Light Meter


Technically, anything more than 10x magnification qualifies as Microphotography. Microphotography is a fairly specialized field, as you can imagine, and one might be inclined to think that it’s best left to the researcher, professional or hard -core enthusiast who has plenty of $$ to spend on an expensive microscope-camera setup.

However, if one is willing to settle for less than the very best and latest equipment, there are plenty of options for the stubbornly dedicated amateur who wants to put together a microphotography kit for under $100, including the illumination. The secret? Old College microscopes that appear with startling regularity on eBay. You can get a nice new microscope for about $250 -$500 these days, (mostly imports from China and India, and pretty decent optics), but that’s not being thrifty and adventurous.

Also, many of the new telescopes are made of lighter materials – they are designed for optical quality, and for the most part they are expected to be used with lighter digital cameras with a C adapter, or “in-tube” digital USB cameras that fit into the viewing tube in place of the ocular (eyepiece) and are connected to a computer display. Fitting a full size manual or film or even digital SLR camera on these newer telescopes can cause problems with vibration and shake. Older telescopes were constructed solidly. They generally feature all metal construction and this makes for a rigid camera platform.

I’d look for the full size ones that have been pulled from Colleges – stay away from the toy microscopes that have low grade optics and are 7 inches tall. The full size microscopes are HEAVY, and are about 12-14 inches tall. They weigh about 8-10 lbs. The weight is needed to support your camera… most colleges these days are pulling their Monocular microscopes in favor of the Binocular or Trinocular scopes that have built in illumination and can take a digital camera attachment. Too fancy for me… and too expensive for an amateur looking for the cheap, affordable microphotography solution.

College surplus monocular microscopes are ideal – they generally come with an 10x eyepiece (ocular) and a couple of objective lenses (generally 10x and 40x) – this gives a 100x and 400x magnification. Its important to look for a microscope with a 25mm outer diameter tube and 23mm diameter eyepieces. Luckily, microscopes were standardized early on, and unless you choose a really old antique from the 1900’s you should be okay. If you’re lucky, you might find a complete microscope, with eyepiece, objectives, stage, condenser, spring clips, fine and coarse controls AND illuminator.

Most microscopes come with some sort of illuminator – its good to have a electric source for consistent lighting needed for photography. Also, it isn’t sufficient to have lighting just on the underside – we need a bright beam focused ON the stage as well. A halogen table lamp serves pretty well for surface lighting.

I was lucky to find a German made Wolfe Wetzlar monocular microscope with a 15x eyepiece, 10x and 45x objectives, a decent Abbe condenser and an electrical illuminator with a blue filter and on/off switch. The combination gives me a 150x and 675x magnification. However, at 675x, the field is pretty dim, even with the electric illuminator.

More recently, I picked up a Japanese-made Propper microscope for a very reasonable price, (less than $20) thinking that I could just scavenge the optics off of it and throw away the frame… the Propper has a set of fine British made Cooke-Vickers Microplan objectives – a 5x, 10x and 40x, and a zoom eyepiece (10x-15x-20x), so I will just clean it up and use it for general microscopy.

Ideally, one would want 40x (or 50x), 80x, 100x and 150x magnifications for photography. Remember that high magnifications are very hard to illuminate. About 150x is easy to handle in terms of lighting. To get these magnifications one would have to keep keen tabs on eBay or other online sources for cheap eyepieces and objectives – don’t worry if it’s DIN or JIS – see the note below.

Surplus Shed is a good online place to pick up additional objectives and eyepieces. They stock lots of very reasonably priced objectives from India, and ship quickly at low cost. I was happy with their service (no, I’m not affiliated with them in any way, just a happy customer). Another place that stocks used microscope objectives and eyepieces at a reasonable prices is NY Microscope, a school supplier. They generally have other microscope parts as well, in case you want replacement parts. I haven’t bought anything from them yet, but they were quick to reply to my email inquiry, so thats a very good sign.

Here is what you can add over time, unless you get lucky and get them cheap like I did with the Propper – 10x, 15x and 20x eyepieces and a 4x and 20x objectives. Fit the microscope with the 4x, 10x and 20x objective and put the 40x and higher power objectives away, since you wont be using them much. Don’t waste your money on a 100x objective, unless you got it with the microscope – they’re usually oil immersion objectives and require that a drop of type A oil be placed on the slide between the objective and glass. This is a pain. The oil apparently becomes part of the optical system gives the high magnification in conjunction with the 100x objective and eyepiece.

At least one of the eyepieces should be a widefield (WF) if possible – these are designed for wider viewing fields and also provide greater eye relief (image is formed at a little distance above the top of the microscope eyepiece). This eye relief is for use with glasses, but serves us even better in photography since the camera will “see” a bigger field than with a normal eyepiece where only the center of the microscope field is imaged on the film.

To complete the setup, I also purchased a camera to 25mm microscope tube adapter. One end is a T-mount thread and the other end clamps on to the tube. The adapter tube comes apart in the middle – the smaller end which goes on the microscope body receives the eyepiece, and the other end receives the camera. They generally go at $30-35 plus shipping on eBay, but you can usually pick up one new for about $20 from SurplusShed.

