DSLR "Crop factor misinformation

audiobomber · 11-05-2014, 08:24 AM

Originally posted by wizzster

I was only trying to say that IMHO, camera and lens manufacturers are misleading people by saying e.g. 50mm lens is euivalent to a 75 mm lens. Tha's all I was trying to say. I was wondering if I am the only bothered by this.

I am severely bothered by manufacturers who advertise equivalent focal lengths but never convert to equivalent aperture. If you haven't watched this video yet, I highly recommend it. It speaks exactly to your point.

You Tube

normhead · 11-05-2014, 09:16 AM

Depth of Field is the distance between the nearest and furthest point in acceptable focus.
It's not an aperture setting, it's a distance.
Exposure is the combination of ISO, Aperture and shutter speed. It is common across all formats. ƒ2.8 represents the same thing on all formats, FF, APS_c ? It doesn't matter.

This video causes more confusion than it clears up, in that the primary function of Aperture is exposure. The DoF context is secondary.. and as shown in the film pretty useless. When doing product settings you often want to know, "how much DoF do I need to have my whole subject in focus?" Theoretically if you have both an APS-c and FF camera with equivalent lenses, you could calculate the DoF using a DoF table for each lens and work out which lens would give you sufficient DoF to accomplish what you want. I fail to see what advantage it would be to work that out for both systems, but you could do it. Or , you could take an image, if the DoF isn't enough, stop down. Why you would be shooting with two different formats is beyond me? As a photographer you should know from experience which format you want to use for which shoot. Using DoF calculations would be a waste of time IMHO.

You'll notice that in the video, the companies, except for one, who list the Aperture as function of DoF sell Full frames. It's marketing ploy, and hardly of any practical use at all. When at school, shooting 8x10 , 645 and APS-c I can't remember even once, anyone using this ridiculous methodology. It's the stuff everyone should know after 10 minutes with a camera system, whatever format that might be.

wizzster · 11-05-2014, 09:20 AM

Hi,

Thanks for the link. Very interesting, especially the ISO part.

Undot · 11-05-2014, 09:22 AM

Originally posted by BrianR

If you mount a FF lens on an APS-C body, every time you click the shutter you are murdering photons by sending them screaming into the side of the mirror box instead of letting them meet their destiny by striking your sensor or film.

I believe we finally found the source of dark matter!

The next Nobel prize will go to PentaxForums for sure.

So it does seem rather philosophical after all. In the end you pick the tool for the results you want.
At first crop factor was declared to make the digital move easier for analog users. Whereas someone purely digital like me sees it more like extra focal length for less money. Not because manufacturers advertise it as such, but because I don't have any comparison to the old age and interpret it that way.

LFLee · 11-05-2014, 09:31 AM

Originally posted by wizzster

When camera companies cite the equivalence of a camera with a small sensor as being euivalent to a 35 mm film camera with a longer focal length they are giving the impression that this is a good thing. It is not. You are NOT gaining resolution. You are simply losing field-of-view.
So the 35mm equvalent really refers to the field of view and not the resolution. For example, the K-3 has an "APS-C' sized sensor which is 23.5 x 15.6 mm. The 35mm film camera is 24 x 36 mm. This is a crop factor of 1.5. It is NOT the equivalent of a 1.5x increase in resolution. It is a 1.5x DECREASE in field-of-view. Take this to an extreme. Suppose a camera has a sensor that is 2.4 mm x 3.6 mm. Would this be the same as having a 10X longer focal length ? I don't think so !

Anyway, sorry for the rant. This is a great forum.

you are right, but pro-apsc user will continue to say they get more "reach", which is not true.

The amount of "compression feel" you get on a pic from a 35mm lens on APSC is NOT equal to the one using the 50mm lens on FF.

normhead · 11-05-2014, 10:34 AM

Lord help us....

flaviopetrone · 11-05-2014, 11:23 AM

Originally posted by normhead

Lord help us....

In the end you gave up?

normhead · 11-05-2014, 12:06 PM - **1 Like**

They wore me down... chewed me up and spit me out...

bossa · 11-05-2014, 03:22 PM

The original post was about formats and not the ability to crop the hell out of an image based on pixel density. The part of the post which mentions "you are not getting more resolution" obviously was not taking into account the greater pixel density of many smaller formats which does translate to greater resolution depending upon the quality of system components. But in the context of the original post I believe the OP meant to say "magnification": magnification of the format is only supplied by the value of the crop factor at output and mainly due to the standardisation of our viewing systems.

Cropping 1:1 has nothing to do with the format per se and I believe that it was not the intention of the OP to speak to that subject. If you're going to crop a lot then APS-C v FF is moot. In that case pixel density, the quality of the high ISO noise response, lens quality (CA and diffraction) issues become the most important considerations.

