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Low-Light Performance Calculator

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Dogger View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Dogger Quote  Post ReplyReply Direct Link To This Post Posted: October/14/2008 at 08:27

opticsmike, not an easy task to distill all the physics behind this issue into a form that the laymen among us can understand and use but I applaud your efforts!

Thanks,
Craig
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Ed Connelly Quote  Post ReplyReply Direct Link To This Post Posted: October/14/2008 at 08:35
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Gunshow75 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Gunshow75 Quote  Post ReplyReply Direct Link To This Post Posted: October/14/2008 at 09:07
Ed, I think you captured the essence of the matter. Trying to distill some kind of homebrew doesn't make it physics.


Tom



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Post Options Post Options   Thanks (0) Thanks(0)   Quote Dogger Quote  Post ReplyReply Direct Link To This Post Posted: October/14/2008 at 09:18
While that may be true it's also outside the capability of most of us to understand the physics behind this effort.  Will have to leave that to you more knowledgeable folks.
 
If a system even with imperfections helps us to understand the low-light issue more succinctly then it is still a worthwhile effort.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote mike650 Quote  Post ReplyReply Direct Link To This Post Posted: October/14/2008 at 09:50
Originally posted by Dogger Dogger wrote:

While that may be true it's also outside the capability of most of us to understand the physics behind this effort.  Will have to leave that to you more knowledgeable folks.
 
If a system even with imperfections helps us to understand the low-light issue more succinctly then it is still a worthwhile effort.


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Gunshow75 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Gunshow75 Quote  Post ReplyReply Direct Link To This Post Posted: October/14/2008 at 09:55
Originally posted by Dogger Dogger wrote:

While that may be true it's also outside the capability of most of us to understand the physics behind this effort.  Will have to leave that to you more knowledgeable folks.

If a system even with imperfections helps us to understand the low-light issue more succinctly then it is still a worthwhile effort.

Please don't sell yourself short. All of you are more than capable of understanding how optics work. What is important to me is that you are not misled by things that are not true.

Unfortunately, Opticsmike's "system" doesn't just have imperfections, it is fundamentally wrong in many ways.


Tom



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opticsmike View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote opticsmike Quote  Post ReplyReply Direct Link To This Post Posted: October/14/2008 at 13:15

Lets see, so far gunshow75...

1. You referred to a source that suggested that the Stevens' Power Law is less accurate than the Weber-Fechner Law, while the article made a ridiculous comparison of a complex form of the Weber-Fechner Law to the basic form of the Stevens' Power Law, without acknowledging the use of modernized complex forms of the Stevens' Power Law for complex scenes. Complex forms of brightness calculation do not even apply to my calculation, as I have based the brightness scale upon a target with a uniformly dark background and surround, which is the basic form of brightness scaling calculations.

2. You assumed that my graphs were reflecting magnification as the cause for light gain instead of reading my explanation of the exit pupil/eye pupil relation as causing the brightness to increase with magnification.

3. Instead of outlining why you believe the Steven's Power Law is not appropriate, you just say it's like talking to a liberal, yet I had provided numerous sources from highly regarded recent studies supporting the Steven's Power Law as more appropriate.

4. You say my Theoretical Light Gain and Realistic Light Gain definitions should be omitted because luminance can't be measured with our eyes. Ever hear of a light meter to measure light within an area? Or how about making calculations based upon known criteria? Well supposedly you didn't, and you instead continue to blame your misunderstanding on my so-called half-truths.

5. You utilize an example of my calculation at a magnification point at which exit pupil/eye pupil relation is no longer a factor when exit pupil diameter is less than eye pupil diameter. You then assumes that is reason enough for exit pupil/eye pupil relation to never be a factor.

6. You incorrectly redefine my calculation to eliminate the relation of Scoped-Eye-Pupil-Light/Uscoped-Eye-Pupil-Light so that it deduces to just magnification as the sole factor, and then you say that I would have everyone believe that my calculation is all about magnification.

7. You sarcastically write off the Stevens' Power law because it's used for determining brightness scaling for computers, even after I have discussed the real world tests that make it applicable.

8. You had claimed three times now that target image resolution does not increase with magnification.

9. You still didn't understand exit pupil/eye pupil relation so you just claimed it was irrelevant because it's not used for Twilight Factor nor Relative Geometric Brightness. No kidding. That's one of three reasons why my calculation is a significant improvement.

10. You created a formula that simply multiplies eye pupil diameter into it, and then proved that the calculation can produce the same result without eye pupil diameter. No kidding, but you left out the exit pupil/eye pupil relation of my calculation which can not produce the same result without eye pupil diameter.

11. You continue to reject something because you do not understand it. You can not reject something unless you understand it and you can understand what is incorrect.

12. Your repeated mistakes and unjustified judgements are reason enough to show everyone that you don't have a clue.

13. Oh yea, your sarcasm is disrespectful and unhelpful.

14. Pretty much anything you say at this point is meaningless to me.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote opticsmike Quote  Post ReplyReply Direct Link To This Post Posted: October/14/2008 at 13:20
For everyone else, this should help illustrate the transition process...
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Skunk Quote  Post ReplyReply Direct Link To This Post Posted: October/14/2008 at 16:56
Originally posted by opticsmike opticsmike wrote:

Lets see, so far gunshow75...

