Focal lengths on lens's...

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Lukeeee1990

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Name
Luke
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Right, I have the following lens's:

17-70mm
55-200mm

I understand that i'm going to be using the 17-70mm lens for shot's that won't require a great deal of zooming...i.e. Car shots, landscapes...etc.

And I ASSUME the 55-200mm would be used for shooting thing's further away without having to crop pictures on a lower focal length lens..

...Correct me if i'm wrong on the above so far...

But i've just been browsing the forums and came across someone selling these 2 lens's....surely you would have no need for both, but if there is a huge difference between the 2 please inform me as to what the difference would be...

Sigma 10-20mm f/4-5.6 EX DC HSM Lens
Sigma 12-24mm f/4.5-5.6 EX DG Aspherical HSM Lens

Many thanks...also any insight you can give me regarding lens/focal lengths would greatly be appreciated :)

Cheers guys

Luke
 
If you don't know what a lens is for - then you don't need it. How many pictures have you taken with whatyou have??
 
The difference is the DC vs. DG on a Sigma lens. The 10-20 is designed for crop sensor cameras and the 12-24 is for full-frame. The physical design of the lens and the area of the sensor it will cast an image on differs.

Once you take into account the effective angle of view then it would be reasonable for someone with both cropped and full frame bodies to have both of these lenses if they wanted both bodies to be able to cover the same range as a back-up for each other.
 
awp said:
If you don't know what a lens is for - then you don't need it. How many pictures have you taken with whatyou have??
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I wouldn't buy a lens just for the sake of having an extra focal length if that's what you're getting at...i'm not one for buying it because it's there...i'll only buy it if i'm going to benefit from it, especially with the price of lens's! :lol:

Umm quite a few I guess, I use the 17-70mm more as it's more usable "on the move"...where as I struggle to find use for the 55-200mm, although I guess if i knew more what it was for I may use it more often...why do you ask?

Thanks

Luke
 
The more productive answer is the key difference lies in the DC/DG names. In sigma terminology DC will only work properly on crop format lenses whereas DG will work on Full frame and crop cameras, though with those two lenses I think you'd be daft to chose the DG version for anything other then full frame. Stick with DC (its cheaper and lighter) for crop sensors
 
Alastair said:
The difference is the DC vs. DG on a Sigma lens. The 10-20 is designed for crop sensor cameras and the 12-24 is for full-frame. The physical design of the lens and the area of the sensor it will cast an image on differs.
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Getting technical now Al, :P Crop sensor cameras and full frame? I've often heard the terms so I assume I should know a little about them...:thinking:...can you put it simply for me please? :(

Alastair said:
Once you take into account the effective angle of view then it would be reasonable for someone with both cropped and full frame bodies to have both of these lenses if they wanted both bodies to be able to cover the same range as a back-up for each other.
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effective angle of view...lost me?
 
Further to what I was saying.. to understand the codes Sigma use against their lenses have a read here.
 
boyfalldown said:
The more productive answer is the key difference lies in the DC/DG names. In sigma terminology DC will only work properly on crop format lenses whereas DG will work on Full frame and crop cameras, though with those two lenses I think you'd be daft to chose the DG version for anything other then full frame. Stick with DC (its cheaper and lighter) for crop sensors
Click to expand...

That's a little more what I was after mate...although as mentioned in above post, I'm a little lost on terminology when it comes to "full frame" and "crop sensors"...is this down to the camera body? :thinking: :cuckoo:
 
Som e of the worlds BEST photographers used one lens, and not a zoom at that. For the sake of it, buy a 35mm fixed focal length or a 50mm and put yourself in the best position by zooming with your feet. Do it for 6 months. Then decide what lenses you really need.
 
Lukeeee1990 said:
Getting technical now Al, :P Crop sensor cameras and full frame? I've often heard the terms so I assume I should know a little about them...:thinking:...can you put it simply for me please? :(
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ok a crop sensor is one of reduced size (24mm x 16mm on Nikon cameras). This allows as massive cost saving both on camera and lens. Has some other advantages too.