IOW Format means almost nothing in the context of extreme cropping and pixel density is paramount.

stevebrot · 11-05-2014, 03:35 PM

A new member posts a bait-type message in the welcome area and ignites 50+ responses. What a great howdy doody! Did we cover all the bases on this thread yet (crop factor, equivalence, FF, pixel density...)?

Steve

**luftfluss** · 11-05-2014, 03:39 PM - **1 Like**

Originally posted by stevebrot

A new member posts a bait-type message in the welcome area and ignites 50+ responses. What a great howdy doody! Did we cover all the bases on this thread yet (crop factor, equivalence, FF, pixel density...)?

Steve

All the sheep I know consider the "crop factor" to be how green the grass is on the field across the street.

BrianR · 11-05-2014, 03:49 PM - **1 Like**

Originally posted by luftfluss

All the sheep I know consider the "crop factor" to be how green the grass is on the field across the street.

I thought "crop factor" was how bad the sheep's tails hurt after the procedure.

flaviopetrone · 11-05-2014, 03:51 PM

Originally posted by BrianR

I thought "crop factor" was how bad the sheep's tails hurt after the procedure.

I think that you're wrong.

"Crop factor" is a way in which women comb their hair.

**clackers** · 11-05-2014, 04:21 PM - **1 Like**

Originally posted by LFLee

The amount of "compression feel" you get on a pic from a 35mm lens on APSC is NOT equal to the one using the 50mm lens on FF.

Oh, no ....

**luftfluss** · 11-05-2014, 04:25 PM

Perhaps we should all cut the crop and go back to making photos...

11-05-2014, 09:16 AM	#47
normhead Pentaxian Join Date: Jun 2007 Location: Near Algonquin Park Photos: Gallery \| Albums Posts: 40,451	Depth of Field is the distance between the nearest and furthest point in acceptable focus. It's not an aperture setting, it's a distance. Exposure is the combination of ISO, Aperture and shutter speed. It is common across all formats. ƒ2.8 represents the same thing on all formats, FF, APS_c ? It doesn't matter. This video causes more confusion than it clears up, in that the primary function of Aperture is exposure. The DoF context is secondary.. and as shown in the film pretty useless. When doing product settings you often want to know, "how much DoF do I need to have my whole subject in focus?" Theoretically if you have both an APS-c and FF camera with equivalent lenses, you could calculate the DoF using a DoF table for each lens and work out which lens would give you sufficient DoF to accomplish what you want. I fail to see what advantage it would be to work that out for both systems, but you could do it. Or , you could take an image, if the DoF isn't enough, stop down. Why you would be shooting with two different formats is beyond me? As a photographer you should know from experience which format you want to use for which shoot. Using DoF calculations would be a waste of time IMHO. You'll notice that in the video, the companies, except for one, who list the Aperture as function of DoF sell Full frames. It's marketing ploy, and hardly of any practical use at all. When at school, shooting 8x10 , 645 and APS-c I can't remember even once, anyone using this ridiculous methodology. It's the stuff everyone should know after 10 minutes with a camera system, whatever format that might be. Last edited by normhead; 11-05-2014 at 10:11 AM.

11-05-2014, 03:35 PM	#55
stevebrot Otis Memorial Pentaxian Join Date: Mar 2007 Location: Vancouver (USA) Photos: Gallery \| Albums Posts: 42,007	Amazing!!! A new member posts a bait-type message in the welcome area and ignites 50+ responses. What a great howdy doody! Did we cover all the bases on this thread yet (crop factor, equivalence, FF, pixel density...)? Steve

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
a "crop" factor question	bull drinkwater	Pentax Medium Format	11	05-16-2014 04:29 AM
Adjustable crop factor?	Unregistered User	Photographic Technique	8	11-25-2013 03:53 PM
Mis-Understanding "Crop-Factor"	Gerard_Dirks	Troubleshooting and Beginner Help	13	10-10-2013 11:11 AM
Does the "crop factor" just crop?	jboyde	Troubleshooting and Beginner Help	8	01-03-2010 08:18 AM
Crop Factor question... 35mm, DA and dslr	mediaslinky	Pentax SLR Lens Discussion	10	05-06-2007 11:13 AM

11-05-2014, 09:20 AM	#48
wizzster New Member Join Date: Mar 2014 Location: boston Posts: 24 Original Poster	Hi, Thanks for the link. Very interesting, especially the ISO part.

11-05-2014, 09:22 AM	#49
Undot Senior Member Join Date: Aug 2014 Posts: 176	Originally posted by BrianR If you mount a FF lens on an APS-C body, every time you click the shutter you are murdering photons by sending them screaming into the side of the mirror box instead of letting them meet their destiny by striking your sensor or film. I believe we finally found the source of dark matter! The next Nobel prize will go to PentaxForums for sure. So it does seem rather philosophical after all. In the end you pick the tool for the results you want. At first crop factor was declared to make the digital move easier for analog users. Whereas someone purely digital like me sees it more like extra focal length for less money. Not because manufacturers advertise it as such, but because I don't have any comparison to the old age and interpret it that way.

