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09-23-2014, 09:10 AM   #1
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With only APS-C glass, does FF offer any advantages?

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.

09-23-2014, 09:20 AM   #2
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Well, with a FF sensor even with lenses designed for APS-C, there will be an increase in resolution, but there will be a crop factor, so like using a FF lense on an APC-C camera, the crop factor is 1.5x respectively, so you have a 50mm lense designed for a FF camera, that is 50*1.5=75 so that lense on an APS-C camera is effectively equivalent to a 75mm lense. It would be the same thing for an APS-C lense on a FF camera. The only difference in that respect is a narrower FoV, beyond that there really aren't any negative effects, however, the full frame size isn't for everyone, in all honesty, unless you are blowing up images to some insane size, a 16MP APS-C sensor is more than enough, now with the FF at the same 16MP sensor (just in the 36x36 size) the FF sensor is going to have more resolution, and with the FF sensors typically we also see other advantages such as higher ISO and better NR.
09-23-2014, 09:22 AM   #3
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Your DA*55, 35 2.4, M100 are FF lenses, they will be wider, on FF than on APS_c, so your 35 2.4 will be a wide angle, not a standard lens, and you 55 will be standard lens, not a telephoto. You M100 will be like a 100mm on film, not like the 150mm it is on a crop sensor. If you planned it right, you could orchestrate two bodies to increase your range of lenses so that switching from FF to APS-c gave extended functionality at the wide and (FF) and long end (APS-c).

The notion that FF provides more resolution is only relevant when shooting with a full frame camera of equal or greater MP. D610= slightly more resolution but no worth paying for. 6D means less resolution, D810 means significantly more resolution...

The big thing in FF is it is the system where you can achieve the narrowest DoF if you fall into the extremely narrow DoF niche.
Anything else it's out-performed by a 645z and out convenienced by APS-c.

Last edited by normhead; 09-23-2014 at 09:31 AM.
09-23-2014, 09:23 AM   #4
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Some of your DA lenses might already work on full frame:
https://www.pentaxforums.com/forums/10-pentax-slr-lens-discussion/31629-da-le...ts-thread.html
And third part lenses are mostly full frame as well:
https://www.pentaxforums.com/forums/10-pentax-slr-lens-discussion/183420-curr...me-lenses.html

Either way, not really. The thing is, full frame is bigger and you get a wider field of view with the same focal length. So if you have a 35mm lens on crop, its not really wide angle, but on full frame, it is wide. I think this is the main draw to full frame. The other thing is shallow DoF. Since the sensor is bigger, the DoF looks comparatively more shallow.
So I would say if you do landscape photography or interior photos where you want wide angles, FF might have an advantage, even though these days you can find ultra wide lenses for crop sensors as well. And if you do portrait or abstract photography where you want really shallow DoF, then FF might have an advantage.

The benefits of noise performance and diffraction are less and less prominent, because technology is catching up and reaching its limits. But since FF cameras are usually expensive and top tier, they often have other features like fast burst rate or improved AF, metering. So when the FF comes, don't judge it only by sensor, keep in mind the other features.

All that being said, the K-3 is, as many say, the best crop sensor DSLR available. So I really doubt you would regret buying it, especially with some of the nice discounts we have seen recently. Of course, some are hoping that the K-3's price will go down when/if the FF is announced, but who knows. Maybe the price will go up, since new people will join Pentax now that it has an upgrade path
Oh, and I am sure if/when an FF comes, it will also allow a crop mode to use crop lenses. Or at least you can crop photos in post production. Then there is no difference, except some area of the sensor that is simply not being used with those lenses.


Last edited by Na Horuk; 09-23-2014 at 09:31 AM.
09-23-2014, 09:28 AM   #5
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I've been struggling a little with this question and I have a ton of glass that covers the FF circle. If you don't have glass that will cover FF, then there really isn't any point in going FF (unless you buy new glass too). The only sure advantage of FF, I think, is better depth of field control. You MIGHT get more resolution, or you MIGHT get bigger pixels with hte same resolution (potentially better high iso performance) or some combination. The resolution advantage of, say 24 vs 36 mp, would be the ability to print larger. But that's controlled by lines/inch, which means your advantage is a function of the square root of the change. 24 to 36 is 50% more pixels, but only 22% more lines/inch. If the max print size at 300 dpi is 13"x20" for 24 mp, the max for 36 mp is 16"x24". You can print lower than 300 dpi, or resize the image, but like-for-like will always mean about 22% larger.

