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From digital to OM10


New Member
For the past 14 months or so, I've been using 2 different digital cameras, neither Olympus.

Today I found this OM10 with 1:1.8/50mm lens and manual adaptor (and T20 flash - not tried that yet). I have loaded a film and begun to take a few pictures. I also downloaded the maunal to get me started with a few bits and pieces - this SLR world is all new, especially this more traditional style!

Now, being a young 'un and someone fully used to digital and computers and teleporters etc (well, maybe not), I'm not fully sure what I'm doing.

- On the top, where you can set 'Auto' or 'manual adaptor', what is 'B', the third option?
- Also on this dial, what are the numbers (ASA and 1, 2, . in red and blue, and how are they changed?

- On the lense, closest to the camera, what are the numbers, and red dot, and how is it changed?

I think that's all for now. Any other tips or information would be most appreciated.


Well-Known Member
> I'm not familiar with the OM-10 but have used the OM-1, -2, and -4. What follows is from memory--check what I say against the manual: >

> - On the top, where you can set 'Auto' or 'manual adaptor', what is > 'B', the third option? > Possibly "Bulb," a term from the days when shutter releases were pneumatic (L-o-o-ng ago!). If that's what it is, it means the shutter will stay open as long as you hold down the release. (Digital cameras often set upper limits on shutter-open time; film cameras do not, or at least didn't use to.) > - Also on this dial, what are the numbers (ASA and 1, 2, . in red and > blue, and how are they changed? > ASA usually refers to film sensitivity, or "speed," -- same as ISO in a digital camera. But with film, ISO/ASA is a function of the film you load, not the camera settings: you change ISO by switching to a different film type, and then set the camera's dial to provide proper exposure of that film. Some cameras now read codes on the film cartridge and set themselves automatically to that film's ISO, but can be overriden (see next paragraph).

You can vary a film's effective ISO, to some extent, by processing it differently, but you're probably not developing your own film, so that doesn't apply. You can also reset the ISO to cause deliberate under- or overexposure: With ISO 100 film, setting the dial to 125 causes a 0.3-EV underexposure; setting it to 80 overexposes by 0.3 EV. But modern film cameras, probably including yours, usually have a separate exposure-compensation control like that on a digital camera.

On older cameras, which have no built-in exposure meters, ASA dials were strictly to remind the user what kind of film was loaded -- they did not affect camera operation at all. > - On the lense, closest to the camera, what are the numbers, and red > dot, and how is it changed? OM lenses have a footage scale (ending with an infinity symbol) for focusing -- or, more often, for reading the distance once you've focused by trning the lens until the viewfinder imae was sharpest. No autofocus.

Then they have an aperture, or f-stop, scale, with numbers that vary by ~1.4 (square root of 2): f/2, 3.5, 4, 5.6, etc. Just as with the aperture adjustment on digital cameras, each number sets the lens to let in half as much light as the next smaller number, twice as much as the next larger one. For ex&le, if proper exposure is f/5.6 with a shutter speed of 1/200 second, it will also be proper at f/4 and 1/400 or f/8 and 1/100. [It becomes easier to understand if you realize that f/4 means the aperture size is 1/4 the lens's focal length, f/8 means 1/8, etc. Lens transmission is proportional to the _area_ of the aperture tha tlets the light in, and area is figured from the square of the diameter; so doubling the diameter multiplies the aperture size by 4, which is the square of two.]

Using a smaller (higher-numbered) aperture increases the depth of field; if you want everything from nearby to the distant hills in focus, use a small aperture like f/11; if you want to emphasize a nearby subject by blurring the background, use f/2. On OM cameras, the meter sets the shutter speed according to the f-stop you select (aperture priority).

On other OMs, and maybe yours, the scale closest to the camera body is for manual setting of shutter speeds, with numbers like 125 (1/125 sec), 250, 500, etc. These only work in manual expoosure mode-in auto-exposure mode, the camera sets the speed regardless of setting.

The red dot is a guide when you're changing lenses. To remove a lens, find the lock button on the lens (check the manual), press it, and turn the lens about 1/4 turn counterclockwise (as seen from in front of the lens); to mount a lens, line its red dot up with the red dot on the camera lens mount, insert the lens, and turn 1/4 turn clockwise until it clicks. When the lens is in place, it covers the red dot on the mount, so you waon't see that. >

George S.

NO! if the camera is an OM-10, there's no shutter speed dial on the front of the body, but the shutter speeds are changed by turning the manual adapter, of course. the numbers and the red dot that were mentioned are on the lens and not the camera body. The numbers are a depth of field indicator. You focus the lens and the camera to subject distance is seen opposite the "red dot". You also must set the ASA film speed on the top, and keep the bold white line straight, the numbers 1, and 2, refer to exposure compensation, just keep the bold white line centered (for no compensation). For further info, go to:
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Well-Known Member
If you would like to learn more about your OM camera I recommend that you find and purchase an excellent book called "How to Select and Use Olympus SLR Cameras" by Carl Shipman. It is available used on, and sometimes on ebay.

Again, this book is EXCELLENT. Not only does the author explain everything you could ever want to know about your OM-10 (as well as other OM models), but he also includes really, really good explanations about how SLR cameras work, how exposure works, etc.


New Member
Thank you for all the information, and I shall indeed look into purchasing that book when I have the money.

I was having trouble understanding changing the ASA film speed, but after asking my parents, it's all clear.

I have the manual adaptor, so I realised it wasn't shutter speed, but now I see the 'm' and 'ft', so it should have been clearer.

What are the numbers either side of the red dot though, what are they used for?


Well-Known Member
Jacqueline, that's a depth of field scale. Unfortunately they are not found on many lenses today, but were included on almost all lenses back when your camera was made.

The numbers are aperture settings. Basically the part of your focusing scale (feet or meters) between the two corresponding markings (e.g. f16) will be the part of your picture that will be in focus.

The DOF scale also helps you to find set your lens at hyperfocal distance. It gives you an easy way to ensure that your entire picture will be in focus.

Here is a good site about hyperfocal distance:

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New Member
Thanks for all the information, it's all new for me and very interesting!

I handed in and got back my first film from it today, and it was much better than I predicted! I was expecting most to be out of focus, overexposed, underexposed, dodgy colour, all of the above, and nothing at all! But I'm quite pleased with some of the results, so I might stick with it!

Just wondering, is there a cheaper way to have films developed, other than doing it yourself? I paid just over £6 for an hour developing.


Active Member
Jacqueline, the other factors were uncertain to be sure, but as it is an SLR and you can see how well it is focussed in the viewfinder before you take the photo then I would hope that the level of focus in your photos would not be a surprise!!


Well-Known Member
Jacqueline, regarding processing film, I am in the U.S., so I don't know what you have available there. Here the cheapest places to do it are at large discount stores (Walmart, Kmart, etc.). Drugstores (chemists) and supermarkets are probably a little higher and of course camera dealers charge even more (but probably offer more quality and even some custom processing options). Also, sometimes the cheapest way used to be by mailing the film to a processor. There used to be cheap mail order envelopes in magazines. I remember trying it once and got acceptable results.