28mm prime lens comparison, shot on Sony a7R: second round

In this second round of legacy 28mm prime lens testing, we continue to evaluate the impact of field curvature, at the optimal aperture for landscape shooting. Since two of the lenses being tested are slow 28mm f/3.5 lenses, we’ll also measure light falloff in the corners, using Imatest. The source files for those measurements were set to equal exposures in Photoshop, which made the numbers relevant across both lenses. Here are the corner measurements:

SMC Pentax-M 28mm f/3.5 at f/3.5: -3.34 (f-stops)

Vivitar(Kiron) 28mm f/2.0 at f/4: -2.69 (f-stops)

At ~f/10, both lenses were nearly equal, at -1.99 (f-stops) and -1.86 (f-stops), respectively. To sum it up, you do pay a corner darkness penalty with slow glass on a full-frame sensor, but it’s largely gone after the lens is stopped down hard.

The other SLR lenses that were also evaluated for flat fields on the Sony a7R were the Olympus G-Zuiko Auto-W 28mm f/3.5, the Minolta MD Celtic 28mm f/2.8, and the Canon FDn 28mm f/2.8 lens.

Ease of focus at long distances: The center focus point was on the “5610″ street address, on the back of the building. The worst of the bunch for focusing was probably the Canon FDn 28mm lens; it always seemed like either one side or the other was slightly blurry. The Olympus 28mm lens doesn’t have a half-stop mark between f/8 and f/11, which isn’t really focus-related, but it makes the lens feel cheap. The Pentax 28mm lens probably gets the nod here, 1 point.

Lens contrast: Center contrast appears adequate on all of these lenses; this is a subjective call, and it’s influenced by things like changing light conditions, and unequal exposures.

Sides of the images: The Pentax 28mm lens(2 points) takes a narrow win over the Vivitar 28mm lens(1 point). Look at the “5620″ street number, towards the left side of the picture, is it readable? The Olympus 28mm lens has a problem with the left side, which seems to be par for the course for that brand. The Minolta MD Celtic 28mm lens is weak on both sides, with the left side being slightly worse. Don’t look at Minolta for a clean 28mm legacy prime, for full-frame sensor use.

Center of the images: The 36mp Sony a7R seems to favor the centers of every lens that it sees. Would there be more substantial differences between the lens center areas of these photos, if a higher density crop sensor camera was used for this testing? The biggest center failure was with the Oly, but it’s not by much, possibly even in the realm of a slight mis-focus. You have to look hard to see it.

Summary: SMC Pentax-M 28mm f/3.5, all the way. In addition to everything else, it could have the smallest amount of CA. The Vivitar 28mm f/2.0 lens is the winner of the consolation round, at least so far. Both copies of that lens showed very slight out-of-focus areas at wider apertures, at the same spots. We’ll take a look at more apertures than just f/10, with both of those lenses, at a later date. Brands to avoid in the legacy 28mm focal length are the losers here; Canon FDn 28mm f/2.8, Olympus due to unreliability(3 out of 3 build quality failures for this author), and all of the legacy Minolta 28mm prime lenses, except possibly the f/2.5 version, which has a problem with yellow glass. That radioactive yellow tint should be fixable with UV light, similar to what you would do with the old Pentax 50mm Takumars.

What is the next step? Locate and test a Pentax 28mm f/2.8 lens; they are reputed to be slightly better than the slower f/3.5 Pentax lens that was tested here. The unfortunate problem with some of these legacy 28mm lenses is the fact that multiple brands only offered five aperture blades in their camera lenses, which can make for some funky bokeh at certain times. In general, though, 28mm is a big step up over 24mm lenses, on the Sony a7R.

Here is the test image, it’s about 21mb in size, **be sure and view it at 100% size**:


Dan Euritt



Sony a7R at 10000 iso, photos of drag racing at night

This is what the Sony a7R looks like at 10000 ISO, using only ambient lighting from the floodlights at the drag strip. ISO noise reduction on the RAW files was done with DXO Optics Pro 9, using the PRIME setting. There are some comparison photos of the same cars, shot in perfect light, using HSS fill flash from the Sony HLVF60M. The lens was a Vivitar(Kiron) 28mm f/2.0, shot at f/2.8. At wide apertures like f/2.8, there is a lot of field curvature in this Vivitar lens. No hood was used, and there were issues with flaring and reflections from floodlights on both sides of the track.

This is a problematic comparison, because it’s roughly 1/1000th vs. 1/2000th shutter speed, 10000 ISO vs. 800 ISO, f/8 vs. f/2.8, etc. At slower shutter speeds, vehicle movement blurs the image significantly. Ultimately, though, the biggest problem was that 10000 ISO really kills the resolution, even after cleaning up the noise with DXO Optics Pro in PRIME mode. The best results came from properly exposing the picture, even when that meant raising the ISO from 8000 ISO to 10000 ISO. Leaving a little bit of clean grain kept the image from looking too overprocessed.

The location was trackside at the drag strip at Barona CA, for the Match Race Madness #5 event. This race pits evenly matched competitors in a heads-up start on the tree, no bracket racing, best two out of three wins the match.

Track info at http://baronadrags.com

To purchase pictures from the event, or to check out more photos of this race, please see http://peteliebigphotography.smugmug.com/

Dan Euritt

Surfing & body surfing big waves at the Wedge, Newport Beach, Hurricane Marie

Tropical storm Marie developed into a category 5 hurricane in August of 2014, with winds up to 160mph. As Hurricane Marie, it brought Southern California some pretty big surf, which is unusual for the summer months. The eastern Pacific area off of Baja has already seen four category 4 hurricanes this summer, which is the sort of thing that typically happens only during El Nino years.

These hurricane swells arrive in So Cal at steep SSW angles, bringing with them a very strong longshore current, out of the SSW. This energy is focused on beaches facing southwards, like the Wedge in Orange County. The Wedge is also next to a long jetty, that compresses the swell into a corner of the beach, which sort of magnifies and mutates the energy, into something that is both spectacular and dangerous.

This particular swell peaked early in the morning, and most of the bodysurfing photos were taken as the swell was dropping. The only long lens on hand was an old manual focus Tamron SP 60-300 Adaptall-2 zoom lens. It had noticeable vignetting even at f/8, and the resolution wasn’t a match for the 36mp sensor in the Sony a7R. These pics where mostly shot at f/8, iso800, 1/2000th of a second shutter speed.

Dan Euritt

2014 Police Motorcycle Training & Competition Carlsbad CA

The San Diego County Motor Officers’ Association  hosts an annual motorcycle skills contest for West Coast law enforcement agencies. Participants come from as far away as Tijuana, San Francisco, and Las Vegas. They engage in slow speed contests around orange cones, one of which involved two bikes tied together with a short strap. Pop the strap, start over; it’s tougher than it sounds.

There were two road courses, run against the clock, with penalties assessed for knocking over cones. The turns were tight, and the cones were stacked closely together. Not so easy on a full-size motorcycle.

Most of the bikes in attendance were manufactured by BMW, but there a couple of police departments still riding classic Harley Davidsons, as well as Honda and even Kawasaki motorcycles.

The following police motorcycle photos were shot with the Sony a7R and a Minolta Celtic 200mm f/4 lens, at f/8 and 400iso.

Dan Euritt