Mike A said:I'm trying BTZS and was wondering.
Can I use the f stop and shutter speeds that corrispond with the given EV number as I move the f stops up and down the scale of the meter?
Mike A
Jorge said:Sorry but Donald is wrong, at least if you are using the BTZS the way it was designed. The only thing the meter does is measure the contrast range, the exposures are determined by your tests and combination curves. This is why if you are shooting 400 spedd film it does not matter if you read the EV difference with your meter set at 100 ASA. Once you have obtained your SBR you have to consult the appropiate charts for your specific film tests and developer combination. The SBR curves will give appropiate exposures for your film/developer combination. If you use the f stop/shutter speed combination given by your meter what you are doing is dismissing the most important part of the system.
Wrong, what he is asking is if he can use the recomended settings by the meter as the shutter speed/ f stop combinations to take the picture, even if he is using the "correct" ASA in the meter most likely they wont correspond to the the f stop/ shutter speed combinations recommended by the SBR chart.Donald Miller said:Jorge,
Please reread the original question. The answer that I gave was correct for the question that was posed...at least the way that I read it. I think the gentleman was asking if the different shutter speeds and F stops that correspond to each other at a given EV are the same insofar as the exposure given. The answer to that question is still yes.
Jorge said:Wrong, what he is asking is if he can use the recomended settings by the meter as the shutter speed/ f stop combinations to take the picture, even if he is using the "correct" ASA in the meter most likely they wont correspond to the the f stop/ shutter speed combinations recommended by the SBR chart.
IN other words, the meter is used only to obtain a SBR, not to obtain f stop/shutter speed combinations. Unless after he takes an SBR reading, he then changes the ASA in the meter to the speed his tests gave him for that film/developer combination and uses the reading for the low value he obtains after he has changed the ASA parameter.
Donald Miller said:Jorge,
I realize that you read it differently then what I read it. I still think that the question that the gentleman posed is whether any of the corresponding shutter speeds corresponding to differing F stops will be suitable so long as they correspond to the same EV.
The meter does do more then determine the SBR Jorge. It also determines the exposure of the scene. SBR alone will only determine a minor deviation in the film ISO (if the SBR is at departure from 7) and the development time of the film based upon tests. The meter still tells what the proper exposure is. I don't think that BTZS equips one to suddenly sense the proper exposure when it arrives on the winds within the ether.
Irregardless, I will allow you to assume your interpertation if you will allow me my interpertation of the question as it was posed. I can do that without defining you as being wrong. Can you do the same?
Jorge said:Donald, the meter does not determine the exposure unless you have changed the ASA to those speeds obtained from the film tests This is very basic BTZS information.
If the question is "can I use all the different f stop/shutter speed combinations for a given EV value?" then the answer is obviously yes, provided the meter has been reset to the speed value obtained in the tests.
In relation to the BTZS, the answer is simply - no.Mike A said:I'm trying BTZS and was wondering.
Can I use the f stop and shutter speeds that ....
John McCallum said:You gave an absolute answer without the qualification of prior testing/calibration that the BTZS requires.
I guess it is. Is that not what the BTZS is all about?Donald Miller said:Jesus Christ John, that is nitpicking...
John McCallum said:I guess it is. Is that not what the BTZS is all about?
John McCallum said:Perhaps the point is, that someone learning requires specific and accurate information (without assumptions) or they can be sent off on the wrong track.
Oh borther, it gives you the contrast range so you can calculate the SBR, consult your charts (or input them in the palm) and then obtain the appropirate f stop/shutter speed combination based on the proper film speed derived from your tests....got it?Donald Miller said:Jorge, I don't recall reading anywhere in the original question where the gentleman suggested doing anything other then using the determined ASA. The question was about combinations of shutter speeds and F stops as related to a given EV.
In response to your statement, if the meter doesn't suggest the proper exposure, who or what the the heck does?
Jorge said:Oh borther, it gives you the contrast range so you can calculate the SBR, consult your charts (or input them in the palm) and then obtain the appropirate f stop/shutter speed combination based on the proper film speed derived from your tests....got it?
:rolleyes:Donald Miller said:Yes, but the exposure is determined by the EV reading of the meter based on the shadow value...is it not?
Which brings us back to the initial question. That being the one that apparently I interperted correctly. The answer to which is that any combination of shutter speed and f stop can be used that corresponds to the EV of the determined exposure.
Now what is it that has not been gotten and who is it that failed to grasp it?
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