If I'm completely daft, someone smarter than me please jump in and correct me.
09-23-2014, 09:32 AM   #6
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You have three lenes that will work with FF.. DA* 55mm, DA 35mm f/2.4, and M 100mm.. not a bad start.
https://www.pentaxforums.com/forums/10-pentax-slr-lens-discussion/31629-da-le...ts-thread.html

This might help..
QuoteQuote:
Full frame cameras

PROS

  • take full advantage of wide-angle lenses
  • allow the photographer to move in closer to the subject and so reduce the depth of field, which can mean you can blur away distracting backgrounds more
  • the larger sensor has manufacturing advantages that can result in less noise in your images
  • great for landscape photography and often preferred for street photography, art photography, real estate photography or product photography

CONS


  • more expensive than APS-C
  • more difficult to fill the frame with distant, easily-spooked subjects like birds

APS-C cameras


PROS

  • less expensive
  • telephoto lenses behave like something even more telephoto
  • great for sports/wildlife photos and macro where the action can be at a greater distance

CONS


  • wide angle lenses lose some of their wide-angle effect
  • backgrounds can be slightly more in focus and therefore slightly more distracting
  • the smaller sensor can sometimes result in a little bit more noise in your photos
Mark David | APS-C vs full frame

Edit: Wow.. there were zero replies.. then went looking for pro and cons and I guess it took me awhile.
09-23-2014, 09:34 AM - 1 Like   #7
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Kinda depends if Pentax's mythical FF has a crop mode like Nikon's. If you hook a DX lens up to a Nikon FF body, it will use an APS-C sized piece of the sensor rather than the full sensor. On Nikon, the 24 megapixel FF sensor gives a 10 megapixel APS-C sensor, the 36mp d800 gives a 15mp or so crop mode. But you can also turn off crop mode, use the full sensor, and just get an image with varying amounts of vignetting that you can crop in post.
09-23-2014, 09:41 AM   #8
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QuoteOriginally posted by narual Quote
Kinda depends if Pentax's mythical FF has a crop mode like Nikon's. If you hook a DX lens up to a Nikon FF body, it will use an APS-C sized piece of the sensor rather than the full sensor. On Nikon, the 24 megapixel FF sensor gives a 10 megapixel APS-C sensor, the 36mp d800 gives a 15mp or so crop mode. But you can also turn off crop mode, use the full sensor, and just get an image with varying amounts of vignetting that you can crop in post.
Good point.. forgot about crop mode.

09-23-2014, 09:56 AM   #9
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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 you get except for some insanely expensive glass. by putting FF lenses on an APS-C sensor, you effectively crop out the "unwanted" edges and are left with a "sweet spot" of high IQ. So not only does your 300mm lens act like a 450mm lens, you get the higher resolving power of the center extending to your sensor edges.

Another example, I had a Sigma 12-24 that I absolutely loved because as an 18-30mm lens, it was brilliant, with very very little edge distortion on an APS-C sensor, even at the UWA focal length. On a full frame, it would look very similar to the Sigma 10-20 and I'm not sure I like my tree branches at 45 degree angles along the borders.
09-23-2014, 09:57 AM   #10
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QuoteOriginally posted by Tesla Quote
This might help..
Mark David | APS-C vs full frame

Edit: Wow.. there were zero replies.. then went looking for pro and cons and I guess it took me awhile.
Thanks, a nice site.
09-23-2014, 10:32 AM   #11
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compared to a 36mp sensor, the higher pixel density of 24mp crop sensors gives you lower color density, lower dynamic range, lower color depth, less resolution, much worse iso performance, and less latitude... in short, inferior performance, in every possible sensor measurement there is.

36mp can be very advantageous for things like noise and cropping, you have to experience it to believe it... but the resolution gain from 24mp to 36mp isn't linear... 50% more pixels gives maybe 22% more resolution? that's one reason why the 645z has such a horrible price vs. performance ratio.

aps-c wins for price vs. performance, imho... the lenses side of the equation, in particular, favors aps-c.
09-23-2014, 10:44 AM   #12
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QuoteOriginally posted by nomadkng Quote
every lens gets weaker in IQ or distortion the closer to the edge you get except for some insanely expensive glass. by putting FF lenses on an APS-C sensor, you effectively crop out the "unwanted" edges and are left with a "sweet spot" of high IQ.
That's the theory.

