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Field curvature and "flat field" bino.

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Old Sunday 18th February 2018, 20:47   #1
Chris223
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Field curvature and "flat field" bino.

I was wondering myself the effect of a flat field in certain circonstances :

With my actual bino the field is not flat resulting as you know in a out of focus image beginning at maybe 60% of the field.
It was annoying me a little bit looking at long distance in open landscape where most of the FOV is far away.....but this afternoon i took my bino to looking at birds in a flat wetland.
It was a different experience. When at was looking at a bird at maybe 50-100 meters on the ground, most of the field appear to me in focus ! The central subject was in focus and most of the ground which was on a different plan in the lower field was in focus ( i think du to field curvature !)

So my question is : is a flat field in this case will cause an out of focus lower field ?

Last edited by Chris223 : Sunday 18th February 2018 at 20:53.
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Old Sunday 18th February 2018, 20:56   #2
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The simple answer is yes.

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Old Sunday 18th February 2018, 21:44   #3
Chris223
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The simple answer is yes.

David

so flat field is more a choice than a better system...
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Old Sunday 18th February 2018, 22:05   #4
typo
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so flat field is more a choice than a better system...
Definitely! I often prefer field curvature for lower magnifications and flatter for higher for the birding spots round here, but elsewhere, who knows? Just a question of using the best tool for the job.

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Old Tuesday 20th February 2018, 23:08   #5
WJC
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In optics, one size does not fit all. People are all the time asking WHY engineers just don't provide WHAT I LIKE without taking into consideration what obstacles await the optical engineer each time he arrives at his desk. There are many, MANY more off the wall notions than there are REALISTIC answers to those notions.

In optics, the "head bone" is connected to the "foot bone."

Bill
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Old Wednesday 21st February 2018, 15:30   #6
Chosun Juan
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.....People are all the time asking WHY engineers just don't provide WHAT I LIKE without taking into consideration what obstacles await the optical engineer each time he arrives at his desk....
She .....?




Chosun
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Old Wednesday 21st February 2018, 16:12   #7
WJC
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She .....?




Chosun
Chosen:

If you have read my book, you will have noticed it is full of references to "he and she" or "he or she" and the like. However, most women, though not all--you being a test case--avoid optics like the plague. There were 3,000 members of the ATMA (to receive ATM Journal), of which only 6 were ladies, and one of them, Diane Lucas, was an adviser. By the way, she WAS an optical engineer and won an award at Stellafane for her Gregory-Maksutov in 1962.

Bill
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Old Thursday 22nd February 2018, 00:38   #8
Chosun Juan
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Chos(u)n:

If you have read my book, you will have noticed it is full of references to "he and she" or "he or she" and the like. However, most women, though not all--you being a test case--avoid optics like the plague. There were 3,000 members of the ATMA (to receive ATM Journal), of which only 6 were ladies, and one of them, Diane Lucas, was an adviser. By the way, she WAS was an optical engineer and won an award at Stellafane for her Gregory-Maksutov in 1962.

Bill
Bill,

It's hard enough for ordinary folk to navigate this brave new world, what with overreaching attempts here (IMHO) at churning out gender non-specific preschool toddlers! I'm all for LGBTQIO+? rights and equality etc (I voted Yes! in our recent plebiscite ) , and of migrant (or non-Anglo) inclusion etc (let's face it from where I sit - on the couch or in a chair ) I'm seeing more migrants than most! :)

I really can't stand this p*ssyfooting around that we do in this country about allowing fully covered faces, or accused perpetrators that refuse to stand for the magistrate in court from certain religions. It's an open country - show your face and respect the laws of the country for goodness sake!

I think a better approach than the at times PC madness gone wrong that we so often see, is to represent things proportionally, whilst being very careful to avoid exclusion, limit possibilities, or discriminate by omission .... There are a few Sistas floating around these parts, so I'm not the only test case ....

It must be even more fraught for Authors!

If ever I'm writing anything I use 'they', 'them', 'their', 'person' etc, though I do particular like using 'man' as an abreviation of 'human' or 'mankind'. I find it helps to have a 'Gender Nazi' proofread. Of course when accompanied by pictures it's happy days - merely identify the genders correspondingly. Most of my writings are locked away with 'Commercial in Confidence' NDA'S - which expire upon my expiry or 2100 whichever comes first!

