Category Archives: Testing

smc Pentax-FA 645 45-85mm f/4.5 lens performance

In the quest for a lens with a focal length that would be considered close to normal, I tried the following two lenses:

  • smc PENTAX-DFA 645 55mm F2.8 AL SDM AW [IF]
  • smc PENTAX-FA 645 45mm F2.8

The first is the lens that was originally released with the Pentax 645D camera. While the image sharpness was fine at the centre, the soft edges were not acceptable for the type of work I do. Same comments are true for the 45mm lens. I returned both and purchased a 45-85mm zoom to see what it can do.

In my blog post on the 45mm fixed lens, I photographed a brick wall to see how the centre versus corner sharpness compared. The same wall is featured below with the 45-85mm set to 45mm and an aperture of f/8. Due to the closer camera to subject distance of the asphalt in the lower corners, I’ve chosen a crop slightly up from the bottom of the frame.

Pentax-FA 645 45-85mm f/4.5 lens shot at 45mm f/8 - overall view

Pentax-FA 645 45-85mm f/4.5 lens shot at 45mm f/8 – overall view

Pentax-FA 645 45-85mm f/4.5 lens shot at 45mm f/8 - top left corner

Pentax-FA 645 45-85mm f/4.5 lens shot at 45mm f/8 – top left corner

Pentax-FA 645 45-85mm f/4.5 lens shot at 45mm f/8 - top right corner

Pentax-FA 645 45-85mm f/4.5 lens shot at 45mm f/8 – top right corner

Pentax-FA 645 45-85mm f/4.5 lens shot at 45mm f/8 - bottom right corner

Pentax-FA 645 45-85mm f/4.5 lens shot at 45mm f/8 – bottom right corner

Pentax-FA 645 45-85mm f/4.5 lens shot at 45mm f/8 - bottom left corner

Pentax-FA 645 45-85mm f/4.5 lens shot at 45mm f/8 – bottom left corner

Pentax-FA 645 45-85mm f/4.5 lens shot at 45mm f/8 - bottom left corner with chromatic aberration adjustment enabled

Pentax-FA 645 45-85mm f/4.5 lens shot at 45mm f/8 – bottom left corner with chromatic aberration adjustment enabled

The crops from this image demonstrate the superior performance of the 45-85mm zoom compared to the 45mm f/2.8 fixed lens. The centre and corners, except for the top right, are consistently sharp and exhibit good detail. Focus was set to Auto as it is generally more reliable than my eye. Camera was on a tripod and ISO was at 200.

The second last image in the series shows the chromatic aberration that can show up with this lens when it is shot at 45mm. Turning on the correction in Adobe Lightroom (same as Adobe Camera Raw) eliminates the colour fringing very effectively. The lens exhibits barrel distortion which can also be removed by enabling the lens corrections.

I was very impressed with the performance of this lens at the wide end of the zoom range. In the more than three years that have elapsed since shooting this test and creating this post, I have shot with this lens extensively. Focusing manually is challenging with the slow maximum aperture, however I have found using autofocus is mostly reliable and any shortcomings in image sharpness have usually been related to insufficient depth of field or not choosing a focus point that maximizes the available depth of field.

 

Xrite ColorTRUE Review

ColorTRUE iconWhile on Apple’s App Store recently, I happened to notice Xrite’s ColorTRUE app. It promises to bring color management to your iOS device assuming you have a recent Xrite device such as:

  • ColorMunki Smile
  • ColorMunki Display
  • i1 Display Pro
  • i1 Pro 2

Fortunately, the Professional Photography Dept. at Langara College had purchased an i1 Pro 2 earlier in the year so I was in luck.

The setup is remarkably simple. Connect the device to the computer you normally use it with. Ensure it is on the same WiFi network as your iOS device. For my test I used an iPad Air. The larger gamut of the Air compared to the Mini should be noted if you’re a photographer.

When I started the ColorTRUE app on the iPad Air, it automatically went out and looked for the computer with the i1 Pro 2 attached. Connecting was simple and quick. Next, you need to calibrate the i1 Pro 2. After placing it on the calibration plate, a push of the button on the device started the calibration process.

The app flashes white, then red, until you place the device on the iPad’s screen. It auto detects the device when it’s in place and starts reading the patches the app presents on-screen. Total time was roughly three minutes. It looks similar to a monitor calibration sequence with a series of red, green and blue patches followed by several shades of grey.

ColorTRUE screenshot
The ring of circles surrounding the large red circle in the screeshot above shows the number of patches being read.

