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next PZ lens test report - Sigma 14mm f/1.8 DG HSM ART
#1
Depending on how you look at it ... it may be nice ... or not that great ...

 

http://www.opticallimits.com/canon_eos_f...ma14f18art

#2
Great stuff!.. However, I should point out that the Laowa 12mm lens mentioned in the intro isn't f/2, just f/2.8. Smile If you need an example to replace it, there's the Samyang 14mm f/2.4 XP (or whatever it's called). Both this and the Irix are only 1/2 stop (in practice probably even 1/3, because the camera would probably round that aperture down to f/2.5?) brighter than the "norm" though, not 1 1/3 stop, so I'm not sure they really count at all. This SIGMA is totally unique.
#3
was this one taken on tripod ??

 

[Image: 0F6A1014.jpg]

 

 

if yes whay ISO 2400f1.8 otherwise at high pixel count , unless you haveextremely steady hands and did several tries I go for at least 1/2x focal shutter speed 1/15s is too slow for me at leasf

#4
Good well written review!  

 

   Thanks for the secondary review also, on a 22 Mps sensor, as per usual the 50Mps sensor does not flatter.

 

 

  Strangely the Samyang 14mm F2.8 seems to do better (other than distortion) with only a shortfall of one stop. BTW for those who use Adobe PS CS6/ACR 9.0,distortion correction for the Samyang can be found under the Sony A7III category.

 

   The Sigma here is not my bag, the AF is approximative, (so manual focus is almost a given at larger stops), and price/size/ weight are prohibitive!
Dave's clichés
#5
Quote:Great stuff!.. However, I should point out that the Laowa 12mm lens mentioned in the intro isn't f/2, just f/2.8. Smile If you need an example to replace it, there's the Samyang 14mm f/2.4 XP (or whatever it's called). Both this and the Irix are only 1/2 stop (in practice probably even 1/3, because the camera would probably round that aperture down to f/2.5?) brighter than the "norm" though, not 1 1/3 stop, so I'm not sure they really count at all. This SIGMA is totally unique.
 

Ah, right, mixed the Laowa with their 15mm f/2.

Quote:was this one taken on tripod ??

 

[Image: 0F6A1014.jpg]

 

 

if yes whay ISO 2400f1.8 otherwise at high pixel count , unless you haveextremely steady hands and did several tries I go for at least 1/2x focal shutter speed 1/15s is too slow for me at leasf
 

That would have been an exotic tripod ;-)
#6
Two more things. The Specifications section describes the hood as "bayonet mount, built-in". I thought it's one or the other? This lens definitely has a non-removable hood. Smile Also, you said that the MC-11 converter is for using the lens on the Sony and Sigma mirrorless cameras while in reality it's only about the Sony cameras - you can use it to adapt the Sigma / Canon mount lenses to a Sony camera (with whichever version of the adapter), not the Canon mount lenses to the Sigma. Smile 

#7
Quote:Yes, it offers an insane max. aperture at this focal length but at least technically you won't find greatness at f/1.8. the corners are soft. Whether this matters at this aperture is a different question. Astrophotographers may have hoped for more (at least at 50mp) whereas it's a not an issue in shallow depth-of-field scenarios really.
 

Did you do a resolution test at  âˆž ? Otherwise I just ask how do you rate the lens for astrophotography? And a very sharp center very wide open is just not great enough? I don't want to talk away the soft borders, but I'd like to discuss ultra wide shots, available lights and the importance of sharp corners  ^_^

The stair house shot could not have benefitted of better corners - due to DoF the corners already are soft.

Emphasiszing something in the corners and a lot of blurred background? Don't know, so far I didn't feel my composition sucks because of weak corners.

 

However, I don't agree with the weak corners at âˆž and I know, you guys usually test at 25-50 × f which in that case would be 50 × 14mm = 700 mm distance between test chart and sensor. That's a bit bold to conclude from this distance to it's behaviour at distances suitable for astro.

 

[Image: i-MnSdccX-L.jpg]

 

Here's the full res.

 

Typically, I use the lens mostly for this kind of subjects

 

[Image: i-N7gWzBv-L.jpg]

 

or that one

 

[Image: i-VXNSRTn-L.jpg]

 

Soft corners? I don't care much, I'm not using this lens for reproductions of flat objects wide open  Big Grin

 

Of course I understand you're using the standards of PZ or OL for your tests and for all lenses, but there's were trouble starts: Not all lenses are needed/bought for the same purposes. Sharp corners are very interesting for a couple of subjects - just not for all and if it comes to wide angle lenses tested not even close to infinity, I scratch my head about the testing method.

 

What if the field curvatures radius approaches ∞ at âˆž? You haven't tested that, otherwise you would have told us.

 

And the Laowa 15/2 is only made for Sony E mount...  Tongue

#8
At any rate, this lens looks great, a vast improvement over the predecessor. I have and love the said predecessor, but it doesn't even come close to being sharp across the frame (APS-H mind you...) until ~oh say~ f/13 or so, and even then it depends on the orientation of the scene (a sign of strong field curvature). I haven't analyzed it formally of course, just had the time (7,5 years and counting) to get used to its quirks. 20 years of lens design haven't passed for nothing...

 

The price / size is another matter entirely. Smile I'm not going to upgrade but if Sigma had released a wider prime - say, 12mm - I would've been more willing.

#9
I also was thinking about and got a sample to try very briefly the Irix 11/4. Less heavy, less costly and adjustable focus stop for ∞. THis is where I am sceptical - even if the Sigma would be great for astro-stuff, how to focus it at âˆž ?

 

If a lens like this needs AF is something everyone should decide for himself*. For landscape I don't see much of a benefit. For other stuff it's helpful, especially in LiveView ad with electronic shutter (I don't think, with an OVF one gets the focus right at f/1.8) and at this kind of weight, it's easier to manouever with AF.

 

*but if the answer is "yes", it's good to adjust it at more than only one distance. I feel this feature falls very short in most tests of Tamrons or Sigmas. -_-

 

As well as I say: If I have AF, I also have a focus motor and can remote control the lens. Meaning, the camera can be so close at the floor, that I don't see properly the screen, or I need to but it back to the wall to get the full room. Then it becomes handy, controlling the  camera with a smartphone or tablet and setting the focus ring.

 

Oh, and dave: you forgot in your list "no filter thread"

#10
No, I didn't test at infinity but at f/1.8 there was quite some field curvature anyway. Even in the theoretical event that the lens is better at infinity, the field curvature would hit astro-photographers.

  


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