Please help me confirm my conclusion on DX lens compatibility with FX body

[CaptainNapalm]

When I bought my first FX body not long ago, the Nikon D600, it came from factory with the Auto-Crop mode activated. Until today, I didn't realize you can turn it off. After turning it off I realized that this created some great opportunities for one of my favourite DX lenses - the wide angle 12-24 f/4 which delivered superb wide angle photos on my D7000.

Unfortunately, with the crop mode activated on the D600, this lens worked only using the middle portion of the FX sensor producing decent images at about 10MP at any focal length. This wasn't enough to satisfy my needs so for the past few weeks I've been looking around for FX wide angle lenses which are certainly not cheap. However, with the crop mode turned off when I shoot with the 12-24mm at 12mm there is some vignetting on the corners but should I do the cropping myself in post this still leaves much more image for me than what the camera does in crop mode. Nevertheless, I don't want to be bothered with cropping all the time, so let's just say at 12mm it's useless. However when I zoom in a bit to say 16-18mm (common focal length for FX wide angle lenses) the vignetting disappears and I'm left with a clean, 24MP image. (Note: had I still been in crop mode at that focal length the camera would still chop the image in half but with it turned off it doesn't).

Now here is what I'm thinking, why would I spend $1200-$1500 on an FX wide angle lens like the 16-35mm f/4 or similar when I can deliver the same photos on my DX 12-24mm lens zoomed in to just enough for the vignetting to disappear. I mean other than perhaps just a slight improvement in IQ from the more expensive lens, would there be any other benefit of my buying a dedicated wide angle FX lens if I can make my 12-24 DX work the same at 16 or 18mm? The images are resolving at 24MP at that focal length, I'm still benefiting form great ISO performance, the lens itself is lighter and more compact, and this isn't a cheap bad optic lens. Am I missing something obvious here? Why would the camera maker not make the crop-mode a "smart mode" so to speak so that it recognized the unusable portions of any DX lens and any given focal length and maximizes the field of view accordingly, rather than just applying the same annoying crop at all focal lengths. Hoping to hear your thoughts. and thanks in advance for your input.

 

[480sparky]

You can always shoot in FX mode regardless of the lens used, but the sensor coverage will vary from lens to lens, and even focal length of a zoom.

You may find the outer edges of the image aren't all that great.... CA might be a huge issue 'outside the DX box'.

But if you can live with the shortcomings, by all means go for it. However, your 12-24 zoomed in to 24 to prevent vignetting doesn't help you get a FOV an FX 12mm would.

 

[CaptainNapalm]

You can always shoot in FX mode regardless of the lens used, but the sensor coverage will vary from lens to lens, and even focal length of a zoom.

You may find the outer edges of the image aren't all that great.... CA might be a huge issue 'outside the DX box'.

But if you can live with the shortcomings, by all means go for it. However, your 12-24 zoomed in to 24 to prevent vignetting doesn't help you get a FOV an FX 12mm would.

Thanks for the input Sparky. I know what you mean about the FOV being different between my 12-24 zoomed in to 24 vs 12mm on FX, however with this particular DX lens I only need to zoom in to about 16mm to prevent all vignetting and the FX I was considering for wide angle would be the 16-35, so wouldn't the FOV for both be the same at 16mm?

 

[480sparky]

You can always shoot in FX mode regardless of the lens used, but the sensor coverage will vary from lens to lens, and even focal length of a zoom.

You may find the outer edges of the image aren't all that great.... CA might be a huge issue 'outside the DX box'.

But if you can live with the shortcomings, by all means go for it. However, your 12-24 zoomed in to 24 to prevent vignetting doesn't help you get a FOV an FX 12mm would.

Thanks for the input Sparky. I know what you mean about the FOV being different between my 12-24 zoomed in to 24 vs 12mm on FX, however with this particular DX lens I only need to zoom in to about 16mm to prevent all vignetting and the FX I was considering for wide angle would be the 16-35, so wouldn't the FOV for both be the same at 16mm?

