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12-26-2008, 11:18 PM   #1
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Silly question for old timers and techies!

I've had a 50mm f/2 M lens for a few months and have messed with it a few times. Clearly when you turn the body on, my K20 asks what focal length to select since it's an old lens with no electronics.

I've always said 50mm as that is what it is. Should I take into consideration the conversion factor and set it at 75mm??? Just wondering what your experience says.

12-26-2008, 11:21 PM   #2
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Set it for 50.
12-26-2008, 11:27 PM   #3
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a 50 is a 50 is a 50.

the focal length does not change, the aps-c camera is really just cropping to the center of the lens' image circle more than its designed-for 35mm format.
12-26-2008, 11:44 PM   #4
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A 50 is a 50 is a 50, set it for 50. Just to reinforce what architorture and SpecialK say.

Off topic, but considering the other glass listed in your profile, you might want to consider the A50/1.7 or 1/4. The 50/2 used to be called the 50mm body cap, and not without reason, compared to the others.


Last edited by clm; 12-27-2008 at 12:49 AM. Reason: atrocious spelling
12-27-2008, 12:31 AM   #5
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Thanks all. At least my first thoughts were correct.

For a "cheap" lens, I think it will serve just fine to mess around with. My other lenses are "top" dollar, but it's fun to mess around with an older M lens.

Jamie
12-27-2008, 08:30 AM   #6
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QuoteOriginally posted by CaymanImaging Quote
For a "cheap" lens, I think it will serve just fine to mess around with. My other lenses are "top" dollar, but it's fun to mess around with an older M lens.
Many old manual lenses are indeed considerably *better* than much of what is available today. The 50/2, frankly, isn't really one of the best of the older lenses - it's pretty clearly not as good in any way as the 50/1.7 or 5/1.4 - but it's still a fine lens.
12-27-2008, 08:43 AM   #7
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QuoteOriginally posted by CaymanImaging Quote
Thanks all. At least my first thoughts were correct. For a "cheap" lens, I think it will serve just fine to mess around with. My other lenses are "top" dollar, but it's fun to mess around with an older M lens.
Jamie, you are 100% correct. Even for an inexpensive lens it is no slouch.

M 50/2

Check the above link to see if yours is one of the later types. If so it may have a little collector value as a bonus.

woof
12-27-2008, 09:52 AM   #8
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QuoteOriginally posted by CaymanImaging Quote
I've had a 50mm f/2 M lens for a few months and have messed with it a few times. Clearly when you turn the body on, my K20 asks what focal length to select since it's an old lens with no electronics.

I've always said 50mm as that is what it is. Should I take into consideration the conversion factor and set it at 75mm??? Just wondering what your experience says.
My experience says learn the format you are using and stop making goofy mathematical calculations that try to turn the lens into something it isn't.
And RTFM, it does go into some detail about this.

12-27-2008, 10:33 AM   #9
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QuoteOriginally posted by woof Quote
Jamie, you are 100% correct. Even for an inexpensive lens it is no slouch.

M 50/2

Check the above link to see if yours is one of the later types. If so it may have a little collector value as a bonus.

woof
That was a neat site... Thanks for posting the link!
12-27-2008, 10:45 AM   #10
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QuoteOriginally posted by woof Quote
Jamie, you are 100% correct. Even for an inexpensive lens it is no slouch.

M 50/2

Check the above link to see if yours is one of the later types. If so it may have a little collector value as a bonus.

woof

Woof,
That photo on the link is exactly the one I have.

Thanks for the info.
12-27-2008, 11:07 AM   #11
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QuoteOriginally posted by Wheatfield Quote
My experience says learn the format you are using and stop making goofy mathematical calculations that try to turn the lens into something it isn't.
Agree 100%. I never went around trying to multiply my K1000 lens focal lengths by 1.5 after I switched from medium format cameras - I just learned to see 50mm instead of 75mm as giving me a "normal" field of view.

Yet another example of why "equivalent focal length" just confuses the heck out of people.
12-27-2008, 12:55 PM   #12
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I'll get back to you on this. I'm not sure of my experimental results.

Dave

Last edited by newarts; 12-27-2008 at 01:41 PM.
12-27-2008, 01:16 PM   #13
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QuoteQuote:
Yet another example of why "equivalent focal length" just confuses the heck out of people.
Honestly, only some people get confused. For many, it is a convenient way to compare one aspect of lenses.
12-27-2008, 03:03 PM   #14
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QuoteOriginally posted by SpecialK Quote
Honestly, only some people get confused. For many, it is a convenient way to compare one aspect of lenses.
The problem is that for every second people save by assuming that the other guy knows which "50mm" you're talking about, they end up investing an hour clearing up the misconceptions they've caused...

Unfortunately I don't think there's a viable solution, I just find it frustrating...
For my part, I try to always be clear about whether I'm talking about 50mm in terms of it's focal length or in terms of it's field of view in FF equivalent terms.
12-27-2008, 03:57 PM   #15
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QuoteOriginally posted by SpecialK Quote
Honestly, only some people get confused. For many, it is a convenient way to compare one aspect of lenses.
For me, it's useful in communicating people who have experience with 35mm film but not with APS-C / digital. I have only very limited experiencing actually *using* a 50mm lens on film, but I understand the crop factor business, I have a pretty good what it would look like - it's a little narrower than my 28mm and a little wider than my 40mm. So when film people talk about using a 50mm lens on their film cameras, I have some idea what they are talking about.
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