[dbs]

Yes it was. I had to have my thought confirmed about exposures being the same from one format to another and a little info to win my bet with a buddy.



VERY interesting indeed. I had to run to the store to pick more popcorn up. 😀




THANKS Dave its the only group/forum I belong to and enjoy it very much.

No worries Photobill

Dave

[From1980]

The answer is really simple - back to my first post where I mentioned visualising the image circle cast by the lens. Well the apsc lens would only throw an effective circle of a size that the apsc sensor alone can sit in. But the light intensity at any point within that circle would be identical to the light intensity at that point with a ff lens. So same fstop for both.

...and I still think this simple reply was all that was ever needed to succinctly answer the OP's confusion. Hard to believe this is still going around and around days later. But I warned you the first day. Never-ending droning on like this may be the main reason so many long time members have thousands of posts. Just my observation.

[clackers]

If pixel size differs between compared cameras

When someone shines a light on you in the kitchen, you dart out and hide under the table, Fogel. When the torch is shone under the table, you scuttle across the floor and under the fridge.


The situation in Post 70 was very straightforward.


For the third and last time, what are the four values?


I know you don't win a prize if you get it right, but there is the matter of the remaining respect you have from other readers.

[clackers]

Crop factor only concerns field of view - nothing else.

If crop factor was all that important, then all of the hand held light meters would have a sensor size input. Guess what, they do not.

Absolutely correct, PDL.

The K-1 and K-5 sensors are cut from the same Sony wafer. Each pixel is 4.9 micrometres in size.

When in Photoshop you crop out the middle 50 percent of a K-1 image, you get a K-5 image.

The resolution is not affected, since the pixels are the same size. The amount of light on each pixel is the same so the image doesn't suddenly turn a stop darker, a pixel with real data doesn't suddenly become a pixel with noise, the dynamic and colour ranges are unchanged and the depth of field is unaffected so the model with one eye in focus doesn't suddenly become a model with both eyes in focus.

All that's missing is the outer fifty percent of the picture, no optical properties have changed.

It's why APS-C is also called 'crop'.

---

Last edited by clackers; 08-21-2019 at 09:47 PM.

[Fogel70]

Crop factor only concerns field of view - nothing else.

If crop factor was all that important, then all of the hand held light meters would have a sensor size input. Guess what, they do not.

As I said in my post you quoted, when using same FOV, DOF and perspective on different formats FOV will obviously not be concerned as it is the same on both.

But try to repeat those things I said.
Let say you shoot same type shot with Pentax K-1 and Pentax Q (With crop factor of 5.5).
The lens used on K1 is FA 43 f/1.9 and on Q you use Prime 1 which is 8.5 mm and f/1.9. For closest match in FOV.

The shot on K1 is shot at f/11, 1/50s and ISO100.
To match DOF on K1 you need to use f/2 on Q and shutter speed has to be set at 1/1600s to avoid overexposure at ISO 100.

[GUB]

As I said in my post you quoted, when using same FOV, DOF and perspective on different formats FOV will obviously not be concerned as it is the same on both.

But try to repeat those things I said.
Let say you shoot same type shot with Pentax K-1 and Pentax Q (With crop factor of 5.5).
The lens used on K1 is FA 43 f/1.9 and on Q you use Prime 1 which is 8.5 mm and f/1.9. For closest match in FOV.

The shot on K1 is shot at f/11, 1/50s and ISO100.
To match DOF on K1 you need to use f/2 on Q and shutter speed has to be set at 1/1600s to avoid overexposure at ISO 100.

Why do you always twist things?
The entire thread was about one lens on different formats and majoring in exposure.
That makes PDL correct.
And for that matter Clackers on DoF.
You have put a different focal length lens on the Q.

[mikesbike]

As I said in my post you quoted, when using same FOV, DOF and perspective on different formats FOV will obviously not be concerned as it is the same on both.

But try to repeat those things I said.
Let say you shoot same type shot with Pentax K-1 and Pentax Q (With crop factor of 5.5).
The lens used on K1 is FA 43 f/1.9 and on Q you use Prime 1 which is 8.5 mm and f/1.9. For closest match in FOV.

The shot on K1 is shot at f/11, 1/50s and ISO100.
To match DOF on K1 you need to use f/2 on Q and shutter speed has to be set at 1/1600s to avoid overexposure at ISO 100.

