I built my phrugal phototent... does it show?

[Patrick Taylor]

Today I built my phrugal phototent, using PVC and cardboard wrapped in tinfoil for the ceiling and reflector. I plan to add walls and a better roof to contain the light more, but it's mostly there (I think).

I took some photos, using my Sony prosumer digital (non-SLR:() with the aperture set to 8.0 and the white balance calibrated using the background.

Do these look any good? I'd love some photo critiques. (don't bother with the turning critiques! ;)) Any comments on camera and exposure settings is greatly appreciated too. FYI, I used imageshack to host higher resolution shots.

Thanks!

http://img526.imageshack.us/img526/8739/dsc08240xg1.th.jpg (http://img526.imageshack.us/my.php?image=dsc08240xg1.jpg)http://img116.imageshack.us/img116/2575/dsc08217vz3.th.jpg (http://img116.imageshack.us/my.php?image=dsc08217vz3.jpg)http://img523.imageshack.us/img523/4500/dsc08222ze3.th.jpg (http://img523.imageshack.us/my.php?image=dsc08222ze3.jpg)
http://img248.imageshack.us/img248/7467/dsc08236rb8.th.jpg (http://img248.imageshack.us/my.php?image=dsc08236rb8.jpg)http://img516.imageshack.us/img516/6023/dsc08239ax0.th.jpg (http://img516.imageshack.us/my.php?image=dsc08239ax0.jpg)

[Chris Barton]

I'll let the pros comment on the photography but, it looks like it works well. I need to consider some sort of dedicated photography set up too.

[Walter Yamamoto]

Pics look great. The setup seems to allow for good flexibility in lighting to account for different shadow/highlight needs.

The only thing you might want to do is to make sure you adjust the exposure compensation on the camera. With so much white in the background, it is making the autoexposure darken the image too much.

All camera auto settings try to "average" the scene to 18 percent gray. All the white pushes the the average too high (histogram) so the camera darkens everything. Try adjusting the the exposure compensation up by one or two stops, or go full manual if your camera is capable.

Happy photographing!
Wayne

[Patrick Taylor]

...
All camera auto settings try to "average" the scene to 18 percent gray. All the white pushes the the average too high (histogram) so the camera darkens everything...
Wayne

That's a great explanation and it makes perfect sense! I'll try that next time.

I used the aperture set at 8.0. Is that the best for getting good depth of field? Also, is it better to step back and zoom in, or move closer and zoom out?

[Bernie Weishapl]

Patrick I am not a photo expert but your turnings are beauties. I think the pictures look great.

[Walter Yamamoto]

What camera and lens are you using? For most point/shoot cameras, the parameters of the lens is such that you get a pretty deep depth-of-field regardless of f-stop (unless you're in macro mode). The depth of field at a given f-stop is also determined by the focal length setting of the lens. The more you zoom in (higher focal length setting) the shallower the depth of field will be at a given f-stop.

With digital cams it's easy to experiment cuz you can just dump what you don't like.

As far as zooming in or widening out, you will get more distortion with the lens at its wide setting. If you are looking for a more accurate representation of the object, then it is best to go higher on the focal length. Be careful, too high and you get some compression of the image (though it's not as noticeable to most people). In 35mm film work, it is generally regarded that a 90 to about 135mm focal length is the most accurate and pleasing. The only problem is that most digital cams don't show that type of information so again - experiment to see what setting looks best for your camera/lens.

Wayne

[Patrick Taylor]

What camera and lens are you using

I have the Sony DSC-V3 (http://www.dpreview.com/news/0408/04082904sonydscv3.asp). It's treated me well so far, but it's no SLR. I wasn't aware that higher focal length gives a more realistic image. I'll try moving back and zooming in. For these, I was about 4 feet away and zoomed in just slightly to frame the shot.

[Jamie Donaldson]

.. when you add the missing L and R sides, very important elements in bouncing the light that is now escaping out the sides! The foil rather than a white top can also be too reflective, resulting in the shadow rings visable at the base of the turnings. For the white background, an exposure compensation setting of +1 is about right if your camera has such capability, or you could make exposure corrections from a gray card or manually adjust to about +1 if possible. The depth of field at f 8 may be sufficient, but use the longer focal lengths (telephoto) rather than WA to avoid barrel distortion. You're close, but fine tuning will hit the image jackpot!!! ;-)))

[Keith Burns]

Patrick, I think you are off to a good start. If I was a pro I could tell you what do do, but I'm not, so I won't. I do think the shadows are a little harsh but basically I think you just have a little tweaking to do.

[Patrick Taylor]

.. when you add the missing L and R sides, very important elements in bouncing the light that is now escaping out the sides! The foil rather than a white top can also be too reflective, resulting in the shadow rings visable at the base of the turnings. For the white background, an exposure compensation setting of +1 is about right if your camera has such capability, or you could make exposure corrections from a gray card or manually adjust to about +1 if possible. The depth of field at f 8 may be sufficient, but use the longer focal lengths (telephoto) rather than WA to avoid barrel distortion. You're close, but fine tuning will hit the image jackpot!!! ;-)))

Thanks Jamie, and thanks for the original article. I see what you mean about the foil up top. I do intend to add the sides, and I agree that it will help a lot. I just need to find something white that's 3'x3', which is actually harder than it seems!

