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10-28-2008, 04:31 PM   #196
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Pretty balanced comparison of sensor formats

I found Joseph James' Essay on comparing sensor formats (Equivalence) to be very informative.

It makes many good points about how to do a fair comparison between sensor formats.

I particularly learned that FF is less demanding on lenses (with the exception of extreme corners in particular with wide angle lenses). FF glass can be slower and less sharp and will still give the same IQ as APS-C glass.

Joseph makes the point that these two system would have to be considered to be equivalent:

17.3mm x 13mm sensor (ISO 100-3200)
12-60 / 2.8-4
50-200 / 2.8-3.5
50 / 2 1:2 macro

vs

34.6mm x 26mm sensor (ISO 400-12800)
24-120 / 5.6-8
100-400 / 5.6-7
100 / 4 1:1 macro
(glass can be half as sharp as the in the above setup)

Note that the FF system needs much better ISO performance, but only if one wants to achieve the same DOF as possible with the small format sensor system.

An FF system has better noise performance, but only if it uses shallower DOF or there is sufficient light and no potential for image blur so that it can use a slower shutter speed.

On of the pivotal points he makes is that one has to compare using the same DOF (aperture) and not the same f-ratio (f stop).

The essay is looooooong but makes much more good points than I listed above.

P.S.: I found the following to be a gem of a quote, in particular for Pentaxians:
"While many argue that in-lens IS is superior, it is definitely not superior if the lenses you use do not have it.".


Last edited by Class A; 10-28-2008 at 04:41 PM.
10-29-2008, 02:54 PM   #197
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QuoteOriginally posted by Class A Quote
I found Joseph James' Essay on comparing sensor formats (Equivalence) to be very informative.

It makes many good points about how to do a fair comparison between sensor formats.

I particularly learned that FF is less demanding on lenses (with the exception of extreme corners in particular with wide angle lenses). FF glass can be slower and less sharp and will still give the same IQ as APS-C glass.

Joseph makes the point that these two system would have to be considered to be equivalent:

17.3mm x 13mm sensor (ISO 100-3200)
12-60 / 2.8-4
50-200 / 2.8-3.5
50 / 2 1:2 macro

vs

34.6mm x 26mm sensor (ISO 400-12800)
24-120 / 5.6-8
100-400 / 5.6-7
100 / 4 1:1 macro
(glass can be half as sharp as the in the above setup)

Note that the FF system needs much better ISO performance, but only if one wants to achieve the same DOF as possible with the small format sensor system.

An FF system has better noise performance, but only if it uses shallower DOF or there is sufficient light and no potential for image blur so that it can use a slower shutter speed.

On of the pivotal points he makes is that one has to compare using the same DOF (aperture) and not the same f-ratio (f stop).

The essay is looooooong but makes much more good points than I listed above.

P.S.: I found the following to be a gem of a quote, in particular for Pentaxians:
"While many argue that in-lens IS is superior, it is definitely not superior if the lenses you use do not have it.".
Hi, you've had many good input in this thread, and turned the arguments around, so we could try and reach some fruitful conclusions.

This Joe Mama is fine, but a FF defender in a somewhat extreme degree. I've learned from discussions with him, but he is not the most neutral player. And there are other established and Professional Photogs that I place more emphasis on.
I'm sorry if my English can't frase it properly, Joe has some worthy input, but you shouldn't let his findings stand alone.

It was Joe that James talked about, in this other thread, stating :
The stern defender of all things canon Joemama admitted the inconsistent image performance [50 mm lens] even focusing is not a concern.
https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/39630-former-c...han-35-f2.html
(Second post of his, in the thread)


On the topic, here is from another recent discussion. A more balanced view :
https://www.pentaxforums.com/forums/pentax-dslr-discussion/39490-interesting-...tml#post369349

Last edited by Jonson PL; 10-29-2008 at 03:03 PM.
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