Nikon FA front focus adjust

A very short post about solving (at least hoping to have solved it) a front focus problem I had with my newly bought 1987 (probably) Nikon FA (here shown side by side with an Olympus OM30):

Nikon FA vs. Olympus OM30

There is a lot of nice attention to details in the construction of the Nikon FA. With age, however, some of the settings will change. I was unhappy to see that none of my lenses seemed to focus correctly to infinity (the lens barrel would show 6 m when the split prism viewfinder would indicate infinity focus). Thus, a front focusing problem. What to do ?

Since there was also a slight misalignment of the mirror angle itself (image in focus in the center but out of focus in the upper part of the focusing screen was one good diagnostics), I tried to move the only screw that looked like the ‘eccentric pin’ for mirror adjustment mentioned in the FA manual. Turning clockwise for maybe 15° seems to have solved the problem.

Nikon FA mirror eccentric pin

Both the focusing and the lack of  parallelism with the film plane of the viewfinder are gone. I took me several hours to dig some information on this matter (without actually founding a lot) and 5 minutes to actually solve it by using a kitchen knife. There was a risk of damaging the camera, so don’t follow this advice if you don’t feel at ease with fine mechanics. It is important that you first diagnose the problem correctly. Good luck.


Tamron Adaptall 28mm

Why another lens ?

Finding an Olympus OM-30 camera on a garage sale a few weeks ago rekindled my interest in film photography.
Olympus OM-30 SLR camera (OM-F)

Now, the Olympus camera only came with the standard 50mm f/1.8 compact lens and I thought it would be fun to see how film works with a 28 or 24mm wide angle without the crop factor that applies to APS-C size digital cameras. The only widely known group of lenses that are interchangeable between different cameras, if provided with the right adapter, is the Tamron’s Adaptall series (see for more information).

From the different Tamrons I had the occasion to use, with one exception, the late plastic version of a 28-70mm f/3.5-4.5 zoom, they were all optically good to excellent. One special mention goes to the famous Tamron 90mm f/2.5 (or f/2.8, there are several models) macro lens. A compact, fast zoom is the 35-80mm f/2.8-3.8 which delivers excellent image quality and is a pleasure to use. Let me show it to you, mounted on a Nikon D40 dSLR:

Tamron zoom model 01A

Tamron 28mm f/2.8, cheap, heavy, good

The lens shown in the following images is not the typical Tamron 28mm f/2.8 only because it is not painted black. I did not like the look of the black ones, that’s why the sample I have is brushed aluminium:

Tamron 28mm f/2.8 white, front

The characteristics of the lens, as borrowed from the Tamron official site (in Japanese, thank you Google Translate) are:

Model: CW-28
Lens configuration: 7 lenses in 7 groups
Minimum Aperture: 16
Minimum focusing distance: 0.25m
Filter Diameter: 52mm
Weight: 240g
Maximum Overall Length X Diameter: 65mmx42mm
Produced between 1976 and 1979

Not mentioned – aperture has 5 blades.

The lens was replaced by a more compact version that is also lighter but, alas, takes 49mm filters. On Nikon I’m used with 52mm filter diameters.It’s much easier if all the lenses have interchangeable caps. Mounted on a D40, the lens looks impressive, due in part to the perspective distortion of the Fuji E900 lens when taking the picture:

Nikon D40 with Tamron 28mm f/2.8 adaptall lens

In fact the lens is pretty compact even if it cannot compete with the Nikon series E 28mm, which has a lot more plastic and a simpler optical formula (so there is a difference of 5 cm in the minimal focusing distance – 25 cm for the Tamron and 30 cm for the Nikon):

Tamron 28mm vs Nikon 28mm

A  few more images of the lens before jumping to conclusions about handling and optical quality:

Tamron 28mm f/2.8 front

Tamron 28mm f/2.8 side view

Tolo Toys and Tamron

Handling is excellent, the lens has the right size and bulk (for my hands in any case). Manual focusing is very pleasant though not always easy (an f/2 lens would have been better, but that’s a lot more expensive and does not exist in the Tamron’s adaptall line).

Depth of field preview on a D40 ?

The Tamron was built in the 70s and intended for use on many different cameras. Some of these, I imagine, were not able to allow focusing and metering with the lens wide-open and to stop down “automatically” only at the very moment the picture was taken. For those cameras, the Tamron has a switch on the side (marked A, for Automatic, I imagine). The A gets covered by the switch when moved and the lens aperture closes to the value set on the aperture ring:

Tamron 28mm f/2.8 depth of field preview switch

Now I have a depth of field preview on my Nikon D40!

Even if the camera had such a function it would be close to useless due to the size of the image in the viewfinder. On a full frame camera the situation would be different. Anyway, while the depth of field preview is extremely useful on film, when you cannot see the result immediately the lack of such a function became much less problematic on digital SLRs.

Image quality (on APS-C sensor)

Excellent! That sums up a few hours of tests and comparisons. At f/2.8 there is some loss of contrast and I would not use the lens wide open. However, from f/4 the images are crisp with good contrast and with plenty detail showing everywhere. Take this opinion cautiously because I am no expert and, for me, the series E Nikon, generally badly rated (see for example this evaluation, in French, of several Nikon lenses or another one on Bjørn Rørslett’s site), has a lot to offer. I just don’t like its handling as much as I like the handling of the Tamron.

Quick 100% crop from images taken with the Tamron vs the excellent 18-55mm Nikkor kit lens:

Tamron vs Nikon kit lens

At left, there is no much difference at f/4 between the center resolution and contrast (kit at left, Tamron at right). Extreme left side of the image (right image) shows that the Tamron keeps more resolution, which would be expected from a prime vs a consumer zoom lens. Color rendition is different. The Tamron lets in less light at the same aperture too.

In conclusion, by taking pictures with the Tamron, one “benefits” from a marvelous mechanical device and gets similar or better results than with the kit lens. That’s all that I needed to know. Some other test and sample images follow.

Sample images with the Tamron 28mm f/2.8

Flowers at f/5.6 without or with camera flash

Evening place de Catalogne, f/4

Night on rue d'Alesia, long exposure

f/4 vs f/2.8 Tamron 28mm

Flare Tamron 28mm

Flare 2, Tamron 28mm f/2.8 at f/4

Pretty funny internal reflexions and ‘rainbows’ when the sun is in frame. However, contrast is preserved to a good extent in the shadows and that’s important. The BBAR (Broad-Band Anti Reflection) coating seems efficient.

Summary and conclusion

There are several good points about the Tamron 28mm f/2.8:

  • Excellent mechanical construction and a pleasure to handle
  • Very good image quality from f/4
  • Depth-of-field preview integrated in the lens (not really useful but funny to use)
  • Adaptall system that allows the use of the lens on other brand film or digital cameras
  • Takes Nikon-type 52mm filters, unlike its descendant, the 28mm f/2.5, which takes 49mm filters

And of course, there are downsides:

  • Aperture with “only” 5 blades. But I did not see any adverse effect to that. It’s not only the number of blades that determines the out of focus areas appearance. It is true that the macro Tamrons have 9 blades and the zoom I was mentioning before has 8.
  • Quite heavy and bulky – the more compact Tamron that followed (28mm f/2.5) may have a more convenient size.
  • Not that good at f/2.8

In conclusion: a pretty/ugly lens that’s a pleasure to use.

If you have any comments or negative or positive experience with Tamrons, it would be great to share our opinions.