I ran these tests some months back but have avoided sharing results because the photos are a bit rubbish. Finally, I’ve swallowed my pride and gone ahead and published.

I’ve long wanted to test the famed Kodak Aero Ektar 7 inch against the far-lesser appreciated Dallmeyer Pentac 8 inch. Afterall, the Aero Ektar was based on the design of the Pentac which has been around since the early 1900s and was used in the first as well as the second world war. Both are very fast, aerial reconnaissance lenses with similar focal length and maximum aperture.

I wanted to take pictures of the same subject in the same setting using both the Aero Ektar and Pentac…which proved to be a bit of a faff as I only have one lens board and kept needing to unscrew and remount the lens. For reference my Aero Ektar is a 1944 no-coloured-dot variety. My Pentac is a British Air Ministry version from the same year.

I’m a fan of the Pentac. Maybe because I’m British. But it’s much smaller and lighter than the Aero Ektar, is not radioactive and, with the help of a little plumbers’ tape, mounts happily to lens boards designed for the Aero Ektar (I have a JoLo that I got about 15 years ago when I first acquired the Pentac).

The important thing, of course, is how well the lenses perform. I wanted to test sharpness, resolving power and contrast and took a portrait shot and a ‘still life’ (a couple of bottles from my kitchen cabinet) with each of the lenses.

The background in both cases was an Oleander tree outside my window. The lighting was not ideal. The subject was in shadow while the Oleander was in bright sun. Although I metered for the subject, there was about 4-5 stops between the subject and the background, making it difficult to control contrast and shadow.

But, while these pictures are not exactly works of art they do serve the intended purpose.

In use there are notable differences between the lenses. I use an 8x loupe to focus on the ground glass of my Speed Graphic and it’s easy to dial in a sharp image with the Aero Ektar fully open (f2.5). By contrast, the Pentac never seems to project a fully sharp image when fully open (f2.9). With the Pentac it’s more a case of fiddling with the focus until it’s least unsharp.

That said, the Pentac is capable of producing a sharp picture as the still life below shows:

The first thing you’ll notice is that the ‘bokeh’ with both lenses is almost identical. Look closely, however, and you’ll see that the Pentac has rounder circles of confusion because of its far greater number of aperture blades. Both look similarly sharp, although on close inspection, the Aero Ektar has a very slight edge.

Contrast-wise, the Aero Ektar produces a much higher contrast image than the Pentac. Far more adjustment was needed to the Pentac image to get the two pictures close to one another in contrast. This also increases the perception of sharpness for the Aero Ektar image.

Now to the portrait. The model in these two images was pissed off that I was using an old camera and somewhat impatient while focusing, despite me explaining beforehand not to move too much once focus was set. That kind of shows in the pictures. I took three images with each lens and one Pentac and one Aero Ektar example are shown below:

The portrait really shows the difference between the two lenses. Again, contrast needed bringing up a lot more on the Pentac image than the Aero Ektar. With these images, both shot wide open, there is no doubt that the Aero Ektar image is much sharper (focus point in both cases was the eyes). Note that the circles of confusion appear difference sizes because I didn’t move the camera enough to account for the one inch difference in focal lengths of the two lenses.

One could argue that the Aero Ektar image is too sharp. It seems to be able to keep a greater depth of sharpness on the close subject than the Pentac, something that gives that classic Aero Ektar look. I hate to admit it, but the Aero Ektar now seems a better lens to me.

The Pentac is still great. It has arguably better bokeh than the Aero Ektar and the greater flare (which is partly responsible for the reduced contrast) creates more of a ‘glow’ effect on images. I think it’s a good lens if you want a ‘pictorialist’ look in the style of Julia Margaret Cameron. It’s also one tenth the price of an Aero Ektar or less, which is quite compelling.

It’s worth noting that there are many variables in this test. Firstly these are both 80-year old lenses with an unknown history, meaning they may not be the best examples of each out there. Secondly, the notable lack of sharpness on the Pentac portrait shot may have something to do with the model moving (although I did take three separate images and all were similar in appearance).

I still want to run more tests. But I think I’ll be using the Aero Ektar for portraits going forward. Leave a comment below and let me know what you think….