16 on an FX lens = 16 on a DX lens. The only difference would be the size of the image projected. If 16mm on a DX zoom covers the FX sensor, you're good to go if the edge/corner IQ is there.

 

[CaptainNapalm]

You can always shoot in FX mode regardless of the lens used, but the sensor coverage will vary from lens to lens, and even focal length of a zoom.

You may find the outer edges of the image aren't all that great.... CA might be a huge issue 'outside the DX box'.

But if you can live with the shortcomings, by all means go for it. However, your 12-24 zoomed in to 24 to prevent vignetting doesn't help you get a FOV an FX 12mm would.

Thanks for the input Sparky. I know what you mean about the FOV being different between my 12-24 zoomed in to 24 vs 12mm on FX, however with this particular DX lens I only need to zoom in to about 16mm to prevent all vignetting and the FX I was considering for wide angle would be the 16-35, so wouldn't the FOV for both be the same at 16mm?

16 on an FX lens = 16 on a DX lens. The only difference would be the size of the image projected. If 16mm on a DX zoom covers the FX sensor, you're good to go if the edge/corner IQ is there.

Thanks Sparky. I'll definitely take some more photos tomorrow and examine the quality around the corners/edges to see if there are any issues which would warrant a new FX wide angle lens purchase.

 

[cgipson1]

When I bought my first FX body not long ago, the Nikon D600, it came from factory with the Auto-Crop mode activated. Until today, I didn't realize you can turn it off. After turning it off I realized that this created some great opportunities for one of my favourite DX lenses - the wide angle 12-24 f/4 which delivered superb wide angle photos on my D7000.

Unfortunately, with the crop mode activated on the D600, this lens worked only using the middle portion of the FX sensor producing decent images at about 10MP at any focal length. This wasn't enough to satisfy my needs so for the past few weeks I've been looking around for FX wide angle lenses which are certainly not cheap. However, with the crop mode turned off when I shoot with the 12-24mm at 12mm there is some vignetting on the corners but should I do the cropping myself in post this still leaves much more image for me than what the camera does in crop mode. Nevertheless, I don't want to be bothered with cropping all the time, so let's just say at 12mm it's useless. However when I zoom in a bit to say 16-18mm (common focal length for FX wide angle lenses) the vignetting disappears and I'm left with a clean, 24MP image. (Note: had I still been in crop mode at that focal length the camera would still chop the image in half but with it turned off it doesn't).

Now here is what I'm thinking, why would I spend $1200-$1500 on an FX wide angle lens like the 16-35mm f/4 or similar when I can deliver the same photos on my DX 12-24mm lens zoomed in to just enough for the vignetting to disappear. I mean other than perhaps just a slight improvement in IQ from the more expensive lens, would there be any other benefit of my buying a dedicated wide angle FX lens if I can make my 12-24 DX work the same at 16 or 18mm? The images are resolving at 24MP at that focal length, I'm still benefiting form great ISO performance, the lens itself is lighter and more compact, and this isn't a cheap bad optic lens. Am I missing something obvious here? Why would the camera maker not make the crop-mode a "smart mode" so to speak so that it recognized the unusable portions of any DX lens and any given focal length and maximizes the field of view accordingly, rather than just applying the same annoying crop at all focal lengths. Hoping to hear your thoughts. and thanks in advance for your input.

Why have a nice FX body, and cripple it with DX lenses? GOOD FX lenses will have better IQ, Focusing, etc...

Or to Paraphrase you from above: "why would I spend $1600-$2000 on an FX" BODY and then not take advantage of it... by using lenses not designed for it?

You would have been better off spending that money on better lenses for your D7000... than buying a D600 and using DX lenses.

To each their own... I just do not understand the reasoning behind this.... lol! If you are happy with 6mm's of zoom ... then fine, have fun!

The CROP mode is based on current sensor sizes... not some variable that would vary from lens to lens. And since the camera was not designed to be use in FX mode with DX lenses... the manufacturer probably never thought anyone would do that...