11-05-2014, 09:31 AM	#50
LFLee Veteran Member Join Date: Aug 2009 Location: Southern California Photos: Gallery \| Albums Posts: 2,292	Originally posted by wizzster When camera companies cite the equivalence of a camera with a small sensor as being euivalent to a 35 mm film camera with a longer focal length they are giving the impression that this is a good thing. It is not. You are NOT gaining resolution. You are simply losing field-of-view. So the 35mm equvalent really refers to the field of view and not the resolution. For example, the K-3 has an "APS-C' sized sensor which is 23.5 x 15.6 mm. The 35mm film camera is 24 x 36 mm. This is a crop factor of 1.5. It is NOT the equivalent of a 1.5x increase in resolution. It is a 1.5x DECREASE in field-of-view. Take this to an extreme. Suppose a camera has a sensor that is 2.4 mm x 3.6 mm. Would this be the same as having a 10X longer focal length ? I don't think so ! Anyway, sorry for the rant. This is a great forum. you are right, but pro-apsc user will continue to say they get more "reach", which is not true. The amount of "compression feel" you get on a pic from a 35mm lens on APSC is NOT equal to the one using the 50mm lens on FF.

11-05-2014, 10:34 AM	#51
normhead Pentaxian Join Date: Jun 2007 Location: Near Algonquin Park Photos: Gallery \| Albums Posts: 40,451	Lord help us....

11-05-2014, 11:23 AM	#52
flaviopetrone Veteran Member Join Date: Aug 2014 Location: Reggio Emilia Photos: Albums Posts: 1,153	Originally posted by normhead Lord help us.... In the end you gave up?

11-05-2014, 12:06 PM - 1 Like	#53
normhead Pentaxian Join Date: Jun 2007 Location: Near Algonquin Park Photos: Gallery \| Albums Posts: 40,451	They wore me down... chewed me up and spit me out...

11-05-2014, 03:22 PM	#54
bossa Veteran Member Join Date: Jul 2011 Location: Adelaide Posts: 4,546	The original post was about formats and not the ability to crop the hell out of an image based on pixel density. The part of the post which mentions "you are not getting more resolution" obviously was not taking into account the greater pixel density of many smaller formats which does translate to greater resolution depending upon the quality of system components. But in the context of the original post I believe the OP meant to say "magnification": magnification of the format is only supplied by the value of the crop factor at output and mainly due to the standardisation of our viewing systems. Cropping 1:1 has nothing to do with the format per se and I believe that it was not the intention of the OP to speak to that subject. If you're going to crop a lot then APS-C v FF is moot. In that case pixel density, the quality of the high ISO noise response, lens quality (CA and diffraction) issues become the most important considerations. IOW Format means almost nothing in the context of extreme cropping and pixel density is paramount.

11-05-2014, 03:39 PM - 1 Like	#56
luftfluss Site Supporter Join Date: Jun 2011 Location: NJ Photos: Gallery \| Albums Posts: 11,626	Originally posted by stevebrot A new member posts a bait-type message in the welcome area and ignites 50+ responses. What a great howdy doody! Did we cover all the bases on this thread yet (crop factor, equivalence, FF, pixel density...)? Steve All the sheep I know consider the "crop factor" to be how green the grass is on the field across the street.

11-05-2014, 03:49 PM - 1 Like	#57
BrianR Veteran Member Join Date: Dec 2010 Location: Ontario Photos: Gallery Posts: 3,332	Originally posted by luftfluss All the sheep I know consider the "crop factor" to be how green the grass is on the field across the street. I thought "crop factor" was how bad the sheep's tails hurt after the procedure.

11-05-2014, 03:51 PM	#58
flaviopetrone Veteran Member Join Date: Aug 2014 Location: Reggio Emilia Photos: Albums Posts: 1,153	Originally posted by BrianR I thought "crop factor" was how bad the sheep's tails hurt after the procedure. I think that you're wrong. "Crop factor" is a way in which women comb their hair.

11-05-2014, 04:21 PM - 1 Like	#59
clackers Otis Memorial Pentaxian Join Date: Jul 2013 Location: Melbourne Photos: Albums Posts: 16,397	Originally posted by LFLee The amount of "compression feel" you get on a pic from a 35mm lens on APSC is NOT equal to the one using the 50mm lens on FF. Oh, no ....

11-05-2014, 04:25 PM	#60
luftfluss Site Supporter Join Date: Jun 2011 Location: NJ Photos: Gallery \| Albums Posts: 11,626	Perhaps we should all cut the crop and go back to making photos...