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06-03-2012, 04:20 PM   #556
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You know what should be done...
Something like kickstater, if you want pentax FF so badly then make a commitment in making a preorder.

I wonder how many of you're willing to commit $1500 or so into this so they can start making one.

Ps. i'm just talking about the camera now not the lenses.

06-03-2012, 04:29 PM   #557
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QuoteOriginally posted by tjk911 Quote
We're talking about fullframe digital sensors, not 35mm film. And one really simple example of how the APS-C or M4/3 ISN'T outperforming FF sensors is depth of field. A 70-200 f2.8 on APS-C and FF have different depth of fields, even after cropped to ensure same focal length comparisons.
Actually if you crop to ASP-C and use the same focus distance then the DOF is precisely the same, why would it be different?

The IQ between APS-C and FF isn't there really and i'm saying this with the work I've done on photos taken with 5D mark II and 24-70 L lens compared to my Pentax experience.

When compare value for money then i think the smaller formats easily win.
06-03-2012, 05:03 PM   #558
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Hmm, I'll have to test again but my experiences comparing my 16-50, 50-135 with Canon's 24-70 and 70-200 L2 showed significant depth differences. I've even tested the Takumar 55mm f1.8 on my K-5 and Canon's 5D with the m42 mount.

That said though, I'd love to see a kickstarter lol. But I'm skeptical Pentax's first FF would be priced at $1,500 when you factor in R&D and whatnot.

Also, quick google brought this link up which might be a lot more accurate than just my own tests.

Digital Camera Sensor Sizes: How it Influences Your Photography
06-03-2012, 05:09 PM   #559
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I would not think it would make any difference with FF vs APS-C either from reading but I have no way to compare. thanks for the info.

But then again, I am using primes like the 50mm f/1.2 so I probably would not pick up on it.

Shot done with a Auto Takumar f/1.8 and a old *stDS. Looks like plenty of creamy DOF here




Last edited by mikeossur; 06-03-2012 at 05:28 PM.
06-03-2012, 05:30 PM   #560
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QuoteOriginally posted by mikeossur Quote
I would not think it would make any difference with FF vs APS-C either from reading but I have no way to compare. thanks for the info.

But then again, I am using the 50mm f/1.2 so I probably would not pick up on it.
Depth of Field, Digital Photography and Crop Sensor Cameras - Bob Atkins Photography

Long read, but if you scroll down to the Relative DOF table you'll get what I mean. So if we go by that, your 50mm f1.2 L lens on APS-C would have "more DOF" than it being on a FF camera.

Atkins summarizes it quite well by saying

"This also explains why consumer digicams, some of which have sensors 1/6 the size of 35mm film, have such a large depth of field and one of the reasons why it's almost impossible to get blurred backgrounds when using them."

And answering Anvh's experiences, Atkins also elaborates it slightly after the Relative DOF table in the article.


APS-C Canon 30D left, FF Canon 5D right (50mm f1.4 lens shot @ f2.8)

Last edited by tjk911; 06-03-2012 at 05:36 PM.
06-03-2012, 05:47 PM   #561
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QuoteOriginally posted by Anvh Quote
I wonder how many of you're willing to commit $1500 or so into this so they can start making one.
I'd easily commit to that.

QuoteOriginally posted by tjk911 Quote
50mm f1.2 L lens on APS-C would have "more DOF" than it being on a FF camera.
Good practical example. This difference matters most at the widest apertures of lenses. And that's one property that would create further appeal to the FA Ltds.
06-03-2012, 06:28 PM   #562
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QuoteOriginally posted by tjk911 Quote
Hmm, I'll have to test again but my experiences comparing my 16-50, 50-135 with Canon's 24-70 and 70-200 L2 showed significant depth differences. I've even tested the Takumar 55mm f1.8 on my K-5 and Canon's 5D with the m42 mount.
Also, quick google brought this link up which might be a lot more accurate than just my own tests.

