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Nostalgia Nexus - early and pre-digital discussion Want to discuss the really early days of digital and even film - here is the place for you.

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  #16  
Old 21st November 2012
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Re: OM Users' Den?

Quote:
Originally Posted by Naughty Nigel View Post
I love the picture of your little girl. Enjoy her before she gets too cheeky - and expensive!

Hmmm.... I can tell she is getting in some practise for both.

Are you having problems with the metering on your OM1? I believe they need mercury cells (which are no longer available), or a modification to allow them to work with current lithium, zinc and silver cells. (There are regular threads about this on the AP forum.)

The meter seems to work, I did change the battery after buying the OM1 on Ebay, as the meter did not work, I installed a new (watch type) battery and it seems to respond fine to aperture and shutter speed changes. Is there something evident on my image that shows my metering is out?


However, I would be wary of using a digital camera as an exposure reference, as the ISO sensitivity of digital cameras is often very different to the stated speed. (For example, the true ISO sensitivity of digital cameras is often much lower than stated on the speed dial, to help reduce sensor noise.)

I am beginning to appreciate the true strength of ISO on the om1, and how it can be used more significantly in the changing of my images.... much more than digital.

Its still evident that getting a good shot in digital is pretty easy... to get a good shot on film takes more photographic skill.

If you think about it, the ISO sensitivity of a digital camera can be whatever it wants, as it only has to meter for the CCD in that camera. In other words, it is a closed circuit, and doesn't need to conform to any third party standards. Meanwhile, the exposure meter in a film camera must be both reasonably accurate, and consistent throughout the speed range, as film emulsions are formulated to provide a standard ISO sensitivity as stated on the box.

I am sticking with the 400 ilford.... I have seen results high up the iso scale and not so many lower down in the iso range .

Its going to take me a lot more than my 3 rolls (2 x failed & 1 x success) to get so many examples.
Thanks Nigel,

The om1 I find is a stunning camera to hold and view, the viewfinder gives a very different view than the E3 with the same lens.... I struggle getting the focus through the viewfinder with the prism confusing a little....

Best wishes.

Alan
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  #17  
Old 22nd November 2012
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Re: OM Users' Den?

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Originally Posted by kidslateinlife View Post
Thanks Nigel,

The om1 I find is a stunning camera to hold and view, the viewfinder gives a very different view than the E3 with the same lens.... I struggle getting the focus through the viewfinder with the prism confusing a little....

Best wishes.

Alan
Hi Alan,
The exposure of your shot looks good, but I picked up on your comment that " I can take a shot with digital........then offer up my OM1n under similar settings and by the exposure meter I know I am going to get a decent exposure and timing............... need to work on my iso settings!"

This made me think that your camera's exposure meter was not working properly.

Firstly, you really need to use the correct settings for the film in the camera. There are circumstances where you can benefit from deliberately under or over exposing, but by and large, if you are using 400 ASA film then set the camera to 400 ASA.

Please note that film speed has nothing to do with shutter speed, except that a faster film allows you to use faster shutter speeds (in the same light and with the same f stop setting) than a slower film.

Digital cameras will give broadly simialr results whatever ISO speed they are set to, although image quality is usually better when using the lower ISO speed settings. Images shot at higher ISO settings (usually 400 and above on the E-System) tend to suffer more from electrical noise.

However, I would not reccomned using any digital camera to determine exposure for another camera, whetehr film or digital, for the reasons that I gave yesterday. The only possible exception would be if you knew exactly what the true ISO sensitivity was at any given ISO setting.

(For example, you might find that the true ISO sensitivity of a digital camera at 100 ASA was closer to 125 ASA, whilst the true sensitivity at 640 ASA might only be 400 ASA - to help reduce noise).

The two important points here are that a): the true ISO sensitivity of two identical digital cameras will not necessarily be the same, and b): the true ISO sensitivity of two different digital cameras is very unlikely to be the same!

Just to illustrate this, I have just set my E5, Canon PowerShot G11 and OM4Ti to 100 ASA, and set their lenses to f 5.6.

Pointing the cameras at the same uniform patch of wall, the E5 says half a second, (0.5 second), the G11 says 0.6 second, and the OM4Ti, which I would trust my life with, also says half a second.

However, if I now set the E5 and G11 to 800 ASA, the E5 says 1/15 of a second (which is about right), but the G11 says 1/10 of a second, which is clearly not consistent with 0.6 seconds at 100 ASA.

(If the ISO sensitivity was consistent across the speed settings, this should have been about one thirteenth of a second.)

As you can see, if you used either of the digital cameras to set the exposure for your OM1, there is a risk that you would over or under expose. This wouldn't matter too much if you were using negative film (colour or B&W), but transparency films are much more critical of exposure.
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  #18  
Old 22nd November 2012
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Re: OM Users' Den?

Quote:
Originally Posted by Naughty Nigel View Post
Hi Alan,
The exposure of your shot looks good, but I picked up on your comment that " I can take a shot with digital........then offer up my OM1n under similar settings and by the exposure meter I know I am going to get a decent exposure and timing............... need to work on my iso settings!"

This made me think that your camera's exposure meter was not working properly.

Firstly, you really need to use the correct settings for the film in the camera. There are circumstances where you can benefit from deliberately under or over exposing, but by and large, if you are using 400 ASA film then set the camera to 400 ASA.

