Question regarding 50mm 1.4 v 1.8

[CapM]

I've been looking at pictures from the blog of a local professional photographer, and now I am looking at the EXIF data. Most of the pics of her kids were with her 50mm at f/1.4, but some are f/1.8. However, on a 1.4 lens (Canon), the next stop up looks like 2.0. Does this mean she has a 1.4 AND a 1.8 lens? And if so, why would anyone put on the 1.8 over the 1.4 (except for larger apertures)? Thanks.

 

[reznap]

A 1.4 will stop down to 1.6, 1.8, 2.0 and so on.. they stop down in 1/3 stop increments.

It's most likely all from the EF 50mm f/1.4 lens.

 

[Overread]

Yes some camera bodies can do 1/3rd stop increments - 1/2 or full stop changes in aperture. Most DSLRs that I know of are default set to 1/3rd stop increments. So that explains how a f1.4 lens can get to f1.8.

Otherwise I can't think many reasons for a person to want the 1.8 over the 1.4 save for a weight reduction; but even then that will be a fairly minor factor.

 

[CapM]

Oh, okay. I just finished Bryan Peterson's book, so I am trying to understand when you might want to use bigger and smaller apertures. I now know the difference between 2.8, 11, and 22. But under what conditions would you step down from 1.4 to 1.8? Thanks.

 

[Overread]

Most lenses are not their sharpest when used wide open and can also show slightly more abborations. Furthermore the depth of field at f1.4 is very small so if you've the light stopping down even a little to f1.8 not only allows for a better optical quailty, but also for a slightly greater depth of field.

Furthemore an f1.4 lens can still reach to f1.4 for when the light is too little or for when the photographer really wants the razor thin depth of field. Further a larger max aperture allows for better AF performance in dimmer lighting conditions and a brighter viewfinder image.

 

[Big Mike]

Oh, okay. I just finished Bryan Peterson's book, so I am trying to understand when you might want to use bigger and smaller apertures. I now know the difference between 2.8, 11, and 22. But under what conditions would you step down from 1.4 to 1.8? Thanks.

Usually, you use a larger aperture (lower F number), when you want a faster shutter speed.

Of course, you can use your aperture to help control your DOF, but getting the DOF you want, won't be any good if you can't get a sharp shot because your shutter speed was too slow.

So it obviously depends on the lighting conditions you have. If you have plenty of light, then you can be more free to choose the aperture you want for the DOF and optimum quality.
But if you don't have a lot of light, and you are shooting hand held and/or you are shooting moving subjects, then you may have to choose an aperture that allows for the shutter speed that you want/need.

 

[CapM]

I don't have a 50mm yet, but tonight using the D7000 kit lens (18-105) we were trying to take some inside action photos of the dog jumping. Apparently the lighting in our house was too low for using shutter priority at a fast speed even at 18mm. The pics came out pitch black until the shutter was decreased down to 1/4 second! Is this typical of this lens not to handle something like a 1/500 shutter speed? So, if I got the 50mm 1.8 (slightly used one available locally for $100), would this handle this indoor action photo? Thanks yet again.

 

[fokker]

Yeah, a kit lens in dim lighting isn't going to get you far. I assume it's max aperture is 3.5 at 18mm, if you were at f/1.4 you would have an extra 2 2/3 stops of light available, meaning you could get the shutter up to about 1/30. To get any faster than that you have to either up the ISO or add more light.

 

[Studio7Four]

I don't have a 50mm yet, but tonight using the D7000 kit lens (18-105) we were trying to take some inside action photos of the dog jumping. Apparently the lighting in our house was too low for using shutter priority at a fast speed even at 18mm. The pics came out pitch black until the shutter was decreased down to 1/4 second! Is this typical of this lens not to handle something like a 1/500 shutter speed? So, if I got the 50mm 1.8 (slightly used one available locally for $100), would this handle this indoor action photo? Thanks yet again.

Two quick points. First, it seems like you might be confusing focal length (18mm to 105mm on this lens) with aperture. Changing the focal length alone will not (appreciably) change the light getting to your sensor. You don't say if/how you changed your aperture settings when you were trying to shoot the dog jumping - that will affect your shutter speed.

Second (and I forgot to see if you list what brand you use), if you're talking about the Canon 50mm f/1.8, that retails brand new for $100. If you meant the 50mm f/1.4, then $100 is a really good deal and I'd jump on it. I use the 50mm f/1/4 and love it, it's pretty much my standard lens. (If you're shooting another brand, sorry, not as familiar with the available lenses and their prices, though I'd expect them to be fairly in line with the Canon models.)

 

[CapM]

Yeah, a kit lens in dim lighting isn't going to get you far. I assume it's max aperture is 3.5 at 18mm, if you were at f/1.4 you would have an extra 2 2/3 stops of light available, meaning you could get the shutter up to about 1/30. To get any faster than that you have to either up the ISO or add more light.

Bummer. I guess I would have thought that an f/1.8 lens would at least allow for some action photos indoors. The light in our house may not be great (kitchen has 4 100 watts floods), but I guess that's not good by photography standards. If we were to just use the on-camera flash, would that allow for a much greater (1/500 range) shutter speed?

 

[Dao]

A hot shoe flash maybe a good idea. Especially one that can do High Speed Sync with your camera. Otherwise, the build-in flash will limit your shutter speed to 1/250 which is the flash sync speed of your camera. But I think 1/250 should be decent for most of the indoor action stuff unless you are trying to catch a fast running rat in your kitchen.

 

[CapM]

Thanks all. I went ahead and made a deal ($100) to pick up a 1-month old 50mm 1.8. I'll give it a test run tonight!

 

[fokker]

You know they only cost $100 new, right?

 

[CapM]

You know they only cost $100 new, right?

No, the Nikkor is now $124.99 at B&H and $139 at Ritz for the non-greys. I think the Canon is cheaper.

Anyhow, we tried the experiment with the dog jumping, at 1/250 in poor indoor lighting with a in-camera flash, and it was pretty darn good - not perfect. I can't wait to try the 1.8 this weekend (daughter's birthday party) in good lighting.