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09-23-2014, 01:28 PM   #16
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QuoteOriginally posted by kp0c Quote
Just to be clear, are you saying that you'd rather have to carry one lens and two camera bodies that one camera body and two lenses? I'm not sure I'd agree with that. I see what you mean though, just not sure it could be seen as a true advantage.

Edit : I was referring to the idea of having a "compact kit" in my comment (2 cameras 1 lens versus 1 camera 2 lenses...)
That's an illustration of a point. For example, instead of carrying a 21, 31, 50,70, 135, 200..400, you carry a 31 ( Same as 21 on APS-c, a 70 for the FF same as 50 on APS_c, a 135, same as 200 on APS-c and 400, same as 600 on APS_C.

Thus with a 31, a 70, a 135 and a 400 and two bodies, you can leave 4 lenses at home...

Imagine 31, 77, 135 and 300 with the 1.4 TC and 1.7 TC. You cover everything in APS-c 21 mm to FF 630mm in prime lenses with 4 lenses and two TCs and have everything top quality glass, except the 135 is imaginary. It could be an efficient way to work.

09-23-2014, 01:54 PM   #17
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QuoteOriginally posted by kp0c Quote
Just to be clear, are you saying that you'd rather have to carry one lens and two camera bodies that one camera body and two lenses? I'm not sure I'd agree with that. I see what you mean though, just not sure it could be seen as a true advantage.
I'm thinking of a kit with two bodies, and a range of lenses.

At the moment, for serious shooting, I take two APS-C bodies and 5 or 6 lenses.
That could be reduced to one FF body, one APS-C body, and 3 lenses.

It's usually good to have two bodies.
09-23-2014, 02:34 PM   #18
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Those of you saying that larger pixels equal better quality.. while this is true in theory, modern technology is pushing these limits. Crop sensor is quite acceptable, and modern FF cameras have photosites almost as small anyway. Also, the 12MP Sony shows that significantly larger photosites only offer a relatively small improvement. And that is 12MP, full frame, special purpose sensor. A regular FF sensor with 24-36MP... meh
09-23-2014, 03:11 PM   #19
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Agreed, that's a good resource. Thanks, Tesla.

Read all the informative and helpful responses, and then read your original question again, because I felt that somehow I had gotten lost in some of the numbers and "better this, better that" replies, as well as the legitimate, but also rather funny 2-body-1-lens or 2 lenses-1-body exchange.You had the words "real benefit" in your original question. Depends on what you need it for, and what real benefit means. You also said something about technical at the end, so maybe I'm off track.

Real benefit means the same for me as 20% less fat in ads. Compared to what? For me it's not a really useful concept, because qualitative aspects such as perception and psychology and preferences and subjectivity and functionality and bokeh are part of the mix. Some objective real benefit exist, sure, but in other cases an aspect is more of a subjective benefit. Downloaded a 645Z image a while back and it's huge, and then, while madly scrolling through it in LR at full size, I realized that the size in itself has some serious drawbacks. I sometimes print a few 8x10s for my office and study walls, but as someone who is essentially a hobbyist, full frame presents zero attraction to me right now. Don't "need" it. My K5 is still fine. I might be excited for a while by the large files of a full frame camera, and the more flexible depth of field and sharper edges and corners and all the other "better" criteria that we photographers can get excited about, but ultimately a great or even just a personally satisfying picture probably has little to do sensor size. I wouldn't be happier with a fancy full frame. The next and the next models are going to make sure of that. I like APS-C just fine. I also try to learn about and work within the confines of whatever I use. Full frame opens some doors, but closes others.

Comparing the K5 output to that of the DS, some of my favourite images are still those taken with the DS. I will probably end up with a full frame one day, not because it's "better" (I've stopped drinking marketing kool-aid a long time ago), but because a used one will be cheap enough after 3 or 4 years on the market (how old is the K5 now?) that it won't be a big decision to change tools. Ultra HD TV, anyone?

