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04-23-2023, 03:07 PM   #16
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Image #1.

I want to make it clear, that absolutely no Post work was done on any of these images I am about to share with you. My focal point is where it has always been since I have

owned this camera, dead center and in this image right between the two dark lines on the structure over the bridge. Not included in EXIF data, White Balance with built-in

flash unit. Here goes. TT

As you can see, some barrel distortion on top of the picture frame, none on the bottom. Overall sharp as I like it with very good color rendition. Taken at 70mm.

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Last edited by Tonytee; 04-23-2023 at 03:12 PM.
04-23-2023, 03:10 PM   #17
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QuoteOriginally posted by pschlute Quote
He is talking about the hexagon
I’m not positive; my impression was that he has placed the focus point in a place on the image. And that that portion of the image isn’t in focus. So I think he’s talking about both… but heck I’m not sure now. I’m re-reading.
04-23-2023, 03:12 PM   #18
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QuoteOriginally posted by UncleVanya Quote
No he’s talking about both
I am only going on what I read............


QuoteOriginally posted by Tonytee Quote
It appears as though I misspoke regarding which light. I meant to refer to the In-Focus Hexagon
04-23-2023, 03:18 PM   #19
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Image #2.

Settings remain the same, only difference is I tried a little different composition, (well, it is an experiment) however the focal point is exactly the same. I set the lens on

a distance of 100mm although EXIF Data reveals 103mm, but shouldn't matter as far as being in focus is concerned. Again, no loss of resolution here and still very good

color rendition along with very decent exposure.

TT

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04-23-2023, 03:26 PM   #20
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QuoteOriginally posted by Tonytee Quote
Areas where the focal plane did not come into contact with, were sharper than areas that did come into contact with the Focal Plane. The center was alright, but not as sharp as the other areas that were afar from center.

Yes, the Auto-Focus Indicator was dead on the subject, shake reduction was not on because I used my tripod.
This suggests the af point selected was on a part of the subject that did not turn out in focus despite the green hexagon being full lit up (stated in another post).

What isn’t clear is how well the af fine tuning has been done. A zoom lens can squire tuning at different focal lengths and like any lens it can vary by focus distance as well.

Focus tuning is required due to PDAF sensors not being on the same plane as the sensor. Additionally the focus is achieved with the lens wide open so any stopped down focus shift is not directly measured. Mirrorless systems have changed this paradigm by using the sensor during viewing and allowing stopped down focusing - all of this makes the sensor part of the focusing system eliminating many sources of error. This doesn’t make mirrorless better - just different - but it does make this type of focus miss less likely.
04-23-2023, 03:31 PM   #21
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Image #3.

I must admit, this turned out better than I had expected and hoped. I cannot detect any loss of resolution, color rendition or even an exposure miscue. The graininess in the

blue areas are a reflection of an accurate reproduction since that is exactly how the painting in these areas are in reality. Again at 180mm, I am impressed with the efforts

of my gear. I have to say in all honesty that I would make some adjustments in post prior to uploading.

TT
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04-23-2023, 03:52 PM   #22
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Image #4.

Once again, even at 210mm, I believe I am impressed with the results. I do detect a marginal loss of resolution, color rendition and exposure however, it turned out to be

much better than I expected. Not ideal, but I would say within the realm of acceptability, which I understand is subjective.

Alright, my conclusion, for what it is worth:

If we could do a side by side comparison with the very first image I uploaded on this thread, (The Peruvian Lily) we could see a different subject, different colors, different

shooting lengths and most importantly, very different lenses. All things considered, the main difference is the lens used for the image of the Peruvian Lily. As others have

indicated, I should have gone with a higher shutter speed and higher number for my lens setting, however I do not see how that would correct the problem of having focus and

out of focus areas all over the image. DoF might assist in this case, but I do not believe it would be a panacea for all ills. The best thing for me to do at this point is to take

the same gear used on a Peruvian Lily at different exposure lengths and judge the results. Well, I do hope this project has been helpful to some as I do believe it has been

for me at least to the degree that there is nothing wrong with the K-7. In fact I failed to mention that all these images were taken handheld. )

Tonytee.

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04-23-2023, 04:10 PM   #23
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QuoteOriginally posted by Tonytee Quote
however I do not see how that would correct the problem of having focus and out of focus areas all over the image
Tony, the photo of the Lily ....how far was the front of the lens from the closest part of the plant ?

