Conclusions:

Two images I took this morning (31-OCT-2007).

In the PP I exaggerated a bit the black level and gamma for better sees the propeller.






So, no “Focal Plane Shutter Aberration” when the object moves parallel to the shutter path.

Just as our experts explained above in this tread!

Thanks for share your knowledge.


Best regards.
________________
Dirk TROTTEYN.
K10D+ Sigma 18-50 1:2.8 DC Lens.

Gentlemen,

First at all, many thanks to the participants for his rewarding concepts and his valuable time.

I forgot to mention than last night I did some basic maths about the blade tip travel at a given shot time for consistency with what we see in the images:

- Propeller circumference= 1.8 mts (dia) x 3.14 (phi)= 5.65 mts/turn
- Propeller rotation speed= 2500 RPM
- Propeller tip linear travel in 1 minute= 5.65 mts. X 2500 RPM= 14,130 mts.
- Propeller tip linear travel in 1 sec. = 14,130 mts./min / 60= 235.5 mts.
- Propeller tip linear travel @ 1/4000 s (obturation time) = 235.5 mts./sec/4000=0.0588 mts.
- Propeller tip linear travel @ 1/250 s (obturation time) = 235.5 mts./sec/250=0.94 mts.
- Propeller tip linear speed @ 1/1600 s (obturation time) = 235.5 mts./sec/1600=0.147 mts.

The final conclusion is, that the values obtained here, are coherent whit the images. So, the only meaning for the shooter speeds is the visible blade angle (not related with the curved prop pattern).

I will do some shots (will try) whit the propeller at the horizontal travel and the camera in normal position (or prop vertical and camera in portrait).

This phenomenon is not an issue for my and don’t bother in absolute, just a curiosity I wanted share with the forum members…


Best regards.
________________
Dirk TROTTEYN.
K10D+ Sigma 18-50 1:2.8 DC Lens.

Gentlemen,

I shot through the airplane´s propeller many times, and observed this:




Comparing whit images from a Sony DSC-W1, I noted that in the K10D shots, the propeller looks curved toward the rotation sense, when in the Sony shots look without this curious effect. I have hundreds of this kind of images all with the same curiosity and appearance.

As you can see in the image, the exposure time don´t affect this extraneous behavior, just change the visible blade angle (at faster shooting speed narrower visible angle). The propeller RPM are more or less the same in the four situations.

My vague idea about this effect is the different obturation systems; in the K10D the obturation perhaps is progressive (as the curtain of the film camera) when in the Sony perhaps is instantaneous, I don´t know…

Can you help elucidate these phenomena?

Thanks for your participation.


Best regards.
________________
Dirk TROTTEYN.
K10D+ Sigma 18-50 1:2.8 DC Lens.

Congratulations Prieni, a very well deserved first place!

Thanks Gartmore for the “highly commended” and for the very fast and good judging work.


Best regards.
________________
Dirk TROTTEYN.
K10D+ Sigma 18-50 1:2.8 DC Lens.

"Vestige of Diaguita-Calchaquí indians settlement of the 16 centuries in La Ciénaga, Tucumán, Argentina"





Best regards.
________________
Dirk TROTTEYN.
K10D+ Sigma 18-50 1:2.8 DC Lens.
[/b]

Good night Brian,


My critiques for the first image:

The intensity of details and the colors of the girl dress vie with her. I think all the attention must point to the model. The dress must be as simple as possible (in shape and colors).

The transition between the focused/non focused areas in the girl dress distracts me a little. I think that getting the entire dress in focus with a most compliant DOF will help.

The position of the right shoulder (hiding the girl jowl) would work better with a naked shoulder.

The image background is not the appropriate for me.

The beauty of the girl eyes are very good captured.

For the second:

Here, the girl dress is more appropriate.

I´m sure the girl will not be pleased with how his left arm sees (I can see some not good toned musculature) and appears to be a little bit fat (as a not very young girl). And finally, illuminating tenuously her left face for lightening a bit this heavy shadows.

As with the first image, the background don´t work, this time catch to much attention (I can see highlights in the bottles labels).

Photographing models is not always an easy challenge.

Sorry for be so hard critique, but I think is better and more constructive than a yielding one.

Brian, have success with model photography.


Best regards.
________________
Dirk TROTTEYN.
K10D+ Sigma 18-50 1:2.8 DC Lens.

I see the image a little flat. Perhaps a most generous cropping could help.

You get beautiful colors here.

Before investing in Lightroom give a test at Silkypix Developer Studio (free for 14 days full functionality).


Best regards.
________________
Dirk TROTTEYN.
K10D+ Sigma 18-50 1:2.8 DC Lens.

Alex you arrived at the better site in the Pentax world for learn. You will find here friendly people with a deep and great knowledge in all the photography matters, all around the forum, disposed to help you.

In your same conditions I arrived here three-four months ago, and I can say that this forum was converted for me in the best learning source…(and some books).

So, Mr. Alex Hirst, in what to my concerns, you are welcome.

What I can see in your images is that you have a good photographic eye.

Best regards.
________________
Dirk TROTTEYN.
K10D+ Sigma 18-50 1:2.8 DC Lens.

I think the shot is very good. The DOF worked well for give a good 3D image. Very nice colors!

But next time, look two times at the background.



Best regards.
________________
Dirk TROTTEYN.
K10D+ Sigma 18-50 1:2.8 DC Lens.

Dear hotshota4u2c,

You selected this image for upload to this forum section for any special reason. I think this special reason is just the originality of the image.

Generally a person shows here his photos with a particular interest; for exhibit to the public his photographic achievements; for get some comments and critiques from other photographers, and get in this way, a feedback for improve his art. And also (in some cases), for auscultate the public opinion about the aesthetics, morality, censorship, etc of his work.

What I mean in my comment and critique, is just what my eyes seen in your photography, and is IMHO, the input you were looking for.


Best regards.
________________
Dirk TROTTEYN.
K10D+ Sigma 18-50 1:2.8 DC Lens.