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Thread started 20 Dec 2015 (Sunday) 07:25
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# What is the G9 equivalent DOF/Aperture Value?

Dec 20, 2015 07:25 |  #1

Hi

What is the G9 (wth macro setting) equivalent aperture value to get the same DOF as my 550d at 50mm (with a 12mm extension tube) at f/11 and 1/100 - ISO 100? I want to do some photo tests to compare iq.

Thanks

NelPhotos.co.uk
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Play: Kiss X4 + 15-85 IS + 10-22 + 50 1.8 II + Vivitar 1 70-210 3.5
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Dec 20, 2015 08:19 |  #2

You can use the DOF calculator at dofmaster.com Don't know if they list the G9 but you can pick an equivalent.

No photographer is as good as the simplest camera. - Edward Steichen.

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Dec 20, 2015 08:32 |  #3

If FL = long dimension of frame, and if extension tube = FL, and shooting distance provides 'the same' magnficiation (e.g. 1:1) in both shots (...but the area seen within frame is proportional to the long dimension of the frame), the DOF is proporational to the FL used.

For example:

1. 15mm frame length vs. 36mm frame length, and
2. 15mm FL on 15mm extension vs. 36mm FL on 36mm extension, and
3. 0.1 m distance vs. 0.2 m distance, yielding about 1.3:1 in both cases

0.12 m DOF zone vs. 0.24 m DOF zone (both at f/8)

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Dec 20, 2015 10:50 |  #4

Hi
I didn't expect thisߘ I expected it to be the other way round.

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NelPhotos.co.uk
Work: 7D + Sigma 100-300 4
Play: Kiss X4 + 15-85 IS + 10-22 + 50 1.8 II + Vivitar 1 70-210 3.5
EOS-M + 18-55 + FD 50 1.4 + FD 135 2.8 + Tamron 35-80 1A
G9, SX280 HS + CHDK, Casio EX-FH 100, Toshiba L505-144 & iPad 2

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Dec 20, 2015 12:50 as a reply to  @ Arte Automobilistica's post |  #5

Is there some reason you compare f/32 vs. f/11?

Have you considered that a smaller sensor requires you to magnify the image more to fill the same 8x10" print, and therefore you are magnifying to a greater degree the lens diffraction of a tiny aperture? A smaller sensor normally means that you need to use a LARGER minimum aperture for it to be 'usable'...for example I can use f/22 on medium format vs. f/16 on FF vs. only f/11 on APS-C, before diffraction effects are objectionable. You defy wisdom in using f/32 on a tiny sensor camera.

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Dec 20, 2015 15:00 |  #6

Wilt wrote in post #17825951
Is there some reason you compare f/32 vs. f/11?.

Hi Wilt thanks for replying.

I am trying to compare image quality at the same DOF. It is at f/32 that according to dofmaster the g9 has the same DOF as the X4 at f/11. I expected it to be lower.

It is interesting that FF f/16 = f/11 aps-c. The G9 with its 7.6mm sensor has: a FF crop factor of 4.61 and an aps-c crop factor of 2.5 so FF f/16 = Aps-c f/11 = G9 f/3.48?

Can I assume that 3.48 is the G9's optimum aperture before diffraction starts to take effect?

The G9 50mm is 80mm on the X4, but shutter speed and ISO remain the same.

Does my shooting macro make any any difference?

Thanks

NelPhotos.co.uk
Work: 7D + Sigma 100-300 4
Play: Kiss X4 + 15-85 IS + 10-22 + 50 1.8 II + Vivitar 1 70-210 3.5
EOS-M + 18-55 + FD 50 1.4 + FD 135 2.8 + Tamron 35-80 1A
G9, SX280 HS + CHDK, Casio EX-FH 100, Toshiba L505-144 & iPad 2

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Dec 20, 2015 19:18 |  #7

Arte Automobilistica wrote in post #17826114
I am trying to compare image quality at the same DOF. It is at f/32 that according to dofmaster the g9 has the same DOF as the X4 at f/11. I expected it to be lower.

Comparing different formats makes it hard, in part because we are assuming that lenses for smaller formats are 'proportional' in terms of lines of detail resolution per millimeter at the sensor (or film), and in the (wrong in your case about f/32 for the G9) assumption about acceptable f/stops. Now you know it is wrong to assume f/32 is acceptable on the tiny G9 format, even though it is quite acceptable on 4x5" sheetfilm!

