# Thread: GND & ND filter

1. ## GND & ND filter

Recently i just bought this 2 filter but still not sure how to get the right exposure.
For example ND 0.9 filter, let said without this filter, the right exposure are

ISO 100 F11 and Shutter 1/30

If i put the ND 0.9 filter, ISO and Apperture remain the same, what is the right shutter speed ?
how to calculate to get the right shutter speed ?

For now, i just guessing to get the right shutter speed.
Any pro please teach and explain.

2. ## Re: GND & ND filter

Neutral density filter - Wikipedia, the free encyclopedia

0.9 is 3 stops,
so original exposure of ISO 100 F11 and Shutter 1/30 after adding a 0.9 ND filter (3 stops),

the new exposure setting of ISO 100, F11, and the shutter speed should be __________________.

3. Hi TS. Instead of learning how to calculate, there are some tools to assist you in getting the right exposure after you put on the filter. 1. iPhone app: Longtime. 2 download and print a long exposure chart (google it). One advise from me is, many time i put 1 stop lower give me a correct exposure. Hope that's help. Cheers !

4. ## Re: GND & ND filter

1 stop = double exposure time...

0.9 ND = 3 stops = 2^3 = 8 times exposure time

You can do the math, cheers!

5. ## Re: GND & ND filter

thanks alot, get the idea.

and the longtime apps very easy to use .. hahahaha

6. ## Re: GND & ND filter

Originally Posted by Eddie77
thanks alot, get the idea.

and the longtime apps very easy to use .. hahahaha
with your finder put on the camera shutter speed dial, just turn three stops down,

compare to

search for the app
click open
hit enter
find shutter speed dial,
turn the shutter spend to shutter speed indicated by the app.

the choice is yours

7. ## Re: GND & ND filter

Originally Posted by catchlights
with your finder put on the camera shutter speed dial, just turn three stops down,
Until you go beyond 30 seconds, then have to x 2 manually.. :P

8. ## Re: GND & ND filter

thanks alot, i nearly forgot 1 dial equal to 1 stop
btw if beyong 30 sec , how you all count ? manually in mind or use stopwatch
Lean something from Pro today

9. Originally Posted by Eddie77
thanks alot, i nearly forgot 1 dial equal to 1 stop
btw if beyong 30 sec , how you all count ? manually in mind or use stopwatch
Lean something from Pro today
Either u are good with mental sum (not difficult since times 2 to 30 sec is a minute, so working in from there is easy), or u multiply the original shutter speed by the required value (say 8 for nd0.9 or 64 times for 6 stop nd and such).

My mental sum got better with photography. Hahahah

10. ## Re: GND & ND filter

Originally Posted by Eddie77
thanks alot, i nearly forgot 1 dial equal to 1 stop
btw if beyong 30 sec , how you all count ? manually in mind or use stopwatch
Lean something from Pro today
30 seconds x 2 = 1 minute

1 minute x 2 = 2 minute...

If you want to do a 32 minute exposure pls be my guest... I haven't had the chance to shoot star trails yet so don't need...

11. ## Re: GND & ND filter

Originally Posted by Eddie77
thanks alot, i nearly forgot 1 dial equal to 1 stop
btw if beyong 30 sec , how you all count ? manually in mind or use stopwatch
Lean something from Pro today
assuming you are using Nikon D800, the default EV step should be 1/3 stop, turning the dial 1 time = 1/3 stop, 3 times = 1 stop, so you will need to turn 9 times to get 3 stops.

12. ## Re: GND & ND filter

Originally Posted by Eddie77
thanks alot, i nearly forgot 1 dial equal to 1 stop
btw if beyong 30 sec , how you all count ? manually in mind or use stopwatch
Lean something from Pro today
At the start, you can use stopwatch. Alternately, if you got extra budget, you can go for intervalometer. It act like a cable release cum timer.

13. ## Re: GND & ND filter

Originally Posted by Eddie77
thanks alot, get the idea.

and the longtime apps very easy to use .. hahahaha

14. ## Re: GND & ND filter

Originally Posted by Eddie77
thanks alot, i nearly forgot 1 dial equal to 1 stop
btw if beyong 30 sec , how you all count ? manually in mind or use stopwatch
Lean something from Pro today
if you wear a watch....... get the drift?

15. Originally Posted by skybroodz

At the start, you can use stopwatch. Alternately, if you got extra budget, you can go for intervalometer. It act like a cable release cum timer.
Bulb mode got timer, no?

16. Originally Posted by nitewalk

Bulb mode got timer, no?
You are the timer when in bulb mode.

17. Originally Posted by Blur Shadow

You are the timer when in bulb mode.
Er wait. I've got a timer in bulb mode.

18. ## Re: GND & ND filter

Originally Posted by nitewalk
Bulb mode got timer, no?
Certain cameras have... Most don't, I think.

19. Originally Posted by edutilos-
Certain cameras have... Most don't, I think.
Oh. I tried using 3 different models and they all have the timer somewhere. So I thought all models of camera have the timer. Oops. Hahah

20. Originally Posted by Eddie77
thanks alot, i nearly forgot 1 dial equal to 1 stop
btw if beyong 30 sec , how you all count ? manually in mind or use stopwatch
Lean something from Pro today
Use an intervalometer. Very useful accessory for a string of other functions.

Ryan

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