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**UncleVanya** · 07-11-2018, 07:30 AM

Originally posted by mroeder75

Similar photos, but not identical.

The sharper one, #1257 is comprised of 6.51 MB taken with SMC Pentax-DA1:1.8 50mm lens.

#1269 is comprised of 10.3 MB, was taken with my old manual focus Focal MC Auto 1:2.8 manual focus lens acquired in 1983. These were sold at KMart, likely manufactured by Tokina.

Not surprising as the second shot has a lot more detail - mostly in the form of the background being less out of focus. I assume the aperture was more stopped down on that shot.

**Mikesul** · 07-11-2018, 07:56 AM

Originally posted by mroeder75

Similar photos, but not identical.

The sharper one, #1257 is comprised of 6.51 MB taken with SMC Pentax-DA1:1.8 50mm lens.

#1269 is comprised of 10.3 MB, was taken with my old manual focus Focal MC Auto 1:2.8 manual focus lens acquired in 1983. These were sold at KMart, likely manufactured by Tokina.

I guess I do not see what you are trying to show here.

photoptimist · 07-11-2018, 08:30 AM

Originally posted by mroeder75

Similar photos, but not identical.

The sharper one, #1257 is comprised of 6.51 MB taken with SMC Pentax-DA1:1.8 50mm lens.

#1269 is comprised of 10.3 MB, was taken with my old manual focus Focal MC Auto 1:2.8 manual focus lens acquired in 1983. These were sold at KMart, likely manufactured by Tokina.

Notice that the first image shows very little of the complex background and what is shown is very out of focus.

The second image shows a lot more background detail and that detail is more in focus, especially those high-contrast backlit leaves at the top of the frame.

**UncleVanya** · 07-11-2018, 02:29 PM

Originally posted by photoptimist

Notice that the first image shows very little of the complex background and what is shown is very out of focus.

The second image shows a lot more background detail and that detail is more in focus, especially those high-contrast backlit leaves at the top of the frame.

My conclusion also.

**jatrax** · 07-11-2018, 08:08 PM

Agree with the above, the difference in file sizes from those images is exactly what I would expect to see. Large areas of identical color allow greater compression. Frequent changes in color, even if the total number of colors is small make for relatively poorer compression.

As I understand it jpeg compression works like this: Instead of each pixel being assigned a color value the jpeg file says: assign color value xyz to the next 50 pixels in this row and only has to change if the color changes. So if no change in the color value the amount of space required to describe the image can be very small. I am sure it is much more complex than that but I hope my simple example helps.

I think someone above already mentioned this but shoot an image of a blank wall that is all the same color and evenly lit, look at the file size for that image.

**mikesbike** · 07-11-2018, 08:35 PM

There is simply more in the 2nd shot, so a higher mp file. Using the K-5's built-in flash would have been a good idea.

**mroeder75** · 07-11-2018, 10:02 PM

The megabytes were so many more I just thought it would be something more than background detail. I asked my 2nd cousin to practice shoot with the manual focus lens on inanimate objects so he knew how to shoot with manual focus / which I refer to as semi-automatic focus Pentax technology with vintage manual focus lens. This is outside the experience of Canon devotees. The MB difference is not small between the auto focus lens and the manual focus lens. He shot this grille with the manual focus lens while practicing which was more than 10.3 MB.

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Last edited by mroeder75; 07-11-2018 at 10:15 PM.

**mikesbike** · 07-11-2018, 11:59 PM

Again, it is really not AF vs. MF. And not even between lenses per se. It boils down to how much information the lens brings to the sensor. Here, you again have a scene with many objects, which are not too far out of focus so they present detail. In order to render detail, this requires more pixels.

**twilhelm** · 07-12-2018, 04:51 AM

If you want to see how much the amount of detail can change the file size, convert an image to black and white. The color vs grey scale is a huge difference just in the color details. The same holds true for two color photos, the more detail there is, the larger the file size.

**jatrax** · 07-12-2018, 11:47 AM

Originally posted by mroeder75

The megabytes were so many more I just thought it would be something more than background detail.

Nope. The lens does not make any difference. AF versus MF does not make any difference. The amount of changes in data in the file are what determine the file size.

**UncleVanya** · 07-12-2018, 04:16 PM

Really it is simple. Take two photos with lenses with the same coverage one AF and one MF of the exact same subject at the exact same framing and with the same options and compare. There will be insignificant differences at best in file size. The easy way to do this is to setup a small studio scene but you can do it outdoors also if you can control the scene enough.

pxt · 08-25-2018, 09:37 AM

For me it not should be any difference in size, because is only sensor dump plus additional info about camera settings fx. mode, parameters of photo.

