Why can't they?

oscaletrains · 10-17-2015, 03:19 PM

Maybe this is a really stupid question, but I just got up from a nap and am a little out of it still. As we are all too aware, when we grab a lens and stick it on most of our DSLR's, we have to remember that the 15mm we just attached is really acting like a 22mm, or our 55-300 zoom is really like using a 82-450.

They make all kinds of 1.4x and 1.7x and 2x and 3x extender/converters...so why not a converter that would work the opposite...and make that 50mm lens REALLY react like a 50mm lens on the DSLR instead of 75mm? Or is there some physical reason it won't work? Wouldn't it be more or less like looking through a pair of binoculars backwards?

Adam · 10-17-2015, 03:23 PM

Said device does exist...search for the "speed booster". Due to physical limitations it's not available in the k mount, however.

As for focal lengths, they never change. A 50mm on aps-c is still a 50mm. It just feels more like a telephoto lens than a standard lens due to the smaller sensor size. IMO, this shouldn't be seen as a problem that needs fixing.

Jedi_Strings · 10-17-2015, 03:25 PM

Originally posted by oscaletrains

Maybe this is a really stupid question, but I just got up from a nap and am a little out of it still. As we are all too aware, when we grab a lens and stick it on most of our DSLR's, we have to remember that the 15mm we just attached is really acting like a 22mm, or our 55-300 zoom is really like using a 82-450.

They make all kinds of 1.4x and 1.7x and 2x and 3x extender/converters...so why not a converter that would work the opposite...and make that 50mm lens REALLY react like a 50mm lens on the DSLR instead of 75mm? Or is there some physical reason it won't work? Wouldn't it be more or less like looking through a pair of binoculars backwards?

I thought focal length equivalence was only an issue when using APS-C cameras. Are there "effective" focal length issues on all DSLRs?

**jatrax** · 10-17-2015, 03:34 PM - **1 Like**

I think you are somewhat confused. A 50mm is a 50mm, nothing you can do will change that. Using a 50mm lens with a m4/3 sensor will give you one angle of view, using it on an APS-C sensor another, using it on a FF sensor yet another and using it on a 645z will be different as well.

Your reasoning makes sense only if you believe that "FF" or 135 film is the only proper angle of view for a lens. Which is untrue. Despite 135 film being quite popular it is by no means the only format available or in use.

Originally posted by oscaletrains

As we are all too aware, when we grab a lens and stick it on most of our DSLR's, we have to remember that the 15mm we just attached is really acting like a 22mm

No we don't. That attitude comes from a 135mm centric view. Those of us that use other sensor formats or use multiple sensor formats are either used to a different angle of view or to understanding how our cameras work with different lenses and sensors.

If you simply must have the 135 angle of view then you need to get a camera with a sensor that uses that angle of view. If you use an APS-C sensor camera (as most Pentax users do) then the angle of view is what it is.

**pepperberry farm** · 10-17-2015, 03:48 PM

I guess I've never had this issue; a 50mm is a 50mm no matter what camera you you mount it on... the field of view may be different, of course, but you aren't seeing through a 75mm lens, it's a 50....

oscaletrains · 10-17-2015, 04:07 PM

Originally posted by Adam

Said device does exist...search for the "speed booster". Due to physical limitations it's not available in the k mount, however.

As for focal lengths, they never change. A 50mm on aps-c is still a 50mm. It just feels more like a telephoto lens than a standard lens due to the smaller sensor size. IMO, this shouldn't be seen as a problem that needs fixing.

Did the search you suggested and read about it. Looks a lot like what I was thinking of. Of course, naturally, it isn't available for Pentax nor my EF-s lenses.

But in reading about it and how it works, it certainly looks like something I would buy if it came in a Kaf mount.

What are the physical limitations that make it non Pentax friendly?

---------- Post added 10-17-15 at 04:10 PM ----------

Originally posted by jatrax

I think you are somewhat confused. A 50mm is a 50mm, nothing you can do will change that. Using a 50mm lens with a m4/3 sensor will give you one angle of view, using it on an APS-C sensor another, using it on a FF sensor yet another and using it on a 645z will be different as well.

Your reasoning makes sense only if you believe that "FF" or 135 film is the only proper angle of view for a lens. Which is untrue. Despite 135 film being quite popular it is by no means the only format available or in use.

No we don't. That attitude comes from a 135mm centric view. Those of us that use other sensor formats or use multiple sensor formats are either used to a different angle of view or to understanding how our cameras work with different lenses and sensors.

If you simply must have the 135 angle of view then you need to get a camera with a sensor that uses that angle of view. If you use an APS-C sensor camera (as most Pentax users do) then the angle of view is what it is.

