Nikon 20mm f/1.8 vs Sigma 20mm f/1.4

[Hector Javkin]

<p>I need a 20mm, and both the Nikon f/1.8 and the Sigma f/1.4 have had good reviews. Right now, their prices are very close. The Nikon seems excellent. So does the Sigma, and it is beautiful, very solidly built, but significantly heavier. I have tendinitis in my hands, and the weight is important.</p>

<p>Last night, I was shooting a party in a very dimly lit restaurant with prime lenses on a D750. On my 28mm f/1.8 the autofocus was sometimes a little slow. It seemed better with my 50mm f/1.4D and 85mm f/1.4D (both screw-drive lenses vs the 28mm f/1.8's AF-S!) but that was just one evening's shooting, a small sample.</p>

<p>For my purchase of a 20mm, if autofocus would work better in similar conditions with the Sigma f/1.4 vs the Nikon f/1.8, I would put up with the higher weight of the Sigma. Would it work better? If there are any other things I should think about in considering these two lenses, please let me know.</p>

[ilkka_nissila]

The AF on the 20/1.8 Nikkor is very fast and decisive in my experience. I have not used the Sigma.

[Andy Murphy]

<p>I use Nikon copy on D800 and D5300 and appreciate light kit. Just be careful of flare possibilities.</p>

[lornesunley]

<p>When the light levels are very low, the wider aperture lens will likely focus better, it lets in more light.</p>

[Dieter Schaefer]

<blockquote>

<p>the wider aperture lens will likely focus better, it lets in more light</p>

</blockquote>

<p>I don't think it is as clear cut as that; there are many factors that influence the AF performance and I don't think a general statement that an f/1.4 lens will do better than an f/1.8 one can be made.</p>

<p>With regards to Sigma vs Nikon: the Sigma is 950g vs 375g for the Nikon - quite substantial difference I say. Also, the Sigma doesn't take filters (unless on uses a contraption like the one necessary on the 14-24).</p>

[ShunCheung]

Generally speaking, f2.8 lenses will AF faster or at least more accurately than f4 under dim light. However, I am not sure

f1.4 will have much of advantage over f1.8. On the flip side, the larger elements could slow down AF. That is why those modern 70-200mm/f2.8 zooms only focus with a smaller group of elements in the middle of the barrel, resulting with focus breathing.

 

Additionally, a lot of these f1.4, 1.8 lenses are not designed for fast AF. Instead, depth of field is shallow at f1.4. Rather,

the emphasis is accurate AF. Fast AF that tends to overshoot and then hunt around is not necessarily desirable.

 

I only have the Sigma 35mm/f1.4. Optically it is great, but IMO all that metal construction and heavy weight is

unnecessary for these rather small lenses. I also tend to avoid something with a bulging front element that is vulnerable.

That is why I don't use my 14-24mm AF-S very often.

[Dieter Schaefer]

<blockquote>

<p>I also tend to avoid something with a bulging front element that is vulnerable.</p>

</blockquote>

<p>Which is why the Sigma 20/1.4 won't find its way into my camera bag. I never damaged the fornt element of my 10.5mm fisheye - but didn't like to have to clean it all the time either.</p>

[rodeo_joe1]

<p>DXOMark measures the transmission speed of the Sigma at T1.8, and the Nikkor at T2.1, so the real difference in brightness is less than 1/3rd of a stop. However the Sigma looks to be 1 stop ahead on sharpness and vignetting, but less good when it comes to CAs.</p>

<p>My money would go with Nikon on balance, unless resolution was the only criterion that mattered.</p>

[chip_chipowski]

<p>One stop worth of sharpness? </p>

[Hector Javkin]

<p>Thank you very much to all your thoughtful answers.<br>

Ilkka and Andy, your experiences with the Nikon lens encourage me to get the lens I would prefer to prefer to be lifting when shooting hand-held.<br>

Lorne, Dieter, Shun, and Rodeo Joe, I knew that the larger aperture of the Sigma should help with autofocusing in dim light, but also that other factors such as transmission characteristics can play a role. I also hadn’t realized that the Sigma can’t take filters, which is important to me.<br>

Chip, I think it means that the Sigma will retain the same sharpness as the Nikon at 1 stop larger aperture.<br>

Again, thank you all. I will go with the Nikon. Best regards.<br /><br /></p>

[Two23]

<p>I have the Sigmas 35mm and 50mm f1.4A and love them. They are very heavy though. I was looking at 24mm lenses but ended up with the Nikon 24mm PC-E because the movements are so important to me. The 24mm wasn't quite wide enough at times on my D800E though. I tried both the Sigma 20mm f1.4 and Nikon 20mm f1.8G. The weight of the Sigma was a turn off since I want to use the lens on an Ioptron astro tracker at times. The Sigma Art lenses are my favorite--I'm not a Nikon "fan boy." However, I ended up with the Nikon 20mm f1.8G because it's such an outstanding lens. Looking at DxO etc. the Sigma just didn't look much better, over all. Not enough that I'd ever see the difference. The Nikon does focus very quickly and surely. I think I read somewhere that the modern Nikons don't AF any faster because a lens is faster than f2.8. There's sort of a limit on how fast the AF can use. So yes, I've been very happy with the Nikon 20mm. It has low distortion, low CA, and is very sharp. They've been out long enough now that there are used ones available. That's what I got.</p>

<p>Kent in SD</p><div></div>

[thadley]

<p>The only thing I can offer is that I purchased the Nikon 20mm 1.8 recently and I am happy with it.</p>

[Hector Javkin]

<p>Kent, interesting discussion, and a great photo. Kent and Tony, thank you.</p>

[eric_arnold]

<p>in your case, the nikon seems like the better option, mainly because its almost 1/3rd less weight, and that is a concern for you.</p>

[robert_stig]

<p>I have the 50 and 24 sigma art lenses. For me weight is not an issue and i do love the heft and mass. But since you have a problem with weight, havibg tendinitis you should lean towards the nikon. For me though iq is priority and low situation is a plenty for me in weddings so i went with the sigmas. I didnt get the nikon 24 1.4 because its just twice the price and images i saw were worse vs the sigma. The art lenses have raised the bar. </p>

[Hector Javkin]

<p>Thank you all. I purchased the Nikon.</p>