Choosing a used exposure meter
eos meter

Since the advent of digital photography, separate, hand-held exposure meters are no longer as necessary as they were. With digital photography, after all, you can take a picture; check the exposure on the back of the camera; and re-shoot if you don't like it. If you have any sense, and if you have the time, you will check the exposure before you take an important picture. Thus, for example, if you're waiting for something to happen, and the light is not changing much, you will shoot a test picture for exposure, then delete it.

Eos meter

Metrawatt should have sued Canon... They introduced the Eos meter in 1938, priced 50/-, roughly the equivalent of £80 in 2010 terms. The Tempiphot, from the same firm, was about 8x as sensitive. Very old meters seldom work. This one doesn't.

What, though, if you don't shoot digital? There is no doubt that film cameras have all kinds of advantages. They're a lot cheaper, for a start. Medium and large format cameras can deliver better quality than digital cameras costing ten times as much. Film cameras need not be battery dependent. You get a new, clean sensor for each picture. Slides and negatives have a physical existence, rather than being magnetic domains on storage media: domains in formats which may become obsolete, on media that may become obsolete and which will not, in any case, last forever. And film has (or can have) a unique look that you just can't get with digital - especially if you shoot black and white. For actually using meters, see Meters and Metering: the present module is more in the nature of a (very rough) guide to what to look for.

Of course, quite a lot of film cameras have meters built in: the first 35mm camera to have a built-in meter was the 1935 Zeiss Contaflex, and the first more or less modern through-lens meter appeared on the Topcon Super D in 1963. But quite a lot of film cameras don't have meters, especially in medium and large format, and if you use old cameras, for whatever reason, the meter may have died of old age.


There are still quite a few new meters on the market, and Gossen's web-site is probably the best source for information on a wide variety of the best. If you can afford it, a new meter is often the best idea. But what if you are in the market for a second-hand meter, or if you want to know a bit more about how meters differ?


Sekonic flash/ambient meter



New meters don't always work either, especially if they haven't been used for a few years. This one was passed on to us a couple of years after the owner died; we don't know how long it had lain unused before that.


There are, after all, quite a few variables in meter design. Sensitivity is one of the most obvious: old meters tend to run out of sensitivity at low light levels. Angle of acceptance is another. Incident light meters may actually read slightly more than 180°; old selenium-cell reflected light meters commonly read 60°, newer photoresistive meters normally read around 30°, and you can find spot meters reading down to 0.5°. Selenium-cell meters don't require batteries, but photoresistive meters do. These can range from common types, available anywhere, to arcane types that have to be specially ordered. Size and weight can vary considerably, as can price. A variable that most do not consider is speed of response: cadmium sulphide meters have a 'memory', and can take half a minute or more to stabilize at a definitive reading, though in most cases the immediate reading is accurate enough, and the reading after a few seconds is better still. And finally, durability is important, along with its cousin, reparability.

Selenium cell meters

The epitome of the selenium cell meter is the Weston Master, which has a long and complicated history, not least because there were both US-built and UK-built versions: the UK company started as a subsidiary of the US-based company (which was founded by an Englishman) and became 51% UK owned (as Sangamo Weston) in 1936.

The Weston Master Universal was introduced in 1939 and remained in production in the UK until about 1950, though the Weston Master II was introduced in the United States in 1945/6. The Weston Master III appeared in 1956; the Weston Master IV in 1965; the Weston Master V in 1967; and the Euro-Master in 1970. Even after Weston lost interest, the Euro-Master was manufactured by Kilbride Instruments in Scotland from 1980 to 84 and then as the Euro-Master II by Megatron in London from 1984 to 2010.


3 westons

Weston III, IV and V

You can see many of the differences here: the switch to the metal body, the adoption of the needle lock (a slider on the IV, a button with a twist-lock on the V), the switch from a scale in candelas/sq. ft. from the IV to the V, and simplification of the shutter speed and aperture scales on the IV, with a return to complication on the V. The III is the only one still in good working order, though for any given speed it recommends one stop more exposure than our modern meters.