1. You referred to a source that suggested that the Stevens' Power Law is less accurate than the Weber-Fechner Law, while the article made a ridiculous comparison of a complex form of the Weber-Fechner Law to the basic form of the Stevens' Power Law, without acknowledging the use of modernized complex forms of the Stevens' Power Law for complex scenes. Complex forms of brightness calculation do not even apply to my calculation, as I have based the brightness scale upon a target with a uniformly dark background and surround, which is the basic form of brightness scaling calculations.

2. You assumed that my graphs were reflecting magnification as the cause for light gain instead of reading my explanation of the exit pupil/eye pupil relation as causing the brightness to increase with magnification.

3. Instead of outlining why you believe the Steven's Power Law is not appropriate, you just say it's like talking to a liberal, yet I had provided numerous sources from highly regarded recent studies supporting the Steven's Power Law as more appropriate.

4. You say my Theoretical Light Gain and Realistic Light Gain definitions should be omitted because luminance can't be measured with our eyes. Ever hear of a light meter to measure light within an area? Or how about making calculations based upon known criteria? Well supposedly you didn't, and you instead continue to blame your misunderstanding on my so-called half-truths.

5. You utilize an example of my calculation at a magnification point at which exit pupil/eye pupil relation is no longer a factor when exit pupil diameter is less than eye pupil diameter. You then assumes that is reason enough for exit pupil/eye pupil relation to never be a factor.

6. You incorrectly redefine my calculation to eliminate the relation of Scoped-Eye-Pupil-Light/Uscoped-Eye-Pupil-Light so that it deduces to just magnification as the sole factor, and then you say that I would have everyone believe that my calculation is all about magnification.

7. You sarcastically write off the Stevens' Power law because it's used for determining brightness scaling for computers, even after I have discussed the real world tests that make it applicable.

8. You had claimed three times now that target image resolution does not increase with magnification.

9. You still didn't understand exit pupil/eye pupil relation so you just claimed it was irrelevant because it's not used for Twilight Factor nor Relative Geometric Brightness. No kidding. That's one of three reasons why my calculation is a significant improvement.

10. You created a formula that simply multiplies eye pupil diameter into it, and then proved that the calculation can produce the same result without eye pupil diameter. No kidding, but you left out the exit pupil/eye pupil relation of my calculation which can not produce the same result without eye pupil diameter.

11. You continue to reject something because you do not understand it. You can not reject something unless you understand it and you can understand what is incorrect.

12. Your repeated mistakes and unjustified judgements are reason enough to show everyone that you don't have a clue.

13. Oh yea, your sarcasm is disrespectful and unhelpful.

14. Pretty much anything you say at this point is meaningless to me.
 
+1 on points 1-10
+100 on points 11-14
Let me give you my two scents worth
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Post Options Post Options   Thanks (0) Thanks(0)   Quote cheaptrick Quote  Post ReplyReply Direct Link To This Post Posted: October/14/2008 at 18:08
 
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supertool73 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote supertool73 Quote  Post ReplyReply Direct Link To This Post Posted: October/14/2008 at 18:34
I don't think Tom (Gunshow) is trying to pick a fight, he just wants to make sure all details are in fact correct.  Regardless of the debate, this has been very educational for me and probably wouldn't have been near as good without the debate.  Good job guys.   

My low light tests consists of this.  If it is under $200 don't bother.  $200-$600 use mostly as a day scope.  $600-$1000 morning and evening time is going to be looking pretty good.  $1000+ watch out animals I am shooting you know matter what time it is.  Big%20Smile
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koshkin View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote koshkin Quote  Post ReplyReply Direct Link To This Post Posted: October/14/2008 at 18:46
All right, since cheaptrick has landed I feel that I should intervene before he goes ballistic (againFurious).

A couple of points:
1) Gentlemen, we have to learn to disagree in a civilized manner (or I will let loose THE cheaptrick)

2) I have not really looked into the technical details of the argument.  There are two reasons for that: there was a bunch of stuff linked that I did not have time to read thoroughly and, for my purposes, this calculator is not really useful since I mostly compare different brands and designs to each other.  When I have time, I will dig into it a little more.

As a possible suggestion to opticsmike, have you considered writing a proper white paper/application note on what your calculator is doing and why?  By referring to a bunch of different sources without a reasonably coherent and verbose explanation of what you are actually doing, you are making sure that none really understands what you are up to except for someone hell bent on proving you wrong.

For example, I have some fairly relevant background in this stuff, and without spending some time on this, I do not find what you are doing here at all clear.  See if you can come up with a way to explain it to a person without an optics background.

To gunshow75, if you disagree with someone, try to do it in a nice way.  When you write a reply that gets you all emotional, try re-reading it a time or two before you hit the "Post" button.  I do not recall what you do for a living, but I remember when I spent a lot of time in an academic environment, being rude and obnoxious was an absolute norm.  Having several scientists in the same room was akin to watching several spiders in a glass jar: only one was going to come out alive.  Out in the real world, politeness is a virtue, you are not dealing with E here after all.

