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Sigma 18-35 1.8 zoom for APS

Guy Mancuso

Administrator, Instructor
Just finished shooting a test round with this lens. Wow from the LCD alone this maybe the sharpest zoom I have every tried and no not at 2.8 but a unheard of 1.8. Eating a very bad breakfast first. Lol
If I don't stroke out from it than I will have images up for viewing. But it's a winner and a surprise for A7r users. No vignetting at about 28mm setting so its a full 36 mpx which translates to maybe a 36mm on FF. now that's interesting. Explain more later
 

Guy Mancuso

Administrator, Instructor
I might be rethinking the A7r and this as if the crop factor is off than it's shooting at 36mpx. So if the vignette stops at 28 and longer than it is considered a FF 28 and higher lens at 36mpx. Hmmm
 

Guy Mancuso

Administrator, Instructor
These images are blazing sharp. I noticed on my corner tests at least by F4 all corners are tack sharp at all focal lengths and a couple even at 2.8.

This lens once again Sigma Art series lenses are proof they are very serious about image quality.
 

Guy Mancuso

Administrator, Instructor
Yea I'm going to run another test for the A7r this lens can be shot on it at full 36mpx. I want to see where the vignetting starts and ends in regards to focal lengths. We have just found a 28 and 35 1.8 lens .
 

Guy Mancuso

Administrator, Instructor
Okay let me show you real quickly here the A7R with the Sigma 18-35 and the Sony 4 adapter.

Now this is in crop mode this first image at 18mm which is a 26mm FF equivalent.




Now from the same spot take off the crop mode setting in the camera you get this.




Now if I take the crop mode image and overlay it over the non crop mode image you will see you get a lot of extra image area to work with.




Okay I went into that image and keeping the same aspect ratio I was able to squeeze even more out of it so maybe 24 or 25mm

 
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Guy Mancuso

Administrator, Instructor
So looking at this you can crop in several directions and get a wider image and /or taller image. Maybe even squeeze a 24mm lens out of it. Now shooting this way by the time you crop lets say you get to basically a 15-18mpx camera depending on how you crop. So maybe not the ideal way to shoot this lens but we have another option.

What if I did not turn off the crop and just zoomed out past the hard vignetting of the lens and I am still shooting 36mpx size. Well I tried that and about 28mm the hard vignetting went pretty much away.

Now not sure I really focused here but just to give you a idea and we could fix that hard vignette at this setting. So looking at this all of a sudden a APS designed lens is full frame from 28mm and longer. Now i want to test this out more completely here but this has some serious promise and i will tell you why there is no 28MM 1.8 lens on the market for the A7r for one and no 35 1.8 lens either. Dah!!! we may have found a great solution here

 

Guy Mancuso

Administrator, Instructor
Same image with a quick fix in LR and now we have a Clean 36mpx A7r 28mm 1.8 lens. Folks the world just opened up

 

Guy Mancuso

Administrator, Instructor
Now if its a critical corner than I would say go to 30mm on the lens take a half a step back and your in at 28mm


But here is another cool tidbit this is also a 35mm 1.8 although a truck of a lens it is faster than the 35mm FE lens. For me that is sitting on a Sigma 35mm 1.4 ART lens than it brings up a option.
 

Guy Mancuso

Administrator, Instructor
Okay that was a brief intermission from the main story and something I would like to do is go out and shoot that more for real on the A7r as there is some real power there with this lens.


Now lets get back to the A77II at 18mm wide open shot this time. This is crazy nice

 

Guy Mancuso

Administrator, Instructor
It has decent bokeh maybe a touch nervous but I only see out of everything the only downside. Touch of Ca wide open but easily fixed as well. Its a keeper no doubt in my mind and it focuses extremely fast
 

iiiNelson

Well-known member
Can you take a picture of what this lens looks like mounted on the A7r? I'm just curious to see how large it is in relation to the camera. Might be a viable wide option. Makes you hope that Sigma brings out some native FE lenses for sure.
 

msadat

Member
did the same thing yesterday with the a7ii and sigma, shooting a family gathering. a really nice combo, you get, is mega pixel, sharp lens, fast af camera.
 

Guy Mancuso

Administrator, Instructor
That's my lens hood. I use metal screw in hoods. I put all original caps and hoods in box so I don't lose them
 
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