There were lots of detail changes in its life, but the basic shape and design remained unchanged. The big differences came with the IV and consisted of a needle lock; an improved Invercone (incident light attachment); and a metal body instead of Bakelite. Lesser changes included a switch from Weston speeds to ASA during the life of the III (about 1958); different styles of needle lock; different film speed locks; and various changes to the scales.

In the experience of most users of Weston Masters, the earlier meters ( II and III) have often stood the test of time better than newer ones, where the cells go bad and the glass surprisingly often cracks, but fortunately all models remain reparable: there are a few repairers in both Europe and the USA. The II instruction book is reproduced in its entirely in a small module on the Weston II/III.

A point that is well worth noting is that pre-1959 Westons are marked with Weston speeds, not ASA: set the next lower Weston speed, such as 100 for 125, 320 for 400, etc. To add to the confusion, ASA speeds themselves changed in 1959/60, dropping the former one-stop safety factor. As a result, the nominal speeds (though not the actual speeds) doubled.



Weston IV

Left: trapdoor closed for readings in strong light. Centre: trapdoor open for readings in weaker light, showing the (Weston-patented) 'honeycomb' on top of the cell. Opening the trapdoor automatically switched the scales on the front of the meter. Right: Invercone fitted.

The other classic selenium-cell meter started life in 1947 as the Spectra; was soon redesigned as the Norwood Director in 1948; appeared for a while as a Brockwood; and since 1989 has been incarnated as the Sekonic L398M. It is designed principally as an incident-light meter, and relies on fiddly and easily lost accessories over the (quite small) meter cell.

There are other selenium-cell meters from countless makers, including Gossen, but many (except the bigger, better Gossens) have now died of old age. Only the best are likely to warrant repair, and even then, the main reason to contemplate repair is often sentimental attachment, or the (not entirely unfounded) hope that a well-repaired meter should be good for decades more.

Advantages of selenium-cell meters: battery independence, excellent reliability for the better models (get a good one and look after it, and it will last half-way to forever), effectively instant response.

Disadvantages: Low sensitivity: the only route to higher sensitivity is a bigger cell. Very wide angle of acceptance (typically 60°). Many cells are now dead of old age: they like to be protected from light when not in use. The swing-needle ammeter on which they rely can be fragile, especially in smaller meters. The best and most reliable meters ones are quite big and heavy.


early invercone

Early Invercone

Like the later Invercone, the early 2-part model (introduced with the III) can only be fitted with the trapdoor open. First you install the neutral density filter (centre picture) and then the Invercone itself (right).


Cadmium sulphide (CdS) meters

These appeared from countless makers from the 1960s to the early 1980s. Most use swinging needles, in one of two forms. Either the needle indicates a number, which you transfer to a dial, like most selenium meters, or there is a 'null' system. The latter was much favoured for top-of-the-range Gossens. Rotating the dial centers the needle, and you then read off the shutter speed/aperture combinations as with the swinging-needle types. A few use 'traffic lights' (three LEDs, left for under, right for over, centre for correct) and there was a wonderful Zeiss meter from the 60s which used grain-of-wheat incandescent bulbs: the whole dial lit up when the exposure was right. Unfortunately it was not outstandingly reliable.

CdS meters have three significant advantages over selenium, and three significant disadvantages. The advantages are that they are much smaller; they have a smaller acceptance angle (typically 30°); and they are very considerably more sensitive - several stops, in many cases. The disadvantages are that there is a degree of lag or creep in coming to the final reading; that their spectral response is nothing like as linear as that of a selenium cell; and that they are battery dependent.


Sverdlovsk 4

We bought this meter in Moscow in about 1990; you can see on the dial that it proudly proclaims itself to be CdS, albeit not in very legible typography. It is a fascinating and perhaps over-complicated meter, complete with viewfinder (upper left) and swivel-twist-and-drop incident light attachment. The dial is rotated by the thumb-wheel (top right), and exposure is correct when the LED under the viewfinder lights.