09-23-2014, 03:16 PM   #20
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Actually with only APS-C lenses, you probably will get worse performance on a crop-mode FF sensor. Right now APS-C has higher pixel density, so you get more pixels out of the center of your lens on an APS-C sensor than a FF sensor in crop mode. The D810 gets 15mp out of APS-C, whereas you can get 24mp with a native APS-C sensor.

Now - there's nothing wrong with 15mp for 99.99% of photographic work. My first real DSLR was 10mp, it worked fine. It was actually a pretty modern body at the time, too. And to get those extra few APS-C megapixels you're adding on a whole second body. The question is more "can you live with only 15mp if it means you don't have to immediately replace those lenses"?

Seriously though what self-respecting Pentax shooter doesn't own any FF lenses though? No nifty fifty, no FA Ltds, no K/M/M42 lenses, nothing you picked up at a garage sale or thrift store? Really nothing? The above question aside, I'm actually kind of impressed with your self-control.

Last edited by Paul MaudDib; 09-23-2014 at 06:31 PM.
09-23-2014, 04:05 PM   #21
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FF does not always translate into additional resolution. The extra vignetting full-frame lenses have often takes away some of the resolution advantage the FF format may sometimes offer over APS-C.

Not only does FF give you extra vignetting, but often extra distortion too, all of which are not good for resolution, especially if they require software correction.

Pic below related, a typical example of FF format lens problems compared to APS-C. From slrgear.com's review of the very desirable [to me] full-frame Sigma 24-105 f4 zoom. The problems are most acute wide-open, of course, which is where you often want to use such lenses.
09-23-2014, 04:14 PM   #22
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QuoteOriginally posted by rawr Quote
FF does not always translate into additional resolution. The extra vignetting full-frame lenses have often takes away some of the resolution advantage the FF format may sometimes offer over APS-C.

Not only does FF give you extra vignetting, but often extra distortion too, all of which are not good for resolution, especially if they require software correction.

Pic below related, a typical example of FF format lens problems compared to APS-C. From slrgear.com's review of the very desirable [to me] full-frame Sigma 24-105 f4 zoom. The problems are most acute wide-open, of course, which is where you often want to use such lenses.
Yes, this is because you're shooting a FF lens with an APS-C sensor - you're getting the "sweet spot effect". You're using the center of the lens which is the sharpest and least distorted part. You can get a similar effect on full frame - take one of the high-end 645 or 67 lenses and shoot it with an adapter. Your FF sensor uses the sharpest center part. Lots of great astrophotography photos get taken with 6x7 lenses.

Now, where this effect breaks down is wide-angle lenses, because of the crop factor's effect on focal length. A 18mm FF lens is crazy wide on FF. Back in its day it was a special purpose lens that inevitably accepted some compromises like distortion and so on, which was acceptable, because it wasn't something you could get by any other means. But on APS-C, a 18mm is just a semi-wide lens, you can go buy yourself a Sigma 19/2.8 and it'll be sharper, less distorted, and $500 cheaper.

Really high-end modern zooms like the Canon 17-40 aren't total crap on APS-C, but you can still do better for less money.

And this effect doesn't exist at all if you are shooting APS-C lenses on APS-C. Only when you're using a lens with an oversized image circle.

Last edited by Paul MaudDib; 09-23-2014 at 04:19 PM.
09-23-2014, 04:44 PM   #23
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QuoteOriginally posted by Paul MaudDib Quote
you're shooting a FF lens with an APS-C sensor
Of course. But I think - maybe I am wrong - if I took a 24MP Nikon FF and a 24MP Nikon APS-C, and mounted the same Sigma 24-105mm on both, and shot some nice scene wide-open at 24mm, while the resolution in the centre may be about the same, the average level of resolution across the frame (taking into account corners and centre) would be lower on FF, due to the extra vignetting and distortion.

The FF lens would be 24mm f4 whereas the APS-C shot would be 36mm f5.6 'equivalent' with a narrower field of view, of course, but even accounting for that I think the FF shot would, overall, end up looking less crisp than the APS-C, particularly for scenes where one might notice soft edges.