Now you are throwing in a factor the OP sought to eliminate in his original question.

---------- Post added 08-21-19 at 11:40 PM ----------

I should know, but I don't.
When people talk of the deference between FF & APS-C regarding the f-stop they mostly cover the bokeh.
My question is:
When using my SMC Pentax 55mm F1.8 @ 1.8 on a APS-C camera does that sensor get approximately the same amount of light as using it on a FF @ the same f:stop? There is a lot of talk about loosing almost a full f: when using lenses on crop body's but can you please clarify if this is mostly about the bokeh or does it also play a part in exposure?
Sample
I use a light meter and it says shoot the scene @ f2.4 Would I get approximately the same expo with a FF & APS-C body? Or would I need to open up to f:2 or f:1.8 on the APS-C to get the equivalent exposure as on a FF.

As I said I should know this, but I do not ��

Thanks to anyone that can set me straight. ��

Here is the original question^ He is saying most talk regarding the difference between FF and APS-C is about bokeh (= DOF). Then he asks, (aside from the concern over bokeh) is there also a difference in exposure between the two. Just read what he asks after "Sample"- there is no mention at all of including a concern for DOF.

This is a simple question. Some who posted their response apparently were of the opinion that aside from DOF. there IS a difference in setting exposure between the two, from which dissertations appeared regarding how each has different light-gathering properties, blah, blah, blah.

---

Last edited by mikesbike; 08-21-2019 at 11:46 PM.

[PDL]

As I said in my post you quoted, when using same FOV, DOF and perspective on different formats FOV will obviously not be concerned as it is the same on both.

But try to repeat those things I said.
Let say you shoot same type shot with Pentax K-1 and Pentax Q (With crop factor of 5.5).
The lens used on K1 is FA 43 f/1.9 and on Q you use Prime 1 which is 8.5 mm and f/1.9. For closest match in FOV.

The shot on K1 is shot at f/11, 1/50s and ISO100.
To match DOF on K1 you need to use f/2 on Q and shutter speed has to be set at 1/1600s to avoid overexposure at ISO 100.

This is the problem with the equivalence people. Instead of talking about a single lens used on two different bodies they (you) always talk about making the FOV the same from the same spot. The only way you can get the same FOV with two different sized sensors is change the lens to match the FOV for the bodies sensor. We get that.

But:
I, for one, do not care at all about getting the same FOV from two bodies with different sized sensors because I only have APS-C cameras. Now, truth be told, I have some 35mm SLR's and I could go through all that "stuff" to get a equivalent FOV from two formats. Or, I could just take pictures using the features of each format to display different images. Why in the name of heaven would I want to replicate the images between formats? That is a colossal waste of time and effort, as a photographer I gain zip, nada, nothing, bubkis...

As for exposure? Well if I have my light meter set at ISO 400 and it says to use f/8 at 1/250 of a second......
When I expose for my APS-C camera, my film SLR (ILFORD HP5) and my 4x5 monorail (ILFORD HP5). Guess what --------- I use the same "exposure triangle" for each camera. As I said before, there is no "sensor size" setting on my Gossen Digipro F. Again, this exercise would be a colossal waste of time, effort, film/developer and disk space.

Further, if I have a object (box) that is projected on a sensor as image of 10mm high using my FA 50mm f/1.4 on a 35mm film camera and I put the same lens on my K-3II (or K10D or K20D) the box will be..... wait for it 10mm high on the sensor. In other more simple words, exactly the same size. If it is set to f/8 and the shutter is tripped at 1/125 at ISO 400 then the exact same number of photons will hit the 10mm area on the sensor of both the film (so called full frame) and the APS-C sensor. That is because the lens obeys the laws of physics. The physics of the lens is not changed because the sensor size is different.

Good Grief - get real.

[Fogel70]

Now you are throwing in a factor the OP sought to eliminate in his original question.

---------- Post added 08-21-19 at 11:40 PM ----------



Here is the original question^ He is saying most talk regarding the difference between FF and APS-C is about bokeh = DOF. Then he asks, (aside from the concern over bokeh) is there also a difference in exposure between the two. Just read what he asks after "Sample"

This is a simple question. Some apparently were of the opinion that aside from DOF. there IS a difference in setting exposure between the two, from which dissertations appeared regarding how each has different light-gathering properties, blah, blah, blah.