Full Frame sensors are the same size as a 35 mm bit of film (35mm x 24 mm) some great advantages, but at a premium of cost in lens and camera
 
Alastair said:
Further to what I was saying.. to understand the codes Sigma use against their lenses have a read here.
Click to expand...


Thanks Alastair...I'm always a little wary about reading manufacturers stuff as it's more a sales pitch IMO...which is why i'd rather ask you guys who USE the stuff, also...i've just had a quick skim and It doesn't really seem to help...all I can see is "buy me buy me"...for example:

EX (EX Lens)
The exterior of this lens is EX-finished to denote the superior build and optical quality, and to enhance its appearance.

String said:
Som e of the worlds BEST photographers used one lens, and not a zoom at that. For the sake of it, buy a 35mm fixed focal length or a 50mm and put yourself in the best position by zooming with your feet. Do it for 6 months. Then decide what lenses you really need.
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I agree with the zooming with your feet bit...from the experience of losing quality with zooming the maximum amount with the lens

that bring's me on to another question, any major advantage between zoom lens's and fixed focus lens's?

boyfalldown said:
ok a crop sensor is one of reduced size (24mm x 16mm on Nikon cameras). This allows as massive cost saving both on camera and lens. Has some other advantages too.

Full Frame sensors are the same size as a 35 mm bit of film (35mm x 24 mm) some great advantages, but at a premium of cost in lens and camera
Click to expand...

Still a little bamboozled :cuckoo: will have to read up i think :)

Thanks for taking time to reply guys!

Luke
 
Luke (I thought I recognised that user name from somewhere).

Some cameras have a larger/smaller sensor to capture the image than others - and each has there advantages and disadvantages. Your D50 is a crop sensor, that is it's sensor is smaller than a standard 35mm negative. As a consequence this means that any given lens has a narrower field of view than the the same lens would have on a full frame sensor camera. This makes the resulting image look more zoomed in, although it's not really. It's just a smaller section of the same image that a full frame sensor would see.

One thing to bear in mind, with an ultra-wide angle you're going to get some distortion in the image and this gets more noticeable the closer the subject is to the lens.

BTW.. the 10-20 is not bad for FTS if you haven't got a lot of room in front of the tank. I used mine for these shots quite a bit.
 
Lukeeee1990 said:
EX (EX Lens)
The exterior of this lens is EX-finished to denote the superior build and optical quality, and to enhance its appearance
Click to expand...

Not just a sales pitch in this case Luke.. the EX lenses are better than the standard (i.e. non-EX) lenses in the Sigma line-up. Every manufacturer uses some sort of designation to indicate those lenses that are built to a higher quality standard (e.g. Canon's L lenses).
 
Alastair said:
Luke (I thought I recognised that user name from somewhere).
Click to expand...

:P I was browsing ultiamtegrief the other day and someone had asked where you'd disappeared too - new guy heading photography section now...any new tanks on the horizon?

Alastair said:
Some cameras have a larger/smaller sensor to capture the image than others - and each has there advantages and disadvantages. Your D50 is a crop sensor, that is it's sensor is smaller than a standard 35mm negative. As a consequence this means that any given lens has a narrower field of view than the the same lens would have on a full frame sensor camera. This makes the resulting image look more zoomed in, although it's not really. It's just a smaller section of the same image that a full frame sensor would see.

One thing to bear in mind, with an ultra-wide angle you're going to get some distortion in the image and this gets more noticeable the closer the subject is to the lens.

BTW.. the 10-20 is not bad for FTS if you haven't got a lot of room in front of the tank. I used mine for these shots quite a bit.
Click to expand...

Ok that makes a little more sense...so a camera with a full frame sensor would be a better camera?

I think i've been ok with the 17-70 for FTS's, although never used the tripod UNTIL i sold that 680 on...will experiment with the new tank when it's up and running...if i'm honest I only bought it as it had "macro" in the lens name...turns out it's not even a real macro :( my bad
 
Ultra wides don't actually give you more distortion, in fact they normally give you much less distortion than a "standard" lens would as they're normally better corrected. What they do do is make perspective more obvious and if for example you tilt the lens up or down or move forward or back this may be more apparent, but it's not actually distortion as such, that's a different thing.
 
