[starbase218]

F4 is F4

Correct me if I'm wrong but iso 100 1/250" and f4 produces the same exposure on the Q and a D800.

True, but: a given focal length will produce different perspectives on fullframe and APS-C. So you adjust focal length to e.g. 200mm on fullframe and 135mm on APS-C. But now the DOF is shallower on FF. So you stop down to F5.6 on FF while you keep F4 on APS-C. To be able to use the same shutter speed, you increase ISO to 200 on FF while keeping it at 100 for APS-C. The FF sensor is larger anyway, so it can cope better with noise.

However, the difference between F4 and F5.6 is approximately 1.4 (square root of 2). But APS-C sensors are more than 1.4 times smaller than FF sensors. In case of Pentax, it's a 1.5x crop. So F5.6 on FF will still give a slightly shallower DOF than F4 on APS-C, given equivalent focal lengths of 200 and 135mm respectively. And noise performance on the FF sensor at ISO 200 will be slightly better than the APS-C sensor at ISO 100, assuming the sensor technology is comparable.

However, this point is moot, since we were trying to equalize the DOF. So although the FF performance is slightly better, its DOF will still be a little shallower as well.

A few cases where fullframe is better than APS-C:
- The detail level at the same ISO levels
- Ability to create a shallower DOF at wide viewing angles with the same F-number
- Ability to shoot in darker environments by using higher ISO's and the same F-number if you don't mind (or are actually aiming for) the shallower DOF

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Last edited by starbase218; 09-27-2013 at 12:16 PM.

[Andi Lo]

However, this point is moot, since we were trying to equalize the DOF. So although the FF performance is slightly better, its DOF will still be a little shallower as well.

I dont think it's moot. You've explained it quite well: FF can do basically everything APS-C can, and some more, with little added weight. (and cost if you want SR)

APSC has its good points as well, but claiming that FF has no advantage is absurd.

Where's the FF f5.6 lens that's lighter, faster, and cheaper than my APS-C f4 stuff (and also has equivalent microcontrast, rendering, and color rendition)?

I assume you mean:
DA 60-250 > Tamron 70-300 VC for a third of the price (slightly worse lens, but not a bad performer, one stop extra DOF at 70mm), or 70-200 /4 VR/IS for the same price (one stop extra DOF and shutter speed)

DA 12-24 > Canon 17-40L (for the same price, one stop extra DOF if you need), Nikon dont have a one under $1100 but tons of third party ones that perform well at f/8. To be fair this is where APS-C might be better value, as most of the FF offerings of equal price need stopping down to achieve results that equal even humble APS-C UWAs like Sigma 10-20; There's the Tokina 16-28 that if you buy used is rather affordable though.

DA 16-45 > Any film age FF standard zoom that has decent reputation (same price)

DA 15 > Nikon 20/2.8 (cheaper), not sure about Canon.

The size of all these FF lenses are slightly bigger but not unweildingly so.

[DogLover]

I think, originally, most people were calling the new flagship the 'K-3' because the K-30 was announced back then.. but Ricoh then spent money to align the lower tiers with the top (5xx)

No, it's because the last two flagships have been K-7 and K-5. Natural progression makes the next one K-3. Right or wrong, that was the general assumption.

[lytrytyr]

The size of all these FF lenses are slightly bigger but not unweildingly so.

Yet the FA 20 is smaller and lighter than the DA 14.

[Andi Lo]

Yet the FA 20 is smaller and lighter than the DA 14.

I think DA 14 even though it's a decent performer is too much of a rush job and shouldn't represent the best that APSC can offer (DA lims are). There are actually old 14mm/2.8 FF lens designs that are the same size as DA 14 (granted they're not amazing performers). Perhaps all pentax did is cut out the uneeded image circle area? I really doubt that it's as simple as that, but I wonder.

FWIW the MF Samyang 14mm is a great lens save the moustache distortion for a very good price in FF world

[starbase218]

I dont think it's moot. You've explained it quite well: FF can do basically everything APS-C can, and some more, with little added weight. (and cost if you want SR)

The point that was moot is that a FF camera has slightly better noise performance. Because, while that is true in my example, the DOF is not entirely the same anyway (using F5.6 on FF and F4 on APS-C). It is like using a slightly faster lens: you can slightly lower the ISO and achieven slightly better image quality.

Fullframe does give you some extra possibilities when compared to APS-C: you can create shallower DOF and resolution at the same ISO will be better. But if you want to shoot the same photos you have been shooting with APS-C (including the same DOF), don't expect an upgrade. The IQ will most likely be similar.

