View Full Version : GN on Olympus 35 DC

10-04-2009, 04:03
Hello everybody,
My friend sent me an Olympus 35 DC rangefinder camera and I am trying to figure it out. Can anybody explane how GN window and BLC button work? I found a manuel on line but not in detail. Thanks.

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10-04-2009, 06:04

The BLC button is for backlight compensation. It gives metering priority to the rangefinder patch when calculating exposure. Not sure about the GN window. A free manual is available for download here, but please note the required log in and password at the top of the page:


Steve Gandy also has info on the Oly RD and RC at CameraQuest:


Sounds like a sweet little camera. Have fun.


10-04-2009, 07:03
The GN (GN=Guide Number) window is for use with manual flashes. You set the GN in the window and the camera calculates the f/stop based on the focus setting. I'm not that familiar with this model. There will be some way of switching between normal metered operation and flash. It may be some setting on the camera and might be triggered automatically when the camera feels a flash in the hot shoe. When in the flash mode, the shutter speed is probably set to 1/30, or thereabouts, so that it is compatible with both electronic flash and flash bulbs. The latter work fine with zero delay X-sync (needed for electronic flash) when the shutter speed is set that slow.

GN explanation: http://en.wikipedia.org/wiki/Guide_number

10-04-2009, 07:51
The GN flash mode works really well in my RD and RC. Keep in mind though that it is primarily for 100ASA film. If your film is for example 400ASA, you need to tweak the GN accordingly.

10-04-2009, 08:25
Thank you Mablo, Dwig and Greg.

I will use 100 ASA film and I am not planning using flash. Not sure in what conditions I should use BLC button for backlight compensation. I guess I will figure it out better after a few example shots..

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10-04-2009, 12:58

BLC would be used if the subject is darker than the prevailing background, for example you're shooting someone wearing dark clothing standing in front of a bright window. Otherwise, the meter would "see" the bright background and tend to underexpose the true subject. If you center the darker subject in the RF patch and press the BLC button, it meters off that subject giving a better exposure. It would be similar to dialing in +1 EV or so in a camera with exposure compensation, though the BLC button should do an even better job since it's actually metering the subject instead of having you guess at a compensation value. So you could also say that the BLC button is a sort of spot meter, albeit a somewhat wide spot.

Of course with a digital camera that displays a histogram you can really nail the exposure, but that would be cheating and it's not as cool as film! :cool:

10-04-2009, 13:18
Right BLC stands for "Back Light Compensation," and it compensates the exposure by a stop, I think. Or it might be a bit more -- 1 1/2 stops. I don't recall the exact amount.

What it means is if the light is in back of your subject, you press and hold the button before and while you press the shutter release.

10-04-2009, 13:19
Thanks Greg, it was very helpful.
I mostly use digital camera, once I tried Yashica Electra 35 RF, film really has very different color and look.

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10-04-2009, 13:24
Initially, I had said it opens the aperture, which it does, but because it's "programmed autoexposure," it also then moves it to a slower shutter speed.

So perhaps the total is closer to two stops. I'll have to check the camera to be sure.

10-05-2009, 02:40
Thanks ZeissFann, less or more I got the idea.


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