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Alastair said:
Not just a sales pitch in this case Luke.. the EX lenses are better than the standard (i.e. non-EX) lenses in the Sigma line-up. Every manufacturer uses some sort of designation to indicate those lenses that are built to a higher quality standard (e.g. Canon's L lenses).
Click to expand...

Upon closer inspection it seems you are right...I didnt really take that in :bang:
 
Lukeeee1990 said:
:P I was browsing ultiamtegrief the other day and someone had asked where you'd disappeared too - new guy heading photography section now...any new tanks on the horizon?
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Not for me.. I enjoyed photographing them more than maintaining them. Selling up was a way of funding lens purchases ;)

I saw that thread before it was cleaned - I do drop in once a month or so to see what's happening. The new guy seems to be doing ok.

Ok that makes a little more sense...so a camera with a full frame sensor would be a better camera?
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It's horses for courses. For tank shots there are a few advantages to having the smaller sensor.. but full frame also tends to have a better low light response. But there's always a better camera coming along, better to stick with what you've got until you hit the wall where it really can't do what you want it to and you've also reached the point where you've learned to do everything that it can do.

I think i've been ok with the 17-70 for FTS's, although never used the tripod UNTIL i sold that 680 on...will experiment with the new tank when it's up and running...if i'm honest I only bought it as it had "macro" in the lens name...turns out it's not even a real macro :( my bad
Click to expand...

The macro label is probably the most abused by lens makers.. and pretty much all of the sub-£200 lenses marked as macro will be next to useless for tank macros. The best macros for that purpose will always be primes (non-zoom).
 
Alastair said:
Not for me.. I enjoyed photographing them more than maintaining them. Selling up was a way of funding lens purchases ;)

I saw that thread before it was cleaned - I do drop in once a month or so to see what's happening. The new guy seems to be doing ok.
Click to expand...

Ahh telling me! The next tank is going to be as simple as possible...not even sumping it, yet...you know what it's like :P

Yh seems to be pretty good :)

Alastair said:
It's horses for courses. For tank shots there are a few advantages to having the smaller sensor.. but full frame also tends to have a better low light response. But there's always a better camera coming along, better to stick with what you've got until you hit the wall where it really can't do what you want it to and you've also reached the point where you've learned to do everything that it can do.
Click to expand...

To be honest Al, i'm not looking so much for the tank photography side of things...i'm after equipment that's quite flexible that can be used for more than one purpose :) By the sounds of things, buying a camera with a "crop sensor" sounds to be the worse of the two..."full frame" seems to be where it's at across the board (based on what you are saying)...By no means am I after the best thing going, as long as it does what I want :)

Alastair said:
The macro label is probably the most abused by lens makers.. and pretty much all of the sub-£200 lenses marked as macro will be next to useless for tank macros. The best macros for that purpose will always be primes (non-zoom).
Click to expand...

I'm not suprised, especially on ultimatereef...everyone want's one don't they :lol: the pictures you can get with them are amazing though :love: Well this sigma 17-70mm "macro" seemed to retail around £300-£400 when I bought it...although some of that will be the Sigma name stamped on it, I think paying £160 is fair going :) it's served me well...get's used all the time, better quality than the kit 18-55mm I feel :)
 
Luke, the bigger the number, the more "zoom" a lens has, i.e., it can make faraway objects appear closer in the viewfinder. Small numbers like 10 and 16 are ultra wide angle lenses that fit a hell of a lot in.
 
trencheel303 said:
Luke, the bigger the number, the more "zoom" a lens has, i.e., it can make faraway objects appear closer in the viewfinder. Small numbers like 10 and 16 are ultra wide angle lenses that fit a hell of a lot in.
Click to expand...

That's what I'd already understood...but i just couldn't see the difference between a 10-20mm and a 12-24mm :cuckoo: (see earlier post)

Turns out the difference between the lens's isn't actually the focal length as such...more to do with the lens itself
 
The focal lengths are different all right, but the formats for which the lenses are designed for are also different.
 
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