A few questions about Automotive (car) Photography

[AJHill]

Hey guys, I've got a few questions on automotive photography. Any answers would be greatly appreciated!

http://farm9.staticflickr.com/8446/7830557334_54a08b52a6_c.jpg

In this photo, I'm just wondering what it is that makes this photo the way it is. It's the DOF that I'm specifically interested in. The way the background is blurred while the entire length of the car is still in focus. When I try to capture an image with either my 35mm 1.8 or my 50mm 1.8, I can seem to reproduce this effect while fitting the entire car into the shot. I can do a front fender, but when I move further away to fit the entire car in, I have to readjust my focus, and in turn the bacground comes back into focus.

Is it solely the fact that my D7000 is not a full frame camera? (And this picture was taken with a D700, which is full frame.)
Or is a lot of this dependent on the actual lens itself. I understand that I'm trying to reproduce a shot originally taken with an 85mm 1.4, and both of my lenses are 1.8s.
If it is the lens, does the focal length of the lens have any sort of effect on focusing on large, far away objects? Or could this be reproduced with a 35mm 1.4?

Here are some more similar shots (The first two are both also coincidentally taken with an 85mm 1.4):
http://farm9.staticflickr.com/8216/8313012414_b0213c4bcc_c.jpg

http://farm9.staticflickr.com/8058/8221259736_ea49eab0c9_c.jpg

http://farm9.staticflickr.com/8459/8058272896_86f9002a2b_c.jpg

http://farm9.staticflickr.com/8030/8070952313_970200d7b7_c.jpg

Thanks in advance, guys!

Note: TPF FAQs prohibit the posting of images to which a person does not hold either permission or copyright. We have edited this post leaving LINKS to the images from their original location.

 

[powasky]

Its the length of the lens, along with the wide aperture.

Using a 35/1.4 (stopped down to f/2 on a crop), shooting with the car 10 feet away, you get a DoF of about 2ish feet. Not what you want.

Using an 85/1.4 (stopped down to f/2 on a FF body), shooting with the car 40 feet away, you get a DoF of about 8 feet, which gives you the look you want.

 

[tirediron]

DoF is primarily a function of three factors. Focal length (longer = less), aperture (larger = less) and camera-to-subject distance (closer = less). Sensor size does have an effect, but it's not as significant as the other factors. For a more graphical explanation, try this calculator.

 

[TCampbell]

Use a DOF calculator.

For example... if you use a 50mm lens, set it to f/4, and shoot the car from about 20' and rather than focusing on the grille, try focusing on the front tire, you'll get a DoF of about 7-1/2'. Everything from about 17' to about 24-1/2' will be reasonably sharp and everything beyond that will be going soft.

I have an app on my smartphone that calculates this stuff, but you can go to the DoFmaster.com website to use their free online calculator.

 

[AJHill]

Wow! Thanks for the tips and quick replies guys!

 

[djacobox372]

DoF is primarily a function of three factors. Focal length (longer = less), aperture (larger = less) and camera-to-subject distance (closer = less). Sensor size does have an effect, but it's not as significant as the other factors. For a more graphical explanation, try this calculator.

Sensor size can have a significant effect if u consider that it allows you to reduce subject distance at the same focal length.

 

[boborone]

Use a DOF calculator.

For example... if you use a 50mm lens, set it to f/4, and shoot the car from about 20' and rather than focusing on the grille, try focusing on the front tire, you'll get a DoF of about 7-1/2'. Everything from about 17' to about 24-1/2' will be reasonably sharp and everything beyond that will be going soft.

I have an app on my smartphone that calculates this stuff, but you can go to the DoFmaster.com website to use their free online calculator.

ios or android? If android, what app do you use?

 

[12sndsgood]

from what i'm seeing the entire back half of the car is out of focus. id guess his deapth of field is around 5-6' deep at most. This type of shot can be done on a D7000, that's what i use myself. i'd get this type shot using my 70-200 you don't need a 1.4 lens to get this type shot.

 

[AJHill]

DoF is primarily a function of three factors. Focal length (longer = less), aperture (larger = less) and camera-to-subject distance (closer = less). Sensor size does have an effect, but it's not as significant as the other factors. For a more graphical explanation, try this calculator.

Sensor size can have a significant effect if u consider that it allows you to reduce subject distance at the same focal length.

That was the reason I asked.
Like this photo: Ryan B. | Flickr - Photo Sharing!

It's got the effect I like, but it was taken with a 50mm (not sure whether 1.4 or 1.8) and with a 5D Mk II, which is full frame. It may help that the car is almost completely sideways, so there's less depth needed.

Would the conversion between the crop factor (x1.6 for Canon & x1.52 for Nikon) apply in this instance? It looks like a 50mm on a full frame would behave like an 80mm on a cropped sensor.

I guess even if this was the case, the cheapest way for me to duplicate the effect would be to buy an 85mm (or similar focal length and aperture) lens, versus buying a full frame camera.

 

[12sndsgood]

no need for a full frame to get that type image.