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new to digital SLRs

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OK this may sound like a dumb question but here goes :)
I have been doing 35mm film photography for quite a long time, i recently bought a digital SLR camera, and i know that when i use my current lenses i have to convert to focal lengths by 1.5x so my prime 50mm on the DSLR would be a 75mm.
My question is, if I buy a new lens, is the marked focal length of the lens already converted. i.e. is a 15mm lens for a DSLR a 15mm lens or is it a 10mm lens.
So that if I use the 15mm DSLR lens on my 35mm SLR it will work as a 10mm lens?

How can i check?
You are not now, nor will you ever be, good enough to not die in this sport (Sparky)
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OK this may sound like a dumb question but here goes :)
I have been doing 35mm film photography for quite a long time, i recently bought a digital SLR camera, and i know that when i use my current lenses i have to convert to focal lengths by 1.5x so my prime 50mm on the DSLR would be a 75mm.
My question is, if I buy a new lens, is the marked focal length of the lens already converted. i.e. is a 15mm lens for a DSLR a 15mm lens or is it a 10mm lens.
So that if I use the 15mm DSLR lens on my 35mm SLR it will work as a 10mm lens?

How can i check?



You have that almost backwards. Your 15mm DSLR lens on your 35mm will be 15mm.
You multiply by 1.6 (or other variable, depending on the camera) because the sensor on the DSLR is smaller in surface area than a 35mm opening would be/is. You can open the two cams side by side and see exactly what I'm referring to.
So...the marked focal length of lenses is almost always the 35mm equivalent, but the actual width/focal length is varied in a DSLR depending on the brand of camera you've purchased.
There are a lot of threads on this subject here, and on the web.

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No sir... the focal length is the same whether it's on a film or digital SLR. The conversion factor is due to the sensor size, not the length of the lens.

With that said - the old rule of thumb for hand-holding the camera (shutter speed >= 1/focal length) needs to include the 'zoom equivalency' of the lens focal length x sensor multiplier.

Example: 1.5x sensor multiplier, 100mm lens = minimum handheld shutter speed of 1/150 sec.

Clear as mud?
Mike
I love you, Shannon and Jim.
POPS 9708 , SCR 14706

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that's what i wanted to know, I know the sensor is the determining factor, but i didnt know if lens manufactures compensated for their camera by including the conversion on the DLSLR lenses.
so this effectively mean that I need to by a much wider lens for my DSLR than i had to for my 35mm. to get a 24mm equivilent
You are not now, nor will you ever be, good enough to not die in this sport (Sparky)
My Life ROCKS!
How's yours doing?

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No sir... the focal length is the same whether it's on a film or digital SLR. The conversion factor is due to the sensor size, not the length of the lens.

With that said - the old rule of thumb for hand-holding the camera (shutter speed >= 1/focal length) needs to include the 'zoom equivalency' of the lens focal length x sensor multiplier.

Example: 1.5x sensor multiplier, 100mm lens = minimum handheld shutter speed of 1/150 sec.

Clear as mud?

Yes Mike very clear , knew all of that :)
You are not now, nor will you ever be, good enough to not die in this sport (Sparky)
My Life ROCKS!
How's yours doing?

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...so this effectively mean that I need to by(sic) a much wider lens for my DSLR than i had to for my 35mm. to get a 24mm equivalent



Yes this is correct. i.e. to get the same field of view that a 24mm lens has on a 35mm film camera on your DSLR, you would buy a 15-16mm lens. And no, the manufacturers do not include the conversion on the lens. 15mm is 15mm whether it is on a small DSLR, a 35mm film camera, or a medium format camera. It is just your field of view that varies. BTW, the crop factor for Canon's lower end DSLRs is 1.6. For Nikon it is 1.5x.

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...so this effectively mean that I need to by(sic) a much wider lens for my DSLR than i had to for my 35mm. to get a 24mm equivalent



Yes this is correct. i.e. to get the same field of view that a 24mm lens has on a 35mm film camera on your DSLR, you would buy a 15-16mm lens. And no, the manufacturers do not include the conversion on the lens. 15mm is 15mm whether it is on a small DSLR, a 35mm film camera, or a medium format camera. It is just your field of view that varies. BTW, the crop factor for Canon's lower end DSLRs is 1.6. For Nikon it is 1.5x.

yes i got all that from the previous post :P
BTW I have a Pentax which is also 1.5x conversion:)
You are not now, nor will you ever be, good enough to not die in this sport (Sparky)
My Life ROCKS!
How's yours doing?

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No sir... the focal length is the same whether it's on a film or digital SLR. The conversion factor is due to the sensor size, not the length of the lens.

With that said - the old rule of thumb for hand-holding the camera (shutter speed >= 1/focal length) needs to include the 'zoom equivalency' of the lens focal length x sensor multiplier.

Example: 1.5x sensor multiplier, 100mm lens = minimum handheld shutter speed of 1/150 sec.

Clear as mud?