[Wired]

True, but: a given focal length will produce different perspectives on fullframe and APS-C. So you adjust focal length to e.g. 200mm on fullframe and 135mm on APS-C. But now the DOF is shallower on FF. So you stop down to F5.6 on FF while you keep F4 on APS-C. To be able to use the same shutter speed, you increase ISO to 200 on FF while keeping it at 100 for APS-C. The FF sensor is larger anyway, so it can cope better with noise.

However, the difference between F4 and F5.6 is approximately 1.4 (square root of 2). But APS-C sensors are more than 1.4 times smaller than FF sensors. In case of Pentax, it's a 1.5x crop. So F5.6 on FF will still give a slightly shallower DOF than F4 on APS-C, given equivalent focal lengths of 200 and 135mm respectively. And noise performance on the FF sensor at ISO 200 will be slightly better than the APS-C sensor at ISO 100, assuming the sensor technology is comparable.

However, this point is moot, since we were trying to equalize the DOF. So although the FF performance is slightly better, its DOF will still be a little shallower as well.

A few cases where fullframe is better than APS-C:
- The detail level at the same ISO levels
- Ability to create a shallower DOF at wide viewing angles with the same F-number
- Ability to shoot in darker environments by using higher ISO's and the same F-number if you don't mind (or are actually aiming for) the shallower DOF

I'm well aware of the differences in FOV and DOF, but the argument was made for "Faster" which typically means light. Hence why F4 is F4

[ElJamoquio]

Where's the FF f5.6 lens that's lighter, faster, and cheaper than my APS-C f4 stuff (and also has equivalent microcontrast, rendering, and color rendition)?

Amazon.com: Sigma 300-800mm f/5.6 EX DG HSM APO IF Ultra Telephoto Zoom Lens for Canon SLR Cameras: Camera & Photo

[regor]

Interesting to see the FF debate. Part of me wants FF, and if Pentax can fit a FF sensor in the K-3 body we're seeing with the same spec, 24Mpix etc., it would indeed be extremely tempting, almost hard to resist. Wonder if Pentax made the K-3 FF ready ? i.e. the only difference would be the sensor (and possibly power mgmt), which would mean that the K-03 already has a larger prism, viewfinder etc.

[johnmflores]

This thread went 8 pages before devolving into a FF debate. Must be some kind of record.

[konraDarnok]

Interesting to see the FF debate.

Is it really?

"FF's advantage is shallower DOF at a given aperture."

"That's true, but APS-C's advantage is a greater DOF at a given aperture."



Worst part is it's all reactionary. If tomorrow Pentax brought out a 1500$ 645D that could achieve DOF equivalences at narrower apertures than FF, people would just bitch about the loss of absolute light gathering ability. These people want Pentax to be Nikon or Canon; I can't figure out why they just don't switch systems. Frankly wears me out.

[starbase218]

I'm well aware of the differences in FOV and DOF, but the argument was made for "Faster" which typically means light. Hence why F4 is F4

F4 is F4, but that doesn't say much. Faster is a difference in time. If you don't mind (or even like) the shallower DOF, you can generally get away with setting the ISO twice as high on a fullframe camera, so you will need only half the shutter speed.

So, IMHO, the "speed" of a lens depends on more than the maximum aperture of that lens.

[repaap]

Oh boy,

I just went a way from this thead for a moment. It was fun before it. New camera is coming! Possibly best AF so far, can it be...
Now for last 2 pages, you guys make me scratch head a bit...what are you talking about.

As Was said, F4 is still F4. Someone else said, faster means less time...really! If you don't like too little Dof you can stop down a little and make it up with ISO..... Slower lenses are lighter, that is true!

Can't see speculation of K-3 anymore...thanks guys, you kind a spoiled it up for me. There is actually place for FF threads, you did know that... (unsuscribes from thread 3,2,1..)

[skankin_giant]

These people want Pentax to be Nikon or Canon; I can't figure out why they just don't switch systems. Frankly wears me out.

Very well put! enjoy Pentax for what it is, not what you want it to be!

Cheers, Steve

[Wired]

F4 is F4, but that doesn't say much. Faster is a difference in time. If you don't mind (or even like) the shallower DOF, you can generally get away with setting the ISO twice as high on a fullframe camera, so you will need only half the shutter speed.

So, IMHO, the "speed" of a lens depends on more than the maximum aperture of that lens.

Yes I agree. I'm just trying to figure out why all things being equal in exposure settings people say A lens is faster on FF