willowdogger
Senior Member
Can someone explain to a non techie what the difference would be with 35mm FX lens and a 35mm DX lens on my D7000? Does one of them crop the image?
Thanks.
Thanks.
More expensive lens means a better image.
- Thread starter willowdogger
- Start date
This would be a good question to pose in a new thread. But the quick answer is nothing. Both lenses will perform the same and give the same field of view.
The only difference is the size of the image's circle projected into the camera. The FX will have a larger circle. The DX lens only needs to be large enough to cover the DX-size sensor.
A crop-sensor body will record the same image with either one.
willowdogger
Senior Member
So, if my camera is a DX, there is no reason to look at an FX lens? Sorry I'm so stupid.
Horoscope Fish
Senior Member
Not a stupid question at all and it is a bit confusing at first I think... With that being said I think it would be foolish to rule out an FX lens if you have a DX body just because the lens is FX.
For example I regularly use both the 85mm and 50mm f/1.8G lenses on my DX bodied D7100 because they're outstanding prime lenses; as do a lot of DX-body users. The fact that they're both FX lenses has nothing to do with... Well... Anything, really.
...
Since you shoot DX now and if you plan to stay there for the foreseeable future, DX lens tend to be less expensive. What Sparky and others told you was that you can also use FX lenses in the same manner as DX lenses. If you think you might change to a FX body then you might want to invest in full frame lenses.
Bottom line, you should look at the focal length AND speed/aperture required to capture the images you desire. Fast lens in either format will cost more and enable you to control the background blur (bokeh).
willowdogger
Senior Member
I have the same prime lens as horoscope fish, does the lens CROP what I see through the viewer? I'm sure that the shots I took at a race on Monday were different to what I thought I had taken. People weren't as centred in the frame as I thought they were. Probably my imagination...
Horoscope Fish
Senior Member
No, it does not.
I'm not always good at explaining this stuff but here goes.
It's not the lens that determines the crop factor you're concerned about. The crop factor comes into play because the sensor in a DX camera is smaller than that of an FX camera. So, to repeat: It's the SENSOR that makes the difference. What the lenses do remains unchanged but some are designed to work with certain sensors. Even so, we can use this to our advantage.
To wit: An FX lens can be used on a DX body because the lens is designed for the larger FX sensor; it projects a "big" image. Putting this gig image on a small sensor is no problem because the image covers the entire sensor. But, if you reverse this, and use a DX lens on an FX sensor you've put a lens designed for the smaller sensor on a camera with the larger sensor. See the problem? The smaller image projected by the DX lens was NOT designed to cover the larger FX sensor and the defecation rapidly impacts the rotary oscillator.
Big image (FX lens) on a small sensor (DX body) = Joy!
Small Image (DX lens) on a big sensor (FX body) = No joy!
Hopefully that helps clarify.
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willowdogger
Senior Member
Maybe I should have taken up golf ...
The actual, physical size of the FX and DX sensors are different:
This is readily apparent if you look at an FX body next to a DX body, and can see the actual sensors when both are set to "Mirror Up for Cleaning":
So how does this translate into anything meaningful out in the 'real world'? Well, lets' pretend we're out there taking photos. And we come across this peaceful scene:
Now, an FX lens on an FX body has to project a large enough image to cover the larger FX sensor, so it will project an image into the camera that looks like this:
(Yeah, I know.... it's right-side-up. In reality, the image would be upside-down, but let's ignore that for the purpose here.)
The lens needs to create a large enough image to cover a sensor measuring 24x36mm (represented by the white rectangle):
So an FX lens/body will record the final image as:
Now let's take the same focal length lens, but only it's a DX-format lens. It will project a smaller circle:
Because it only needs to cover a sensor that measures 18x24mm:
So the same focal length lens, on a DX body, will record a final image as this:
Now, if we put the two final images (FX and DX) side by side, we end up with this:
Notice how the subjects in both images are exactly the same size? It's just that the DX sensor recorded a smaller portion of the scene because the sensor is physically smaller! This results in a narrower field of view.
So if you compare the sensor size:
with the above two images, you should be able to understand the 'crop sensor' effect on field of view.
This is readily apparent if you look at an FX body next to a DX body, and can see the actual sensors when both are set to "Mirror Up for Cleaning":
So how does this translate into anything meaningful out in the 'real world'? Well, lets' pretend we're out there taking photos. And we come across this peaceful scene:
Now, an FX lens on an FX body has to project a large enough image to cover the larger FX sensor, so it will project an image into the camera that looks like this:
(Yeah, I know.... it's right-side-up. In reality, the image would be upside-down, but let's ignore that for the purpose here.)
