[jeffrey.wetherill]

So am I safe to assume the following .... in general, using a DA lens on a FF camera reduces the megapixels to approx 15 because you are only using a portion (cropped area) of the FF sensor. It's NOT that image quality is being degraded. Rather, the megapixels are reduced because you are using LESS real estate (i.e. a portion) on the FF sensor. Is that correct?

Thanks again to everyone for their great insights around this topic.

Jeffrey
wethersnaps.com

[pres589]

What's square crop ala Firmware v1.3 like with a DA 15? Does this become a more useful proposition for those folks wanting a wide prime on the K-1?

[pschlute]

So am I safe to assume the following .... in general, using a DA lens on a FF camera reduces the megapixels to approx 15 because you are only using a portion (cropped area) of the FF sensor. It's NOT that image quality is being degraded. Rather, the megapixels are reduced because you are using LESS real estate (i.e. a portion) on the FF sensor. Is that correct?

Thanks again to everyone for their great insights around this topic.

Jeffrey
wethersnaps.com

Your thought pattern is correct, but it is the crop mode the camera is set to that dictates whether you will get a 36mp FFimage or a 15mp crop image. The lens itself has nothing to do with it, unless you set the camera to auto-crop mode.

Of course some DA lenses will not cover the FF sensor but that is an entirely different subject.

[bdery]

My understanding is that using a DA lens on the K1 will reduce an image to 15 megapixels? Is that correct? And if correct, what does that technically mean?

Crop mode is exactly that, a crop. You use the center area of the sensor, as if you had an APS-C sensor.

Also, will using a DA lens on the K1 in crop mode reduce the quality of an image?

It does not, the only difference is the reduced resolution.

One thing to be aware of is that if you use a DA lens in FF mode, you loose all auto lens correction functionalities.

[jatrax]

So am I safe to assume the following .... in general, using a DA lens on a FF camera reduces the megapixels to approx 15 because you are only using a portion (cropped area) of the FF sensor. It's NOT that image quality is being degraded. Rather, the megapixels are reduced because you are using LESS real estate (i.e. a portion) on the FF sensor. Is that correct?

No, your are still missing the point. The lens might make an image that is 36mp, 30mp, 28mp, 24mp, 15mp or any size in between. You have no way of knowing without testing each lens in FF mode. The CAMERA if set in crop mode will produce an image of about 15mp with ANY lens regardless of whether it is DA or FA or DFA. It does that by throwing away anything outside of the worse case APS-C image circle.

Lens has nothing to do with crop mode. That is purely a camera function.

Note that you can use a FF lens in crop mode and achieve smaller images, and a faster burst rate. But this has nothing to do with the lens, only the camera mode.

[Na Horuk]

Generally correct.
Think of it this way - FF is like 35mm film. And then you just take scissors and cut off the sides. So now you come down to APSC size. This is a function of film or digital sensor, not the lens. But some DA lenses will simply not cover the whole FF sensor with the image. So cropping makes sense in those, unless you enjoy having black edges.

[pschlute]

One thing to be aware of is that if you use a DA lens in FF mode, you loose all auto lens correction functionalities.

Really ? I have just put a DA* 300 mm on my k1 and the lens correction settings still show as on

[acoufap]

On this topic I focused with the following threads / posts. Maybe you're interested.

https://www.pentaxforums.com/forums/122-lens-clubs/86234-15mm-limited-control...ml#post3779899

https://www.pentaxforums.com/forums/190-pentax-k-1/320529-ff-mode-da15-crop-f...ml#post3635591

https://www.pentaxforums.com/forums/169-pentax-full-frame/336183-pentax-ff-ne...ml#post3860248


P.s. I love using my DA lenses in FF and square mode. But IMO it's mostly useful if you shoot raw and like to get the best out of your image in post processing.

[UncleVanya]

Really ? I have just put a DA* 300 mm on my k1 and the lens correction settings still show as on

That lens and the DA* 200 have special profiles that support FF use with lens corrections. I think that those two are the only two DA lenses that are specifically accommodated that way.

---------- Post added 01-09-17 at 03:06 PM ----------

Ooops! I forgot the DA 560 which is also setup with a profile for FF use.

Certain DA lenses are actually based on film-era optical designs, such as the DA* 200mm F2.8 and DA* 300mm F4. These two lenses, along with the DA 560mm F5.6, are actually officially supported by the K-1's full frame mode; the K-1 contains special full-frame lens correction profiles for these lenses in addition to the standard crop profiles used by all other Pentax DSLRs. Full frame mode will still need to be manually activated for these lenses.

Read more at: https://www.pentaxforums.com/articles/photo-articles/pentax-k-1-lens-compatib...#ixzz4VITZj1Zy

[pschlute]

Thank you Uncle.

[UncleVanya]

Thank you Uncle.

You are welcome.