Ugly Hedgehog® - Photography Forum
Home | Photography Digest | Active Topics | Newest Pictures | Search | Login | Register | Help
Main Photography Discussion
Zoom lens conversions for fixed-lens digital cameras
If you want to reply, then register here. Registration is free and your account is created instantly, so you can post right away.
Page: 1 2 next>>
Oct 17, 2017 13:41:59   #
lwerthe1mer
 
I read on in my edition of Bryan Peterson's UNDERSTANDING EXPOSURE a section discussing the conversion aperture openings on DSLRs to the aperture openings on fixed-lens digital cameras. A f/2.8 aperture on a fixed lens camera is equivalent to an aperture opening of f/11 on a DSLR. The spread between the two camera types continues throughout the range of f-stops.

Why the difference? What are the repercussions -- can't blur background? What else?

It looks like fixed-lens cameras are indeed different animals from DSLRs.

| Reply
Oct 17, 2017 13:52:56   #
Mac
 
lwerthe1mer wrote:
I read on in my edition of Bryan Peterson's UNDERSTANDING EXPOSURE a section discussing the conversion aperture openings on DSLRs to the aperture openings on fixed-lens digital cameras. A f/2.8 aperture on a fixed lens camera is equivalent to an aperture opening of f/11 on a DSLR. The spread between the two camera types continues throughout the range of f-stops.

Why the difference? What are the repercussions -- can't blur background? What else?

It looks like fixed-lens cameras are indeed different animals from DSLRs.
I read on in my edition of Bryan Peterson's UNDERS... (show quote)


You're right, he says that, I looked it up in my copy of the book, but I don't understand it. The f/number is the ratio of the diameter of aperture to the focal length of the lens and I don't see how camera type can change that.
I'm looking forward to reading what others say about this.

| Reply
Oct 17, 2017 13:55:43   #
Bill_de (a regular here)
 
lwerthe1mer wrote:
I read on in my edition of Bryan Peterson's UNDERSTANDING EXPOSURE a section discussing the conversion aperture openings on DSLRs to the aperture openings on fixed-lens digital cameras. A f/2.8 aperture on a fixed lens camera is equivalent to an aperture opening of f/11 on a DSLR. The spread between the two camera types continues throughout the range of f-stops.

Why the difference? What are the repercussions -- can't blur background? What else?

It looks like fixed-lens cameras are indeed different animals from DSLRs.
I read on in my edition of Bryan Peterson's UNDERS... (show quote)


Maybe ask the author. He may know what he meant, or maybe the section was written on April first.

---

| Reply
Oct 17, 2017 13:59:40   #
Screamin Scott (a regular here)
 
I'm sure it can all be traced back to the smaller sensors

| Reply
Oct 17, 2017 17:16:05   #
lwerthe1mer
 
Along with the very high f-stops, Peterson says the shutter speed can be much higher (not lower) than on a DSLR. With higher f-stops, shouldn't the shutter speeds can lower? I'm more confused than usual and understand fixed-lens cameras less than before I read Peterson.

| Reply
Oct 17, 2017 17:42:40   #
Bill_de (a regular here)
 
lwerthe1mer wrote:
Along with the very high f-stops, Peterson says the shutter speed can be much higher (not lower) than on a DSLR. With higher f-stops, shouldn't the shutter speeds can lower? I'm more confused than usual and understand fixed-lens cameras less than before I read Peterson.


This same confusion has been going on for years. Google brings up quite a few instances.

https://www.dpreview.com/forums/thread/2557412

--

| Reply
Oct 18, 2017 06:54:42   #
jerryc41 (a regular here)
 
lwerthe1mer wrote:
I read on in my edition of Bryan Peterson's UNDERSTANDING EXPOSURE a section discussing the conversion aperture openings on DSLRs to the aperture openings on fixed-lens digital cameras. A f/2.8 aperture on a fixed lens camera is equivalent to an aperture opening of f/11 on a DSLR. The spread between the two camera types continues throughout the range of f-stops.

Why the difference? What are the repercussions -- can't blur background? What else?

It looks like fixed-lens cameras are indeed different animals from DSLRs.
I read on in my edition of Bryan Peterson's UNDERS... (show quote)


This seems like the type of statement that serves no purpose other than to generate discussion and debate. An f/2.8 is better than an F/5.6 in terms of light gathering. When it gets to the point that you have to do math to take a picture, it's time to look for another hobby.

| Reply
Oct 18, 2017 08:16:19   #
kymarto
 
It’s not about fixed lens, it is about sensor size and exposure equivalence. The basic idea (I guess, because I have not read the passage in question) is that a smaller sensor is noisier than a larger sensor, so you can set a larger sensor to a higher ISO and come up with an image that is equivalent in look (in terms of noise) to that of a smaller sensor at a much lower ISO. The example seems to be of a small sensor 4 EV noisier than a larger sensor. So if the correct exposure is f2.8 at 1/125 at ISO 100 (for instance), you can set the larger sensor to f11 at 1/125 at ISO 1600 and have an image with an equivalent amount of noise (with sensors of similar architecture and the same number of pixels)

| Reply
Oct 18, 2017 08:51:03   #
James Slick
 
Mac wrote:
You're right, he says that, I looked it up in my copy of the book, but I don't understand it. The f/number is the ratio of the diameter of aperture to the focal length of the lens and I don't see how camera type can change that.
I'm looking forward to reading what others say about this.



