The Canon also features fast, silent and accurate USM (Ultrasonic Motor) focusing with FTM focusing - also a big advantage. I tested my 18-135. It also had problems with losing focus if you tilt the hood. Not very much though. But enough to cause suspicion. Here you have to be careful, because if you do it to hard, the lens will zoom. Also annoying, but it needs some force.

I shot some more in the morning but haven't had a chance to review on my computer but based on what I can see from LCD chimping so far- Ok, so here’s the Sigma 18-50 2.8 mounted on my own Sony A6400. It may have a shorter range than the Sony 2.8 and especially the Tamron, but at 60x76mm it’s comfortably more compact than either model, and at just 288g, roughly half their weight too. In terms of controls, there’s just two: a fairly narrow manual focusing ring with ribbing that’s flush to the barrel making it a little awkward to turn at times, and a wider zoom ring that extends the barrel by about 24mm. Like the other two premium options, Sigma supplies the lens with a plastic hood, although the 55mm filter thread is narrower than the 67mm on the Sony and Tamron.Thus I wonder if these lenses really deserve their reputation. The Panasonic look better, but, IMO, all kit lenses I handled in shops felt cheaper than the Pentax 18-55, and wobbled too. The petal shape looks cool, and another advantage of this hood shape is easier installation alignment (simply align the small petal to the top), though a round-shaped hood enables the lens to stand on its hood (if conditions permit). Vignetting is correctable during post-processing with increased noise in the brightened areas being the penalty, or it can be embraced, using the effect to draw the viewer's eye to the center of the frame. The Sigma 18-50mm F2.8 DC DN Contemporary produces quite nice sunstars when stopped-down to f/22, as shown below, although it it a little prone to flare when shooting directly into the sun. It features a rounded 7-blade diaphragm which creates an attractive blur to out-of-focus areas of the image and an internal focusing mechanism which means the lens barrel doesn't move.

At the wide end, this lens is impressively sharp at f/2.8 with little improvement showing or needed at f/4. Neither the DL 18-50 or DL 24-85 offer built-in viewfinders, an omission many will find problematic, but they do both have a hotshoe which along with Speedlight flashguns can accommodate an optional EVF accessory; also available as a kit. I am however pleased to report the screens on both models tilt and are touch-sensitive. You can get the Sigma cap on and off with the lens hood in place, but unless you have long, strong fingernails, it is easier to remove the hood first. I do not consider my copy a dud because I have seen many kit lenses and even Canon 24-105L's some with wobble, and some without, and none have ever been prime like in quality throughout focal lengths, etc.

Coma is absent in the center of the frame, gets worse toward the edges/corners, and generally appears as a comet-like or triangular tail of light which can be oriented either away from the center of the frame (external coma) or toward the center of the frame (internal coma). I had an underlying discomfort with the fact that the Nikkor Z DX 18-140mm f/3.5 did not, at least match, the Nikkor Z DX 50-250mm f/4.5 image quality, and natural color fidelity. So I really scrutinized each original image in your comparison, on one of my 5K displays. I first used my Reducing Glass to view the screen clearly at a distance to get an overall impression, that a reducing glass can provide. Then, I held the reducing glass close to the screen, which allowed me to examine image exposure, detail and focus overall. The 18-140mm sharpness was never as good or consistent as the 50-250mm f/4.5, and further, the 18-140mm showed focus really falling off considerably near the edges - getting very soft, while the 50-250mm f/4.5 maintained focus from the center, with very little fall off out to the edge of the frame - never getting really soft. The Sigma 18-50mm F2.8 DC DN Contemporary feels solid enough in your hand, despite its mostly polycarbonate construction. Yes I agree, MFT primes can be pricy and there are a few Pentax primes that are very well priced lately. Sigma have used an iris diaphragm with 7 rounded blades for a fairly pleasing rendering of the out-of-focus highlights.

I've actually been using the 50-250DXVR more and more often these days. If I need wider I'll shoot a panoramic for 28mm (42mm eq) FOV. How do the edges look if you go to 5.6? The samples in the Pentax forums review are low light shots which are not high contrast. Here’s another example of focus-pulling for video, starting with the Sigma 18-50 at 50mm f2.8 and now for comparison the Sony 16-50 at 50mm f5.6 where again there’s much less blurring possible. Axial CA remains somewhat persistent when stopping down, with the color misalignment effect increasing with defocusing.Also the specs say the macro capability is not as good as previous versions but I was somewhat impressed...maybe I just didn't test out the previous version enough in this regard. So, why has Pentax made some designs with lose front lens? Even for the more expensive 18-135? Strange. My standard disclaimer: You should be aware that there are potential issues with third party lenses. All I look for is an image which is sharp enough or can be sharpened, raw/jpeg/sharpened doesn't matter, if the image is too soft at the edge, it can't be fixed. At f/4, vignetting decreases by approximately 1 stop, with little reduction seen after f/5.6, where about a stop of shading remains deep in the corners.

Now here’s the Sigma on the left and the Sony on the right, both from the same distance, both set to 50mm and their maximum apertures of f2.8 and f5.6 respectively. Here the two stop benefit of the Sigma on the left is obvious with a much shallower depth of field, but the rendering is much more attractive too with the blobs from the Sony on the right suffering from much more obvious onion-ring textures within. So as expected, the Sigma offers a step-up in rendering quality over the basic Sony kit zoom. The rear portion of the hood is rubberized to, along with the mold-ribbed ring, facilitate installation and removal. The lens is supplied with plastic lens caps and a plastic flower-shaped lens hood (LH582-02) - there's no lens bag included. The filter size is 55mm. Focal Range As of review time, Canon and Sony do not publish extension tube specs or manufacture these items in compatible mounts, but third-party extension tubes are available.

I have not much used my 18-55 since. Thus I decided recently to take it around, as I might lend it to my daughter in some coming occasions.