Get a few glass slides, or even an old UV camera filter, drop it on the stage with a bug or leaf or whatever, get the illumination going, mount your trusty camera loaded with 100 or 200 film, and you’re set. Exposures will be long – 2-5 seconds at lower magnifications, greater for higher – reciprocity failure will happen anyway, so don’t worry – easiest is to set the camera on B, and give it a good 5 or 10 second exposure. The camera is mounted solidly, but since it’s all metal to metal connections, anything that will reduce vibration is a good thing. If possible, use a camera that has a mirror lockup. An old OM-1/OM1n is ideal since it has the mirror lock-up feature especially if it has a working meter. If your camera does not have mirror lockup, don’t worry about it. Minimize other sources of shake as far as possible, and use a cable release.

Note: A word about DIN and JIS – one is the German Standard, the other Japanese. The diameters, thread pitches etc are exactly the same. However, when magnification is stated, the DIN standard bases its calculation on a 160mm microscope tube length while the JIS standard uses 170mm tube length as the basis. In both systems, the standard eyepiece diameter is 23.2 mm, generally stated as 23mm. (there are 30.5mm diameter tubes as well, but they are much newer, and not cheap, so we will not get into that discussion). Now, no matter what the sellers say, the 2 systems are completely interchangeable – although magnification will not be correct – it will differ by approximately 10%. For our purposes, that’s not important.


text and images © 2007 ajoy muralidhar. all names, websites, brands and technical data referenced are the copyright or trademark of their respective owners.
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Light meters or Exposure meters were once an essential piece of equipment for any photographer, until the advent of in-camera meters and TTL metering.

We became spoiled, and worse, got used to accepting the “average” readings that the meters gave us, leading to photographs which were muddy grays, with no life in them… gone were the pristine whites and deep liquid blacks, and the fine gradations that characterized black and white photography in the 30’s 40’s 50’s and even the 60’s. With the in-camera meter, came the age of the drab grays… if you don’t believe me, look at older black and white pictures and you will know what I mean.

Then came color, and contrasts became less important – in fact, contrasty light which was previously ideal for textures that defined and dignified black and white photography was undesirable… and we became accepting of colors that weren’t true to life, and blamed the processor for the lack of brightness.

Honestly, I think there still a place for a light meter in every camera bag. Used meters are so cheap that there no real excuse for not having one – the solid well made feel of a rugged selenium (or for that matter CdS meter) is a pleasure to hold and use.

I’ve 3 of them – a direct reading GE PR-3 (when it works), a beautiful old GE PR-1, and a lightweight Weston Master 6. They all agree on within a 1/3 stop of each other, and the PR-1 and Weston 6 are spot on.

The Weston 6 was a little pricey, I must say, but still only cost a third as much as a comparable Gossen Lunasix. The GE Light meters are a real bargain – less than $10 most days on eBay.

When buying a light meter, remember that the older Westons used their own film rating scales, and not ASA – they are about a 1/3 stop off. Weston started using ASA ratings from the Weston III onwards. The Weston 4, 5, and 6 and the Universal meters are all good meters and worth having.

The crème de la crème, of course is the Weston Ranger 9, designed by Weston with Ansel Adams – for the Ansel Adams Zone system. The GE meters always used ASA ratings so they don’t need to be compensated.

I also have a couple of specialized incident light meters – a SPER Scientific that I’ve had for ages from my Grad school days, and a Gossen Panlux that I picked up recently really cheap from a scientific instrument seller . These are not really meant for photography, though they can be used in a pinch, if one has a reference table.


text and images © 2007 ajoy muralidhar. all names, websites, brands and technical data referenced are the copyright or trademark of their respective owners.
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The OM-1 is a totally mechanical camera – it does have a light meter, but the use of that is up to you, you can keep it turned off if you wish. The meter takes a 1.35v mercury cell anyway, which is impossible to get since they are banned all over the world. Although you can use a 1.5 volt silver oxide cell, it does require compensation since the incorrect voltage gives a reading that is a full f stop off, if not more.

Some owners have taken the drastic step of having their meters re-calibrated for the newer batteries, but there are very few OM camera technicians around who can do a good job. Who needs more scratches on the camera anyway? Besides, you might not want to spend the extra $$. It probably costs more than what you paid for the camera in the first place. However, if you do want to take the plunge, I’ve heard the folks at Zuiko.com and Camtech do a great job.

More often than not, the meters on these old gems are flaky anyway, since the light sensing selenium cells are shot. So, I thought I would try using the old Sunny 16 rule with one of the OM’s to see what kind of pictures would result. Besides, from the early days, photographers had been using “guesstimates” for their exposures, before light meters came along and made our lives easier. But it also made us dependent upon the technology. So much so that all the later OM cameras will not even work without batteries. Not so the venerable OM-1. It works just fine at all shutter speeds. No batteries needed. It even has a mirror lock-up to avoid the noisy mirror slap of most SLRs.

