Wednesday, April 14, 2010

Depth of Field … One More Time *updated*

Moose responded in the comments section, see my reply and new shots at the end of this article.

Ok, just one more time. Taking a quote from an early mini-review of the HS10 … I already addressed this once, but I just have to do it again.

If you plan to take most of your photos outdoors in bright light situations (kids soccer games/wildlife/landscapes), the HS10 can stand up to to many entry level Digital SLR’s in terms of image quality. Pro photographers may be able to see subtle differences between the images when blown up to 100% on their computer monitor, but in a 4×6 print most people wouldn’t be able to tell the two images apart. Again, this only applies to photos in outdoor (bright light) situations. Once you go indoors, DSLR’s have the advantage due to their larger sensors and ‘noise free’ images in low light situations.

The key comment in there is “in a 4x6 print most people wouldn’t be able to tell the two images apart” …

Now, for landscape shots in good light this is probably fairly true. So long as the ISO is low and the print very small, the two will look a lot alike. But tiny sensor cameras tend to smudge diustant foliage and other details, and that will show on a print. I don;t think he can say such a thing with a lot of caveats.

But when he mentions kids’ sports, things get *really* dicey. Say you are shooting from short to medium distance at focal lengths like 80 to 100mm, what difference would we see?

To show the potential differences, let’s take the Panasonic ZS3, a camera with a sensor about the same size as that in the HS10, and the D700, a full frame dSLR. This test simulates the kind of differences one would see when you are shooting at 30 feet and there are people and fences on the other side of the pitch.

So … the ZS3 cannot throw much out of focus at these relatively normal distances. Here is what this test looks like.


The background is slightly blurred, but it is pretty obvious what it is. In the soccer scenario, the background would be pretty clear, if not perfectly focused.

Now the D700 rendering from the same position.


Sorry, but I don’t care how small the print is … you’d have to be blind to see no difference in the subject isolation. And that’s why people buy dSLRs …

Disclaimer: There are more variations of subject and background distance than you can shake a stick at. So don’t bother pointing out that there will be situations in which the difference is less than this … much less, even. That’s all pretty obvious. But there will *always* be a difference. And it won’t be all that small if the dSLR has a nice lens on it.

Moose’s reply: You can read the whole reply in the comments section. But the gist comes down to these points:

1. Test shots between 400mm and 720mm have similar DOF to 200mm shots on D90 (which is 300mm effective.)

2. Most soccer moms won’t use a D700 with 70-200mm f/2.8 lens.

3. 300mm on HS10 gives wonderfully blurred shots at similar distances to shooting soccer.

4. Most DPReview members have confirmed shallow DOF at longer focal lengths. Fuji did a great job.

5. dSLR has advantage of closer distances in my earlier test. Great portraits can be had at close distances by zooming to 300mm and beyond.

Now, my responses:

1. Irrelevant. First, I perform apples to apples tests, not apples to oranges. Second, shooting at massive focal lengths means stepping a long way back, behind the audience, to get the same framing. Not goona be as useful as it sounds, unless you want head shots all day, and there are much better situations in which to shoot those.

2. Fair enough. So I will repeat the test with the D300 and a consumer lens.

3. No, it does not. I will prove that in a moment.

4. DOF Master will confirm that based solely on the laws of physics. We don;t need “confirmation.” Now, if you had said “wonderful bokeh”, that would be a different statement, since that depends on control of aberrations in the lens.

5.  Not sure how the dSLR can have an advantage when shot from the same location.

So … let’s repeat the test. D300 (same sensor size as *all* Nikon consumer dSLRs) with 70-300VR (inexpensive consumer lens) set at 180mm (270mm effective) shot against the F70EXR at full zoom (which is 280mm or 270mm, I forget … I put 280mm on the test image.) 6400iso for the dSLR against 800 ISO with flash for the F70EXR (to get something close to sharpness indoors.)

Both shot at f/5.6 and the the consumer zoom shot at f/22 for illustrative purposes.

Same subject as the original test, shot at about 12 feet and the background (same hound’s tooth as last time) about 8 feet behind. This more or less simulates shots just past half way across the pitch. The relative amount of blur will be consistent, if somewhat more or less depending on subject distance.


A few observations:

1. Laws of physics are not to be denied. The DOF on the small sensor cam (and this sensor is *larger* than that in the HS10 remember) is not even as shallow as the consumer cam at f/22.

2. The clarity of the consumer dSLR at 6400iso (and remember that the D90 is slightly cleaner and the D5000 slightly cleaner again than the D90) is far better than that of the F70EXR at 800iso with flash assist. Translated to the pitch, this means that details in shadow (midday creates those) will be awful. And the struggle for shutter speed for evening games (kids play a lot of those) will be never-ending. Boosting ISO will not be a good answer, even with the alleged extra stop or two of efficiency on the BiCMOS sensor.

My point is simple … for soccer moms shooting the latest kits (D5000 2-lens kit) that cost a small premium on the price of the HS10, the output will destroy that of the HS10 in all lighting conditions. Which means that even 4x6 prints will show obvious differences in overall image quality for most shooting circumstances.

Which further means that I cannot agree with any of your responses. Sorry about that.

