[ShawnH]

Hi, Can anyone tell me the MODSET file# for KS2 DEBUG mode?
I am wondering if it is possible to extend focus adjustment range. Even if it is not possible, I would appreciate the info so I can take look around. There is a huge amount info on this subject, but I could not find anything on KS2. Thanks!

[clackers]

A guy on DPR claims:

"Create on SD card file "00077860.551" with "[OPEN_DEBUG_MENU]" and LF char.
Create on SD card file "DEVELOP.MOD" exact 10 bytes long with binary content:
Hexbytes: 07 1A 02 0A 19 18 1B 1C 05 11
Turn off camera, plugin this SD card. Leave card door open. Hold "menu" button and turn camera on."

Source: Hacking Pentax Debug mode: Pentax SLR Talk Forum: Digital Photography Review

But if you require more than -10 or +10, the fault is a misalignment requiring mechanical adjustment, not some electronic shimming. It may even be at an angle.

[stevebrot]

But if you require more than -10 or +10, the fault is a misalignment requiring mechanical adjustment, not some electronic shimming. It may even be at an angle.

...or a significant issue with the lens (e.g. decentered, damaged, or unable to create a sharp enough image for AF).


Steve

[ShawnH]

A guy on DPR claims:

"Create on SD card file "00077860.551" with "[OPEN_DEBUG_MENU]" and LF char.
Create on SD card file "DEVELOP.MOD" exact 10 bytes long with binary content:
Hexbytes: 07 1A 02 0A 19 18 1B 1C 05 11
Turn off camera, plugin this SD card. Leave card door open. Hold "menu" button and turn camera on."

Source: Hacking Pentax Debug mode: Pentax SLR Talk Forum: Digital Photography Review

But if you require more than -10 or +10, the fault is a misalignment requiring mechanical adjustment, not some electronic shimming. It may even be at an angle.

Thank you so much.
When the center point is adjusted (+9), the extreme left and right focus points are not sharp. However if I use the center point and recompose then areas correlated with those points are sharp enough. This is with 35mm f2.4. Other lenses have the same issue but not to this degree. I guess it is a combination of mirror and lens as you suggested. I thought there may be a way to individually calibrate focus points I will run some tests using Live View (eliminating the mirror) to see if right and left of the image are soft. The sensor on KS2 is razor sharp. At least focus and recompose works well enough.

[Merv-O]

Thank you so much.
When the center point is adjusted (+9), the extreme left and right focus points are not sharp. However if I use the center point and recompose then areas correlated with those points are sharp enough. This is with 35mm f2.4. Other lenses have the same issue but not to this degree. I guess it is a combination of mirror and lens as you suggested. I thought there may be a way to individually calibrate focus points I will run some tests using Live View (eliminating the mirror) to see if right and left of the image are soft. The sensor on KS2 is razor sharp. At least focus and recompose works well enough.

True: the 20mp sensor on the K-S2 in my opinion is very sharp. In fact, I find it as sharp as the K-70's 24mp...if you think about it, the 4mp differential is small and the slightly larger pixels provide even more light capture.
If the 35mm f2.4 has the most aberration, what other prime lenses have you used that show slight softness. As you know, some lenses are designed (certain SONNAR designs, for example) to be "softer", though almost any digital exposure in center focus, is sharper than the average film SLR of yesteryear if calibrated equally, IMO.

[ShawnH]

True: the 20mp sensor on the K-S2 in my opinion is very sharp. In fact, I find it as sharp as the K-70's 24mp...if you think about it, the 4mp differential is small and the slightly larger pixels provide even more light capture.
If the 35mm f2.4 has the most aberration, what other prime lenses have you used that show slight softness. As you know, some lenses are designed (certain SONNAR designs, for example) to be "softer", though almost any digital exposure in center focus, is sharper than the average film SLR of yesteryear if calibrated equally, IMO.

Agreed, Ihave the K70 as well and cannot tell the difference in sharpness although K70 seems to have lower noise and higher dynamic range.My other prime is a FA 35mm f2 (BTW: Gorgeous image quality) same issue to a lesser degree. The lenses are sharp across the frame if using the center point. Live view confirms that. However when using a side focusing point the target area is very soft. I am just trying to get the maximum image quality I can from this camera. Knowing the limitation of your equipment is key in developing an effective technique.

[stevebrot]

However when using a side focusing point the target area is very soft

Conventional wisdom is to always use the center point for AF fine adjust and to not evaluate the adjustment at other than center. On the KS-2, the center point is both cross-point and f/2.8 sensitive*. The other points are f/5.6 sensitive and intrinsically less capable at detecting OOF than the center point. Note too that the two side points are not cross-point and are fully sensitive to horizontal/vertical lines only (sorry, I don't remember which...I believe vertical).

As for evaluation away from center, the purpose is to determine the on-axis focus performance and not to test for field curvature.


Steve

* Focus sensitivity is sort of hard to explain. Perhaps the easiest to say that the f/5.6 points "see"/detect OOF condition at f/5.6 or the lens maximum aperture, whichever is narrowest.

[Merv-O]

* Focus sensitivity is sort of hard to explain

That is why Pentax provides a fine adjustment mode for most of its cameras. Steve, I use the "SpyderLens Scale" adjustment tool, as I noted several of my FF lenses were a bit off focus and many needed at least +/- 3 in camera adjustment. I started using it on my APS-c lenses too, but noticed less aberration on those. The lenses that required the least adjustment were the Pentax LImiteds: the 70, 40 & 20-40mms' all worked with no adjustment. Perhaps ShawnH needs fine adjustment on some of his lenses as well.

[stevebrot]

Originally posted by stevebrot >>
* Focus sensitivity is sort of hard to explain

That is why Pentax provides a fine adjustment mode for most of its cameras.

Not quite, but you are quite correct in that AF fine adjustment is a good feature and worth doing if either front/back focus is evident in one's photos.


Steve

[ShawnH]

I started on this project to overcome field curvature on my Tamron 16-50. But it seems with the large number of factors in the chain such as sensitivity Cross/horizontal, f2.8/5.6, lens alignment, body tolerance etc it is best just to use live view or focus and recompose for off center composition.

[Merv-O]

I started on this project to overcome field curvature on my Tamron 16-50. But it seems with the large number of factors in the chain such as sensitivity Cross/horizontal, f2.8/5.6, lens alignment, body tolerance etc it is best just to use live view or focus and recompose for off center composition.

You can try that but it may not solve your elementary issue of unwarped field curvature. The bottom line on these zoom lenses is that they are going to have some significant "wavy" barrel distortion at their widest focal points. Sometimes you get the center "bulge" look too. Generally, these reasoanable cost zoom lenses operate best when in the middle of the range, but if you are expecting zero aberration, this lens may not be the one to use at its extremes.

---------- Post added 05-16-19 at 11:12 AM ----------

Not quite, but you are quite correct in that AF fine adjustment is a good feature and worth doing if either front/back focus is evident in one's photos.


Steve

Clearly, there appears to be wavy or barrel distortion and the 16-50 is well known to have this type of aberration at the extremes. The curvature will not disappear completely unfortunately. on that Tamron mini-zoom. (16-50mm)

[ShawnH]

I meant plane of focus curvature. The distortion is incurable...Thank you all for your help and support.
I know the mirrorless design does not suffer from this issue and "What You See is What You Get" is important to many. However I prefer the optical viewfinder because I strive against limitations to capture the scene that has caught my eye.