# Is this because of focus breathing?



## Timppa (Mar 14, 2017)

Hi!

So today I went to the camera store to test out tamron 150-600 and nikon 200-500
I concluded to take the nikon, because I just felt that the tamrons have issues with VR, it just 'twitches' when I look, I don't know, its weird!.
Anyway, this is not what I wanted to talk about, I took for fun a picture with my Tamron 16-300 and compared the 300mm with the nikon 200-500 at 300mm. Now, put sharpness and blur on the side, because its obvious who is the winner, but just look at the difference of the picture!

This is the Nikon AT 300 VS Tamron at 300







This is the Nikon at 200 VS tamron at 300





It looks like the Tamron isn't even close to 300mm! It's more like a Tamron 16-220 or something!
When I read many reviews and blogs about wildlife photography, I see many pictures posted at 300mm, and I'm thinking, how do they get so close to the wildlife? If I take one more step, they fly! But its clear that I'm not getting the same reach as they are with their 300mm!

Is this focus breathing? differences between FX and DX lens? or just Tamron lying?


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## nickgillespie (Mar 14, 2017)

Wait... so the fx lens says that it's a 300mm lens? And the DX lens says that it's a 200mm lens?

If this is what you're saying... it makes sense. It sounds like you have two of the same focal lengths, but a 200 dx lens on an fx body looks like a 300mm lens. 

What you're friends probably have is a 300mm FX lens on a dx body... coming out to 450mm.

Sorry if I'm misunderstanding.


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## Timppa (Mar 14, 2017)

nickgillespie said:


> Wait... so the fx lens says that it's a 300mm lens? And the DX lens says that it's a 200mm lens?
> 
> If this is what you're saying... it makes sense. It sounds like you have two of the same focal lengths, but a 200 dx lens on an fx body looks like a 300mm lens.
> 
> ...



Sorry myself, I should have made it more clear. This is both taken with a DX lens (D7100)
but the Nikon 200-500 is a FX lens, and the Tamron 16-300 is a DX lens (but that should make a difference right? Its the body that crops...)


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## zombiesniper (Mar 14, 2017)

This is an issue with quite a few lenses. Some of Nikon and Canons Zooms don't really give you what is advertised either.

Most of the high grade lenses tend to be more consistent and closer to actual focal then the cheaper offerings. Why? Could be QC in the manufacturing process, I don't know but it is an issue. My 75-300 was never really at 300mm when at full zoom.

Could what you are seeing be in part due to some focus breathing? Sure could and it's easy to tell. Put the lens at 300mm in manual focus and rack the focus back and fourth you will see the focal length change in a lens with breathing issues.


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## Timppa (Mar 14, 2017)

( edit spelling mistake in my previous post, I ment to say '(but that should not make a difference right? Its the body that crops...)' )



zombiesniper said:


> This is an issue with quite a few lenses. Some of Nikon and Canons Zooms don't really give you what is advertised either.
> 
> Most of the high grade lenses tend to be more consistent and closer to actual focal then the cheaper offerings. Why? Could be QC in the manufacturing process, I don't know but it is an issue. My 75-300 was never really at 300mm when at full zoom.
> 
> Could what you are seeing be in part due to some focus breathing? Sure could and it's easy to tell. Put the lens at 300mm in manual focus and rack the focus back and fourth you will see the focal length change in a lens with breathing issues.



I just tested this, and yes, the focal length did change. but the difference is so high ! I could expect it to be more like a 270 or even a 250, but its somewhere between 200 and 220! Horrible o_o

I was always leaning towards the sigma or tamron 150-600, because I thought 300mm wasn't even that much... But now its clear to me, Nikon 200-500 it is !


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## nickgillespie (Mar 14, 2017)

Timppa said:


> nickgillespie said:
> 
> 
> > Wait... so the fx lens says that it's a 300mm lens? And the DX lens says that it's a 200mm lens?
> ...


So, I am probably wrong (I've never owned a modern Nikon), but I BELIEVE if it's a dx lens, the numbers on the lens are the equivalents in full frame. What I mean is... if you were to put a 16-35 dx lens on an fx body it would be something like 10-24. So... if your dx lens says that it's 75-300, on an fx body it would be a 50-200. 

So, if you are comparing that lens to a 200mm fx lens, they would appear the same focal length. 

If you want real zoomage... get a 300mm fx lens for your dx body.

Man, I hope I've understood this time. Apologies if my coffee hasn't kicked in yet and I'm still not getting it.


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## Timppa (Mar 14, 2017)

nickgillespie said:


> Timppa said:
> 
> 
> > nickgillespie said:
> ...