The only drawback is that it takes a no-longer-available 3RTS 3.75v battery, unless you have the bulky bolt-on adapter for three AAA batteries. Apparently it can be made to work with four PX625s, as well, and there is an ingenious though complicated voltage-calibration system so it can run on a wide variety of voltages.

The first general disadvantage of CdS meter, the memory, has already been touched upon. A 'snap' reading can be as much as a stop out, but after a few seconds, it should be a negligibly small fraction of a stop, though the final reading may take half a minute or more. Also, the memory is much worse if you are going from very bright to very dim light, or vice versa. If the light is reasonably constant, the memory effect is far less significant.

The second disadvantage is much more important with through-lens meters, where putting filters on the lens could lead to anomalous readings, but it can matter when taking readings under coloured light (e.g. sodium vapour) with a hand-held meter.

The third disadvantage is compounded by the fact that most use mercury 'button' cells, which are no longer readily available, and few have voltage compensation built in, relying instead on the long life at constant voltage of a mercury cell. Zinc-air cells are a good replacement for equipment in constant use, but they exhaust relatively quickly whether they are used or not. Some meters can take silver cells in holders that provide battery voltage compensation (Gossens being the prime example) but these are very much the exception rather than the rule.

Many CdS meters are still working, but only the very best of them are likely to be worth as much as the cost of a repair. With all but the best, it's better to throw 'em away and buy another.


Voigtländer shoe-mount meter on Agimatic

Shoe-mount meters are a lot less common than they used to be, largely because there are so few unmetered cameras any more. To our knowledge, the only recent ones are the Voigtländers and the Gossen Sixti.

The Voigtländer looks better on vintage cameras, in our view, but from the point of view of performance, either beats CdS meters hollow, and CdS meters beat selenium on the grounds of sensitivity.

Silicon and gallium meters

The drawbacks of CdS cells were such that many stayed with their trusty selenium-cell meters, though CdS itself was rapidly replaced in the 1980s by silicon and gallium arsenide photodiodes. These can be designed either as photogenerative meters, with an amplifier, or as photoresistors, and as far as we are aware, they are normally the latter. They have no memory, and by a choice of the appropriate material can be made to have a much better spectral response than CdS. Their only significant drawback is battery dependency, and once again, a lot depends on the choice of battery.

Older meters use mercury cells, but most (as far as we are aware) have voltage regulation circuits and can be used with silver or lithium cells. The all but ubiquitous SR78/LR78, or the lithium CR1/3N where two cells are required (as is normally the case) can therefore be used. Even so, at the expense of a bit of extra bulk we prefer those meters that take AA cells (all the ones we have tried can also be used with rechargeables) or 9V PP3 'block' batteries (again, we cheerfully use rechargeables).

Gossen Sixtomat Digital

An excellent lightweight meter that runs on a single AA cell.


Many still use swinging needles, often with a null system, but a few use 'traffic lights' and quite a few have digital readouts. Normally you can choose between shutter priority (set the shutter speed you intend to use and it tells you the aperture you need) or aperture priority (set the aperture you plan to use and it gives you the shutter speed), and sometimes there are other options too, such as EV and ciné. Although digital readouts are big and clear, they have the disadvantage that if you change your mind you have to cycle up or down through the shutter speeds or apertures (Gossen meters are particularly irritating here, as they show 1/90 second between 1/60 and 1/125), or do a bit of mental arithmetic. With dial-readout meters, all the possible combinations of aperture and shutter speed are shown simultaneously.


Profisix and Luna-Pro F

These are two of Gossen's older 'big guns'. You can see the null metering system, zeroed on the left -hand meter. Twisting the dial nulls the meter. Both run on PP3 9v 'block' batteries and have auto power off.

A great advantage of the null system is that you can take your main reading (incident if you like) and then do a series of close-up readings to check the brightness range of the subject. If it's inside +/- 3 stops, you've no trouble with subject brightness range.

The big drawback of all these meters is that they tend to be quite expensive to repair, though equally, one that has been competently repaired is a much safer bet than another model of the same meter bought second-hand with no guarantee whatsoever of reliability.

