If you need Bellows Exposure calculation down load with filter calculation
Try this wheel for calculations
Dave
If you need Bellows Exposure calculation down load with filter calculation
Try this wheel for calculations
Dave
Group on 9A/9N South Bend Lathe
http://finance.groups.yahoo.com/group/southbendlathe9
The reciprocity timer app for iPhone does all that for you, it's really great and was developed by a LFF member
Check it out on the App Store
https://itunes.apple.com/us/app/reci...459691262?mt=8
Bellows Extension factors need not be nearly as confusing as some suggest.
Placing a known object in the zone of critical focus and then taking a measurement on the ground glass of that object with a unique measurement devise can seem quite daunting.
For years I've used a very simple method to calculate bellows extension compensation, and it's all in your head.
Example, 210mm lens, also known as a 8 1/4" lens ( this measurement is @ infinity ) Convert the length of the lens ( in inches) to an F stop, i.e. 210mm = F 8, if your bellows extension is measured at 11 inches then you allow 1 stop additional exposure, F 8 to F 11 = 1 F Stop, if measured at 14" then allow 1.5 stop increase in exposure.
210mm (8 1/4" ) lens extended to 16" is just slightly lens than 2 full F Stops. BTW, any size lens extended X 2 is life size, i.e. 6" lens extended to 12" or 10" lens extended to 20" produces a life size image on the ground glass and always dictates a 2 stop increase in exposure.
Some may say this method is not accurate enough, for years I did product / table top photography with box specific ISO Ektachrome film and rarely missed a bellows calculation.
Cheers
Of course you can; as long as you know how many stops are between f210 and f420.
There are as many ways to learn this as there are learners.
Smithdoor's wheel is another good way.
As always, the best is to understand the principles and then you can understand why they all work.
Group on 9A/9N South Bend Lathe
http://finance.groups.yahoo.com/group/southbendlathe9
I have pre-calculted the correction for my two most used lenses, 150mm and 210mm.
When in the field, I compose and focus, then measure the total amount of extension. For the 150 (6 inches, right) each inch beyond infinity is one third of a stop extra exposure.
For the 210mm (8.25 inches) the correction that I use is one quarter of a stop extra exposure for each inch beyond infinity.
To each his own: You can make this as complicated as you want. There are many threads on this topic and many methods—some with formulas (Ok: So what if the plural is "formulae).
Try out a few ways and settle on what works for you.
Drew Bedo
www.quietlightphoto.com
http://www.artsyhome.com/author/drew-bedo
There are only three types of mounting flanges; too big, too small and wrong thread!
http://www.salzgeber.at/disc/disc.pdf
I use this simple tool. It works fine and I don't have to use my math challenged brain.
Thanks,
Kirk
at age 73:
"The woods are lovely, dark and deep,
But I have promises to keep,
And miles to go before I sleep,
And miles to go before I sleep"
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