Once all the readings are taken, the brightness is adjusted and the profile is saved to Xrite’s server for use by the iPad being profiled. To get the benefit of the app, you need to view images from the Camera Roll on the iPad. The ColorTRUE app gives you options to view the image calibrated vs. uncalibrated, change the RGB profile (sRGB, Adobe RGB, and Pro Photo RGB) and adjust the white point.

The ColorTRUE page on Xrite’s website mentions that any ColorTRUE aware app will make use of the profile so that more accurate color can be obtained. The reality is that other than images on your Camera Roll or those being viewed in the Camranger app will not get the benefit of the profile you just created. Xrite has made an SDK available to developers. Whether the photographic community petitions the developers of their favorite apps to incorporate the ColorTRUE technology remains to be seen.

Evaluating a couple images left me with the impression that the app has a certain degree of usefulness in particular applications. If you can conveniently transfer your images into the Camera Roll (if they’re not already present) and you are in an environment with relatively controlled lighting, then the slightly improved rendering will be of interest. Should you have images that are in either Adobe RGB or Pro Photo RGB color space, then this app will allow you to see correct color rendering. You are also able to apply a print simulation. This will be of interest for those photographers creating images destined for a printing press. It does not include profiles for inkjet printers.

The ColorTRUE app is one of those bonus add-ons that adds to the value of an existing purchase. It wouldn’t motivate me to purchase a new colorimeter or spectrophotometer, however it will be useful from time to time in my workflow. I’m hoping the developer of the ShutterSnitch app chooses to incorporate the ColorTRUE technology.

Trying out the smc Pentax-FA 45-85mm f/4.5 lens

The pause in blog posts has not been due to lack of happenings, but rather quite the opposite. In the past few posts I’d been discussing the challenges in finding a decent mid-range lens for the Pentax 645D. I have written about the older FA 45mm lens. Most users are going to be disappointed by the performance of that lens. Similarly, the new “digitally optimized” 55mm lens also has poor corner sharpness. Twice bitten, now what?

I had read online about some users obtaining good results with the smc Pentax-FA 645 45-85mm f/4.5 zoom lens. This seems to go against the usual wisdom of a prime lens being sharper than a zoom, but I was willing to try anything at this point. My other option was to turn to a Pentax 67 lens with an adapter for the 645D and that was not a road I was interested in traveling just yet.

There is a camera retailer in the U.K that I had purchased my smc Pentax-FA 645 200mm f/4 lens from in December. Great prices and good service. I figured it was worth another email now that I was looking for the 45-85mm lens. Once again, Mifsuds was excellent to deal with and my lens arrived a little more than a week after my email was sent. I normally try to support my local dealers, however going that route in this case would have meant a 3X surcharge.

It’s worth looking at the recent prices on EBay to see what lenses are proving to be popular on the Pentax 645D. The 35mm, 45-85mm and 120mm Macro have all experienced stronger pricing since the 645D became available outside of Japan. It does not appear the 75mm has seen the same increases, although it is an excellent piece of glass as well.

Within a day of it’s arrival, I was out shooting with the 45-85mm lens. It is tougher to focus manually than the 45mm or 55mm lens since its maximum aperture is about one and a half stops smaller. The focus just doesn’t “pop” as well. This is not unique to this lens, however. It’s just a fact of using a slower lens.

So far, I’ve found the 45-85mm to be a good performer with the autofocus system in the 645D. Most images are in the “keeper” category, though keep in mind that I’m mostly shooting subjects that either don’t move or move very slowly. It’s possible to manually focus this lens successfully in good light.

In my next post I’ll show some examples with the 45-85mm. In the meantime, if you’re looking for a mid-range lens for the Pentax 645D, this is the one to go with or should at least deserve your strong consideration.

Long Exposures and the Pentax 645D

I spent about three hours on New Year’s Day wandering around Cliff Gilker Park in Roberts Creek, BC. On the way back, a spectacular sunset greeted my arrival into Davis Bay. After working in a few photolabs for a combined total of nearly seven years, I thought I more than had my fill of sunset photos. Mother Nature still has some surprises!

The Pentax 645D has very low noise images in general, but I haven’t had the opportunity to really push it to the limits of the marked shutter speeds. The lowest user-selectable speed is 30 seconds. The image below was shot at 25 seconds f/11. I was pretty much tripping over the rocks at that point. It was dark! The subtle fill light in the rocks was from a single street light located at least 50 feet behind me. Fortunately for me, it was sodium vapor so the color matched the sunset quite nicely. This image was shot about 30 minutes after the sun dipped below the mountains on Vancouver Island. The city lights in the distance are Nanaimo.

