Vivitar Series 1 vs. Pentax-A 70-210mm: TNAF #1 Part 2

Pentax-A 70-210mm F4

In Part 1 of the review That Nobody Asked For (TNAF #1), we compared the lenses’ center and corner performance. Here, we check my copies of the zooms for any gross decentered/tilted element problems, compare their mid-distance performance, and examine aberrations.

1. Brick Wall Tests

The first thing I do with a newly-acquired lens is to test it as soon as possible using the wall of a nearby elementary school (when it’s not in session, of course). This way, I can return it within the seller’s return-policy window and save myself from having to deal with the distributor or manufacturer.

Time was not of the essence, however, for testing these two oldies. I acquired the Pentax-A 70-210mm at a local camera swap meet about three years ago. The Vivitar Series 1 was (together with a Pentax-F 35-105mm F4-F5.6) off of Craigslist. When the weather got better this year, I got off my Lazy AF butt and headed to the school.

The source DNG images were all shot in Manual mode on a tripod-mounted Pentax K-1 II in Live View using the 2-second timer. I focused using focus-peaking and changed the aperture on the lenses. I used the camera’s built-in electronic levels to square things up as much as possible.

Here are some of the results. You are going to have to trust my summary that follows, which I based on all of my collected images, including at F11, plus having the luxury of zooming in at full-res on my monitor.

@70mm

Left: Vivitar at F2.8. Right: Vivitar at F4

Before After v70f28v70f4

Left: Pentax at F4. Right: Vivitar at F4

Before After p70f4v70f4
Both lenses at 70mm F4 top left
Both lenses fared well here, but the Pentax had blurry extreme top corners, (worst at 70mm, F4 shown above on the left; ignore the 200mm value in the EXIFs) which surprised me a bit as this did not manifest in the other tests, or in general shooting. I think my copy is ever-so-slightly decentered. Vivitar to the right.

Left: Pentax at F5.6. Right: Vivitar at F5.6

Before After Pentax 70mm F5.6Viv 70mm F5.6

Left: Pentax at F8. Right: Vivitar at F8

Before After Pentax 70mm F8Viv 70mm F8

@135mm

Left: Pentax at F4. Right: Vivitar at F4

Before After Pentax 70-210 135mm F4Viv 70-210 135mm F4

Left: Pentax at F5.6. Right: Vivitar at F5.6

Before After PPentax 70-210 135mm F56Viv 70-210 135mm F56

Left: Pentax at F8. Right: Vivitar at F8

Before After Pentax 70-210 135mm F8Viv 70-210 135mm F8
P-V-710210-135mmF4-TR
Top right corners, 135mm F4. Pentax on left, Vivitar on right.
P-V-710210-135mmF4-M
Centers, 135mm F4. Pentax on left, Vivitar on right.
P-V-710210-135mmF4-BL
Bottom left corners, 135mm F4. Pentax on left, Vivitar on right.

@210mm

Left: Pentax at F4. Right: Vivitar at F4

Before After Pentax 70-210mm 210 F4Viv 70-210mm 210 F4

Left: Pentax at F5.6. Right: Vivitar at F5.6

Before After Pentax 70-210mm 210 F5.6Vivitar 70-210mm 210 F5.6

Left: Pentax at F8. Right: Vivitar at F8

Before After Pentax 70-210mm 210 F8Vivitar 70-210mm 210 F8

 

Many buy these zooms for the long end. Zooms generally suffer most in image quality at the extremes. Here are some 1:1 comparisons at 210mm:

P-V-70210-210mmF4-TR
Top right corners, 210mm F4. Pentax on left, Vivitar on right.
P-V-70210-210mmF4-TL
Top left corners, 210mm F4. Pentax on left, Vivitar on right.
P-V-70210-210mmF4-M
Centers, 210mm F4. Pentax on left, Vivitar on right.
P-V-70210-210mmF4-BR
Bottom right corners, 210mm F4. Pentax on left, Vivitar on right.
P-V-70210-210mmF4-BL
Bottom left corners, 210mm F4. Pentax on left, Vivitar on right.

Summary of Results

Note that the corner results are evaluated at the extreme corners, so the Pentax actually did a bit better than it appears from looking at the table below. Both lenses were pretty good. What is rather surprising is how well the Vivitar performed under these circumstances of closer distance and lower contrast, compared to Part 1.

Resolution
Setting Top Left Top Right Center Bottom Left Bottom Right 1/3 in from edges
70mm @F4 Vivitar Vivitar Tie Vivitar Pentax Tie
70mm @ F5.6 Vivitar Vivitar Tie Vivitar Tie Tie
70mm @ F8 Vivitar Vivitar Vivitar Vivitar Tie Tie
135mm @ F4 Vivitar Vivitar Tie Tie Tie Vivitar
135mm @ F5.6 Vivitar Vivitar Tie Tie Vivitar Vivitar
135mm @F8 Vivitar Vivitar Vivitar Vivitar Vivitar Vivitar
210mm @F4 Tie Tie Tie Tie Tie Tie
210mm @F5.6 Tie Tie Tie Pentax Pentax Tie
210mm @F8 Tie Tie Tie Pentax Pentax Tie
  • Geometric Distortion
  • The Vivitar had a bit less barrel distortion at the wide end, and similarly less pincushion at the telephoto, but, in the digital age, I consider these differences to be minor.
  • Vignetting
  • Wide open, at comparable F-stop settings on the lenses, the Pentax has less light falloff at 70mm, but the Vivitar is more even midrange and at the longer end. Again, I consider this to be largely academic as one can correct in post processing.

