blurredimage

B

blurredimage

New member
I would just like to introduce myself. I have had a on/off relationship with photography for at least 35 years. I currently own/use a Nikon FE2 w/50mm f1.4 lens that I purchased new in the 80's. I live near Nikon's main NY office in Melville LI.I recently brought my camera/lens in for service. Nikon serviced my lens although they no longer service my camera. I have recently completed a college level photography course that has renewed my interest in taking pictures. I am thinking of buying a DSLR. The top contenders are the Nikon D7100 or D610 but I have a few questions as I consider myself new to digital photography. I understand DX/FX formats for sensor size. DX images are cropped 1.4 times larger than FX format images. So my questions are:

1. Is a DX image shot on a D7100 at 24.1MP actually 24.1 MP or 1.4% less due to DX cropping. As compared to same image shot on FX format camera at same resolution.

2. Is the focal length of the AF-S DX NIKKOR 18-140mm f/3.5-5.6G ED VR

Or is the focal length for the 18-140mm actually 25.2mm - 196mm due to DX cropping same as if I use my Nikkor 50mm f1.4 on a DX format the focal length will be 70mm or 50mm x 1.4=70mm In other words are the focal lengths for DX lens correct or do I need to a 1.4 times conversion.

thanks in advance for your input
 
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Pretzel

Senior Member
blurredimage said:
I would just like to introduce myself. I have had a on/off relationship with photography for at least 35 years. I currently own/use a Nikon FE2 w/50mm f1.4 lens that I purchased new in the 80's. I live near Nikon's main NY office in Melville LI.I recently brought my camera/lens in for service. Nikon serviced my lens although they no longer service my camera. I have recently completed a college level photography course that has renewed my interest in taking pictures. I am thinking of buying a DSLR. The top contenders are the Nikon D7100 or D610 but I have a few questions as I consider myself new to digital photography. I understand DX/FX formats for sensor size. DX images are cropped 1.4 times larger than FX format images. So my questions are:

1. Is a DX image shot on a D7100 at 24.1MP actually 24.1 MP or 1.4% less due to DX cropping. As compared to same image shot on FX format camera at same resolution.

2. Is the focal length of the AF-S DX NIKKOR 18-140mm f/3.5-5.6G ED VR

Or is the focal length for the 18-140mm actually 25.2mm - 196mm due to DX cropping same as if I use my Nikkor 50mm f1.4 on a DX format the focal length will be 70mm or 50mm x 1.4=70mm In other words are the focal lengths for DX lens correct or do I need to a 1.4 times conversion.

thanks in advance for your input
Click to expand...


Welcome!

1) The D7100 is a smaller sensor, but you're still using the full sensor, so the images will be 24.1 MP.

2) The focal length on any lens is listed in the 35mm equivalent. When using a crop sensor camera (DX), you will multiply accordingly. I think the Nikons are actually 1.5x though?

Hope ya enjoy the new DSLR!
 
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Dave_W

The Dude
Focal length does not change, so an 18-140 remains an 18-140. And a 24.1 MP image coming from a D7100 is a 24.1 MP image. No math needed.

DX is merely a smaller sensor so it only captures the middle portion (if you will) of the light coming through the lens compared to a full frame (FX) sensor. Because of this it gives an "apparent" focal length equal to 1.5 that of an FX but in reality it's just an image that's cropped smaller.
 
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Don Kuykendall_RIP

RIP :(
blurredimage said:
I would just like to introduce myself. I have had a on/off relationship with photography for at least 35 years. I currently own/use a Nikon FE2 w/50mm f1.4 lens that I purchased new in the 80's. I live near Nikon's main NY office in Melville LI.I recently brought my camera/lens in for service. Nikon serviced my lens although they no longer service my camera. I have recently completed a college level photography course that has renewed my interest in taking pictures. I am thinking of buying a DSLR. The top contenders are the Nikon D7100 or D610 but I have a few questions as I consider myself new to digital photography. I understand DX/FX formats for sensor size. DX images are cropped 1.4 times larger than FX format images. So my questions are:

1. Is a DX image shot on a D7100 at 24.1MP actually 24.1 MP or 1.4% less due to DX cropping. As compared to same image shot on FX format camera at same resolution.

2. Is the focal length of the AF-S DX NIKKOR 18-140mm f/3.5-5.6G ED VR

Or is the focal length for the 18-140mm actually 25.2mm - 196mm due to DX cropping same as if I use my Nikkor 50mm f1.4 on a DX format the focal length will be 70mm or 50mm x 1.4=70mm In other words are the focal lengths for DX lens correct or do I need to a 1.4 times conversion.

thanks in advance for your input
Click to expand...



18 - 140mm Comparable 35mm Focal Length: 27 - 210 mm

The D7100 is 24.MP as stated. Depending on what you are shooting and what mode depends on how big the file size is. I shoot Raw all the time and my files average 25 to 33 MB per photo.

I just recently got my D7100 but you can see some of my photos at http://nikonites.com/project-365-daily-photos/20941-dons-d7100-daily-dabblings-13.html#post284712
 
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Mike D90

Senior Member
blurredimage said:
DX images are cropped 1.4 times larger than FX format images.
Click to expand...


DX images are not cropped larger. They are cropped smaller. Imagine looking at a photo taken from a full frame sensor then cropping it smaller all the way around its perimeter by 1.5%.

DX viewfinder gives a field of view of that of a FX viewfinder zoomed by 1.5% closer. So a 50mm lens on a DX camera gives you the same field of view as a 75mm lens on a full frame camera.
 
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nickt

Senior Member
I'm going to answer the question you did not ask YET, lol. But it helps answer your original question from a different point of view.

What is the difference between a 300mm dx lens and a 300mm fx lens?

They are both 300mm.

The fx lens is a regular 300mm lens, same as you would use on 35mm film camera. It will work the same way on either a dx or fx camera. A dx sensor will not capture the entire image. Some of the image will be cast outside the footprint of the sensor, hence the 'crop'. In processing, that image will be enlarged to a standard size, creating the zoom effect, giving a smaller field of view like a 450mm lens would have given.

The dx lens is still 300mm, however, corners were cut, literally and figuratively. It was designed to be a less costly lens for use on the smaller dx sensor. It casts only enough image to cover the dx sensor. If you used it on a fx body, you would get vignetting or your Nikon camera will automatically crop it to dx size if you want.

Also a point to note on 24mp dx vs 24mp fx... the pixels on the dx are smaller.
 
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