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romans001
Joined: 06 Aug 2013
Posts: 41
Location: Slovakia
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 Posted: Wed Aug 07, 2013 5:24 pm Post subject: Landscapes? 28mm manual with crop factor or 40mm digital? |
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romans001 wrote:
hi folks
i am using pentax manual 28mm lens on my pentax k-r for landscapes
recently i was thinking like "28mm film lens is like 44mm on my digital right?" so why dont use pentax da 40mm xs lens instead?
40mm is better for capturing wide landscapes then 44mm!
but when i compared both lenses, 28mm manual is capturing more space around then 40mm digital. Why so? 1.6 is cropp facor right?
what i am doing wrong? 
thx! |
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Aanything
Joined: 27 Aug 2011
Posts: 2187
Location: Piacenza, Italy
Expire: 2014-05-30
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| Posted: Wed Aug 07, 2013 5:39 pm Post subject: |
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Aanything wrote:
The focal length is 40mm even if the lens is designed for a crop sensor.
So all 40mm lenses, no matter if they're intended for 35mm film, medium format or digital crop sensors will look the same when used on the same "sensor"
So your 40mm for crop sensor will look equivalent to a 64mm on FF.
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lenny
Joined: 23 Feb 2013
Posts: 47
Location: British Columbia
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| Posted: Wed Aug 07, 2013 5:43 pm Post subject: |
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lenny wrote:
The focal length doesn't change with the format - you have to apply the crop factor to both lenses. So, your 40mm is equivalent to 60mm with the crop factor. |
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GeorgeSalt
Joined: 09 Feb 2013
Posts: 336
Location: Norfolk, UK
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| Posted: Wed Aug 07, 2013 5:50 pm Post subject: |
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GeorgeSalt wrote:
| lenny wrote: |
| The focal length doesn't change with the format - you have to apply the crop factor to both lenses. So, your 40mm is equivalent to 60mm with the crop factor. |
And in case your confused, you need to remember why a smaller sensor sees less of the image. The projected image circle of any given lens is constant regardless of the camera, but a smaller sensor sees less of the total image than a larger sensor. |
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wuxiekeji
Joined: 15 Aug 2012
Posts: 213
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| Posted: Wed Aug 07, 2013 5:52 pm Post subject: |
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wuxiekeji wrote:
| lenny wrote: |
| The focal length doesn't change with the format - you have to apply the crop factor to both lenses. So, your 40mm is equivalent to 60mm with the crop factor. |
More accurately the field of view is equivalent, but that's the limit of it. The out-of-focus regions will differ greatly between say a 40/1.4 on crop vs a 60/1.4 on full-frame.
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romans001
Joined: 06 Aug 2013
Posts: 41
Location: Slovakia
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| Posted: Wed Aug 07, 2013 5:55 pm Post subject: |
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romans001 wrote:
thanks people!!
but ??
40mm is Modern lenses designed for Pentax DSLRs so even for these lenses i have to apply crop factor?
i though that these new lenses are specialy designed for smaller sensors
i understand it right
so from now, i will use crop factor for all lenses
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visualopsins
Joined: 05 Mar 2009
Posts: 11058
Location: California
Expire: 2025-04-11
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| Posted: Wed Aug 07, 2013 6:40 pm Post subject: |
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visualopsins wrote:
Yes, lens focal length doesn't change, even when lens doesn't cover a full size sensor -- crop factor always applies when comparing different size sensors.
Newer lenses designed for the crop-size sensor project a smaller image circle than a lens designed to cover full frame sensors and 35mm film.
"Crop factor" is useful only for switching from full frame camera to crop camera. If a person would use a 50mm lens on full frame, a 30mm lens on crop camera will yield approximately an equivalent field of view. Crop factor is basically useless otherwise, such as to a person never using a FF camera before, imho. The term was useful when dSLRs first were marketed, to people used to 35mm film cameras, however, now, the term only causes confusion among new crop camera users.
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romans001
Joined: 06 Aug 2013
Posts: 41
Location: Slovakia
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| Posted: Wed Aug 07, 2013 6:46 pm Post subject: |
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romans001 wrote:
thank you for additional details! appreciate |
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