant aperture len I can stay at the aperture even though I change the focal length?

 

[limwhow]

Yes, Burnings.
With a constant aperture lens, if you have set your aperture at f/2.8 in M mode or Av mode, even after you have zoomed and then do a half-press of the shutter, the aperture remains.

 

[Rashkae]

So with a constant aperture len I can stay at the aperture even though I change the focal length?

Yes, that's why it's "constant aperture".

But, with your current lens, if you set it at 5.6, it will stay at 5.6 no matter how you change the focal length.

 

[Burnings]

Thanks all gurus for the explanations for clearing my doubts. I have another question about macro lens. If for eg I have a 100mm macro lens, it means that the focal length is set at 100mm? As I tried to set my current lens at 100mm and to me it seems impossible to shoot macro at this focal length...

 

[gimumancer]

Thanks all gurus for the explanations for clearing my doubts. I have another question about macro lens. If for eg I have a 100mm macro lens, it means that the focal length is set at 100mm? As I tried to set my current lens at 100mm and to me it seems impossible to shoot macro at this focal length...

yes, macro lens can focus very close to the subject and are optimized to be sharp at macro focus distances which your lens is not

 

[horizon_grazer]

Yes, usually dedicated macro lens is fixed at a certain focal length only. (We call prime lens also)
Usually the minimum focusing length will be lower & allow u to focus closer to ur subject.
The magnification factor will also be higher, usually 1:1, which means that ur macro subject will appear larger after u take the shoot than non-dedicated macro lens