Mike Chaney's Tech Corner

Technical Discussions => Cameras => Topic started by: testerd on January 27, 2011, 05:39:08 PM



Title: Depth of field and f-stop
Post by: testerd on January 27, 2011, 05:39:08 PM
Hi.

I have a Canon SX100 IS and a Canon SX130 IS.

The SX100 has f-stop range from F2.8-4.3
The SX130 has f-stop range from of F3.4 to 5.6

I'm a newbie.

One of the things I would like to be able to do is have a shallow depth of field for some of my photos.

If I understand correctly, the lower the f-stop setting the shallower the depth of field can be.

So does that mean, the SX100 can produce images with a shallower depth of field than the SX130?

Thank you.


Title: Re: Depth of field and f-stop
Post by: Terry-M on January 27, 2011, 05:59:27 PM
Hi testered,
Quote
If I understand correctly, the lower the f-stop setting the shallower the depth of field can be.
That is correct.
Quote
So does that mean, the SX100 can produce images with a shallower depth of field than the SX130?
If the focal length of the lenses are the same, it should be the case. However on this type of camera, the focal length is quite short, even at full zoom so the depth of field is not particularly shallow anyway. The factors that reduce the depth of field are a wide aperture (small f number), a longer focal length and close subject to camera distance. Google the subject, there'll be plenty of tutorials to read.
Why not do some test shots to compare the 2 cameras. You probably won't see a great deal of differnce. You need to take shots of a receding scene that has definite makers like fence posts, or at closer distances, looking along a ruler.
Terry


Title: Re: Depth of field and f-stop
Post by: testerd on January 28, 2011, 03:08:04 AM
The reason I haven't compared is because I haven't opened the SX130 yet. It was a gift to replace the SX100 but I was thinking that if it doesn't help me get a more shallow depth of field, I might as well sell it.

Thanks for the reply and information.


Title: Re: Depth of field and f-stop
Post by: jeffjessee on January 29, 2011, 10:08:50 PM
For really narrow depth of field, you will need a digital SLR with interchangable lens and a large sensor. Most consumer cameras have a very small sensor and therefore short focal length lenses, which often results in everything from 5 ft to infinity being in fairly good focus. If you are wanting to explore the artistic possibilities of narrow depth of field, you will want to move up to an SLR. Canon digital Rebels might fit your needs.


Title: Re: Depth of field and f-stop
Post by: testerd on February 07, 2011, 09:44:56 PM
Is the Canon SX30IS more likely to be able to produce a shallower depth of field than the Canon SX130IS? Or is it about the same? 

I can't quite afford a DSLR right now so I'm trying to step up in quality a bit...

Thanks.


Title: Re: Depth of field and f-stop
Post by: jeffjessee on February 08, 2011, 01:47:14 AM
According to the specifications, the SX30 and the SX130 both have DDC sensors that are 1/2.3 (less than half an inch), so neither would have a very narrow DOF, but the SX30 has a f2.7 lens, and the SX130 f3.4, so the SX30 would have a slightly narrower depth at f2.7. Still, since the sensors are so small, compared to an SLR, I don't think you would get the effect you are looking for. You, by your question, have entered the world of wishing to do more "artistic" photography, rather than just "snapshots". For those who are content with snapshots, it's usually an advantage to have most everything in focus at the same time, so this "feature" of point and shoot cameras allows amateurs to shoot an in-focus photo most of the time. (If they can manage not to move the camera. And the IS even helps them if they aren't so steady). Sounds like you've gotten the bug (shutterbug), so you might as well start saving up for the DSLR. They are getting cheaper every year.

Jeff


Title: Re: Depth of field and f-stop
Post by: Fred A on February 08, 2011, 10:32:06 AM
Quote
so you might as well start saving up for the DSLR. They are getting cheaper every year.

Thanks, Jeff.
I didn't have the "cojones" to say that, but I was thinking it!
... and to add to Jeff's suggestion, there are many reliable places, (like Adorama, for example) from which we have purchased used, traded in cameras.
These places guarantee satisfaction,,,, and there is little risk on your part.

Fred