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FE-Lenses for APS-C-Cameras instead od E-Lenses?


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Im not dead positive on this, but I think hes wrong regarding crop factor and light gathering ability of the aperture. He says you have to multiply both the focal length and aperture by the crop factor, so a 50mm f2.0 lens becomes a 75mm f3.0 lens. This is true regarding DOF only I think. It was my understanding that even though the DOF is now an f3.0 in this scenario, that the light gathering ability remains f2.0, so I think he is wrong about that.

 

If anybody knows any better please share.

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Im not dead positive on this, but I think hes wrong regarding crop factor and light gathering ability of the aperture. He says you have to multiply both the focal length and aperture by the crop factor, so a 50mm f2.0 lens becomes a 75mm f3.0 lens. This is true regarding DOF only I think. It was my understanding that even though the DOF is now an f3.0 in this scenario, that the light gathering ability remains f2.0, so I think he is wrong about that.

 

If anybody knows any better please share.

 

Technically the light gathering remains f/2, but you need to bear in mind that full frame sensors gather more than twice the amount of light so, all else being equal, the noise performance will be around a stop better.

 

So, for example:

 

FF with 50mm lens @ f/2, ISO 1600, 1/60th sec

compared to

APS-C with 50mm (75mm) lens @ f/2, ISO 1600, 1/60th sec

 

The exposure on both cameras will be the same, but the noise performance will be around stop better on FF due to the sensor being (more than) twice as big.

 

The FF camera could operate @ f/3 (f/2.8 to be exact), ISO3200, 1/60th, and it would give the similar exposure, DOF and noise performance as the APS-C camera at f/2, ISO1600, 1/60th sec.

 

That's why the 50mm f/2 effectively becomes f/3 on APS-C in terms of light gathering as well as DOF.

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Technically the light gathering remains f/2, but you need to bear in mind that full frame sensors gather more than twice the amount of light so, all else being equal, the noise performance will be around a stop better.

 

So, for example:

 

FF with 50mm lens @ f/2, ISO 1600, 1/60th sec

compared to

APS-C with 50mm (75mm) lens @ f/2, ISO 1600, 1/60th sec

 

The exposure on both cameras will be the same, but the noise performance will be around stop better on FF due to the sensor being (more than) twice as big.

 

The FF camera could operate @ f/3 (f/2.8 to be exact), ISO3200, 1/60th, and it would give the similar exposure, DOF and noise performance as the APS-C camera at f/2, ISO1600, 1/60th sec.

 

That's why the 50mm f/2 effectively becomes f/3 on APS-C in terms of light gathering as well as DOF.

That makes sense, so technically we are both right! Thanks for clearing that up! 

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  • 3 months later...

Hi I'm Coast, new to Rumors, I think it's great. :) I  bought the Sony a6000 on cyber monday and the Zeiss 16-70mm aps-c this march. The kit 16-50mm & the 55-210mm came w the a6000, so I have an all aps-c system now. I'm pretty much set, some day I might get a wide angle.

I'm not a studio guy, I'm outdoors landscape so size & weight matter a lot. I travel as light as possible so I don't see myself w heavier & bigger FF stuff. I love my a6000, having a Ton of Fun!

 

Welcome, dear visitor! As registered member you'd see an image here…

Simply register for free here – We are always happy to welcome new members!

 

I've been wondering  if there's a difference in photo's from a 24 meg FF sensor &  24 meg crop sensor, other than the crop. Thanks to  the Northrup UTube, he seems to me to be saying because 24 megs in a crop sensor are denser than 24 megs in a FF, w a quality aps-c lens photo's should be sharper. Am I correct? What else could the differences be

I checked w DXO & they don't have a rating for my Zeiss & a6000 combination. I would like to know how good the combo is. I love the combo

 

Thank you very much__________Coast

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    • Hmm that's pretty dreadful indeed... My 18-105 for sure is sharper than that. If I have time tomorrow I'll shoot an example with mine at 40mm f/8 side by side with the 16-55. Sold my kit lens when I bought the 18-105 so can't compare those anymore.
    • Thanks for the very useful information. The 16-55 tempts me, I can live with the absence of stabilisation, what holds me is the price tag. As always, there is not such a thing like a free lunch in life. The Sony gives performance at a reasonable size but with no stabilisation and higher price tag, the Zeiss is compact, stabilised and reasonably priced but lower performed, while the Tamron provides performance at very good price and stabilisation at the expense of bulkiness. 😀 All in all, I think I will give a try to the Tamron, once I have taken in my hands. Here are two cutouts taken close to the center of the picture. The sharper one is the kit zoom, the other is the 18-105 mm, at approximately the same lenght around 40 mm at /f 8. The difference is impressive and more impressive for me is that all the lenses in the shop had the same behaviour on two different cameras. At this point looks like a whole batch and not just a lens.  

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    • That's a pity and certainly doesn't match with my experience with the 18-105: mine is definately on par with the 16-50 kit lens (which on its own was as decent as I could expect from such a cheap lens). Sure, dont expect sharp corners especially wide open, but in the center my 18-105 left little to be desired across most of the zoom range. The 16-55 does beat it in every regard except zoom range though. The Tamron 17-70 trades blows with the 16-55 and might be the better choice in some cases. I went for the 16-55 because of the smaller size (I also found the 18-105 too bulky most of the time) and slightly wider FoV. My camera has a stabilized sensor so stabilized optics was no requirement for me. As you noted, I kept the 18-105 on my old A6000 for the occasional video project.
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