# photography question.

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#### Benign

##### Senior Member
:embrass: Can someone help me out with this calculation:

Quite a journey for light to travel and as one would no doubt expects loss of light to the tune of 4 stops occurs.

a) Which meant? full stop or half stops?
b) if the aperture is at f5.6, after 4 stop loss of light? Which aperture is it?
c) Do I have to recalculate the shutter speed as well to compensate the loss of light?

Sorry for the inconvenience :embrass:

Thanks :thumbsup:

#### foxtwo

##### Senior Member
a) if it's half-stop, then it'll be a lost of 2 stops isn't it?

b) 5.6, 4, 2.8, 2, 1.4

c) u either compensate by changing the shutter spd or the aperture. doing both means u compensate twice. Unless the aperture doesn't open enough, then u sld compensate through shutter spd.

#### zaren

##### Moderator
Staff member
Benign said:
:embrass: Can someone help me out with this calculation:

Quite a journey for light to travel and as one would no doubt expects loss of light to the tune of 4 stops occurs.

a) Which meant? full stop or half stops?
b) if the aperture is at f5.6, after 4 stop loss of light? Which aperture is it?
c) Do I have to recalculate the shutter speed as well to compensate the loss of light?

Sorry for the inconvenience :embrass:

Thanks :thumbsup:
a) full stop.
b) f1.4
c) no.

there are other ways of compensating for the reduced light;

i) reduce shutter speed. by halving the shutter speed every time, you allow twice as much light to enter the camera, thus compensating 1 stop of light. e.g. if your original shutter speed is 1/250 s, a 4-stop compensation is 1/15 s.

ii) increase ISO setting. by doubling the ISO every time, you enable the sensor/film to be twice as sensitive to the light entering the camera, thus compensating 1 stop of light. e.g. if your original ISO setting is 100, a 4-stop compensation is ISO 1600.

#### Benign

##### Senior Member
Thanks again to foxtwo and zaren :thumbsup: :bsmilie:

Lucky I had the doubt cleared up by your two sifus, if not, I would have wasted quite alot of 4x5 sheet films, processing cost and time :embrass:

The equipment in question is a piece of nikon accessories: Speed Magny 45 which can be attached to Nikon F, F2 series.
I just received it this afternoon.....so happy now(pity it came with only double sided ritek film holder).

Now need to hunt for grafmatic film holder liao...... :bigeyes:

#### foxtwo

##### Senior Member
wow chio. how much did the 45 back cost ya?

Can you post a picture of the F2 with 45 back? thx!

#### Benign

##### Senior Member
Can you post a picture of the F2 with 45 back? thx!
I will do it when I figure out how to mout the F2 with the 45 back :dunno: Anything mechanical is trivial to me. It took me ages to remove the double sided film back :angry:

The price I paid? Less than \$100 lor. Came with original box some more. Condition would be around 8+

#### user111

##### Senior Member
Benign said:
:embrass: Can someone help me out with this calculation:

b) if the aperture is at f5.6, after 4 stop loss of light? Which aperture is it?
5.6 ->8 ->11 ->16 ->22

result will be f22

#### student

##### Senior Member
Benign said:
Err, which way is it? :bsmilie:
I had wanted to respond to this question. But withheld, expecting this confusion to arise.

My reason for not writing earlier? Your question was not clear. I have absolutely no idea what you were asking, or what you were trying to achieve.

#### Fluorite

##### Member
user111 said:
5.6 ->8 ->11 ->16 ->22

result will be f22
how do you count f stops. i thought it is a multiple of the previous f stop?

#### micky

##### New Member
Fluorite said:
how do you count f stops. i thought it is a multiple of the previous f stop?
The number is double of the the number two stops before....hmm.... i think that doesn't really make sense. maybe writing it out helps..

1.4 -> 2 -> 2.8 -> 4 -> 5.6 -> 8 -> 11 -> 16 -> 22

cool eh?! (haha.. no i didn't discover this by myself). I think this is just the more common scale. I believe there are some cameras that doesn't follow this scale?

#### zaren

##### Moderator
Staff member
Fluorite said:
how do you count f stops. i thought it is a multiple of the previous f stop?
yes, it is the multiple of approximately 1.4 times the previous f-stop, and rounded to 1 decimal place.

#### zaren

##### Moderator
Staff member
Benign said:
:embrass: Can someone help me out with this calculation:

Quite a journey for light to travel and as one would no doubt expects loss of light to the tune of 4 stops occurs.

a) Which meant? full stop or half stops?
b) if the aperture is at f5.6, after 4 stop loss of light? Which aperture is it?
c) Do I have to recalculate the shutter speed as well to compensate the loss of light?

Sorry for the inconvenience :embrass:

Thanks :thumbsup:
my understanding of the question is;

from c), the issue is one of compensating the loss of light.
from the 1st sentence and b), the lost amount of light to be compensated is 4 stops.

so...

to compensate for the loss of 4 stops of light, an aperture of f5.6 will need to be increased to f1.4 as stated in my previous post.

#### user111

##### Senior Member
the multiplying factor is square-root-2. round off will be approx 1.4

as student have pointed out..the question (b) is ambiguous
but the full sequence as listed by mickey is correct

#### +evenstar

##### Senior Member
zaren said:
yes, it is the multiple of approximately 1.4 times the previous f-stop, and rounded to 1 decimal place.
To be precise, it's a multiplication of the previous f-stop by square root of 2 to get the next f-stop

#### student

##### Senior Member
I think it will be easier if Benign clarifies his question and tell us what he was actually trying to do.

Otherwise, a benign question may turn malignant!

#### zaren

##### Moderator
Staff member
from c) we can infer that benign first wants to recalculate the aperture setting to compensate the loss of light.

of course it would be *much* clearer if he had originally written,

"I want to recalculate the aperture setting in my camera to compensate the loss of 4 stops of light. if the aperture is originally at f5.6, what should the new aperture setting be to compensate for the 4-stop loss of light? Do I have to recalculate the shutter speed as well to compensate the loss of light?"

#### Benign

##### Senior Member
Otherwise, a benign question may turn malignant!
Wah lau eh, my nick or question becoming a fiasco liao..... :flush:

I know I am 'lauyah' at asking question.....but dun get bitchy mah :bsmilie:

Thank you Zaren for doing a 'pro' job on my malignant questions :thumbsup:

#### zaren

##### Moderator
Staff member
Benign said:
Wah lau eh, my nick or question becoming a fiasco liao..... :flush:

I know I am 'lauyah' at asking question.....but dun get bitchy mah :bsmilie:

Thank you Zaren for doing a 'pro' job on my malignant questions :thumbsup: