Replacement? (Equivalent)

[janne]

Hi all,

I have a theoretical question, with a hypothetical practical outcome.

Is a 5DII + 24-105F4L IS an adequate replacement for a 7D + 17-55F2.8 IS? Mainly in terms of concert shooting and therefore lighting, not FPS et al. I ask, because I have read about full frame cameras being able to 'catch more light', as it were. Would the first combination result in more light, thus requiring a lower iso?

Thanks in advance,

janne

Edit: added equivalent to the title, which might be confusing.

[neuroanatomist]

The 'FF-equivalent' of the EF-S 17-55mm f/2.8 IS is 27-88mm f/4.5.  So, the 24-105mm on the 5DII is wider, longer, and faster in terms of depth of field for the same framing (i.e. shallower DoF, which you may not want).  There will be no difference in exposure - the 5DII with an f/4 lens would need a 1-stop slower shutter speed than the 7D with an f/2.8 lens  But, the FF sensor in the 5DII does gather more total light, meaning for the same ISO noise you can shoot the FF at 1.3 stops higher ISO, which more than makes up for the loss of a stop.

So, you gain more zoom range, 1/3-stop, and better IQ with the 5DII + 24-105. You lose the superior AF system of the 7D, although if you're using only the center point, the 5DII does better in low light, in my experience.

Now, for concerts and low light shooting with moving subjects, your best bet is really the 5DII with a fast prime, like the 85mm f/1.8, and you're golden.

[briansquibb]

The lens you will need will depend on where you expect to be in the concert hall. If possible a lens with f/2.8 or faster else and f/4 (for the benefit of the AF)

[neuroanatomist]

Would the first combination result in more light, thus requiring a lower iso?

Re-read my post, saw that I didn't directly answer this.

Not quite - a FF sensor would need the same ISO for a given scene, assuming the same aperture and shutter speed. But, the same ISO on FF would have a noise level equivalent to 1.3 stops lower ISO on APS-C, so if you needed, you could shoot 1.3 stops faster and keep the same noise.  With a 1-stop slower lens, you'd only gain 1/3 stop.

[smirkypants]

I'd never shoot a concert at f4. If I were very close or backstage, I'd take the 5D. If I were further out, I'd take the 7D if I were to want tighter shots. I had a lot of luck with my 1D4 using both an 85mm 1.4 and 135mm f2. Your lens really can't be too fast for this kind of work. Hate to be negative, but you won't be happy with f4.

[elflord]

Is a 5DII + 24-105F4L IS an adequate replacement for a 7D + 17-55F2.8 IS? Mainly in terms of concert shooting and therefore lighting, not FPS et al. I ask, because I have read about full frame cameras being able to 'catch more light', as it were. Would the first combination result in more light, thus requiring a lower iso?

Some examples that might help clear things up: suppose you have:

5D:  80mm, f/4, 1/60s, ISO 800
7D:  50mm, f/4, 1/60s, ISO 800

both shots have the same ev (if the 5D is exposed correctly, so is the 7D)
the 5D shot is less noisy
the 5D shot has shallower depth of field

Now consider this:

5D: 80mm, f/4,    1/60s, ISO2560
7D: 50mm, f/2.5, 1/60s, ISO1000

both shots have the same ev, the same depth of field, and comparable noise[edit: oops ... exposure is quadratic with aperture size, not linear.  ]

So yes, the 24-105 f/4 will be an "adequate replacement", but it is a long way from optimal. As others have pointed out, a 135mm or 85mm prime are ideal for this shooting scenario.

[TexPhoto]

5DII - Great camera, great for concerts. 24-105mm - great lens, not so much for concerts.  Not bad mind you, just not great.

Some f2.8 zooms would be great.

I think I'd take a couple fast primes. How about an 85 1.2?  or a 1.8 

[Fleetie]

Would the first combination result in more light, thus requiring a lower iso?

Not quite - a FF sensor would need the same ISO for a given scene, assuming the same aperture and shutter speed. But, the same ISO on FF would have a noise level equivalent to 1.3 stops lower ISO on APS-C

Neuro, can you explain the above to a humble mortal like me? The exact figure of "1.3"? My naive thinking suggests to me that noise would partly be a function of technology as well as the limits that physics imposes. For example, a full-frame 5D classic would exhibit significantly more noise than would a 5D2 under identical conditions; yet your post reads as though the numbers are a physical absolute, derived just from the dimensions of the sensor. Where does the "1.3" come from, and is that a physics-related number, or just something to do with the characteristics of the 5D2?

I guess I'm embarrassed because I have a physics background, yet I am unable to satisfy myself that I understand this!

[elflord]

Neuro, can you explain the above to a humble mortal like me? The exact figure of "1.3"? My naive thinking suggests to me that noise would partly be a function of technology as well as the limits that physics imposes. For example, a full-frame 5D classic would exhibit significantly more noise than would a 5D2 under identical conditions; yet your post reads as though the numbers are a physical absolute, derived just from the dimensions of the sensor. Where does the "1.3" come from, and is that a physics-related number, or just something to do with the characteristics of the 5D2?

I guess I'm embarrassed because I have a physics background, yet I am unable to satisfy myself that I understand this!

1.3 is the number of "stops" from the APS-C sensor area to the full frame sensor area, that is, log(  (36*24)/(22*15))/log(2) =1.39, and therefore the amount of "extra light" the FF sensor gets.

You're right that in practice the difference is quite a bit different. For example, DxOMark scores are 1815 and 854, so the difference in noise performance is more like one stop (according to DxOMark).

[pwp]

I'd never shoot a concert at f4. If I were very close or backstage, I'd take the 5D. If I were further out, I'd take the 7D if I were to want tighter shots. I had a lot of luck with my 1D4 using both an 85mm 1.4 and 135mm f2. Your lens really can't be too fast for this kind of work. Hate to be negative, but you won't be happy with f4.

That's not negative at all, it's real.

For concert & stage work, even f/2.8 glass feels slow and this is with the 1D4 iso cranked up. At dress rehearsals where I can get up close and even onstage when appropriate, my lenses are 24 f/1.4, 50 f/1.4 & 70-200 f/2.8isII.

Paul Wright

[briansquibb]

The OP didn't mention whether the concert was indoors or out, daylight or spotlights.

If taking the pictures from 100yds then a 85mm would be useless whereas a 600 f/4 would be good. If taken from the front of the stage a 85mm would be useless whereas a 24mm or even a 14mm for a small stage would be good.

If it is a big set then the DOF needed could mean that shooting at f/4 was too open - especially with a ff

We dont even know if flash is permitted - you might be surprised how much light can be thrown by two 580's on a bracket

We need more info before solutions can be recommended

My suggestion of 2.8 lens or at least f/4 was based entirely on the AF capability of the 5DII rather than any specific lens.

Of course another option might be to recommend a 1D4 which would be happy snapping away at iso6400 or even iso12800 which would change the dynamics of the lens choice

[neuroanatomist]

@Fleetie - elflord is correct, as usual.   Log₂ (FF area / APS-C area); rounded down because the 5DII 'misses' some of the light because it lacks gapless microlenses.

I'll also add that the predicted number holds pretty well for sensors of the same approximate technology, and that in this specific case (5DII vs. 7D), my own testing shows about 1.3 stops difference.

[briansquibb]

@Fleetie - elflord is correct, as usual.   Log₂ (FF area / APS-C area); rounded down because the 5DII 'misses' some of the light because it lacks gapless microlenses.

I'll also add that the predicted number holds pretty well for sensors of the same approximate technology, and that in this specific case (5DII vs. 7D), my own testing shows about 1.3 stops difference.

+1 The 1.3 matches my intuitive impression.

[janne]

I'll add a bit of info. I've so far had a bit of experience shooting indoor festivals in my homecountry (Belgium). Especially the I Love Techno festival. I used my 7D, 17-55 2.8 IS. 50 1.4 and 70-200 2.8. And indeed, 2.8 is rather slow, most of the time. One has to be lucky. Primes are something I want to invest in, but later on. The reason I asked this question was mainly because, on a second hand site, I saw an offer of a 5DII+24-105F4L IS for 900 euros. (And some more ridiculous deals, such as 5DII + 70-200F4L IS + 50 F1.8 + backpack for 900 euros, even just a body for 900, which still seems very low.)

[briansquibb]

I'll add a bit of info. I've so far had a bit of experience shooting indoor festivals in my homecountry (Belgium). Especially the I Love Techno festival. I used my 7D, 17-55 2.8 IS. 50 1.4 and 70-200 2.8. And indeed, 2.8 is rather slow, most of the time. One has to be lucky. Primes are something I want to invest in, but later on. The reason I asked this question was mainly because, on a second hand site, I saw an offer of a 5DII+24-105F4L IS for 900 euros. (And some more ridiculous deals, such as 5DII + 70-200F4L IS + 50 F1.8 + backpack for 900 euros, even just a body for 900, which still seems very low.)

Not sure what you mean by f/2.8 is rather slow - do you mean that at f/2.8 the shutter speed is too slow? If so just up the ISO

- how much light is there?
- how far from the stage are you going to be?
- can you use flash?
- are they going to mind if you use a large white lens?