I'm a pretty strange cat! In my Engineering course (Mechanical) at Uni there was about twenty - a dozen females to about ~ 200 males when I started, and numbers for new entrants were about the same when I finished six years later (sandwich course). Employers at the time we're quite keen on "Affirmative Action" EEO policies, but competition was still intense - and as with anything competition improves the breed. Things were a little better when I did my MBA (about 40/60 females - males), though the lack of real representation of females at Senior Executive and Board levels (only about ~8%) from there was puzzling to everyone - my Psychology Professor who had specialized in studying the area for the past 20 years included! I suggested to (him) that it was merely the result of a dog eat dog world .....
I proceeded to do a DBA, and even though I had managed admission to the inner sanctum of the Boardroom, found my lack of fluency (or any real ability! :) in the parent company Asian language to be a larger barrier .....

I fear this PC madness will lead to our collective demise - the last straw for me was the unethical (IMHO) sacking of the F1 grid girls
http://www.birdforum.net/showthread.php?t=357243

I am as saddened by the loss of employment opportunities for these young ladies, as I am by the absence of their gorgeous svelte forms on the grid (disclaimer: I've donned the odd pair of hotpants and twirled many an umbrella in my time! :)

F1 just can't stand another hit after it's naturally aspirated (and otherwise unfettered) soul was ripped out in preference to the vacuum cleaners we are left with now, though the prospects of 50%+ overall efficiencies are peculiarly appealing to the gear head in me - if not my ears. Vale the glory days of supercharged V16 BRM's, and the mid noughties pinnacle of the 3ltr NA V10's .....
https://m.youtube.com/watch?v=RBKUQPjQ16I
https://m.youtube.com/watch?v=xKV2WmNsWRI
https://m.youtube.com/watch?v=mHkW7Icu7Qc
Lordy be!


Chosun

Last edited by Chosun Juan : Thursday 22nd February 2018 at 06:27. Reason: spellun n grama n dat
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Old Thursday 22nd February 2018, 02:37   #9
WJC
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Quote:
Originally Posted by Chosun Juan View Post
Bill,

It's hard enough for ordinary folk to navigate this brave new world, what with overreaching attempts here (IMHO) at churning out gender non-specific preschool toddlers! I'm all for LGBTQIO+? rights and equality etc (I voted Yes! in our recent plebiscite ) , and of migrant (or non-Anglo) inclusion etc (let's face it from where I sit - on the couch or in a chair ) I'm seeing more migrants than most! :)

I really can't stand this p*ssyfooting around that we do in this country about allowing fully covered faces, or accused perpetrators that refuse to stand in for the magistrate in court from certain religions. It's an open country - show your face and respect the laws of the country for goodness sake!

I think a better approach than the at times PC madness gone wrong that we so often see, is to represent things proportionally, whilst being very careful to avoid exclusion, limit possibilities, or discriminate by omission .... There are a few Sistas floating around these parts, so I'm not the only test case ....

It must be even more fraught for Authors!

If ever I'm writing anything I use 'they', 'them', 'their', 'person' etc, though I do particular like using 'man' as an abreviation of 'human' or 'mankind'. I find it helps to have a 'Gender Nazi' proofread. Of course when accompanied by pictures it's happy days - merely identify the genders correspondingly. Most of my writings are locked away with 'Commercial in Confidence' NDA'S - which expire upon my expiry or 2100 whichever comes first!

I'm a pretty strange cat! In my Engineering course (Mechanical) at Uni there was about twenty - a dozen females to about ~ 200 males when I started, and numbers for new entrants were about the same when I finished six years later (sandwich course). Employers at the time we're quite keen on "Affirmative Action" EEO policies, but competition was still intense - and as with anything competition improves the breed. Things were a little better when I did my MBA (about 40/60 females - males), though the lack of real representation of females at Senior Executive and Board levels (only about ~8%) from there was puzzling to everyone - my Psychology Professor who had specialized in studying the area for the past 20 years included! I suggested to (him) that it was merely the result of a dog eat dog world .....
I proceeded to do a DBA, and even though I had managed admission to the inner sanctum of the Boardroom, found my lack of fluency (or any real ability! :) in the parent company Asian language to be a larger barrier .....

