Hi, I'm planning to buy a DA 50-200 in the future. As for the longer range, I'm thinking about the smc M200/4 one. I heard if it's a pentax len that is made for non digital camera, it should time 1.5X when used on pentax digital camera. So basically, I got a 300mm len with M200/4 on my *ist DL camera? Thanks!
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smc M200/4 equals 300mm lens for digital camera?
- Thread starter chemdumb
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TheShaman2007
Forum Enthusiast
My understanding is thus:
ANY lens focal length on a Pentax camera needs to be multiplied by 1.5x to get the 35mm equivalent focal length. This is because of the less-than-full frame size of the sensor - has nothing to do with whether the lens is made for digital cameras or not. E.g., the kit lens - DA 18-55mm - is made specifically and only for digital cameras, but the focal length ACTS like a 27-82.5mm lens on a 35mm camera.
SOME companies make full-frame digital sensors - c-n-n, eg - and others make smaller sensors, like Oly's 4/3 system that has a 2x crop factor.
That's what I've gleaned so far.
--
So the combination is one, two, three, four, five. That's the stupidest combination I've ever heard in my life.
That's the kinda thing an idiot would have on his luggage.
What's the combination?
12345.
12345? That's amazing! I have the same combination on my luggage!
ANY lens focal length on a Pentax camera needs to be multiplied by 1.5x to get the 35mm equivalent focal length. This is because of the less-than-full frame size of the sensor - has nothing to do with whether the lens is made for digital cameras or not. E.g., the kit lens - DA 18-55mm - is made specifically and only for digital cameras, but the focal length ACTS like a 27-82.5mm lens on a 35mm camera.
SOME companies make full-frame digital sensors - c-n-n, eg - and others make smaller sensors, like Oly's 4/3 system that has a 2x crop factor.
That's what I've gleaned so far.
--
So the combination is one, two, three, four, five. That's the stupidest combination I've ever heard in my life.
That's the kinda thing an idiot would have on his luggage.
What's the combination?
12345.
12345? That's amazing! I have the same combination on my luggage!
)) volosong
Senior Member
First off, just about every Pentax lens manufactured in the past 50 or so years will work just find on a Pentax digital SLR. Some require the appropriate adapter, but almost all will work.
Second, a 200mm lens of any generation does not, all of a sudden, become a 300mm lens when mounted on a digital. True, there is a 1.5x crop factor, but that is what it is . . . a CROP factor. That same lens on a digital will NOT bring things closer than if the same lens was mounted on a film SLR.
It is similar to a lot of our childhood experiences when we took a used up toilet paper roll and looked through it, pretending it was some type of telescope or binocular. Things did not get closer, they were just cropped so that we did not see as wide of a field-of-view.
That 200mm lens has a field-of-view on a film SLR of about 12.3 degrees. The same lens mounted on a digital SLR, with the 1.5x crop factor is only about 8.2 degrees. You are not seeing the whole "image", only the center portion, that was not "cropped" out by the crop factor.
That is also why some lower quality lenses, infamous for being soft at the edges produce decent results on a digital. The crop factor is deleting the worst optics of the lens and only using the assumidly better center part of the optics.
The subject of the photo is not closer to you when using a lens on a digital body, the scene is just cropped, (field-of-view is smaller).
Steven
GMT -8
Second, a 200mm lens of any generation does not, all of a sudden, become a 300mm lens when mounted on a digital. True, there is a 1.5x crop factor, but that is what it is . . . a CROP factor. That same lens on a digital will NOT bring things closer than if the same lens was mounted on a film SLR.
It is similar to a lot of our childhood experiences when we took a used up toilet paper roll and looked through it, pretending it was some type of telescope or binocular. Things did not get closer, they were just cropped so that we did not see as wide of a field-of-view.
That 200mm lens has a field-of-view on a film SLR of about 12.3 degrees. The same lens mounted on a digital SLR, with the 1.5x crop factor is only about 8.2 degrees. You are not seeing the whole "image", only the center portion, that was not "cropped" out by the crop factor.
That is also why some lower quality lenses, infamous for being soft at the edges produce decent results on a digital. The crop factor is deleting the worst optics of the lens and only using the assumidly better center part of the optics.
The subject of the photo is not closer to you when using a lens on a digital body, the scene is just cropped, (field-of-view is smaller).
--
Steven
GMT -8
volosong
Senior Member
spelling error.
first paragraph meant to say that all lenses, even digital only DA series are given in "35mm equivelant focal lengths", and that almost all Pentax lenses work okay on the Pentax digital SLR bodies.
first paragraph meant to say that all lenses, even digital only DA series are given in "35mm equivelant focal lengths", and that almost all Pentax lenses work okay on the Pentax digital SLR bodies.
timo
Veteran Member
Steven I can see what you mean but the distinction seems slightly pedantic to me and even misleading. If, using a 35mm film camera, you shoot an object with a 200 lens, and then shoot the same object with an isds and a 200 lens, and you print the shots on the same-size paper (this is the important point), the object will appear 'bigger' and therefore 'closer' with the 1.5 crop factor than with the 35mm film shot. I agree the focal length hasn't changed, but in effect the subject of the photo is indeed 'closer', just as it is when you crop a portion of any photo and blow it up.
Sure, the image projected onto the sensor is no 'bigger' than the image projected onto the film, but the crop produces a 'closer' effect.
tim
GaryML
Leading Member
The DA 50-200 zoomed out to 200mm and the SMC Pentax-M 200mm will both have the exact same field of view when mounted on a given camera. Virtually all interchangable lenses are listed at the actual focal length of the lens.
However, given the same lens, the field of view may vary from camera to camera based on the size of the film or sensor (assuming the lens image circle covers the entire film/sensor area). With a bigger sensor or bigger film frame, the field of view will be wider. But the magnification at the film plane will be exactly the same, since that is a function of the focal length. The field of view is wider simply because the film frame is wider.
So, the field of view with a 200mm lens and the standard 24x36 35mm film frame is 12 degrees (diagonal). With the current Pentax digital SLRs, the sensor is about 2/3 the size of a 35mm film frame. So the angle of view with the 200mm will be 8 degrees. Place both cameras (35mm and DSLR) side by side with the same 200mm lens and take a picture of the same scene. Then make the same size print of the images. The print from the DSLR will exhibit 50% more magnification than the 35mm print. But, of course, since the original is only 2/3 the size, you will need to enlarge the image 50% more to make the same size print.
TMalford
Veteran Member
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As has been mentioned, the camera won't make a distinction between one 200mm lens and another. Regardless of whether it has a DA designation or not, a 200mm lens is a 200mm lens. So, if you have the DA 50-200 and an M200 you'll have two 200mm lenses that look like 300mm lenses on your DSLR. Kind of redundant.
GMT minus 7
Without gravity, what would we do with water?
http://www.gorgephotos.com/
GMT minus 7
Without gravity, what would we do with water?
http://www.gorgephotos.com/
Good analogy. But, I used the paper towel roll cause I like long lenses =P
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