Skip to main content

Pentax A 28-80 f3.5 - 4.5 lens on Sony a6500

I'm continuing to search for a half decent walk around lens for my Sony a6500, having tried and discarded the Zeiss and Sony offerings. My latest discovery is a Pentax A 28-80 f3.5-4.5 zoom from the film era. I've had my copy for years, bought second hand it's not in the best of condition, with marks visible on the front element and a general slackness in the zoom helicoid. This is what it looks like on the camera.

Be warned, this is a manual focus lens, if that's not your cup of tea, read no further!


It's no lightweight being of mixed metal and plastic construction. With adapter it weighs 502 g, but this is appreciably lighter than the Tamron 28-80 that I have also tested.

How does it perform, I've not conducted any brick wall tripod tests as yet, but having taken a number of shots with it I am reasonably impressed. 

Here's an example. It was a muggy, hazy day with poor visibility, but the image quality is OK

First of all the overall view, the German cruise ship Mein Schiff 3 moored at North Shields terminal. 

(Click any image for a larger view)


Now actual pixel crops from the extreme left and right of the image



The edges are far better than either the modern Zeiss or Sony zoom achieved, but the overall image lacks a bit of contrast. I really do need to do some formal testing on a bright sunny day.

I need to compare this lens with the Tamron 28-80 that I have also tested, and with some of my old film camera primes.

Sadly, further shooting has revealed a fatal flaw with this lens, at closer distances and probably due to the ravages of age, it does not always achieve sharp focus in the centre of the field. Take a look at this image of some ironstone rocks and the actual pixel crops from centre, left and right.


The overall picture


Centre crop


Left crop


Right crop

The camera was focused on the centre point, so this should not be a field curvature issue. Further I have more examples showing the same pattern. Maybe the wobbly focusing ring is the culprit? This particular copy of the lens is unusable, but I would like to get a hold of another example as, surely, this can't be a generic fault!

I've since carried out a tripod and wall test. Out of 15 images only one displays this fault, taken at 35mm and f8. Two other shots at that focal length and aperture do not. 

Edit 28-8-19 - blurred centre!

Labels

Labels:

Comments

Post a Comment

Popular posts from this blog

Sony 28-70 FF lens on a6500

Since my kit 16-50 lens failed and was pronounced unrepairable I've been looking for a replacement walk around zoom, or, in my case, a lightweight lens that I can carry when cycling. I tried the Zeiss 16-70, but as my previous post here demonstrated, that lens was fatally flawed - as well as being expensive. I was persuaded to try the much cheaper 28-70 lens (cost £234 new) that is supplied as part of the standard kit on Sony full frame cameras. Let's give it its full title, the  Sony SEL2870 E Mount - Full Frame 28-70 mm F3.5-5.6 There are things to admire about this lens. It's compact and lightweight and handles well on the a6500. Despite being of plastic construction, it does appear well made, with a metal mount and a robust feel to it. I liked using it. Mounted on a tripod and shooting test pictures against a brick wall the lens is OK, nothing like as sharp at the edges as in the centre, but usable. Here are a few crops from a test shot at 28 mm and f8.  The upper...
4 comments
Read more

Using an enlarger lens and a Sony a6500 to copy negatives

This is very much a work in progress. I've assembled a collection of components and examined the feasibility, but not done any proper testing. Hopefully you will find it interesting. I have a large collection of negatives and transparencies dating back to the early 1960s, and I have scanned quite a number of them using an Epson 4990 Photo flatbed scanner. The results are OK, particularly for 120 film, but not so great for 35 mm. Sadly the film related section of the scanner failed recently, possibly due to overwork or maybe just old age, so I was interested in finding an alternative. If you have a good macro lens read no further, but if, like me, you don't possess a macro lens, then what is the next best thing? Well possibly an old enlarger lens. They were designed to provide the best possible resolution over a flat surface ( the negative) and project onto another flat surface (photo paper), both at close quarters, so, theoretically, they should be well suited to scanning. ...
Post a Comment
Read more