Yes Mike very clear , knew all of that :)


No worries - just wanted to make sure you knew that it affected it (handhold shutter speeds), that's all. Wasn't sure if it was obvious, given the question about lens length.
Mike
I love you, Shannon and Jim.
POPS 9708 , SCR 14706

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Whats the minimum helmet-held shutter speed? :)
The most important effect of a smaller digital sensor when it comes to skydiving is the reduced field of view. People want to know how wide the lens will be. The same lens will be a lot wider on a film camera than a digital camera (other than full frame cameras).

Besides... the minimum hand held shutter speed thing is a silly rule of thumb. Here's a 304mm equivalent at 1/40th. Ok, IS helps a bit... http://www.skydivingstills.com/gallery/5234315_kBXMg#318002289_o3uR5-A-LB

Dave

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Whats the minimum helmet-held shutter speed? :)
The most important effect of a smaller digital sensor when it comes to skydiving is the reduced field of view. People want to know how wide the lens will be. The same lens will be a lot wider on a film camera than a digital camera (other than full frame cameras).

Besides... the minimum hand held shutter speed thing is a silly rule of thumb. Here's a 304mm equivalent at 1/40th. Ok, IS helps a bit... http://www.skydivingstills.com/gallery/5234315_kBXMg#318002289_o3uR5-A-LB

Dave

you have IS AND you panned the camera :P not quite what mike was talking about
You are not now, nor will you ever be, good enough to not die in this sport (Sparky)
My Life ROCKS!
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Dave's a smartass.... :P:)

Nice shot, Dave - I'm jealous!

Let's see... IIRC, Gen 1 IS is good for 2 stops of camera shake - that takes us to roughly 1/70th. I'm making an educated guess that panning would cover at least one more stop due to intertia - now we're at 1/35th (assuming 1 stop "panning IS").
Mike
I love you, Shannon and Jim.
POPS 9708 , SCR 14706

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No sir... the focal length is the same whether it's on a film or digital SLR. The conversion factor is due to the sensor size, not the length of the lens.

With that said - the old rule of thumb for hand-holding the camera (shutter speed >= 1/focal length) needs to include the 'zoom equivalency' of the lens focal length x sensor multiplier.

Example: 1.5x sensor multiplier, 100mm lens = minimum handheld shutter speed of 1/150 sec.

Clear as mud?




Of course without taking in consideration stabilizing systems...
Una volta che avrete imparato a Volare, camminerete sulla terra guardando il cielo perchè è là che siete stati ed è là che vorrete tornare.

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that's what i wanted to know, I know the sensor is the determining factor, but i didnt know if lens manufactures compensated for their camera by including the conversion on the DLSLR lenses.
so this effectively mean that I need to by a much wider lens for my DSLR than i had to for my 35mm. to get a 24mm equivilent



Just to continue the muddiness, I thought the Canon EFS lenses were "compensated" for to be the correct focal length on EFS cameras. In other words, the EFS10-22 is 10-22 on a 30d/40d. Is that not the case?
I promise not to TP Davis under canopy.. I promise not to TP Davis under canopy.. eat sushi, get smoochieTTK#1

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No its not. You can compare a 15mm EF mount on a full frame and it is about the same as a 10mm on an EF-S on a cropped sensor. The EF-S series allows the lens makers to put the rear element deeper into the camera, this allows them to adjust the optics to work better for the cropped sensors by not wasting all that glass outside what is needed for the digtal sensor. This usually leads to smaller and ligher lenses since they can shave off that weight through every element.

DPreview even mentions the real focal lengths of some of the EF-S lenses here: http://www.dpreview.com/news/0408/04081907canon_efs_flash.asp
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Except that AFAIK, ALL IS systems for film are implemented on the lens, none in the film holder (as in the digital minoltas, sonys and I think pentax?)
Una volta che avrete imparato a Volare, camminerete sulla terra guardando il cielo perchè è là che siete stati ed è là che vorrete tornare.

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If you know something that I don't, please illustrate. I've been using in body IS and I think it has several advantages... lighter lenses.... cheaper lenses... all lenses with IS...
Una volta che avrete imparato a Volare, camminerete sulla terra guardando il cielo perchè è là che siete stati ed è là che vorrete tornare.

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Google broken? It's common knowledge, guess why Nikon and Canon have stabilisation in the lenses :S and that's not even with skydiving in mind, where you definitely don't want any stabilisation at all in your stills camera.

ciel bleu,
Saskia

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Not broken... I'm a photographer outside skydiving as well, and that's close to a religion discussion... or what's better, a stiletto or a velocity.
Both have advantages and disadvantages. Canon or nikon fanboys will favor in lens IS... minoltonians will favor in body.
Una volta che avrete imparato a Volare, camminerete sulla terra guardando il cielo perchè è là che siete stati ed è là che vorrete tornare.

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Sigh....
In body is the amateur option: it's cheaper and is better than no stibilization (except of course for skydiving where stabilization can ruin your images and you can possibly ruin the camera as well).
In lens is the pro-sumer and pro option: it's more expensive but it works better because it's optimized for the length of the lens and you still have a usable image in your viewfinder (try doing handheld macro work with a sensor stabilized camera - no way), and also it is the fullframe (and 35mm) option because it's not currently possible to move around a fullframe sensor.
I'll stick with my Nikon thank you very much.

ciel bleu,
Saskia

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