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During our get together on the Ridgeway at the weekend we discussed the use of the QuickDisc as an aid to calculating exposure compensation for bellows extension whilst taking close ups.

For all those interested this is the link http://www.salzgeber.at/disc/

Paul

I tried this out last year but found I had problems using it in the field on my own. I think you really need someone to hold the scale for you.

Thingy wrote:I tried this out last year but found I had problems using it in the field on my own. I think you really need someone to hold the scale for you.

I know what you mean... was shooting some leaves in a beck a few weeks ago where the disc would have just floated away... ended up taking a visual reference as to where the disc would have fitted and measured off that. I always carry some blutack in my bag for attaching it to vertical surfaces.

Paul

Paul,

I tried using one of these a while ago; I too had problems with it blowing away etc. I stopped using it when I lost the little measuring strip

Instead I glued a scale to the length of the camera bed so that I could read off the actual focal length and then wrote up a little table so that for each of my lenses, I could look at the actual extension used and then just read off the bellows factor. The measuring scale was a trimmed down paper measuring tape that I had left over from a trip to a well known Scandinavian furniture store.

Best regards,

Evan

I just use the disk to measure something in the scene and then use the rule against that. No need to leave the disc in the scene really (you don't need absolute accuracy anyway)

Perhaps someone (hint) will devise an app for the iPhone/iPod (with camera) that will automate this process...

Many years ago at college I wondered how to work this out quickly ? I purchased a cheap tape measure ( the kind that are sprung loaded ) to which with some maths I worked out for each lens distances for + 1/3 + 1/2 +2/3 etc these were marked onto the tape - having only 4 lenses at the time I choose two marks on either side of tape thus using a sharpy pen marked off +exposures for for each lens . all i needed to do was measure the distance between front & rear standard job done ? should have sold it as the quick tape ?

an even easier method is just to treat the focal length of the lens and the actual extension as f-stops and just subtract the difference.

So say you're shooting with your 150mm lens and you've got it racked out to 8 inches from the film (you can either measure this or estimate - I have a tapemeasure sewn into the darkcloth). So say 150mm is 5.6 inches, extension is 8 inches, pretend they're f-stops so its clear that f5.6 is one stop away from f8, hence you need 1 stop of bellows correction.