 

[CaptainNapalm]

When I bought my first FX body not long ago, the Nikon D600, it came from factory with the Auto-Crop mode activated. Until today, I didn't realize you can turn it off. After turning it off I realized that this created some great opportunities for one of my favourite DX lenses - the wide angle 12-24 f/4 which delivered superb wide angle photos on my D7000.

Unfortunately, with the crop mode activated on the D600, this lens worked only using the middle portion of the FX sensor producing decent images at about 10MP at any focal length. This wasn't enough to satisfy my needs so for the past few weeks I've been looking around for FX wide angle lenses which are certainly not cheap. However, with the crop mode turned off when I shoot with the 12-24mm at 12mm there is some vignetting on the corners but should I do the cropping myself in post this still leaves much more image for me than what the camera does in crop mode. Nevertheless, I don't want to be bothered with cropping all the time, so let's just say at 12mm it's useless. However when I zoom in a bit to say 16-18mm (common focal length for FX wide angle lenses) the vignetting disappears and I'm left with a clean, 24MP image. (Note: had I still been in crop mode at that focal length the camera would still chop the image in half but with it turned off it doesn't).

Now here is what I'm thinking, why would I spend $1200-$1500 on an FX wide angle lens like the 16-35mm f/4 or similar when I can deliver the same photos on my DX 12-24mm lens zoomed in to just enough for the vignetting to disappear. I mean other than perhaps just a slight improvement in IQ from the more expensive lens, would there be any other benefit of my buying a dedicated wide angle FX lens if I can make my 12-24 DX work the same at 16 or 18mm? The images are resolving at 24MP at that focal length, I'm still benefiting form great ISO performance, the lens itself is lighter and more compact, and this isn't a cheap bad optic lens. Am I missing something obvious here? Why would the camera maker not make the crop-mode a "smart mode" so to speak so that it recognized the unusable portions of any DX lens and any given focal length and maximizes the field of view accordingly, rather than just applying the same annoying crop at all focal lengths. Hoping to hear your thoughts. and thanks in advance for your input.

Why have a nice FX body, and cripple it with DX lenses? GOOD FX lenses will have better IQ, Focusing, etc...

Or to Paraphrase you from above: "why would I spend $1600-$2000 on an FX" BODY and then not take advantage of it... by using lenses not designed for it?

You would have been better off spending that money on better lenses for your D7000... than buying a D600 and using DX lenses.

To each their own... I just do not understand the reasoning behind this.... lol! If you are happy with 6mm's of zoom ... then fine, have fun!

The CROP mode is based on current sensor sizes... not some variable that would vary from lens to lens. And since the camera was not designed to be use in FX mode with DX lenses... the manufacturer probably never thought anyone would do that...

Thanks for the input. I do understand that a more expensive FX lens will generally produce overall better IQ than a less expensive DX lens. I already have two FX lenses that fulfill my needs well for everything except wide angle hence why I'm looking for a wide angle lens and I'm prepared to spend the money on it. However, I won't spend money on it if I can deliver 24MP images at 16-18mm focal length using an existing DX lens I already have provided it meets MY level of desired image quality. I am totally satisfied with 6mm worth of zoom, in fact for my personal preference I would even be content with a fixed focal length wide angle lens had they made one at a competitive price which they don't. The reason I switched over from the D7000 to D600 is for improved low light performance since half of my shooting is either in dim indoor places at night or outdoor evening/night functions and I'm not disappointed one bit with what this upgrade has given me so far. My night shot images are looking much better than what comes out of the D7000.

 

[480sparky]

Why have a nice FX body, and cripple it with DX lenses? GOOD FX lenses will have better IQ, Focusing, etc...
.........

Simple: Not everyone is filthy rich.

 

[cgipson1]

Why have a nice FX body, and cripple it with DX lenses? GOOD FX lenses will have better IQ, Focusing, etc...
.........

Simple: Not everyone is filthy rich.