    2. Aberrations

    Longitudinal Chromatic

    loca-viv-70mm-f28
    Vivitar at 70mm F2.8, +1 exposure compensation.
    Vivitar at 120mm F2.8
    Vivitar at 120mm F2.8.
    loca-viv-210mm-f28
    Vivitar at 210mm F2.8.
    loca-pen-70mm-f4
    Pentax at 70mm F4.
    loca-pen-120mm-f4
    Pentax at 120mm F4.
    loca-pen-210mm-f4
    Pentax at 210mm F4.

    I’d call it a wash. For those non-native speakers of English, that means a tie. The Vivitar might show a bit more green/purple behind/ahead of the focus point, but that’s at F2.8 instead of the Pentax’s F4.

    Purple Fringing

    Let’s look at one of the bugaboos of vintage lenses—the purple halo seen at contrasting edges.

    @70mm

    Left: Pentax at F4. Right: Vivitar at F4

    Before After Pentax 70-210mm at 70mm F4 PFVivitar 70-210mm at 70mm F4 PF

    Using Lightroom’s lens correction slider for purple, I was able to perform miracles.

    Left: Vivitar at F4. Right: Vivitar at F4, defringed in Lightroom

    Before After Vivitar 70-210mm at 70mm F4 PFVivitar 70-210mm at 70mm F4 PF removed

    @120mm

    Left: Pentax at F4. Right: Vivitar at F4

    Before After Pentax 70-210mm at 120mm F4 PFVivitar 70-210mm at 120mm F4 PF

    @210mm

    Left: Pentax at F4. Right: Vivitar at F4

    Before After Pentax 70-210mm at 210mm F4 PFVivitar 70-210mm at 210mm F4 PF

    Pentax for the win.

    3. Minimum Focusing Distance, Colour and Bokeh

    Both lenses have a “Macro” mode. This occurs at 70mm for the Pentax, and from 100mm onwards for the Vivitar. The Vivitar is the clear winner for maximum magnification. For both images, below, lit by Neewer LED panels set to 5600K, I cranked the Saturation slider in Lightroom to 100% to make the colour cast difference between the lenses more apparent.

    Pentax at closest focus F4
    Pentax at closest focus F4, saturation at 100%.
    Vivitar at closest focus F2.8
    Vivitar at closest focus F2.8, saturation at 100%.

    The following images are for bokeh. I was uncertain at first about which set was which, though the Pentax’s warm rendering is somewhat telltale. I was surprised that the Vivitar seems to be a half-stop or more blurry. I find neither objectionable, but the nod goes to the Vivitar because of its extra creaminess.

    @70mm

    Left: Pentax at F4. Right: Vivitar at F4

    Before After Bokeh Pentax 70mm F4Bokeh Vivitar 70mm F4

    @120mm

    Left: Pentax at F4. Right: Vivitar at F4

    Before After Bokeh Pentax 120mm F4Bokeh Vivitar 120mm F4

    @210mm

    Left: Pentax at F4. Right: Vivitar at F4

    Before After Bokeh Pentax 210mm F4Bokeh Vivitar 210mm F4

    4. Brickwall Bonus

    I’m almost 100% sure that, aside from myself, nobody has performed (or requested for that matter) a three-way just-for-kicks comparison between the two 70-210s and the very modern Pentax-D FA 24-70mm F2.8, at 70mm, wide open, making this section a ground-breaking world exclusive, and an almost run-on sentence, except that it’s grammatically fine so it isn’t, and pot is legal where I live.

    p247070f28-brick
    Pentax-D FA at 70mm 2.8.

    Yikes! The fields of view are very different in the Left-Right image comparison below. I’m thinking the Pentax is actually much wider than 70mm at middle object distances.

    Left: Vivitar at F2.8. Right: Pentax-D FA at F2.8 (correction turned off)

    Before After v70f28p247070f28-brick

    Ignore the EXIF information for the Vivitar, below, as the focal length is actually/should be 70mm.

    Center, 70mm F2.8. Vivitar on left, Pentax-D FA on right.
    Center, 70mm F2.8. Vivitar on left, Pentax-D FA on right.
    P-D-FA-Viv-70-TR
    Top right corners, 70mm F2.8. Vivitar on left, Pentax-D FA on right.
    Bottom left corners, 70mm F2.8. Vivitar on left, Pentax-D FA on right
    Bottom left corners, 70mm F2.8. Vivitar on left, Pentax-D FA on right.

    Aside from the degree of vignetting, the vintage Vivitar fares well here against the modern 24-70mm. Keep in mind (optical experts, feel free to chime in) that designing a 3:1 mid-aperture telephoto is easier than for a large aperture 3:1 wide-angle, so where the focal lengths intersect at 70mm, the 24-70mm is holding its own as it should, given the three decade advantage.

    As for the Pentax 70-210mm, it doesn’t do F2.8, but knowing that the Vivitar 70-210mm performs better in this test at F4 (see 70mm section), I’ll let you reach your own conclusions about the vintage Pentax 70-210mm versus the modern Pentax 24-70mm at 70mm.

    So where to now? Keep your Internet eyes peeled here for an upcoming Hands-on look and a final verdict.

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