I fear this PC madness will lead to our collective demise - the last straw for me was the unethical (IMHO) sacking of the F1 grid girls
http://www.birdforum.net/showthread.php?t=357243

I am as saddened by the loss of employment opportunities for these young ladies, as I am by the absence of their gorgeous svelte forms on the grid (disclaimer: I've donned the odd pair of hotpants and twirled many an umbrella in my time! :)

F1 just can't stand another hit after it's naturally aspirated (and otherwise unfettered) soul was ripped out in preference to the vacuum cleaners we are left with now, though the prospects of 50%+ overall efficiencies are peculiarly appealing to the gear head in me - if not my ears. Vale the glory days of supercharged V16 BRM's, and the mid noughties pinnacle of the 3ltr NA V10's .....
https://m.youtube.com/watch?v=RBKUQPjQ16I
https://m.youtube.com/watch?v=xKV2WmNsWRI
https://m.youtube.com/watch?v=mHkW7Icu7Qc
Lordy be!


Chosun
People have routinely told me I couldn't make any profit doing all the extras I did for my customers. Well, I suppose that's so considering most were coming from the position that the average 20-year old today will have 8 "jobs" and 3 "careers" before hanging up his (or her ... gotcha!) spurs. It was my lengthy, applied experiences that taught me the tricks of the trade that those job jumpers could never understand. And, not only that, I did as many FREEBIES as possible-that really sent them over the edge. Yep, I gave away the farm. But the fact is I couldn't give stuff away fast enough to keep it from coming back to me in spades! PROFIT and friends. As Schweitzer said:

"Success is not the key to happiness; happiness is the key to success." I loved my work ... and my customers loved it, too. That's why I first had to hire Cory and then had to start turning work away.

We may get into trouble for spouting all this, even though it is more valuable to our respective countries than so much currently afoot.

But, to be safe: Bird, Bird, Bird, Bird!

Bill
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Old Thursday 22nd February 2018, 10:35   #10
Binastro
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Rover BRM turbine car?

And yes, it was daft to sack the F1 grid girls.

The problem in those days was that the cars were lethal.
The tracks were lethal.
Many racing drivers died or were badly injured.
Advanced overpowered but unsafe cars, so something had to be done, and this has helped to reduce road accidents.
I think 7,000 annual deaths here now down to 3,000?
My Mini Cooper S was great and one of the first made, but had I hit anything at those unrestricted speeds I wouldn't be here.

I collected a Rolls Royce 1958? car that the owner had driven to destruction. that had mechanical servo brakes highly complicated. Crazy.
The Silver Cloud had triple drum brakes. You should see the smoke pouring out of them on repeated hard braking from 100mph plus at every roundabout. Disc brakes were not considered.
I used to cruise at 120mph in the early 1960s and was passed on the A1 by a racing E type doing 160mph.
A Daytona Cobra was timed at 185 mph on the M1. The government had to act and the 70mph limit was born.

The Mercedes accident at Le Mans cost over 80 lives. The car was very advanced but magnesium.
There was a magnesium bodied rally car with crazy bhp. The driver should not have driven with a high fever and was killed.

I use to go to Farnborough every year.
Sonic booms were considered mandatory.
And 9g turns within the field.
But the Swallow broke up, probably supersonic.
I missed the year the DH 110 killed 31 people, although my friend saw that.

Test pilots were dying every few weeks.
The sky was full of strange new aircraft.

I measured a white Victor at 63,300 feet with a filar micrometer on my refractor. I wrote to the makers asking why they stated 50,000ft ceiling. They didn't answer.
I used to follow these aircraft up to 250 miles plus in my telescope. Sometimes I saw them coming so followed them for 400 miles.
A Vulcan apparently got up to 80,000 feet plus. Not allowed of course.
And sprint Eagles and Migs. About 3 or 4 minutes to 100,000ft.
Interesting times.
Rather dull nowadays.

Last edited by Binastro : Thursday 22nd February 2018 at 11:47.
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