Arte Automobilistica wrote in post #17826114
It is interesting that FF f/16 = f/11 aps-c. The G9 with its 7.6mm sensor has: a FF crop factor of 4.61 and an aps-c crop factor of 2.5 so FF f/16 = Aps-c f/11 = G9 f/3.48? Arte Automobilistica;178261​14]Can I assume that 3.48 is the G9's optimum aperture before diffraction starts to take effect?

If, by this statement, you are inferring that DOF on the G9 with f/3.5 is about the same as FF f/16...assuming FL appropriate to the format size...you have it right that f/3.5 is proportional 'acceptable resolution minimum' as it is 1:4.5 crop. It is NOT necessarily the 'optimum' aperture size, as the lens' max aperture changes between f/2.8 - f/4.8, so it is perhaps operating at it max aperture when at f/3.5. And we do not know (from published spec) about what FL it actually uses when in macro focus mode.

Arte Automobilistica wrote in post #17826114
The G9 50mm is 80mm on the X4, but shutter speed and ISO remain the same.

Not sure what you are getting at by "G9 50mm is 80mm on the X4".

Arte Automobilistica wrote in post #17826114
Does my shooting macro make any any difference?

By classic definition in photography of 'macro' (on film reproduction scale vs. lifesize, anything larger than 1:2 or half lifesize) the main difference is how much/little of the subject (and surroundings) we can capture at the focal plane. So we capture only 7.6mm of the subject vs. 36mm of the subject at 1:1.

But today's digital photographer ordinarily is NOT thinking per this definition, folks think 'fill the frame' and the term 'macro' has morphed into the amorphous 'shoot really close'. So you might fill the 7.6mm frame with something 30.4mm long (1:4) vs. fill a 36mm frame with something 30.4mm long (1.18:1), and not be shooting 'macro' at all with the smaller format (where 'macro' is > 1:2)

So my response is NOT a direct answer to your question, bucause I first have to understand what YOU mean! I recognize the change in common use (although I do not endorse calling it 'macro'!)

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Dec 21, 2015 00:47 as a reply to  @ Wilt's post |  #8

Hi Wilt thank you for taking the time to reply to my question so comprehensively.

I am trying to find the most cost effective method to do product photography (close up with a pendant filling the frame). The articles I have read seem to sway between the G9 being inferior (which makes sense with its smaller sensor) to there isn't that much difference http://www.cameralabs.​com …_G9/outdoor_res​ults.shtml

It is my intention to do a comparative test and wanted to make sure the settings for both cameras were 'like for like'. This I understand now will be difficult so I'll start with f/11 and f/3.5 and do some pixel peeping. Any advice on this?

Thanks again.

NelPhotos.co.uk
Work: 7D + Sigma 100-300 4
Play: Kiss X4 + 15-85 IS + 10-22 + 50 1.8 II + Vivitar 1 70-210 3.5
EOS-M + 18-55 + FD 50 1.4 + FD 135 2.8 + Tamron 35-80 1A
G9, SX280 HS + CHDK, Casio EX-FH 100, Toshiba L505-144 & iPad 2

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Dec 21, 2015 13:08 as a reply to  @ Arte Automobilistica's post |  #9

With product photos, you are might be 'close focus' ranges and not necessarily trying to do reproduction of tiny objects close to lifesize.
A 3' product and a 12" product and a 1" product are all quite uniquely different from one another photographically speaking, so it is is best to write in specifics rather than broad terms like 'product photography'.
If the pendant you are shooting is 1" across, fitting it into an APS-C requires 25mm object to fit within 14mm frame height, at at close to 0.56X you are indeed within even classic definitions of 'macro' shooting.

Your 550D (a.k.a X4) has 3456 pixels vs. the G9 3000 pixels along the short axis, so the 550D has inherent sensor advantage for detail. Also, the greater degree of magnification required to produce the identical 8" (short dimension) print puts the 550D to advantage.

I do not see a 'macro' ('close focus') lens in your list, so one thing to keep in mind is that most lenses are designed for optimum focus distances only to about 18" with reasonable quality, and getting closer may not necessarily yield terrific results. While the G9 sensor is 'handicapped' relative to the 550D, its lens might provide better performance at very close distances.

In short, I cannot generalize an expected result, you need to do testing if your own.

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What is the G9 equivalent DOF/Aperture Value?
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