GDR red filter Jenaer Glaswerk

Morte · 2013-02-26T18:54:50+00:00

Der Filterfaktor, gerade bei Rot, ist auch von äußeren Faktoren wie Tageszeit (Lichttemperatur), Motiv (welche Farben) und dem verwendeten Film abhängig. An...

Morte

Hello everyone, I’ve come across a red filter made in the GDR. Does anyone happen to know the extension factor? The filter itself is unmarked. The following text is printed on the cardboard sleeve: foto-optik ultrasorban filter for black-and-white film B - M 58 x 0.75 R 6 11.85 Also written in pen, almost illegible (presumably): 401 The price and thread size are clear, of course. P.S. Oh blimey, I’ve ended up in the wrong forum. Oh well, please bear with me.

Morte

michael-kielgmxnet

If the designation R6 corresponds to the current designation KR6, I would estimate a factor of around 2.

pittyman

The filter factor, particularly with red filters, also depends on external factors such as the time of day (light temperature), the subject (which colours) and the film used. If I were you, I’d expose your standard film at +2, +3 and +4 with the filter. Once developed, you’ll see how it turns out. But as I said, particularly with red filters, the other factors shouldn’t be overlooked if you’re aiming for ‘perfectly’ exposed negatives. Best regards, Dirk

Morte

Thanks for now! Is it perhaps possible to rely on TTL exposure metering in this case? It works with my yellow filters, but it might be a completely different story with red filters …

sputnik

Probably not. A correction of +1 to +1.5 EV would certainly be advisable with TTL. Depending on the time of day. Why don’t you just give it a go? You’ll have no choice in the end anyway. No one knows what sort of filter it is, so no one will be able to give you precise details. Incidentally, I don’t use the filter factors specified by Heliopan and B+W either; I use my own. Just as there isn’t THE right exposure, there isn’t THE extension factor either, because it always depends on what you want the end result to be. ;-)

SxDx

And it also depends on the light and the subject. To give an extreme example, a brick house at sunset needs a different exposure setting to a blue car in a Nivea advert :D I wouldn’t rely on TTL metering either, at least not with the simpler systems. As far as I know, they’re particularly sensitive to green.

pittyman

TTL metering is by no means precise and can sometimes be completely unreliable! For this reason, Zone VI has offered a specially modified version of the Pentax spot meter, as colours can sometimes ‘falsely suggest’ the ‘wrong’ brightness levels. Spot meters only measure reflected light, but as you can see, this is a physically very complex field. Greetings from the darkroom Dirk

TR

Just as there is no single ‘correct’ exposure, there is no single ‘extension factor’ either, because it always depends on the desired result.

However, in a conservative sense, the correct exposure is the one where the shadows are still well defined. That is, if you divide your image into zones, Zone II on the negative still contains image information. If the extension factor is set too low, you will lose image information in this critical area. However, as already mentioned, the colour of the light also plays a role. Now in winter, with a closed cloud cover, there is a higher proportion of blue in the light throughout the day (in which case a red filter will at best reduce contrast). So, theoretically, a longer exposure time would be required than with light containing a high proportion of red (e.g. direct sunlight). But to what extent should this actually be taken into account? I don’t know. I simply hold my filters up to the light meter in ‘neutral’ light and work out my exposure times that way – if they aren’t marked on the filter.

sputnik

In the conservative sense, the correct exposure is the one where the shadows are still well defined. That is to say – if you divide your image into zones – Zone II still contains image information on the negative. If the extension factor is set too low, you will lose all image information in this critical area.

Correct: in the conservative sense. In theory. In practice, however, it is the photographer who determines what falls into which zone and what they want to be defined and what they do not. BTW: If you expose so generously with a red filter that your shadows are still fully defined, the red filter effect in a landscape shot is 100% lost.

I simply hold my filters up to the light meter in ‘neutral’ light to work out my extension factors – if they aren’t marked on the filter.

This works well with most filters, but with a red filter you’ll never, ever get the shadow detail you demanded earlier as a condition for ‘the right’ exposure. ;-)