As an aside, white balance can be an easy tool to altering the appearance and mood of an image. A cool white balance for images of people is seldom attractive unless going to a particular style. Warm it up a bit and the skintones look attractive.

For the image above, I played with the white balance setting on the camera then tweaked it further in Lightroom. The fluorescent setting can give quite an attractive appearance to this sort of image. As is standard on most DSLRs these days, the 645D offers further tuning on the cyan/blue versus yellow/red axis as well as the magenta versus green axis. Very handy!

Back to noise characteristics… I mentioned there was a street light behind me and to my right. It provided some fill on the rocks in the foreground, however the sky was changing quickly and the light was fading. To wait for better balance between the street light fill and the sky wasn’t going to happen. Plus it was cold. After a half hour crouched over the tripod I was done. No suffering for my art. Adjust in post.

Below is a 100% crop from the rocks near the waterline in the center of the image.

Bringing more detail into this area can be accomplished via a number of methods in Lightroom / Camera Raw or later in Photoshop. While I don’t favor the extreme brightening in the image below, it shows what lies in the shadows of a 645D image.

The Fill Light slider was moved to a setting of 50 from its default of zero. Noise reduction is at zero for Luminance and 10 for Color. Reducing the Color slider to zero shows some noise, however if you consider that the default setting is 25, I don’t feel zero is a realistic setting.

I think the engineers at Pentax should be lauded for the excellent long exposure noise characteristics of the 645D. (Kodak too, since they manufacture the sensor) Compared to some other cameras on the market, this looks great. To top it off, the long exposure noise reduction (dark frame subtraction) didn’t even kick in at 25 seconds. In other words, there was no waiting after each exposure before taking another. Wow.

smc Pentax-FA 645 45mm f/2.8 review

After spending an hour with the 45mm on the Pentax 645D and capturing a variety of images, I headed back to the computer to evaluate the results. I’ve spent a over a week in denial. I’ve read online at the disappointing results of the manual focus version of this lens and somehow hoped the autofocus version wouldn’t be in the same boat. Not so.

Back to the brick wall…

Bear with me on these as there is a practical example at the end. For some users, the same soft detail in the corners issue that plagues the the 55mm may not be a characteristic that bothers them. When a client points out that the image is soft during a shoot, that is a huge problem in my books. 100% crops processed with sharpening but no lens corrections are below with f/stop noted underneath. The corner crops are shown from the lower left hand corner, however all four corners showed the same effect.

smc Pentax-FA 645 45mm f/2.8 lens on Pentax 645D – overall view

Center crop @ f/2.8 – soft, lacks in contrast

Center crop @ f/8 – improved sharpness and contrast

Center crop @ f/16 – sharpness is similar to f/8, little degradation from diffraction

Lower left hand corner @ f/2.8 – completely unusable (vignetting as expected)

Lower left hand corner @ f/8 – sharpness is improved, but doesn’t compare to the center

Lower left hand corner @ f/16 – still not delivering the detail of a 40MP sensor

Granted a photographer is not going to be making money shooting brick walls. As a more practical example, how does this affect image quality when shooting the front of a building? The excellent “Tapenade” restaurant in Steveston provides an example.

Positioned square to the building, this is the view of the south side.

Taking a center crop just to the left of the sidewalk and entrance shows good contrast and sharpness at f/9.

Sliding over to the left side of the image is another story. I’ve used Lightroom 3.3 to process the DNG files. Lens corrections were shut off to show a “truer” version of the results from this lens. I’m not averse to using technology wherever possible, so a version of the left side image will be shown with lens corrections turned on, too.

The grass and hedge are becoming a green blob without the detail shown in the center crop. There is also lateral (or transverse) chromatic aberration visible in the shutters. Turning on the lens correction feature in Lightroom 3.3 / Camera Raw 6.3 resolves this issue. Unfortunately it doesn’t improve the sharpenss.

While small JPEG crops don’t really cut it to show the issues being discussed here, the effects are certainly visible. Should you have sufficient bandwidth and want to see the original DNG files, they are available for download from the links below. Each files is nearly 70MB in size.

Brick Wall image with 45mm lens at f/8
Restaurant image with 45mm lens at f/9

The Pentax 645D is a very capable medium format digital camera. The larger sensor compared to the 35mm full-frame cameras and lack of an anti-aliasing filter gives the camera an edge when high quality glass is used. Lens choice is key with this camera and the 645D owner needs to closely evaluate not only what is sufficient for their requirements, but how their particular lens performs as manufacturing tolerances come into play. Also, with so many used 645 lenses on the market, you don’t always know the history of the second-hand lens you’re putting on your camera.