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07-11-2018, 07:30 AM	#16
UncleVanya Loyal Site Supporter Join Date: Jul 2014 Photos: Gallery \| Albums Posts: 28,472	Originally posted by mroeder75 Similar photos, but not identical. The sharper one, #1257 is comprised of 6.51 MB taken with SMC Pentax-DA1:1.8 50mm lens. #1269 is comprised of 10.3 MB, was taken with my old manual focus Focal MC Auto 1:2.8 manual focus lens acquired in 1983. These were sold at KMart, likely manufactured by Tokina. Not surprising as the second shot has a lot more detail - mostly in the form of the background being less out of focus. I assume the aperture was more stopped down on that shot.

07-11-2018, 07:56 AM	#17
Mikesul Loyal Site Supporter Join Date: Sep 2009 Location: Phoenix, AZ Posts: 7,594	Originally posted by mroeder75 Similar photos, but not identical. The sharper one, #1257 is comprised of 6.51 MB taken with SMC Pentax-DA1:1.8 50mm lens. #1269 is comprised of 10.3 MB, was taken with my old manual focus Focal MC Auto 1:2.8 manual focus lens acquired in 1983. These were sold at KMart, likely manufactured by Tokina. I guess I do not see what you are trying to show here.

07-11-2018, 08:30 AM	#18
photoptimist Pentaxian Join Date: Jul 2016 Photos: Albums Posts: 5,129	Originally posted by mroeder75 Similar photos, but not identical. The sharper one, #1257 is comprised of 6.51 MB taken with SMC Pentax-DA1:1.8 50mm lens. #1269 is comprised of 10.3 MB, was taken with my old manual focus Focal MC Auto 1:2.8 manual focus lens acquired in 1983. These were sold at KMart, likely manufactured by Tokina. Notice that the first image shows very little of the complex background and what is shown is very out of focus. The second image shows a lot more background detail and that detail is more in focus, especially those high-contrast backlit leaves at the top of the frame.

07-11-2018, 02:29 PM	#19
UncleVanya Loyal Site Supporter Join Date: Jul 2014 Photos: Gallery \| Albums Posts: 28,472	Originally posted by photoptimist Notice that the first image shows very little of the complex background and what is shown is very out of focus. The second image shows a lot more background detail and that detail is more in focus, especially those high-contrast backlit leaves at the top of the frame. My conclusion also.

07-11-2018, 08:08 PM	#20
jatrax Site Supporter Join Date: May 2010 Location: Washington Cascades Photos: Gallery \| Albums Posts: 12,992	Agree with the above, the difference in file sizes from those images is exactly what I would expect to see. Large areas of identical color allow greater compression. Frequent changes in color, even if the total number of colors is small make for relatively poorer compression. As I understand it jpeg compression works like this: Instead of each pixel being assigned a color value the jpeg file says: assign color value xyz to the next 50 pixels in this row and only has to change if the color changes. So if no change in the color value the amount of space required to describe the image can be very small. I am sure it is much more complex than that but I hope my simple example helps. I think someone above already mentioned this but shoot an image of a blank wall that is all the same color and evenly lit, look at the file size for that image.

07-11-2018, 08:35 PM	#21
mikesbike Site Supporter Join Date: Dec 2016 Location: Southeastern Michigan Posts: 4,566	There is simply more in the 2nd shot, so a higher mp file. Using the K-5's built-in flash would have been a good idea.

07-11-2018, 11:59 PM	#23
mikesbike Site Supporter Join Date: Dec 2016 Location: Southeastern Michigan Posts: 4,566	Again, it is really not AF vs. MF. And not even between lenses per se. It boils down to how much information the lens brings to the sensor. Here, you again have a scene with many objects, which are not too far out of focus so they present detail. In order to render detail, this requires more pixels.

07-12-2018, 04:51 AM	#24
twilhelm Loyal Site Supporter Join Date: Feb 2009 Location: Florida Photos: Gallery \| Albums Posts: 2,369	If you want to see how much the amount of detail can change the file size, convert an image to black and white. The color vs grey scale is a huge difference just in the color details. The same holds true for two color photos, the more detail there is, the larger the file size.

07-12-2018, 11:47 AM	#25
jatrax Site Supporter Join Date: May 2010 Location: Washington Cascades Photos: Gallery \| Albums Posts: 12,992	Originally posted by mroeder75 The megabytes were so many more I just thought it would be something more than background detail. Nope. The lens does not make any difference. AF versus MF does not make any difference. The amount of changes in data in the file are what determine the file size.

07-12-2018, 04:16 PM	#26
UncleVanya Loyal Site Supporter Join Date: Jul 2014 Photos: Gallery \| Albums Posts: 28,472	Really it is simple. Take two photos with lenses with the same coverage one AF and one MF of the exact same subject at the exact same framing and with the same options and compare. There will be insignificant differences at best in file size. The easy way to do this is to setup a small studio scene but you can do it outdoors also if you can control the scene enough.

08-25-2018, 09:37 AM	#27
pxt Senior Member Join Date: Jul 2018 Posts: 290	For me it not should be any difference in size, because is only sensor dump plus additional info about camera settings fx. mode, parameters of photo.

Photo Megabytes - Autofocus - Manual Focus

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