I did not respond to OP , I responded to someone else.

The OP have also asked a question like this in the thread.

Does not a lens have a maximum opening? This opening would only allow in a maximum amount of light. Yes deferent sizes of sensor's can absorbs deferent amounts of light from the same lens but the exact same amount of light passes through the aperture???

In my example above with K1 and Q, they used same sized "openings".

[swanlefitte]

Youtu.be

Youtu.be

Needed intermission 😀
It is funny/pertinent to this thread in multiple levels.

[Fogel70]

This is the problem with the equivalence people. Instead of talking about a single lens used on two different bodies they (you) always talk about making the FOV the same from the same spot. The only way you can get the same FOV with two different sized sensors is change the lens to match the FOV for the bodies sensor. We get that.

But:
I, for one, do not care at all about getting the same FOV from two bodies with different sized sensors because I only have APS-C cameras. Now, truth be told, I have some 35mm SLR's and I could go through all that "stuff" to get a equivalent FOV from two formats. Or, I could just take pictures using the features of each format to display different images. Why in the name of heaven would I want to replicate the images between formats? That is a colossal waste of time and effort, as a photographer I gain zip, nada, nothing, bubkis...

So why on earth did you quote my post if are not in any way interested to discuss the content of what I wrote?

[beholder3]

The resolution is not affected, since the pixels are the same size. The amount of light on each pixel is the same so the image doesn't suddenly turn a stop darker, a pixel with real data doesn't suddenly become a pixel with noise, the dynamic and colour ranges are unchanged and the depth of field is unaffected so the model with one eye in focus doesn't suddenly become a model with both eyes in focus'.

You are both right and wrong.

You are right when judging the situation on the sensor itself and thereby when using *different* output formats („print sizes“). In your example you watch both the full image and the cropped from the same distance. The cropped piece is just that. cropped. Smaller.

Now the bad thing.

The typical comparison assumes equal print sizes. Yes this is an assumption and a deliberately chosen one. And it is not „right“ or „wrong“. It just happens to be widespread.
It does change everything. Including what you said into „wrong“.

Why?
Because everything we talk about is essentially about human perception. This human perception in physical terms does „downsampling“ and „averaging“ and is limited by what our eyes can resolve.

That is where my previously posted bit about „magnification“ comes into play. Magnification changes everything.
Yes, if you take an analog film print on paper and watch it from a closer distance then (perceived) noise changes. As dynamic Range is fully dependend on noise that changes as well. And since DoF is dependend on circle of confusion size the DoF changes as well. All just by moving the print piece of paper closer to your eyes or farther away.

This is easiest to understand when first tackling the noise topic. And here using a related topic from newspaper prints of photographs. At normal viewing distance they look fine and not very „noisy“ (yes it isnt exactly noise but the function is the same). But if you look at them very closely suddenly you will notice ugly „pixels“. The newspaper still is exactly the same. You just have „cropped“ away a lot of surroundings from your field of view and watched it from less distance thus using a larger magnification. And behold: the perceived „noise“ has changed.

[GUB]

So why on earth did you quote my post if are not in any way interested to discuss the content of what I wrote?

Probably because you were replying to his post.
Whew this is getting complicated!!

[GUB]

So why on earth did you quote my post if are not in any way interested to discuss the content of what I wrote?

But you are right - why bother responding when your response (post 140) has no relevance to the post you were referring to nor for that matter no relevance to the entire thread.

[Dartmoor Dave]

Whew this is getting complicated!!

It really isn't. You, Clackers, PDL and one or two others are talking about factually understood things about cameras and lenses that have been known and proven for over a century. Others are talking about something that they think must be right because they read it on the internet.

People who say that a bigger sensor has lower noise because the lens collects more light, ignoring the fact that it's actually because of the noise performance per pixel, are like people saying that a car with a high performance engine goes faster because it has a bigger fuel tank, rather than more horsepower.

"But look," they say, "Here's a Ford and here's a Ferrari. The Ferrari goes much faster and it's got a bigger fuel tank, so that proves it."
"No," you say, "The Ferrari goes faster because it has more horsepower."
"That's not it," they say, "The Ferrari has got a bigger fuel tank. You need lots of fuel to go faster, and the Ferrari has more total fuel."
And so on. . .

I know I said I was done with this, but it's all just too much fun to stay away from.