In practice, it can be different.

If you look at the resolution curves for the A20/2.8 that I posted on my review of that lens
SMC Pentax-A 20mm F2.8 Reviews - A Prime Lenses - Pentax Lens Reviews & Lens Database (Aug. 22, 2013)
you may notice the notorious "mid range dip" at the edge of the APS-C field,
where the performance starts improving again as you move to the edge of FF.

---------- Post added 09-23-14 at 12:51 PM ----------

QuoteOriginally posted by normhead Quote
The big thing in FF is it is the system where you can achieve the narrowest DoF if you fall into the extremely narrow DoF niche.
Anything else it's out-performed by a 645z and out convenienced by APS-c.
The other thing about FF is that wide angle lenses can be more compact.

Compare the FA20/2.8 or A20/2.8 (optically equivalent) with the DA 14/2.8.
The FF lenses for the same equivalent view angle are smaller.

Also, you could plan a compact two-body kit, one APS-C and one FF camera,
and then carry fewer lenses to cover a given range,
since the same lens would give different equivalents on the different bodies.

For instance, instead of an FA 31 and FA 43 on APS-C,
you could use just take the FA 43 and switch it between FF and APS-C.
09-23-2014, 10:53 AM   #13
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QuoteOriginally posted by nomadkng Quote
every lens gets weaker in IQ or distortion the closer to the edge you get except for some insanely expensive glass. by putting FF lenses on an APS-C sensor, you effectively crop out the "unwanted" edges and are left with a "sweet spot" of high IQ.
that's what i always thought, as well... however, if you look at the lens tests for the new tamron 150-600, it performs significantly better on full-frame than it does on aps-c.

that doesn't bode well for the upcoming 50mp ff sensors, perhaps.

QuoteOriginally posted by nomadkng Quote
So not only does your 300mm lens act like a 450mm lens
since the focal length did not change, there is no increase in zoom length, the only thing you are seeing there is the increased pixel density... which was detrimental, in the case of that tamron zoom.
09-23-2014, 01:03 PM   #14
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Advantages of full frame. Bigger pixels mean better ISO performance. Also smaller abberations (halo and colour fringing) They are actually the same, but since your FOV is wider they are relatively smaller. When using lenses that do not outresolve an aps-c sensor, they might outresolve a full frame sensor (because of bigger pixels) so your image will be sharper. It will also be easier to find wide angle primes for full frame (in the used market). You also have relatively more DOF to play with, again because it is narrower relative to the frame. I would advise to just keep your aps-c camera to use your zooms and effectively double your number of primes. a 50 is a 75 on aps-c (i am talking about equivalence so hold your horses people) and a 135 is a 202. aps-c bodies are cheap and you benefit from higher resolution than crop mode and your tele work will have more reach. It makes sense to have more bodies as well as more lenses due to different characteristics.
09-23-2014, 01:10 PM   #15
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QuoteOriginally posted by lytrytyr Quote
That's the theory.

In practice, it can be different.

If you look at the resolution curves for the A20/2.8 that I posted on my review of that lens
SMC Pentax-A 20mm F2.8 Reviews - A Prime Lenses - Pentax Lens Reviews & Lens Database (Aug. 22, 2013)
you may notice the notorious "mid range dip" at the edge of the APS-C field,
where the performance starts improving again as you move to the edge of FF.

---------- Post added 09-23-14 at 12:51 PM ----------



The other thing about FF is that wide angle lenses can be more compact.

Compare the FA20/2.8 or A20/2.8 (optically equivalent) with the DA 14/2.8.
The FF lenses for the same equivalent view angle are smaller.

Also, you could plan a compact two-body kit, one APS-C and one FF camera,
and then carry fewer lenses to cover a given range,
since the same lens would give different equivalents on the different bodies.

For instance, instead of an FA 31 and FA 43 on APS-C,
you could use just take the FA 43 and switch it between FF and APS-C.
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...)
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