[jeremy levine]

My only thought is that , you might have to change the postion of the light to show the side if the bowls a bit better. Great looking stuff :D

[Jamie Donaldson]

.. misconception among photographers regarding the relationship of focal length and depth of field. If the object size is maintained the same in the field of view, the depth of field will remain the same regardless of focal length. The key is maintaining the same object size for close up work, and most shooters use WA to enlarge the field of view, which will then enhance the DOF.

[Jamie Donaldson]

.. at office supply big box stores like Staples, Office Depot, or many art supply houses.

[Patrick Taylor]

.. misconception among photographers regarding the relationship of focal length and depth of field. If the object size is maintained the same in the field of view, the depth of field will remain the same regardless of focal length. The key is maintaining the same object size for close up work, and most shooters use WA to enlarge the field of view, which will then enhance the DOF.


Does that mean that whether I zoom in from far away, or zoom out from close-up, that if the subject is the same size in the field of view the depth of field stays the same? i.e., it doesn't matter given a fixed subject size in the field of view?

[Walter Yamamoto]

Jamie,

What you explained is true about total depth of field expressed as a distance within the focal plane. I was speaking to the focal depth as a percentage of the total focal plane. Perhaps I need to clarify what I was trying to get at. Better yet, perhaps someone else would be better than me at explaining my thoughts.

Here is a great site and a great tutorial about depth of field:

http://www.cambridgeincolour.com/tutorials/depth-of-field.htm#calculator

It even has a great calculator to calculate total depth for you.

"CLARIFICATION: FOCAL LENGTH AND DEPTH OF FIELD

Note how I did not mention focal length as influencing depth of field. Even though telephoto lenses appear to create a much shallower depth of field, this is mainly because they are often used to make the subject appear bigger when one is unable to get closer. If the subject occupies the same fraction of the viewfinder (constant magnification) for both a wide angle and a telephoto lens, the total depth of field is virtually* constant with focal length! This would of course require you to either get much closer with a wide angle lens or much further with a telephoto lens, as demonstrated in the following depth of field chart:
Focal Length (mm) Focus Distance (m) Depth of Field (m)
10 0.5 0.482
20 1.0 0.421
50 2.5 0.406
100 5.0 0.404
200 10 0.404
400 20 0.404
Note: Depth of field calculations are at f/4.0 on a Canon EOS 20D (1.6X crop factor),
using a circle of confusion of 0.0206 mm.
Note how there is indeed a subtle change for the smallest focal lengths. This is a real effect, but is negligible compared to both aperture and focus distance. Even though the total depth of field is virtually constant, the fraction of the depth of field which is in front of and behind the focus distance does change with focal length, as demonstrated below:

Distribution of the Depth of Field
Focal Length (mm) Rear Front
10 70.2 % 29.8 %
20 60.1 % 39.9 %
50 54.0 % 46.0 %
100 52.0 % 48.0 %
200 51.0 % 49.0 %
400 50.5 % 49.5 %
This exposes a limitation of the traditional DoF concept: it only accounts for the total DoF and not its distribution around the focal plane, even though both may contribute to the perception of sharpness. A wide angle lens provides a more gradually fading DoF behind the focal plane than in front, which is important for traditional landscape photographs.
On the other hand, when standing in the same place and focusing on a subject at the same distance, a longer focal length lens will have a shallower depth of field (even though the pictures will show something entirely different). This is more representative of everyday use, but is an effect due to higher magnification, not focal length. Longer focal lengths also appear to have a shallow depth of field because they flatten perspective. This renders a background much larger relative to the foreground-- even if no more detail is resolved. Depth of field also appears shallower for SLR cameras than for compact digital cameras, because SLR cameras require a longer focal length to achieve the same field of view."

So consideration needs to be given on what the total desired focal plane is in relation to the total focal plane of the image - for example the total width of the bowl as it relates to how close the front of the bowl will be to the lens compared to the furthest edge of the bowl.

Cheers

[Jamie Donaldson]

concerning depth of field with a bowl. When you focus on a spot like the rim of a bowl, the DOF extends 1/3rd to the front of that point, and 2/3rds to the rear of the point of critical focus. So to achieve max DOF for a bowl, focus on a spot 1/3rd behind the front of the rim, and 2/3rds from the back of the rim. Sometimes this is hard to see on a tiny camera screen, but I often plug my camera into a 13" monitor and focus manually for critical work.

[Patrick Taylor]

concerning depth of field with a bowl. When you focus on a spot like the rim of a bowl, the DOF extends 1/3rd to the front of that point, and 2/3rds to the rear of the point of critical focus. So to achieve max DOF for a bowl, focus on a spot 1/3rd behind the front of the rim, and 2/3rds from the back of the rim. Sometimes this is hard to see on a tiny camera screen, but I often plug my camera into a 13" monitor and focus manually for critical work.

I've had problems with this in the past, and I tried the 1/3 back method based on your article for the photos I posted. I think it helped improve these quite a bit from my previous photos.