The lens needs to create a large enough image to cover a sensor measuring 24x36mm (represented by the white rectangle):
So an FX lens/body will record the final image as:
Now let's take the same focal length lens, but only it's a DX-format lens. It will project a smaller circle:
Because it only needs to cover a sensor that measures 18x24mm:
So the same focal length lens, on a DX body, will record a final image as this:
Now, if we put the two final images (FX and DX) side by side, we end up with this:
Notice how the subjects in both images are exactly the same size? It's just that the DX sensor recorded a smaller portion of the scene because the sensor is physically smaller! This results in a narrower field of view.
So if you compare the sensor size:
with the above two images, you should be able to understand the 'crop sensor' effect on field of view.
I gave up golf for photography. Much less stress.Maybe I should have taken up golf ...
Horoscope Fish
Senior Member
willowdogger
Senior Member
The actual, physical size of the FX and DX sensors are different:
This is readily apparent if you look at an FX body next to a DX body, and can see the actual sensors when both are set to "Mirror Up for Cleaning":
So how does this translate into anything meaningful out in the 'real world'? Well, lets' pretend we're out there taking photos. And we come across this peaceful scene:
Now, an FX lens on an FX body has to project a large enough image to cover the larger FX sensor, so it will project an image into the camera that looks like this:
(Yeah, I know.... it's right-side-up. In reality, the image would be upside-down, but let's ignore that for the purpose here.)
The lens needs to create a large enough image to cover a sensor measuring 24x36mm (represented by the white rectangle):
So an FX lens/body will record the final image as:
Now let's take the same focal length lens, but only it's a DX-format lens. It will project a smaller circle:
Because it only needs to cover a sensor that measures 18x24mm:
So the same focal length lens, on a DX body, will record a final image as this:
Now, if we put the two final images (FX and DX) side by side, we end up with this:
Notice how the subjects in both images are exactly the same size? It's just that the DX sensor recorded a smaller portion of the scene because the sensor is physically smaller! This results in a narrower field of view.
So if you compare the sensor size:
with the above two images, you should be able to understand the 'crop sensor' effect on field of view.
Brilliant, thanks for that. It has made it one heck of a lot clearer
willowdogger
Senior Member
BUT.... looking at the scene through the viewfinder of a camera with a DX sensor, do I see the same image as the one that is recorded? Does the viewfinder with an FX Sensor capture the larger image? Do I get what I see? You guys are SO helpful
Horoscope Fish
Senior Member
Yes, because not only are the sensors a different size, the focus screens are sized to match them.
Well, he did ask. Do you think we have him totally confused by now or do we need to bury him in more rhetoric?When I first read the OP's heading, I thought...hehehe.. that's like saying "buying a more expensive car will make me a better driver".
Willowdogger, I hope you got the answer you were looking for.
You always get what you see. I think the purpose of the posts were to make you see why it is said that there is a 1.5 multiplication factor for any lens on DX.
I gave up golf for photography. Much less stress.
I do both and I still suck at it.
Now going back to the topic about lenses. Just like what fish have previously mentioned, some lenses have their specific character that I like such as the bokeh or how they render out of focus when you are trying to isolate the subject.
As a lens enthusiast, I've tried various lenses since I started photography. If you are shooting at f8 with good light, you would probably see very little difference. Once you start using larger apertures, then that's where the more expensive zoom or prime lenses excel. When we talk about cheaper lenses, I am pertaining to the typical kit lenses. Some AIS lenses are cheaper now, some are still good but probably not as good as the newer lenses as far as optical performance is concern. This is subjective depending on how you like how the lens renders the image just like the sample image above. I've tried the older and newer lenses. I've kept what I really like.
So why do I and some of the guys tend to buy the more expensive lenses? I have my own reasons that some who are short on cash will probably not agree with my decision but that is just me since I am very particular on how a lens renders the image and not just about sharpness. The bokeh, AF or manual focus operation, color fringing, contrast, flare resistance and built are some of the factors that I consider other than the sharpness and price.
I know if I shoot a subject with a kit lens and a pro lens, I know that I will like what the pro lens will render.
The bottom line is that use whatever you have.
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Before you plunk down a lot of money on a "better" lens, any photographer should look at what they can do with their existing equipment to improve the quality of their photographs. There is a huge misconception, especially amongst more inexperienced photographers, that better equipment will always result in better images. The camera, regardless of the level of sophistication or quality, is only nothing but a recording device. It is what the photographer DOES with it that actually makes a photograph. It is what separates a photographer from a casual "picture taker".
You can lay out a ton of money for a brand new D4 with some very expensive Nikkor lenses and still take lousy photos with it. The most important piece of photographic equipment any photographer has is always the computer that resides between their ears. This is true not only with full manual film cameras as well as auto-everything digital ones.
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