Pre-lightmeter photography gurus had worked out the Sunny 16 rule over the years, and it is simplicity itself. In essence -You have a manual camera which can operate without a light meter, such as an OM-1 – maybe the meter has flaked out when you are in the field, or your battery has run down, or whatever. No need to panic. This is how it works.

We need to do 2 things – figure out a workable shutter speed, and figure out a aperture opening (f/stop) for the light conditions we are working under.

1. You know the speed of the film you are using. Let us assume it’s 200 ASA.
2. Set the shutter speed as 1/film speed (as near as possible, so don’t worry) – since there is no 1/200 sec setting on the OM-1, we will set shutter speed as 1/250 sec.
3. Now for the light conditions – look at the table, and decide what kind of light we are working with.
4. Set aperture suggested for the light conditions – f/16 for bright and sunny etc.
5. Adjust for subject (open up 1/2 stop or stop down 1/2 stop as you think fit – Its easier to just bracket the shot. Take one at the suggested setting, then take 2 more at 1/2 stop increment or decrement on either side)
6. Shoot away. Keep your eye on the light conditions – if it changes, adjust aperture accordingly.

I have been experimenting a bit, and the following table works for me, since I use 200 ASA film most of the time. I strongly advise that everyone should play around with their equipment settings until they figure out what works best with their particular camera, and of course, their preferences for image contrast and exposure. Besides, modern photographers have another thing in their favor… modern 35 mm film. The advanced film emulsions available to us today are very forgiving – medium speed films have a range of up to 4 stops, which is enormous, considering that with the Sunny 16 rule, you will be off by at most 1/2 stop or so under or over exposed.

Retro-photography – doing what the old timers did before fancy exposure meters were available.

Set this Lens Opening for this Light Level when Shadow Type is
and Film Speed with Shutter speed at
f/22 Bright Sun, Snow, Concrete etc well defined 200 ASA ~1/250
f/16 Bright Sun, flat light dark, well defined 200 ASA ~1/250
f/16 Sunny, some clouds (flat light) well defined 200 ASA ~1/250
f/11 Slight Overcast (slightly bluish) Soft around edges 200 ASA ~1/250
f/11 Medium Overcast (bluish cast) Poorly defined 200 ASA ~1/250
f/8 Overcast (blue cast) Barely visible 200 ASA ~1/250
f/5.6 Heavy Overcast (blue cast) No shadow 200 ASA ~1/250
f/4 Sunrise/Sunset (reddish yellow cast) Long Shadows, raking light 200 ASA ~1/250

If you’re planning on using filters, make sure that you compensate aperture settings accordingly – Remember, there are no hard rules about filters – its always to your taste, so go with what pleases YOU. Lots of people LIKE the reddish-yellow cast of early morning and late evening light. If you’re one of them, trying using a Warming filter during sunrise/sunset, or for really spectacular red highlights, try a 85B filter. It’ll knock your socks off :).

Here is the Sunny 16 table with suggested filters and aperture settings compensated for the particular filters suggested for color or black & white.

Light Level Suggested Filter for color film
Suggested Filter  for B & W film
Compensated Aperture
Bright Sun, Snow, Concrete etc Circular Polarizer for color saturation/also cuts reflected light Yellow or Green f/11-f/16
Bright Sun, flat light Circular Polarizer for color saturation Yellow or Green f/8-f/11
Sunny, some clouds, (flat light) Circular Polarizer for color saturation Deep Yellow, Orange or Red f/8-f/11
Slight Overcast, Hazy Warming Filter 81A to compensate for bluish cast Yellow or Orange f/8
Medium Overcast (bluish cast) Warming Filter 81A/812 to compensate for blue cast Yellow f/8
Overcast (blue cast) Warming Filter 81A/812 to compensate for blue cast No filter needed f/5.6-f/8
Heavy Overcast (blue cast) Warming Filter 81A/812 to compensate for blue cast No filter needed f/4-f/5.6
Sunrise/Sunset (reddish yellow cast) Blue Filter 80B to compensate for reddish yellow cast; 85B filter for enhanced reds. No filter needed, use Orange or Red filter for special effects to darken sky f/2.8-f/4

Note -This table works for me with normal Daylight color film. Panchromatic black & white film does not have as wide a latitude as color film does so you’ll have to be a little more careful. In any case, I’d advise that all important shots be bracketed by 1/2 stop just to be on the safe side.

Here are some examples – I used a Zuiko 50mm f/1.8 lens with Fuji Xtra 200 film. Aperture and shutter settings are according to the table above.

Sunny conditions, 50mm, 1/250 sec, f/16
Light Overcast conditions, 50mm, 1/250 sec, f/11
Medium Overcast conditions. 50mm, 1/250 sec, f/8
Overcast conditions, 50mm, 1/250 sec, f/5.6

text and images © 2007 ajoy muralidhar. all names, websites, brands and technical data referenced are the copyright or trademark of their respective owners.
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