Funny.. second time you have said that to me! lol! I WISH I was filthy rich... it would be nice.

 

[Derrel]

Why have a nice FX body, and cripple it with DX lenses? GOOD FX lenses will have better IQ, Focusing, etc...
.........

Simple: Not everyone is filthy rich.

I'm not confident that FX Nikkor lenses are automatically "better" than DX lenses...in fact, I think the opposite might be true, since DX lenses, being designed for smaller sensors, need to deliver higher MTF than FX lenses, which can be lesser in resolving ability, due to the significantly larger image capture area used in FX. This is a lot like the way that 35mm lenses simply MUST have higher MTF than medium format lenses, because 35mm negatives are so,so tiny compared to medium format, with image sizes as large as 6x9 bedding pretty common, with 6x6 and 6x7 also being common. The small-format Olympus lenses designed for 4/3 sensor size have simply OUTSTANDING optical performance...but then they absolutely need to offer stellar resolving capabilities, since 4/3 is like a small postage stamp sized sensor.

Thom Hogan's lens reviews usually specifically discuss how the DX lenses cover the FX image size. In addition to FX, and DX size, the pro Nikon bodies (D3 and D4 series) also offer the 5:4 aspect ratio, which is of course, in between FX and DX in size, and is more-squareish; it is often called 8x10 crop, sometimes referred to as 1.2x FOV mode.

 

[cgipson1]

Why have a nice FX body, and cripple it with DX lenses? GOOD FX lenses will have better IQ, Focusing, etc...
.........

Simple: Not everyone is filthy rich.

I'm not confident that FX Nikkor lenses are automatically "better" than DX lenses...in fact, I think the opposite might be true, since DX lenses, being designed for smaller sensors, need to deliver higher MTF than FX lenses, which can be lesser in resolving ability, due to the significantly larger image capture area used in FX. This is a lot like the way that 35mm lenses simply MUST have higher MTF than medium format lenses, because 35mm negatives are so,so tiny compared to medium format, with image sizes as large as 6x9 bedding pretty common, with 6x6 and 6x7 also being common. The small-format Olympus lenses designed for 4/3 sensor size have simply OUTSTANDING optical performance...but then they absolutely need to offer stellar resolving capabilities, since 4/3 is like a small postage stamp sized sensor.

Thom Hogan's lens reviews usually specifically discuss how the DX lenses cover the FX image size. In addition to FX, and DX size, the pro Nikon bodies (D3 and D4 series) also offer the 5:4 aspect ratio, which is of course, in between FX and DX in size, and is more-squareish; it is often called 8x10 crop, sometimes referred to as 1.2x FOV mode.

I tried to pick two lenses of similar focal length (taking into account crop factor 1.5) and tried to get two lenses of similar cost also. I even picked a DX lens I have been impressed with.. the 10-24 (On D300) at $1000.. and the 16-35 FX (on D600) at $1200... per DXO Mark... the FX is a 23 overall, and the DX is an 11 overall. Pretty significant improvement, I think.

DxOMark - Compare lenses



Notice I added the 14-24 (on D600).. just for comparison, since it is nowhere close in price, unlike the 16-35. But that one is rated at 28 overall... much better yet! Unfortunately, DXOMark doesn't seem to test the DX lenses on FX bodies.. probably because of the amount of degradation it causes... so can't compare that!

 

[cgipson1]

and when comparing those same three lenses on a DX body.. well again.. the 14-24 is better... the other two are equal because of the limitations of the DX body

DxOMark - Compare lenses

 

[Gavjenks]

Looking at MTFs right now, Derrel appears to be correct: the few pairs that can be more or less reasonably compared (such as the 35mm 1.8 DX and the 35mm 2.0 FX) tend to have higher resolution and contrast ratings for the DX lenses, not the other way around. They don't publish MTF data out to the edge of what would be full frame for DX lenses, but all the ones I'm looking at are almost dead flat horizontal at the edge of DX.