I do 100% understand what you mean, also the first time!
But a DX lens at 300mm compared to a FX lens at 300mm on a DX body is still 300mm. 
My tamron 16-300, is acting like a 24-450 in FX comparison
But a Nikon 200-500 on a DX body is like 300-750.
The test I did is Tamron at 300mm and Nikon at 300mm both on DX body, so the MM are staying the same, it would only be different if it was mounted on a FX lens instead.
the 2nd picture is the Nikon at 200mm, to compare how close the Nikon 200mm is towards the tamron at 300mm., clearly showing a lot of focus breathing!


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## Timppa (Mar 14, 2017)

mounted on a FX body* (oh, my fast typing mistakes)


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## Derrel (Mar 14, 2017)

The 16-300 just does not deliver a real 300mm focal length. Part of that could be the less than infinity focus distance, but the majority is likely just advertising hype. Normally a 10% allowance is okay with industry,so 270mm would be about acceptable. Many zooms loose focal length as they get near MFD or minimum focusing distance, and this is probably happening.


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## Timppa (Mar 14, 2017)

Derrel said:


> The 16-300 just does not deliver a real 300mm focal length. Part of that could be the less than infinity focus distance, but the majority is likely just advertising hype. Normally a 10% allowance is okay with industry,so 270mm would be about getting normal.



It clearly does not...
They write indeed that at every focal length there can be a 10% difference, either negative or positive, so the 300mm should be 'normal' between 270 and 330mm. The positive you never get, but the tamron 16-300 is almost 30% off...

And I did test the prime Nikon 300mm F/4 FX lens as well (on the DX body), the 300mm is almost exactly the same as 300mm on the nikon 200-500


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## Derrel (Mar 14, 2017)

Focal lengths are tested at Infinity. At close distances, there is often a substantial loss of effective focal length. This is one of the dirty little secrets of the lens world.


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## SquarePeg (Mar 14, 2017)

So, am I understanding this correctly?  If a FX zoom lens is marketed as whatever-200mm and you use it on a DX body it would give you greater "reach" (say 300mm) although you would be losing that on the wide end but if a DX zoom lens is marketed as whatever-300 and you use it on a DX body you should get at least 270mm.  So the FX 200 and DX 300 would be roughly the equivalent reach on a DX body?


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## Derrel (Mar 14, 2017)

No. Some erroneous information has been introduced to this post.


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## SquarePeg (Mar 14, 2017)

Derrel said:


> No. Some erroneous information has been introduced to this post.



Yeah I thought maybe I was seeing some alternative facts.  I'll just stick to DX lenses on my DX body and not have to think about the rest!


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## Timppa (Mar 14, 2017)

SquarePeg said:


> Derrel said:
> 
> 
> > No. Some erroneous information has been introduced to this post.
> ...



You can use FX lenses on your DX, and it will gave the same reach. 200mm FX or 200mm DX lens is still 200mm on the same body. Its just that there are lenses with focus breathing issues. 

I might confuse people with my explanations, English is not my first language and I even struggle explaining it in my own XD.

Here is a really good video on focus breathing:


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## astroNikon (Mar 14, 2017)

A FX/Full Frame body has a 1:1 in relation to Field of View (FOV).

So a 300mm (FX or DX) lens on a FX will give 300mm FOV though you may get vignetting due to the image circle being too small for a FX sensor.

A 300mm (FX or DX) on a DX camera will have a 1:1.5x in relation to field of view.  So the 300 will act like a 450mm FOV.

The issue here is the zoom lens isn't zooming like advertised .. if I read all that correctly.


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## ClickAddict (Mar 14, 2017)

So you wouldn't happen to have a 1.4 extender attached on your Nikon Lens by chance?    
That would get your 200 to look pretty close to a 300.


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## Timppa (Mar 14, 2017)

astroNikon said:


> The issue here is the zoom lens isn't zooming like advertised .. if I read all that correctly.


exactly 



ClickAddict said:


> So you wouldn't happen to have a 1.4 extender attached on your Nikon Lens by chance?
> That would get your 200 to look pretty close to a 300.


no


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## KmH (Mar 14, 2017)

A 200 mm lens is a 200 mm lens - regardless the camera it's mounted on.

A 200 mm lens mounted on a camera having and APS-C size image sensor will deliver the same Field Of View (FoV)  as a 300 mm lens would mounted on a full frame of the same brand.

Canon APS-C image sensors are a tad smaller than Nikon APS-C sensors, which is why Canon EF-*S* has a crop factor of 1.6 while Nikon DX has a crop factor of 1.5.


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