| Reply
Oct 18, 2017 08:51:54   #
James Slick
 
jerryc41 wrote:
This seems like the type of statement that serves no purpose other than to generate discussion and debate. An f/2.8 is better than an F/5.6 in terms of light gathering. When it gets to the point that you have to do math to take a picture, it's time to look for another hobby.



| Reply
Oct 18, 2017 08:55:59   #
cthahn
 
Bad information.

| Reply
Oct 18, 2017 15:00:25   #
rehess
 
lwerthe1mer wrote:
Along with the very high f-stops, Peterson says the shutter speed can be much higher (not lower) than on a DSLR. With higher f-stops, shouldn't the shutter speeds can lower? I'm more confused than usual and understand fixed-lens cameras less than before I read Peterson.


In 1969, I used graduation money to purchase my first adjustable camera. Reading instructions packed with the camera, I learned to twist the funky knob immediately below the "ASA" window to match the number on the film box. Then, for each picture, I transferred the "EV" number off the light meter directly below the knob to the outermost ring on the lens barrel. The only remaining step was to use the second ring of the lens barrel to allocate exposure control between shutter speed {label on the dial} and aperture {number in window directly below the ring}. In a matter of minutes, I learned to operate this mechanism, and over the next four years I learned about the practical aspects of "exposure".

Thus, I've never felt a need to purchase Mr.Peterson's book, nor have I even paged through it. The things being reported in this thread are just plain wrong - since I have no idea what the context is, I have no idea what "need" Mr. Peterson thinks he is addressing, but the words being reported here are confusing at best, and IMHO have no place in a book meant to teach neophytes about exposure. Exposure is what I outlined in the first paragraph - determining how much light you have and then adjusting real shutter speed and real aperture to give a pleasing picture.


BTW - the camera below is a fixed lens camera. Ten years, and another {this time a Canon} fixed lens camera later, I purchased my first Pentax SLR. I did compare light meter readings between the three cameras, and found them to agree within one EV.



| Reply
Oct 18, 2017 15:22:44   #
lwerthe1mer
 
Since no one seems to know what Mr. Peterson is talking about, this discussion appears to be unproductive. I am tempted to write Mr. Peterson for an explanation, but I don't think I will spend the time to do so.

| Reply
Oct 18, 2017 15:28:10   #
wdross (a regular here)
 
lwerthe1mer wrote:
I read on in my edition of Bryan Peterson's UNDERSTANDING EXPOSURE a section discussing the conversion aperture openings on DSLRs to the aperture openings on fixed-lens digital cameras. A f/2.8 aperture on a fixed lens camera is equivalent to an aperture opening of f/11 on a DSLR. The spread between the two camera types continues throughout the range of f-stops.

Why the difference? What are the repercussions -- can't blur background? What else?

It looks like fixed-lens cameras are indeed different animals from DSLRs.
I read on in my edition of Bryan Peterson's UNDERS... (show quote)


Since f2.8 is always f2.8, the assumption here is that we are talking depth of focus or depth of field. The smaller the sensor, the greater the DOF for the same aperture setting. Usually a cellphone's aperture is f2.8. If one takes a photo at about 8' away with a cellphone, nearly everything will look in focus. With a full frame camera, with the same wide angle and aperture, this will not be true. The back ground will blur. To get the same DOF as the cellphone will require maybe going to f11. Fix lense P&S and compact cameras are more like a DSLR with a prime lense on it. And because of the small sensor, hard to achieve a burred background.

| Reply
Oct 18, 2017 15:57:32   #
rehess
 
wdross wrote:
Since f2.8 is always f2.8, the assumption here is that we are talking depth of focus or depth of field. The smaller the sensor, the greater the DOF for the same aperture setting. Usually a cellphone's aperture is f2.8. If one takes at about 8' away, nearly everything will look in focus. With a full frame camera, with the same wide angle and aperture, this will not be true. The back ground will blur. To get the same DOF as the cellphone will require maybe going to f11. Fix lense P&S and compact cameras are more like a DSLR with a prime lense on it. And because of the small sensor, hard to achieve a burred background.
Since f2.8 is always f2.8, the assumption here is ... (show quote)

But why saying anything about DOF in a book that is alleged to teach about "Exposure"; someone whose level of understand is appropriate for the book needs to completely understand exposure before being introduced to DOF. Add in the reported comments about shutter speed
lwerthe1mer wrote:
Along with the very high f-stops, Peterson says the shutter speed can be much higher (not lower) than on a DSLR. With higher f-stops, shouldn't the shutter speeds can lower? I'm more confused than usual and understand fixed-lens cameras less than before I read Peterson.
just adds to the confusion. This is not the book to recommend to neophytes

| Reply
Page: 1 2 next>>
If you want to reply, then register here. Registration is free and your account is created instantly, so you can post right away.
Main Photography Discussion
Home | Latest Digest | Back to Top | All Sections
Contact us | Privacy policy | Terms of use
UglyHedgehog.com - Forum
Copyright 2011-2018 Ugly Hedgehog, Inc.