So if a DX lens gives you no vignetting at the FL you want to work at, there's a chance that it's actually better than the equivalent FX at IQ it seems. The different in price being the extra glass needed to have no vignetting at ANY focal length. And possibly bells and whistles like build quality.




In particular to this thread, the OP was talking about the FX 16-35 at wide end vs. the DX 12-24 at the tele end. let's compare those two MTFs, wide end and tele end respectively, rescaled to match:

They look almost identical to me out as far as the data goes. And there's no particular reason to believe the DX does any worse out to the edges than the FX does, since the FX already kind of tanks out to the edge at the wide end, like the DX likely does as well.

In this case, you're also paying for 1 stop faster aperture though in the FX.




This doesn't take into account bokeh, flaring, etc., being only MTF charts.

 

[Derrel]

You can't really even compare your first D300 versus D600 comparison...the 12 MP vs 24 MP sensor comparison, and Dx versus FX is messing things up. That's a pretty ridiculous comparison, but it does show just how much more resolution a bigger, newer, double pixel count sensor can bring to the table.

Notice that in the second comparison, ALL on the SAME body, the 10-24mm DX turns in a score of 13 at 10mm, and the FX 16-35 VR zoom turns in a 13, being best at 24mm...so, as I stated, I do not believe that DX lenses are "automatically" better than FX lenses. Looks like I am right....in this case, a wider-angle DX lens equals an FX Nikkor zoom...

So DX lens versus FX lens....basically...the same performance score, 13...despite the DX 10-24mm zoom being much,much wider-angle than the 16-35 VR. Equal test bed, equal performance for the Dx versus FX...cough,cough...

The 14-24mm is a special lens....one of the better zooms ever made, by any manufacturer...better than almost all of Canon's wide primes....better than virtually all of Nikon's older-generation wide primes...and yet at 35mm, its handily blown away by Sigma's new 35/1.4.

Compare DxO Mark's scores of the 14-24mm Nikkor on the D600. The score is 28. The same lens on 16 MP DX sensor is 17. That's what makes your first (so-called) "comparison" so laughable!!! It's like you picked a 1969 VW bus (the D300) and said, "See, the VW bus is not as fast as this (Nikon D600) 2009 Corvette! It is therefore a piece of ****!"

Nice one, Charlie!

 

[cgipson1]

You can't really even compare your first D300 versus D600 comparison...the 12 MP vs 24 MP sensor comparison, and Dx versus FX is messing things up. That's a pretty ridiculous comparison, but it does show just how much more resolution a bigger, newer, double pixel count sensor can bring to the table.

Notice that in the second comparison, ALL on the SAME body, the 10-24mm DX turns in a score of 13 at 10mm, and the FX 16-35 VR zoom turns in a 13, being best at 24mm...so, as I stated, I do not believe that DX lenses are "automatically" better than FX lenses. Looks like I am right....in this case, a wider-angle DX lens equals an FX Nikkor zoom...

So DX lens versus FX lens....basically...the same performance score, 13...despite the DX 10-24mm zoom being much,much wider-angle than the 16-35 VR. Equal test bed, equal performance for the Dx versus FX...cough,cough...

The 14-24mm is a special lens....one of the better zooms ever made, by any manufacturer...better than almost all of Canon's wide primes....better than virtually all of Nikon's older-generation wide primes...and yet at 35mm, its handily blown away by Sigma's new 35/1.4.

Compare DxO Mark's scores of the 14-24mm Nikkor on the D600. The score is 28. The same lens on 16 MP DX sensor is 17. That's what makes your first (so-called) "comparison" so laughable!!! It's like you picked a 1969 VW bus (the D300) and said, "See, the VW bus is not as fast as this (Nikon D600) 2009 Corvette! It is therefore a piece of ****!"

Nice one, Charlie!

Yea.. nice one back atcha Derrel! Older PRO body not good enough! Right! Too bad we can't compare that DX on an FX body... since the FX lenses are LIMITED by any DX sensor... just as any FX sensor will be limited by a DX lens.....