09-23-2014, 05:38 PM   #24
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If I ever get an FF a lot of these questions are going to get answered. But then I'm retired and have no life... other people have places to go and things to see. I'm guessing this kind of thing is pretty far down on the "things to do" list.
09-23-2014, 05:51 PM   #25
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QuoteOriginally posted by rawr Quote
Of course. But I think - maybe I am wrong - if I took a 24MP Nikon FF and a 24MP Nikon APS-C, and mounted the same Sigma 24-105mm on both, and shot some nice scene wide-open at 24mm, while the resolution in the centre may be about the same, the average level of resolution across the frame (taking into account corners and centre) would be lower on FF, due to the extra vignetting and distortion.

The FF lens would be 24mm f4 whereas the APS-C shot would be 36mm f5.6 'equivalent' with a narrower field of view, of course, but even accounting for that I think the FF shot would, overall, end up looking less crisp than the APS-C, particularly for scenes where one might notice soft edges.
It depends on the lens, and the specific resolution at each area of the image circle. You can throw as much sensor resolution at a lens as you want, but if the resolution isn't sharp enough you're not getting anything. And the resolution naturally varies across the image circle.

I don't have real resolution-per-area numbers here so bear with me. Your implicit assumption here is that there's enough resolution in the center of the image to fully utilize a 24mp sensor - so the lens is producing 0.06 megapixels/mm^2 from the center out to the edge of the APS-C frame.

However it's also possible that the lens is not sharp enough to deliver that resolution - let's say that it delivers 0.041 megapixels/mm^2 (36mp across full frame). In this case the 24mp crop sensor is capturing the same number of pixels - but you have a softer image. So in that case the lens might "perform better" on FF in the sense of delivering more megapixels of real resolution, because you're capturing more megapixels out of the corners rather than pumping the center super hard.

A real-world way this plays out is consumer-grade scanners. A V500 is not a fabulous scanner, it peaks at something like 1600dpi real resolution. With a small image circle (35mm negative) it kinda struggles. But give it a big image source like a MF negative and it does pretty well. Now, a CoolScan 4000 is a great scanner - it can pull a lot more resolution out of a 35mm negative. Does that mean it gets a better image from a MF negative than a V500? Well, maybe - assuming there's enough resolution in the original negative to start with. If it's a box cam negative then even a drum scan isn't going to be able to magic up resolution that doesn't exist on the film. And all the DSLR megapixels in the world won't magically produce resolution that the lens can't produce.

(In that scanner example, the answer is usually yes, because the V500 is pretty junky and 1600dpi isn't many lp/mm)

This is obviously an incredibly gross simplification and there's a number of confounding factors. APS-C sensors run into the diffraction limit much faster - a lens needs to be delivering enough resolution to saturate a 24mp APS-C sensor by f/5.6, whereas on a 24mp FF it's closer to f/8 (due to the larger physical size of each individual sensor pixel). Past that the primary limit is going to be diffraction, which rapidly eats your resolution. This is why the Q is such a piece of garbage - it's diffraction limited at a very wide aperture.

It's obviously easier to produce resolution as the lens stops down. So it might not produce enough resolution until it's too small an aperture for APS-C to really use it. Or if a lens is really fast and really sharp wide open, it's possible it could be "better" on APS-C until it hits the diffraction limited aperture, then "better" on FF past that. These kind of things make it hard to give you a definitive "yes" or "no" answer - it's really down to the specific lens and how it performs across the frame at each aperture.

Another caveat is that this makes all your lenses have a narrower FoV, of course. That's really the biggest rub with APS-C, you need a super-wide before you even have a semi-wide left after the crop factor, and old superwides tend not to be the best lenses for pixel peeping. Good luck with M4/3 - a 25mm lens is a 50mm equivalent normal lens. Nice if you want long focal lengths though.