Please note that film speed has nothing to do with shutter speed, except that a faster film allows you to use faster shutter speeds (in the same light and with the same f stop setting) than a slower film.

Digital cameras will give broadly simialr results whatever ISO speed they are set to, although image quality is usually better when using the lower ISO speed settings. Images shot at higher ISO settings (usually 400 and above on the E-System) tend to suffer more from electrical noise.

However, I would not reccomned using any digital camera to determine exposure for another camera, whetehr film or digital, for the reasons that I gave yesterday. The only possible exception would be if you knew exactly what the true ISO sensitivity was at any given ISO setting.

(For example, you might find that the true ISO sensitivity of a digital camera at 100 ASA was closer to 125 ASA, whilst the true sensitivity at 640 ASA might only be 400 ASA - to help reduce noise).

The two important points here are that a): the true ISO sensitivity of two identical digital cameras will not necessarily be the same, and b): the true ISO sensitivity of two different digital cameras is very unlikely to be the same!

Just to illustrate this, I have just set my E5, Canon PowerShot G11 and OM4Ti to 100 ASA, and set their lenses to f 5.6.

Pointing the cameras at the same uniform patch of wall, the E5 says half a second, (0.5 second), the G11 says 0.6 second, and the OM4Ti, which I would trust my life with, also says half a second.

However, if I now set the E5 and G11 to 800 ASA, the E5 says 1/15 of a second (which is about right), but the G11 says 1/10 of a second, which is clearly not consistent with 0.6 seconds at 100 ASA.

(If the ISO sensitivity was consistent across the speed settings, this should have been about one thirteenth of a second.)

As you can see, if you used either of the digital cameras to set the exposure for your OM1, there is a risk that you would over or under expose. This wouldn't matter too much if you were using negative film (colour or B&W), but transparency films are much more critical of exposure.
Nigel

Thank you for the obvious amount of effort and time you have taken with your experienced words.

I will have to see how much I trust the exposure meter over the last 24 of my current roll.

I have a long way to go, and hopefully a lot more time to get there... now that I have given up smoking.


Best wishes again....

Alan
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  #19  
Old 13th December 2012
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Re: OM Users' Den?

I occassionally take out my OM40 and OM4Ti and polish the dust off. I also have enough flashes and leads to light a small temple that are sitting unused (see comment below). At least the zuiko prime lenses get an airing on the E-M5.

Why couldn't Olympus engineer their E-series, PENs, and OM-D to work (fully) with the T20/T32 flash rather than introducing a new system and hot show pin outs? The cable linked multiple flash OTF OM system was excellent and reliable.
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  #20  
Old 19th December 2012
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Re: OM Users' Den?

I am having problems responding to this message. Does anyone know what the problem is?

I can post a short message, but anything more than a few words causes an "Internal Server Error".
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  #21  
Old 20th December 2012
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Re: OM Users' Den?

OK, lets try it this way:

I have a pair of F280's myself, and I agree that it would be good to use them with E-system cameras, but unfortunately that just isn't possible.

The exposure system in OM cameras was very clever, as it was able to measure light reflected off of the film and shutter, (which is why OM shutters have a black and white pattern printed on them). When the meter calculated that the correct amount of light had fallen on the film it would trip the second shutter blade, or if using flash, would quench the flash. This all happened very quickly (in microseconds). It is also worth noting that the exposure speed shown by the meter was in fact only a guide, as unless the camera was set to manual exposure, the second shutter blade was tripped only when sufficient light had fallen on the film (according to the film speed selected), and not when the film had been exposed for the indicated time.

Continued below:
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  #22  
Old 20th December 2012
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Re: OM Users' Den?

Continued:

For various reasons, (mainly to do with the way that light is reflected from digital sensors), the exposure system in digital cameras is rather different, and must be determined before the exposure is made.

In the case of flash photography, digital cameras fire a short pre-flash a few milliseconds before the main exposure is made. (Think of this as a 'test flash').

This pre-flash allows the camera's exposure meter to work out how much flash power is needed, which is then delivered in the main flash. Unfortunately, the older analogue flashguns were not designed to work this way, so when the first signal is received they deliver a full flash, which not only confuses the metering system, but also means that the main charge capacitor is discharged when power is needed.

You can normally use these older guns in manual mode, but the exposure latitude of digital cameras is next to non-existent, so you would need to do a lot of experimentation to get the exposure right.

I should also warn you that some older flashguns present a very high voltage at the hot shoe (300 volts is not unusual), and this is more than enough to comprehensively destroy the electronics in a modern camera. This can easily be checked with a multi-meter, but be careful as it is easy to do a lot of damage with some of this old equipment.
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  #23  
Old 20th December 2012
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Re: OM Users' Den?

Nigel,

Having had more years of OM ownership than I care to count I knew how the "Off The Film" (OTF) flash system worked between OM cameras and the F280/T32/T20 flashes, and know that they have a "safe voltage" for use with modern cameras. But I never knew that digital cameras always fire a pre-flash to "guage the exposure" (if I can put it this way) so it all makes sense. In combination with using short bursts of flash to talk to slave flash units I imagine that a modern setup is more like Blakpool illuminations. I guess I'll have to fork out for a good flash unit someday but until then the T32 looks good on the E-M5 and works well enough.

Thanks for the explanation
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