I don't know that it's an "attitude" really. In my case, I just hate picking up a lens and right away having to take into consideration that my 35mm lens is going to make photos that look like they were taken with a 50mm one.

pathdoc · 10-17-2015, 04:20 PM

The 35mm-centricity is due to the fact that the legacy glass our Pentax DSLRs use today was designed for it. Those who have never shot anything but APS-C or who have been away from film for years do not perceive the issue as much, if at all. It is in any case an "equivalent field of view" and not a true zoom effect, although pics taken with either sensor and printed at the same physical size give the impression that it is.

BrianR · 10-17-2015, 05:13 PM

Originally posted by oscaletrains

I don't know that it's an "attitude" really. In my case, I just hate picking up a lens and right away having to take into consideration that my 35mm lens is going to make photos that look like they were taken with a 50mm one.

Get some black electrical tape to cover up the true focal length of your lens and write the 'aps-c equivalent' focal length on with white out. Problem solved and it will look classy. Bonus- it's reversible in case you want to mount it on the mythical Pentax FF dslr from the future or a Pentax FF film camera from the past.

**hjoseph7** · 10-17-2015, 05:31 PM

Good idea but I never heard of a lens that would shrink the perspective.

**macman24054** · 10-17-2015, 05:32 PM - **1 Like**

I for one really don't notice the difference. I did shot Pentax 35mm SLR and Yashica 35mm range finder. Maybe that is why because I used 2 different types of 35mm cameras. If I can't fit it all in I put a wider lens on. If I need more reach I put a longer lens on. Pretty much what I did in the film days.

oscaletrains · 10-17-2015, 05:41 PM

Originally posted by BrianR

Get some black electrical tape to cover up the true focal length of your lens and write the 'aps-c equivalent' focal length on with white out. Problem solved and it will look classy. Bonus- it's reversible in case you want to mount it on the mythical Pentax FF dslr from the future or a Pentax FF film camera from the past.

Ha! Pentax in some ways is just like if a person is a Cub fan, always waiting for what you want, almost getting there once in a long while, usually a let down to some extent or another, and every hundred years or so, just maybe...but probably not.

tibbitts · 10-17-2015, 06:01 PM

The question isn't so much "why can't they?"; it's "why would they?", even assuming it could be done for k-mount.

**jatrax** · 10-17-2015, 06:08 PM

Originally posted by oscaletrains

I don't know that it's an "attitude" really. In my case, I just hate picking up a lens and right away having to take into consideration that my 35mm lens is going to make photos that look like they were taken with a 50mm one.

"Attitude" might not be the best word. I just mean that this issue is only a problem if you can only see the world at a FF angle of view. I honestly have trouble understanding this problem though for sure it comes up a lot. I shot film for many, many years. When I transitioned to digital it was APS-C. I have no problem with preconceived notions of what a lens is "supposed" to look like. It is what it is when looking through the viewfinder for goodness sake. Trying to make it something else is just not going to work.

If you really want the "FF" experience with your existing glass try a Sony A7 or wait for a Pentax FF digital.

As Adam noted the device you mentioned does exist but from the early reviews I remember no one was very happy with the results and of course there is not one for k-mount anyway.

Just curious but do you use all primes? I mostly use zooms for work and primes only for fun which might be why I have no problems with this.

**Tony Belding** · 10-17-2015, 06:54 PM

If you want to stretch your mind, try shooting with a Pentax Q7 for a while. The "normal" lens is 8.5mm.

oscaletrains · 10-17-2015, 08:07 PM

Originally posted by tibbitts

The question isn't so much "why can't they?"; it's "why would they?", even assuming it could be done for k-mount.

You wouldn't want an accessory that makes your lens a stop faster AND a wider FOV? Ok, whatever. I would.

10-17-2015, 03:19 PM	#1
oscaletrains Senior Member Join Date: Jul 2014 Photos: Gallery Posts: 172	Why can't they? Maybe this is a really stupid question, but I just got up from a nap and am a little out of it still. As we are all too aware, when we grab a lens and stick it on most of our DSLR's, we have to remember that the 15mm we just attached is really acting like a 22mm, or our 55-300 zoom is really like using a 82-450. They make all kinds of 1.4x and 1.7x and 2x and 3x extender/converters...so why not a converter that would work the opposite...and make that 50mm lens REALLY react like a 50mm lens on the DSLR instead of 75mm? Or is there some physical reason it won't work? Wouldn't it be more or less like looking through a pair of binoculars backwards?

