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Re: [ATM] 25" mirror possibilities

> So...that's the basis for my guess of about f6 for the mirror.  At least I can be sure
>>that it is not really "fast" like f2.5.
>>
>>Thanks,
>>Dennis
>>
>>
> why don't you start with the basics and measure its sagitta ? Not so hard to
> use even a makeshift device for that. Just take a straight ruler and place
> it across the mirror then measure the depth at the approximate center (from
> your long ruler that's resting on the mirror edges to the mirror center) .
> That will give you a rough number , but far better than leds on sticks ,
> trying to eyeball ceiling image etc.
> 
> best regards,
> matt tudor
> 

For a 25" f6, the sagitta should be close to 0.26 inch.
If deeper sagitta, it's a smaller f/number
http://www.atmsite.org/contrib/Prewitt/sagitta/
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