System meters

Several Gossens (Lunasix/LunaPro/Profisix) accept a range of clip-on accessories. The Gossen TELE semi-spot accessory has a module to itself, and can also accept clip-in accessories for enlarging (LABOR), microscopy (MICRO), and remote sensing (a fibre-optic 'snake') but the Gossen Profisix system is even more extensive. In addition to the above it accepts plug-in accessories with an electrical connection: a full-scale spot meter head (1-5-10°), a flash metering head, a probe for through-lens metering with large format and even a colour temperature metering head.


Gossen Profisix with Profi-Spot and fibre-optic extension

In our opinion, the 'dumb' accessories are useful if you have need of them (microscopy, darkroom, whatever) but the 'smart' accessories with the electrical connexions are more trouble than they are worth.

Quite honestly, in the 21st century the powered Profisix system is of more interest to historians, collectors and gadget freaks than to photographers. Sure, they work - until they stop working, anyway - but with the exception of the TTL probe you can buy considerably more convenient purpose-built tools to do the same job, better. The 'dumb' accessories are rather more use, assuming you can think of a use for them.

Spot meters

In the module about meters and metering we make the point that spot meters are not for the novice, and that distressingly many people buy spot meters without really having very much idea of how to use them. Bear this in mind before you buy one. If you do not fully understand what a spot meter is, and how to use it, we strongly recommend that you read all our metering modules first. They are only worth buying for top-quality black and white photography, and even then, you can often approximate very closely to a spot meter's recommendation on the basis of experience.

We have tried most of the purpose-made spot meters on the market. Roger's favourite was probably the Minolta, which we no longer have (he dropped it, and it broke). The meters we use mostly are the two Pentaxes, the swing-needle V (Roger) and the smaller, lighter Digital (Frances). Actually, the digital doesn't have a digital readout in the usual sense: you just transfer the digital reading in the viewfinder to the rotating scale, as you do with the bigger, older model, though the scales are in different places on the two meters. Both suffer from using awkward battery sizes. The Gossen Spotmeter II uses a 9v PP3 block battery, but its digital readout is far from convenient unless you choose to use the (substantially pointless) mid-tone index. We also have the spot attachment for the Profisix, but it no longer works, and the precise but highly eccentric SEI Photometer with LED modification.


Pentax Spotmeter V

You can buy so-called 'Zone modified' Pentax meters, but Zone metering is perfectly simple with the I.R.E. scale, if you know what you are doing, and the alleged modification to make the spectral response of the cell match that of Tri-X is little short of risible. Far better to use Pentax's own scale for modifying readings of coloured subjects - which are rarely pure enough colours to make much difference anyway.



Waterfall, Julian Alps

This is one of the few occasions when we have used a spot meter with 35mm, in order to be sure of getting adequate exposure in the nouth of the cave from which the waterfall issues. Roger used a Nikon F and 200/3 Vivitar Series 1, loaded with Ilford HP5 Plus.

Frances uses a spot meter a lot more with her Alpa, but then, 6x9cm is a rather slower and more considered style of photography. And we both use spot meters with large format: 4x5 inch, 5x7 inch, 8x10 inch and above.

Actually, the larger the format, the less critical the exposure: a stop extra, or even two, will often give the most delightful tonality, without any great need for careful exposure.

The bottom line

As we repeatedly say, just about any approach to metering can be made to work - as long as the meter works. A lot of old meters don't, and we believe that it is very foolish to try to economize too much on meters. This is especially true if you buy sight unseen, over the internet. By the time you have bought three or four that need repair, you could have bought one that worked, or had a decent non-working meter (such as a Weston Master) repaired.

We realize that we have touched on only a few makes of meter, mainly Gossen and Weston, and that there are other makes (such as Sekonic and Polaris) that are very good indeed. But armed with the information from this module, we hope you will be better placed to make a choice, no matter what meter you are considering.


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© 2010 Roger W. Hicks