10-17-2015, 03:23 PM	#2
Adam Administrator Site Webmaster Join Date: Sep 2006 Location: Arizona Photos: Gallery \| Albums Posts: 51,595	Said device does exist...search for the "speed booster". Due to physical limitations it's not available in the k mount, however. As for focal lengths, they never change. A 50mm on aps-c is still a 50mm. It just feels more like a telephoto lens than a standard lens due to the smaller sensor size. IMO, this shouldn't be seen as a problem that needs fixing. Adam PentaxForums.com Webmaster (Site Usage Guide \| Site Help \| My Photography) PentaxForums.com server and development costs are user-supported. You can help cover these costs by donating or purchasing one of our Pentax eBooks. Or, buy your photo gear from our affiliates, Adorama, B&H Photo, KEH, or Topaz Labs, and get FREE Marketplace access - click here to see how! Trusted Pentax retailers:

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10-17-2015, 03:25 PM	#3
Jedi_Strings Forum Member Join Date: Sep 2015 Location: Bronx, NY Photos: Gallery \| Albums Posts: 56	Originally posted by oscaletrains Maybe this is a really stupid question, but I just got up from a nap and am a little out of it still. As we are all too aware, when we grab a lens and stick it on most of our DSLR's, we have to remember that the 15mm we just attached is really acting like a 22mm, or our 55-300 zoom is really like using a 82-450. They make all kinds of 1.4x and 1.7x and 2x and 3x extender/converters...so why not a converter that would work the opposite...and make that 50mm lens REALLY react like a 50mm lens on the DSLR instead of 75mm? Or is there some physical reason it won't work? Wouldn't it be more or less like looking through a pair of binoculars backwards? I thought focal length equivalence was only an issue when using APS-C cameras. Are there "effective" focal length issues on all DSLRs?

10-17-2015, 03:34 PM - 1 Like	#4
jatrax Site Supporter Join Date: May 2010 Location: Washington Cascades Photos: Gallery \| Albums Posts: 12,991	I think you are somewhat confused. A 50mm is a 50mm, nothing you can do will change that. Using a 50mm lens with a m4/3 sensor will give you one angle of view, using it on an APS-C sensor another, using it on a FF sensor yet another and using it on a 645z will be different as well. Your reasoning makes sense only if you believe that "FF" or 135 film is the only proper angle of view for a lens. Which is untrue. Despite 135 film being quite popular it is by no means the only format available or in use. Originally posted by oscaletrains As we are all too aware, when we grab a lens and stick it on most of our DSLR's, we have to remember that the 15mm we just attached is really acting like a 22mm No we don't. That attitude comes from a 135mm centric view. Those of us that use other sensor formats or use multiple sensor formats are either used to a different angle of view or to understanding how our cameras work with different lenses and sensors. If you simply must have the 135 angle of view then you need to get a camera with a sensor that uses that angle of view. If you use an APS-C sensor camera (as most Pentax users do) then the angle of view is what it is.

10-17-2015, 03:48 PM	#5
pepperberry farm amateur dirt farmer Join Date: Dec 2014 Location: probably out in a field somewhere... Photos: Gallery \| Albums Posts: 41,660	I guess I've never had this issue; a 50mm is a 50mm no matter what camera you you mount it on... the field of view may be different, of course, but you aren't seeing through a 75mm lens, it's a 50....

10-17-2015, 04:07 PM	#6
oscaletrains Senior Member Join Date: Jul 2014 Photos: Gallery Posts: 172 Original Poster	Originally posted by Adam Said device does exist...search for the "speed booster". Due to physical limitations it's not available in the k mount, however. As for focal lengths, they never change. A 50mm on aps-c is still a 50mm. It just feels more like a telephoto lens than a standard lens due to the smaller sensor size. IMO, this shouldn't be seen as a problem that needs fixing. Did the search you suggested and read about it. Looks a lot like what I was thinking of. Of course, naturally, it isn't available for Pentax nor my EF-s lenses. But in reading about it and how it works, it certainly looks like something I would buy if it came in a Kaf mount. What are the physical limitations that make it non Pentax friendly? ---------- Post added 10-17-15 at 04:10 PM ---------- Originally posted by jatrax I think you are somewhat confused. A 50mm is a 50mm, nothing you can do will change that. Using a 50mm lens with a m4/3 sensor will give you one angle of view, using it on an APS-C sensor another, using it on a FF sensor yet another and using it on a 645z will be different as well. Your reasoning makes sense only if you believe that "FF" or 135 film is the only proper angle of view for a lens. Which is untrue. Despite 135 film being quite popular it is by no means the only format available or in use. No we don't. That attitude comes from a 135mm centric view. Those of us that use other sensor formats or use multiple sensor formats are either used to a different angle of view or to understanding how our cameras work with different lenses and sensors. If you simply must have the 135 angle of view then you need to get a camera with a sensor that uses that angle of view. If you use an APS-C sensor camera (as most Pentax users do) then the angle of view is what it is. I don't know that it's an "attitude" really. In my case, I just hate picking up a lens and right away having to take into consideration that my 35mm lens is going to make photos that look like they were taken with a 50mm one.