Assuming 3.5 foot from the closest part of the plant to the sensor..... at f5.6 you will have 1.5 inches of depth of field. There is your answer.

Last edited by pschlute; 04-23-2023 at 04:29 PM.
04-23-2023, 04:28 PM   #24
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QuoteOriginally posted by pschlute Quote
Tony, the photo of the Lily ....how far was the front of the lens from the closest part of the plant ?

Focusing in @80mm, I would guess at approximately 15 to 16inches. Hard to say using a different subject with different colors and lighting. That's my best estimate.

Tony
04-23-2023, 04:32 PM   #25
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QuoteOriginally posted by Tonytee Quote
I would guess at approximately 15 to 16inches
So DOF of less than 0.5 inch in that case.
04-23-2023, 06:05 PM   #26
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QuoteOriginally posted by pschlute Quote
So DOF of less than 0.5 inch in that case.
Exactly, and excellent point. Many thanks for bringing it up.

Tony

P.S. The more I read into your comment, the more questions I have. However, at this point rather than risk confusing the issue, the best thing for me to do is to

return to this place, find more Peruvian Lilies and do some target practice. I have had this lens for approximately six months and have experienced no issues at

all. It just so happened I noticed this issue prior to uploading and decided to investigate. Again, many thanks.

Tony

---------- Post added 04-23-23 at 06:48 PM ----------

QuoteOriginally posted by UncleVanya Quote
This suggests the af point selected was on a part of the subject that did not turn out in focus despite the green hexagon being full lit up (stated in another post).

What isn’t clear is how well the af fine tuning has been done. A zoom lens can squire tuning at different focal lengths and like any lens it can vary by focus distance as well.

Focus tuning is required due to PDAF sensors not being on the same plane as the sensor. Additionally the focus is achieved with the lens wide open so any stopped down focus shift is not directly measured. Mirrorless systems have changed this paradigm by using the sensor during viewing and allowing stopped down focusing - all of this makes the sensor part of the focusing system eliminating many sources of error. This doesn’t make mirrorless better - just different - but it does make this type of focus miss less likely.

Holy Canoli. Am I glad you mentioned AF Fine Tuning Adjustment. Me and my little pea brain are still struggling to get a handle on this one. I have taken 4 images using my

SMC Takumar F 70~210mm and K-7 body for all four images. I started out with a +10 exposure working my way down to -0 exposure increments. The only difference, which

was very, very marginal, in fact so marginal I had to use a magnifying glass with built-in LED lights to detect the difference between +10 and +5 exposures. I then thought,

to leave the setting at +10 and let it sail from there. Now, one problem that I am guilty of causing is not adjusting to the 9 point AF feature you mentioned. I need to figure

out how to do that. I assumed wrongly that anything in the Focal Plane Grid would be well in focus. Again, many thanks. Tonytee

Last edited by Tonytee; 04-23-2023 at 06:29 PM.
04-23-2023, 07:37 PM   #27
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Greetings,

I have taken the liberty to do some snooping on the Internet and located this thread. A good idea to read all reviews. I understand that these reviews were posted in the year 2010, which makes

everything even more exasperating. Cheers,

Tony


Frustrated with K-7 Auto Focus: Pentax SLR Talk Forum: Digital Photography Review
04-23-2023, 10:03 PM   #28
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Tony. You just need to read up on depth of field
04-24-2023, 12:15 AM   #29
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QuoteOriginally posted by pschlute Quote
Tony. You just need to read up on depth of field
Will do and thanks again.

Tony

---------- Post added 04-24-23 at 12:38 AM ----------

QuoteOriginally posted by pschlute Quote
Tony. You just need to read up on depth of field

pschlute, I have read up on depth of field and it is not something I am unfamiliar with. To prove this, I will upload an image I took on the 15th of this month, the same day I

took a photo of the Peruvian Lily. I will offer my own critique of the image so will see where I am coming from.

Thnx.

TT.
04-24-2023, 12:48 AM   #30
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One Pink, Columbine Flower.

In this image you will notice that the bottom right of the bottom petal has buds that are more in focus than the stamen (center of the flower). The center of the flower is where

my focal point is according to where the red, rectangular light has verified. This photo was taken with a two second delay self-timer while mounted on a tripod, indoors in a

Garden Center, no wind, not even a breeze. The area that is more in focus than the center of the flower, was not even in the Focal Plane.

Thanks again,

Tony.
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