Last edited by Paul MaudDib; 09-23-2014 at 06:37 PM.
09-23-2014, 08:05 PM   #26
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QuoteOriginally posted by Paul MaudDib Quote
This is obviously an incredibly gross simplification and there's a number of confounding factors. APS-C sensors run into the diffraction limit much faster - a lens needs to be delivering enough resolution to saturate a 24mp APS-C sensor by f/5.6, whereas on a 24mp FF it's closer to f/8 (due to the larger physical size of each individual sensor pixel).
Due to the geometry involved, diffraction actually follows equivalent aperture. So you could say that for a given FOV and DOF you have equal diffraction softening, all else the same; independent of sensor size.
09-23-2014, 08:51 PM   #27
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Oh, so complicated! And this is why I enjoy film.

Now, where's that roll of Portra I had kicking around here? Check! ME Super? Check! 18-35mm zoom? Check! Ridiculously awesome viewfinder? Ohh, check indeed!
09-23-2014, 09:14 PM   #28
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QuoteOriginally posted by nomadkng Quote
here's another thought, one that I've been using to justify possibly not switching to FF:

every lens gets weaker in IQ or distortion the closer to the edge
This is very lens-dependent, though, and shouldn't be a blanket reason to fear a larger format. For example, my 20 f/2.8 D is sharper at the edges on FF than my beloved 15mm Limited is on aps-c.

---------- Post added 09-23-14 at 10:27 PM ----------

QuoteOriginally posted by Newtophotos Quote
For those with only APS-C sized lenses (see my signature) is there any real benefit of upgrading to the (supposedly) coming Pentax FF camera body over just upgrading to the K-3 body? Will there be a no advantage over the K-3 and keeping the same glass if the new FF has a selectable AA filter and consummate increase in megapixel count (K-3 = 24, 24x1.5 = FF has 36 megapixels)? I know this is all speculation on the FF, I'm wondering more the technical considerations.
Shooting aps-c lenses on a FF body is possible in any of three ways, each with different level of compromise.

Assuming the Pentax FF body offers auto 1.5x and select-able crop modes (I'm certain it will) ...

1) Use 1.5x auto-crop mode

- The lens/body basically becomes an aps-c combo. With a current 36MP FF Exmor sensor, you get about 15.5MP in the frame with very-slightly higher DR and SNR than a native K5 or D7000 image. A new 54MP sensor would match the K3 in the same manner (a 24MP FF sensor would only give you about 10MP in the frame.)

- Your FPS will go up, less space will be used on the card, and IQ will still likely be exceptional

- unless you're working with a 54MP FF sensor, you'll have less resolution than what the K3 gives you natively. In some cases it might matter to you... But 15MP on the target is still a lot of MP.

- You give up the DOF control advantage as well - it's fully an aps-c shot in that respect also.


2) Use some other auto-crop ratio, like 1.2x or 3:2 (if offered)

- Many and possibly most 'aps-c' lenses will cover a bit more than the aps-c image circle - sometimes a slightly less-drastic auto-crop gives you perfect images, easily (no manual work needed to frame)


3) Shoot in native 'FF' mode, crop manually in post later.

- Lenses will vignette more the further away from the subject you are, and the more you close down the aperture, so it may not make sense to auto-crop everything to the same size - you may want to tweak it manually depending on the subject, amount of vignetting you see, etc.

- Most artistic control, but also most time spent.

I've used auto-crop on a 12MP D700 and a 36MP D800 - it's much more appealing on more MP but you may be surprised how it really is a nice option to have regardless of available MP. It makes the transition to FF that much easier on you and your wallet and personal lens-replacement timeframe.

Fun times ahead!

PS here's an example of auto-crop with my Sigma 50-150 2.8 HSM (an aps-c lens like the DA 50-135) taken in 1.5x crop mode on D800 - his grandma has this in B&W at 11x16 and it looks really nice:



.

Last edited by jsherman999; 09-23-2014 at 09:57 PM.
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