Studio Question | What "mm" to use?

[toucandesign.com]

Equipment: Nikon D70
Lens: Nikon AF-S 18-70mm 1:3.5-4.5G

Here is the situation:
I am going to shoot product shots of chairs in a small studio setup with 2 1000w stobe lights, D70 on a tripod and the subjects approx 15ft away on white paper.

Question:
What "mm" do I set the lens so there is no distortion or fish eye effect either zoomed or wide, like someones eye would see? Pictures will be used for product shots in a catalog.

Any advice would be greatly appreciated.

[Arctirus]

I like to shoot at a minimum of an effective 75mm to avoid distortion. Also the model is usually more comfortable if you're not in their face.

[Photo-John]

I think 50mm should be fine, with your camera lens combo. Any distortion would be around the edges with that lens at 50mm, and the smaller sensor on the D70 will ensure that doesn't happen. I think you'd have trouble getting far enough away at 75mm, as Arctirus suggested. Plus, distortion is going to make a bigger difference for headshots than it will for product photos. I've actually found disortion-free product photos to be a bit square and dead looking. I like to use a bit of wide angle to introduce a sense of perspective and allow for more depth-of-field.

[Peter_AUS]

Generally for Portraiture Photography, which this sort of would be like, lenses between 80 - 135 is considered to be a good length. But as John said 50mm would be fine, as long as it isn't a prime lens, otherwise you haven't got the freedom to move around as much and zooming would be better as well, less distortion as you are worried about.

I take ti the lens you are using is structured for Digital Use, like some of the new small lenses for the Canon Digital cameras, so the true mm remains correct.

[another view]

With large objects and a small studio, you might not even be able to use 50mm - depending on how small "small" is. Might want to leave a little space around the chairs so that the graphics department laying out the catalog has more options to work with, too. Depending on what the background is they may or may not be able to easily clone in more background - but this will make their job easier.

I agree with John that perspective distortion (not what you're talking about) can work to your advantage, and that with that camera/lens combo you probably won't have to worry much about the distortion you are talking about.

[toucandesign.com]

Thank you all for the great advice.

I do have enough room to "back up" from the subject as we are in a warehouse. And yes, I beleive the lens is made for digital use so the mm should be correct. 50mm it is then and I will let you all know how it turns out.

thanks again.

[aj_day]

Equipment: Nikon D70
Lens: Nikon AF-S 18-70mm 1:3.5-4.5G

Here is the situation:
I am going to shoot product shots of chairs in a small studio setup with 2 1000w stobe lights, D70 on a tripod and the subjects approx 15ft away on white paper.

Question:
What "mm" do I set the lens so there is no distortion or fish eye effect either zoomed or wide, like someones eye would see? Pictures will be used for product shots in a catalog.

I shoot a lot of chairs for catalog and web. I like to use the longest focal length possible given the space I am shooting in, because it maximizes my depth of field. If you are shooting @ 50mm focal length, I would be sure to expose the chair @ f-16 or higher aperature. With 1000w/s strobes, this should not be a problem for you.

[christopher_platt]

AJ-
Are you sure you don't have it backwards? Higher focal length=less depth of field. . .
Chip

[aj_day]

AJ-
Are you sure you don't have it backwards? Higher focal length=less depth of field. . .
Chip

Longer focal length lenses yield longer depths of field from front to back. The depth of field as a measure of total area may not be bigger, but a 105mm lens @ F16 will yield a depth of field that is longer from front to back than an 85mm lens @ F16. It will certainly be a narrower depth of field, because of the longer lens, but that actual area of sharp focus will be longer from front to back.

If depth of field is a measure of total area, then the total area in the "sharp focus zone" may be bigger with a shorter lens because of the width, but having a narrower, longer "sharp focus zone" is more conducive to shooting products that have some depth (like chairs).

[JCPhoto1]

AJ you do have it backwards.

If focal length is the only thing varied but everything else--focus distance and f/stop--stays the same, how does DOF change? The longer the focal length, the shorter the DOF. Conversely, the shorter the focal length, the longer the DOF. This explains why wide-angle lenses appear to have so much of their total image in focus while most telephoto images are just the opposite. DOF is expanded with that wide-angle lens.
Now, there are other things going on here but the basic truths of DOF are as follows: 1) The wider the aperture, the shorter the DOF. 2) The further you focus, the longer the DOF. 3) The longer your focal length, the shorter the DOF.

[aj_day]

AJ you do have it backwards.

This double chiding sufficiently motivated me to pull out some of my photo technology textbooks and research this one some more. You guys are right about the focal length /DOF relationship. I even used the near focus distance and far focus distance calculator equations (that I have forgotten about for the last decade) to test my case. This is particularly embarrassing, since I have made my living taking pictures for the last 13 years.

Anyway, I wanted to point out that I do shoot a lot of products, and I really do prefer the results that shooting with a longer lens yield for products like chairs. The longer focal length allows me to back up farther from the subject, which does increase the depth of field, and shows the product with less distortion than a shorter lens.

[JCPhoto1]

Don't think I used my memory to figure out which way it was. I had to look it up too. Age takes it's toll on memory.