ILya
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Gunshow75 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Gunshow75 Quote  Post ReplyReply Direct Link To This Post Posted: October/14/2008 at 19:58
I'm sorry that I don't meet your expectations for being nice, for being polite. I really do read my posts before I hit send.

You can find what I do in my profile, and I still work. I am not now in an academic environment, but I was for the better part of 20 years. Being rude and obnoxious was not the norm.







Tom



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Post Options Post Options   Thanks (0) Thanks(0)   Quote tahqua Quote  Post ReplyReply Direct Link To This Post Posted: October/14/2008 at 20:43
Originally posted by supertool73 supertool73 wrote:

I don't think Tom (Gunshow) is trying to pick a fight, he just wants to make sure all details are in fact correct.  Regardless of the debate, this has been very educational for me and probably wouldn't have been near as good without the debate.  Good job guys.   

My low light tests consists of this.  If it is under $200 don't bother.  $200-$600 use mostly as a day scope.  $600-$1000 morning and evening time is going to be looking pretty good.  $1000+ watch out animals I am shooting you know matter what time it is.  Big%20Smile


Thunbs%20Up ST, you put it all into terms a lot of us understand and that is exactly how it works for me. There is a ton of info here on this thread and it is a good one. I hope it continues.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Dogger Quote  Post ReplyReply Direct Link To This Post Posted: October/14/2008 at 20:59
I have PM'd both opticsmike and Gunshow on different topics and they are both very helpful friendly guys.  I think we're aiming for the same end but with differing views on how to get there.  I really appreciate the effort that OM has put into this and if the end product can be made better by input from Gunshow and Ilya well that's even better.
 
Like tahqua I hope the dialogue can continue in a positive light.  Don't need hurt feelings or egos getting in the way - we are all friends here!  Let us know if/how we can help.
 
Craig
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Post Options Post Options   Thanks (0) Thanks(0)   Quote koshkin Quote  Post ReplyReply Direct Link To This Post Posted: October/14/2008 at 21:29
Just as an addendum, I never said that people have to be nice, just politeCencored.
Heck, if I claimed that we all have to be nice here, I would have to go back and erase 90% of my own posts.

ILya
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Post Options Post Options   Thanks (0) Thanks(0)   Quote opticsmike Quote  Post ReplyReply Direct Link To This Post Posted: October/14/2008 at 21:53

In all actuality, the calculator is very simple. Unfortunately the discussions kept getting off on tangents that kept making it more confusing than it needs to be, and the tone has been even more distracting. I will definitely write up a white paper that explains it in clear terms and I look forward to answering questions and working with like-minded people to make this an easy to understand and beneficial tool. Keep in mind that the usefulness is limited to providing an idea of how much a certain scope configuration will perform over another of the same optical quality, but it is much more useful than anything else we have. The usefulness could of course become pretty amazing if a standard measuring method was utilized for light transmission, resolution, and maybe even contrast. But even then, scopes can vary in optical quality among even the same exact model. But right now as it stands, supertool73's model is much more accurate for anyone wishing to compare scopes among different brands, or better yet, reading the helpful information from eveyone here and asking questions.

The white paper will outline four steps to the calculation that must be understood progressively:

1. Theoretical Light Gain that the scope delivers to the eye pupil.

2. Realistic Light Gain that the scope delivers to the eye pupil.

3. Conversion of Realistic Light Gain to a brightness scale that human beings can relate to.

4. Overall Low Light Performance as a combination of human-perceived light gain and resolution gain.

After writing the white paper, I will modify it to better suit it's ability to answer questions as they come. I also hope that once it is thoroughly understood, some useful contributions could be made by others. Thanks for your support everyone. I look forward to doing everything I can to provide something that is truly useful. Believe me I have much better things to be doing if I didn't believe it to be possible for this to become useful for everyone.

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Post Options Post Options   Thanks (0) Thanks(0)   Quote koshkin Quote  Post ReplyReply Direct Link To This Post Posted: October/14/2008 at 21:56
Excellent.  Please post you write-up when you are done with it.

I have three reviews I need to finish before I can spend any real time on this, so I won't get to dig through this fro a little bit.

ILya
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Post Options Post Options   Thanks (0) Thanks(0)   Quote cheaptrick Quote  Post ReplyReply Direct Link To This Post Posted: October/15/2008 at 05:54
WHAT...NO MORE MISSION?!?!? Loco
 
See ya'll back at the NCO club!! Smile  Drinks are on Optics Mike and Gunshow Wink
 
 
   
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Gunshow75 Quote  Post ReplyReply Direct Link To This Post Posted: October/15/2008 at 06:05
Originally posted by koshkin koshkin wrote:

Just as an addendum, I never said that people have to be nice, just polite ...


"...To gunshow75, if you disagree with someone, try to do it in a nice way. ... Out in the real world, politeness is a virtue, you are not dealing with E here after all."

I took those comments to mean that I wasn't being nice, or polite.


Tom



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