Update 2: I just calculated the crop factor for this camera … a staggering 5.7 (720mm effective / 126mm actual.) Wow … that’s gonna give you an equivalence at f/5.6 of f/32 for depth of field, f/22 on APS-C. Not too shallow, although at 720mm you will still get blur if close enough to the subject. The wide angle at 2.8 will have depth of field equivalent to f/16, f/11 on APS-C. Again, very wide depth of field, especially at 24mm effective.


moose said...

Hey Kim,

Great blog and great points!

If I could I'd like to go into a little more detail as to why I made that statement in my quick review of the HS10...

While the HS10 has no where near the depth of field of a Digital SLR, I will tell you that my test shots between 400mm and 720mm on the HS10 have just as much depth of field as my Nikon D90 with the budget Nikon 55-200mm f/4-5.6G ED attached at an aperture of f/5.6 at full telephoto.

The comparison is between the HS10 and "entry level DSLR's" with entry level lenses attached.

Most "soccer moms" aren't going to go out and purchase a Nikon D700 with an expensive 70-200mm f/2.8 VR lens. Most of them will purchase entry level DSLR's like the Nikon D3000 and equip it with a common zoom lens like the Nikon 55-200mm f/4-5.6G ED.

At full telephoto 300mm (200mm times the focal length multiplier of x 1.5) they will be shooting at an aperture of f/5.6 in bright light conditions. It just so happens that at 720mm on the HS10 the minimum aperture is also f/5.6. Now shooting at 300mm on the HS10 I was able to achieve f/4 which gave me wonderfully blurred backgrounds of my daughter playing outdoors, similar to the same distance a mom would be shooting her kids playing soccer.

Many of the forum members at the dpreview Fuji forum have also confirmed the shallow depth of field at longer focal lengths, so it appears Fuji did a great job this regard.

In your example, the Digital SLR truly has the advantage at closer distances, however, I have been able to take some great portraits with beautiful 'bokeh' at relatively close distances with the HS10 by zooming out to 300mm and beyond.

I hope that helps clarify the point I was trying to get across.

You have some great image tests that I know requires a lot of time. Keep up the great work!

Best Regards,
Moose Montana

Kim Letkeman said...

Moose: Thanks for reading and responding. I adjusted the article to address your points.

moose said...

I really appreciate the time and effort you put into your tests.

Honestly these were just my first impressions, nothing based on extensive testing.

My daughter had a soccer game last Saturday, and I brought both my D90 and my new HS10.

At 100% on my monitors, pixel quality, highlights, and dynamic range were all better handled on the surprise there.

As to the "bokeh" in my test shots. I will say that I was taking shots of my daughter relative to her height, so the angle of the shot was parallel with the ground. The "background" consisted mostly of trees and shrubs on a nearby hill probably 20 to 30 feet away.

I visited my local photography shop last night and printed out 10 (5x7) shots. The 10 shots I printed where similar photos taken with the D90 and the HS10, so there were 5 of each.

Not exactly a scientific method mind you. :)

I laid out all 5 pairings (1 photo from the D90 next to an HS10) and asked the owner to tell me which were from the HS10 and which were from the D90. Out of the 5 pairings, he successfully chose the D90 2 out of 5.

So basically, he chose three photos that he thought were from the D90, but were actually from the HS10.

I realize that this doesn't cover every type of shooting situation in outdoor "bright light" situations, but it does show that at the smaller print sizes it can be difficult to determine large differences.

I do agree that there are specific situations where the HS10 just doesn't measure up to a DSLR, but for the beginner photographer just starting out I truly believe that this is a great tool to learn the basics of photography.

I think when I get to my final review I will try to be a little more detailed in my post as to not confuse or also be too general in my statements. I'm just a photography nut, who just so happens to be a newbie at blogging.


Again, thank you so much for your tests...I'll make sure to visit your blog from time to time.

Best Regards,

Kim Letkeman said...

Moose: That's exactly the kind of test that should be put up on your blog. Obviously, you are quite committed to the statement that the results from these two cameras will be essentially indistinguishable at small print sizes. I note that you used 5x7 instead of 4x6.

Of course, these image pairs were probably shot at slightly different times of presumably similar scenes ... it would be very interesting to be able to critique the pairings themselves for similarity of subject / background distances etc.

It would also be very interesting to be able to see each pair's settings, focal lengths, etc.

At the least, I would be able to choose whether to post an update to my blog.


moose said...

Thanks for the advice, I think you're right about conducting a more accurate experiment...

I'm planning on doing an "in-depth" review (at a later date) of the HS10 after I put it through some more difficult shooting/lighting situations.

I'll also try to conduct a more advanced experiment with similar focal lengths, f-stops, ISO etc... so that we can get a better comparison between the two sets of images.

How are you enjoying your Nikon D700? I rented it during an outing to the Sierra Nevada Mountains and absolutely loved it.

Best Regards,

Kim Letkeman said...

Moose: Sounds great. Looking forward to the deeper tests. Some low contrast detail like DPReview's new feather would be interesting for the next ISO ladder.

The D700 is fantastic. It handled the Globetrotters fan shoot with ease. Workshop season opens in a few weeks and I am really hoping for great things from the D700 and the Tamron 28-75 or Nikon 85 1.8 ... we'll see.