Sony help!

[EvansMomma]

I have a Sony a300 and I've just started to really dive into manual mode & I love it!! Right now I only have my kit lens (hoping that changes for xmas ) its a 18-70mm f/3.5-5.6. But I can't seem to get it to shoot above f/5, and even that is rare. Usually it will only get to f/5.6. I really want to get a shallower depth of field with my portraits, but its just not happening. Is there something I'm doing wrong? Any advice is great! Thanks!!

 

[Dao]

I believe you mean when you set the lens to 70mm, the max. aperture the camera allow you to set was f/5.6. You can't set anything lower like f/2.8 (wider aperture)

If that is the case, then the answer is ...

Yes, you cannot do that because of the lens limitation. Your lens is 18-70mm f/3.5-5.6. What that really means is at 18mm, the max aperture is f/3.5 while at the long range 70mm, it is f/5.6.

If you need to use a wider aperture (smaller the f/ number), you need to get another lens. i.e. 85mm f/1.4

 

[Robin Usagani]

Yeah.. what Dao said. Your lens does not have a constant max aperture.

 

[KmH]

Depth-of-field (DOF) is controlled by 4 factors:

1. lens aperture
2. lens focal length
3. subject to image sensor distance
4. and subject to background distance.

There are online depth-of-field calculators you can use to help you visualize how those 4 factor relate to DOF:

Online Depth of Field Calculator
Understanding Depth of Field in Photography
http://www.tawbaware.com/maxlyons/calc.htm

 

[chito beach]

I have a Sony a300 and I've just started to really dive into manual mode & I love it!! Right now I only have my kit lens (hoping that changes for xmas ) its a 18-70mm f/3.5-5.6. But I can't seem to get it to shoot above f/5, and even that is rare. Usually it will only get to f/5.6. I really want to get a shallower depth of field with my portraits, but its just not happening. Is there something I'm doing wrong? Any advice is great! Thanks!!

at 18mm you can shoot at F3.5 at 70mm you can shoot at F 5.6 lowest.

The camera will only allow you to set the apertures to what the lens is capable of doing.

To overcome the 5.6 you can do several things to increase the OOF in your portraits.

The single biggest thing is to move your subject farther away from your background

 

[EvansMomma]

I believe you mean when you set the lens to 70mm, the max. aperture the camera allow you to set was f/5.6. You can't set anything lower like f/2.8 (wider aperture)

If that is the case, then the answer is ...

Yes, you cannot do that because of the lens limitation. Your lens is 18-70mm f/3.5-5.6. What that really means is at 18mm, the max aperture is f/3.5 while at the long range 70mm, it is f/5.6.

If you need to use a wider aperture (smaller the f/ number), you need to get another lens. i.e. 85mm f/1.4

That explains it! Thanks! I didn't know that's what it meant! Learn something new every day