10-17-2015, 04:20 PM	#7
pathdoc Pentaxian Join Date: Mar 2015 Photos: Gallery \| Albums Posts: 6,381	The 35mm-centricity is due to the fact that the legacy glass our Pentax DSLRs use today was designed for it. Those who have never shot anything but APS-C or who have been away from film for years do not perceive the issue as much, if at all. It is in any case an "equivalent field of view" and not a true zoom effect, although pics taken with either sensor and printed at the same physical size give the impression that it is.

10-17-2015, 05:13 PM	#8
BrianR Veteran Member Join Date: Dec 2010 Location: Ontario Photos: Gallery Posts: 3,332	Originally posted by oscaletrains I don't know that it's an "attitude" really. In my case, I just hate picking up a lens and right away having to take into consideration that my 35mm lens is going to make photos that look like they were taken with a 50mm one. Get some black electrical tape to cover up the true focal length of your lens and write the 'aps-c equivalent' focal length on with white out. Problem solved and it will look classy. Bonus- it's reversible in case you want to mount it on the mythical Pentax FF dslr from the future or a Pentax FF film camera from the past.

10-17-2015, 05:31 PM	#9
hjoseph7 Site Supporter Join Date: May 2014 Location: Minnesota Photos: Gallery \| Albums Posts: 2,046	Good idea but I never heard of a lens that would shrink the perspective.

10-17-2015, 05:32 PM - 1 Like	#10
macman24054 Loyal Site Supporter Join Date: Aug 2013 Location: Axton, VA Photos: Gallery \| Albums Posts: 461	I for one really don't notice the difference. I did shot Pentax 35mm SLR and Yashica 35mm range finder. Maybe that is why because I used 2 different types of 35mm cameras. If I can't fit it all in I put a wider lens on. If I need more reach I put a longer lens on. Pretty much what I did in the film days.

10-17-2015, 05:41 PM	#11
oscaletrains Senior Member Join Date: Jul 2014 Photos: Gallery Posts: 172 Original Poster	Originally posted by BrianR Get some black electrical tape to cover up the true focal length of your lens and write the 'aps-c equivalent' focal length on with white out. Problem solved and it will look classy. Bonus- it's reversible in case you want to mount it on the mythical Pentax FF dslr from the future or a Pentax FF film camera from the past. Ha! Pentax in some ways is just like if a person is a Cub fan, always waiting for what you want, almost getting there once in a long while, usually a let down to some extent or another, and every hundred years or so, just maybe...but probably not.

10-17-2015, 06:01 PM	#12
tibbitts Pentaxian Join Date: Apr 2007 Location: Oklahoma USA Posts: 2,193	The question isn't so much "why can't they?"; it's "why would they?", even assuming it could be done for k-mount.

10-17-2015, 06:08 PM	#13
jatrax Site Supporter Join Date: May 2010 Location: Washington Cascades Photos: Gallery \| Albums Posts: 12,991	Originally posted by oscaletrains I don't know that it's an "attitude" really. In my case, I just hate picking up a lens and right away having to take into consideration that my 35mm lens is going to make photos that look like they were taken with a 50mm one. "Attitude" might not be the best word. I just mean that this issue is only a problem if you can only see the world at a FF angle of view. I honestly have trouble understanding this problem though for sure it comes up a lot. I shot film for many, many years. When I transitioned to digital it was APS-C. I have no problem with preconceived notions of what a lens is "supposed" to look like. It is what it is when looking through the viewfinder for goodness sake. Trying to make it something else is just not going to work. If you really want the "FF" experience with your existing glass try a Sony A7 or wait for a Pentax FF digital. As Adam noted the device you mentioned does exist but from the early reviews I remember no one was very happy with the results and of course there is not one for k-mount anyway. Just curious but do you use all primes? I mostly use zooms for work and primes only for fun which might be why I have no problems with this.

10-17-2015, 06:54 PM	#14
Tony Belding Site Supporter Join Date: Mar 2013 Location: Hamilton, Texas Photos: Gallery \| Albums Posts: 779	If you want to stretch your mind, try shooting with a Pentax Q7 for a while. The "normal" lens is 8.5mm.

10-17-2015, 08:07 PM	#15
oscaletrains Senior Member Join Date: Jul 2014 Photos: Gallery Posts: 172 Original Poster	Originally posted by tibbitts The question isn't so much "why can't they?"; it's "why would they?", even assuming it could be done for k-mount. You wouldn't want an accessory that makes your lens a stop faster AND a wider FOV? Ok, whatever. I would.