Digital Camera Sensor Sizes: How it Influences Your Photography
It's nice you put down a link about sensor size and that's precisely the problem.
You said "even after i cropped FF to match the focal length"
I assumed you meant you cropped the FF to match the APS-C so basiclaly you make the FF the same size as the APS-C meaning the difference is gone.
Or didn't you mean it that way?


Yeah kickstarter might be fun and it mean commitment, simply saying here that Pentax should make a FF is something else then actually putting some of your money towards it. I doubt not even half of the people that answered on facebook will do that...
06-03-2012, 06:31 PM   #563
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I cropped it down so the image size is the same, but the effect of the bokeh/DOF is different. Similar to the image I posted up there, if that makes sense?

06-03-2012, 06:36 PM   #564
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To go on a bit about DOF.

If you use the same lens and use the same focus distance then the DOF will be smaller on APS-C then FF, this has to do with the Circle of Confusion.
Basically you need to enlarge the APS-C more so things are a bit more critical.

But this bogus comparison because you will use 50mm lens differently on APS-C then on FF and so the focus distance will be different and you will get smaller DOF with FF because of that.


I tried to explain in another thread how a different mount could help APS-C in this regards by making faster lenses posiable but lets not go into that
06-03-2012, 06:42 PM   #565
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QuoteOriginally posted by tjk911 Quote
I cropped it down so the image size is the same, but the effect of the bokeh/DOF is different. Similar to the image I posted up there, if that makes sense?
I got it you tried to match the size of the bottle, but there are two ways to do that and both result are different.
If you leave the distance the same and only crop the bottle to the same size you will see that the DOF is the same as well.
But if you change the distance so that the bottles match without cropping you get a different result.

I assumed you did the first one but that isnt the case it seems.
06-03-2012, 06:47 PM   #566
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This wasn't my image actually, so I've no idea how the person got to it. I shot with my 16-50 and 50-135 on my K-5 and compared it to my friend's 24-70 and 70-200 on the 5D. Primarily because the FL is similar after the crop. But yeah, in those tests the DOF was still quite different, but they were subjective tests and I'm far from an expert in this.

I did read up on the CoC aspect and the whole deal about microns and such, but what I've read so far have just been really, really technical and it's kicking my ass. Lol
06-03-2012, 09:37 PM   #567
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Those formats with those lens are very comparable.
The DOF is more then small enough with the DA*50-135 but would like some more with the DA*16-50 but i got the Sigma 30mm f/1.4 for that now.
I wonder how small of a DOF can be really useable.

CoC isn't that hard to understand, it's maximum tolerance for what we will still consider sharp.
Because the image of APS-C will need to be enlarged more hen FF that means that our acceptance for sharpness is more critical/lower with APS-C then with FF.
Something that we might see as sharp (FF) might not be sharp anymore if we enlarge it more (APS-C).
Thats why the DOF is smaller with APS-C in my theoretical example.
06-03-2012, 10:44 PM   #568
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I am a little confused about this. As I understand it, the crop factor is just that. a cropping of the image. The lens is still the same distance from the film plane (err...digital plane ) The focus and DOF should be identical in both FF and 1.6x or 1.3x.... It is just matter of cropping down the visual area. Saying that a 50mm is a 62mm (or there abouts) when a crop factor is added is a little miss leading because there is no magnification involved as would be when you extend the focal length.

How do you like that Sigma 30mm f/1.4. It's too bad that Pentax has always been a little conservative about making fast lenses

Last edited by mikeossur; 06-03-2012 at 10:59 PM.
06-03-2012, 11:28 PM   #569
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QuoteOriginally posted by mikeossur Quote
It's too bad that Pentax has always been a little conservative about making fast lenses
That's probably because lens speed is exponentially proportional to lens size...
The FA Ltd focal lengths and speeds are conceivably the sweet spot for speed whilst keeping the lens compact.
I don't feel limited by f/1.8 much at all - and with FF, that will only get better.
06-03-2012, 11:50 PM   #570
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