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Forum: Pentax DSLR Discussion 1 Day Ago  
The K20D Club
Posted By Ian Stuart Forsyth
Replies: 529
Views: 81,710
A Antheraea-Polyphemus Moth photographed against a window using a flash and the sigma 70-200 2.8


With its rather large wingspan of 41/2 inch its pretty hard to miss one of these fellows
Forum: Non-Pentax Cameras: Canon, Nikon, etc. 4 Days Ago  
Canon R5 under development plus 9 news RF lenses in 2020
Posted By Ian Stuart Forsyth
Replies: 156
Views: 5,881
Being that this lens is for a FF camera that 800mm 11 will give you the same level of low light performance as a 500mm 7.3. while this is not the fastest lens it would be a welcome tool to someone that wants a prime lens that will not break the bank at $899 and as a second lens when someone does not need the use of a 800 5.6 all of the time.
Forum: Pentax K-1 07-04-2020, 12:16 AM  
Sensor Cleaning Advise K1MII
Posted By Ian Stuart Forsyth
Replies: 30
Views: 1,658
I have started to use LensPen for more of the hard stains on the sensor. For the longest time was hesitant to use one but now I never used a wet system on any of my camera bodies.

It is worth noting that I feel that the surface of the sensor is less tacky (prone) contaminates sticking to the sensor. When I was photographing sensor after they where cleaned using the Pen I never had any dust that would take a wet cleaning to remove most of the time a quick blow or a brush at the worst.

Even when the sensor was left out overnight all I really needed to use was the blower for most of the contaminates. Before most of the time i needed several passes with a wet system before photographing them.

When cleaning the sensor it was dead skin flakes that was the hardest to clean off as they are flat and contain some oil using a wetwipe seemed to adherer them to surface of the sensor
Forum: General Photography 06-27-2020, 02:30 PM  
At Long Last...Sunny 16
Posted By Ian Stuart Forsyth
Replies: 39
Views: 1,218
While there is a variation in output from the sun and also the atmosphere haze these most of the time are rather small when compared to change the angle of the rays that reach a surface if we go beyond 45 degree angle to the light source this can vary greater than 1 stop that's half the density of light illuminating a subject and much more than what the atmosphere is filtering out.
Forum: General Photography 06-27-2020, 12:40 PM  
At Long Last...Sunny 16
Posted By Ian Stuart Forsyth
Replies: 39
Views: 1,218
While the difference in the distance between the sun and the subject has not really changed the density of the light striking the surface will vary with the angle of the subject it is striking , tilt the surface of the target further away from 90 degrees to that light source and the density of the light striking the surface will decreases thus less light is being reflected by that surface (for photography) or absorbed by that surface (increasing the temperature).

In photography if you are trying not to blowout a white surface it is best to meter off of the white surface that is nearest to 90 degrees to your light source.

There is also the problem with white balancing if your target is 90 degrees to your light source like the sun as you white target surface tilts away from that right angle to the sun a secondary light source can produce a white balance shift to another color. On a sunny day this could be the blue sky shifting that white surface to a bluer tint as the density of light coming from the main light source the sun has decreased and your second light source the blue sky is shifted to the more dominate light source.
Forum: Photographic Technique 06-21-2020, 11:40 AM  
A dangerous question
Posted By Ian Stuart Forsyth
Replies: 20
Views: 1,412
The way I always look at photography is that its for my enjoyment, what I like often times is not what other find enjoyable.

Overt the last 10 years I have picked challenges to photograph, for the last couple years one was to photograph snowflakes. The technical challenges in doing this also gave way to finding new ways I can apply them to other bodies of my photography. If I had narrowed my focus onto a style of work I would never open doorways into other things that are enjoyable in photography.

How you are processing also falls into what you like. we have to look no further than tonal mapping, I find it atrocious but its not hard to find 1million followers that would like it.

However I do find I like enjoyed many of your photographs :)

Much of the time the enjoyable content of photography is lost to the person viewing the final image.
Forum: Photographic Technique 06-05-2020, 11:49 PM  
PDAF Struggles with Black?
Posted By Ian Stuart Forsyth
Replies: 40
Views: 1,931
Some DSLR have this feature, it will locate the face a focus on it, when your are closer lets say for head and shoulder portraiture it some will select the nearest eye to the camera
Forum: Pentax News and Rumors 05-30-2020, 10:53 PM  
Samyang is clearly phasing out it's K-mount support now.
Posted By Ian Stuart Forsyth
Replies: 234
Views: 11,113
Actually its hard too make, as there is a great deal on the used market for Canon and if you are looking for TS lenses then Nikon has some slim pickings
Forum: Pentax Camera and Field Accessories 05-30-2020, 10:49 PM  
the big grey box project - or where am I going to store 50+ lenses and the rest of it
Posted By Ian Stuart Forsyth
Replies: 39
Views: 2,148
Find soup cans the size of your lenses, most of the time after cutting off the rim with a hacksaw they are sharp enough to use as hole cutters
Forum: Pentax News and Rumors 05-24-2020, 08:49 PM  
New APS-C is
Posted By Ian Stuart Forsyth
Replies: 895
Views: 53,464
I like to have more subject isolation for one















I also like to use faster shutterspeeds when they are called for



---------- Post added 05-24-2020 at 09:17 PM ----------



It probably is but for what I like to shoot its something that does not interest me.



It has nothing to do with this in the least. If I am going out to photograph wildlife I like to use something more like a 300 2.8 on a cropped camera. The issue I have is that there is no 300 2.8 in production from ether pentax or other sources, and when you find one used you windup paying more than what it costs if I where in another mount.



This can be said for anyone including yourself. Take your Nuthatch If it was mine I would not have kept it unless it was some 1 in a 1,000,000 shot. If you are happy with it that is all that matter for yourself.






Its funny how you always bring in this rant into every discussion, it has nothing to do with Nikon but rather I don't like the IQ that a 50-300 and TC will give you. If I was going out to photography wildlife ( meaning I am going specially taking out a camera to photograph wildlife) a 300 2.8 for cropped is what I am after. What you get from a 50-300 + 1.4 tc is not what I am looking for and the time and cost to get into those shooting conditions to photograph wildlife would not be worth it in my mind.



Even when photographing in precarious shooting conditions I have opted for something faster than f9 on a cropped body
Forum: Pentax News and Rumors 05-17-2020, 11:17 PM  
New APS-C is
Posted By Ian Stuart Forsyth
Replies: 895
Views: 53,464
Then why did you ask.

I for one usually like to maximise my purchase as to get the greatest benefit from that investment. If I am going to buy a $1500-$2000 body and a $300- $500 dollar tc I would certainly think about the lens being paired with that body with TC and what conditions I am going to use that combo in.

And when I factor in what my 300 2.8 cost, the price I sold it used and the years I used the lens it cost me around $214 a year

$214 spanning over 1/2 a decade is a very cheap hobby.
Forum: Pentax News and Rumors 05-17-2020, 04:54 PM  
New APS-C is
Posted By Ian Stuart Forsyth
Replies: 895
Views: 53,464
Well there are a great deal of reasons why, first and foremost is the IQ from that lens and tc would not be what I am looking for.
Forum: Pentax News and Rumors 05-17-2020, 03:46 PM  
New APS-C is
Posted By Ian Stuart Forsyth
Replies: 895
Views: 53,464
This is where Nikon gives you an advantage for longer FL lenses, it not hard to find 300mm 2.8 lenses used for under $1600 can.
With pentax you have to be lucky to find anything and usually pay more for it in pentax mount.

When I sold my sigma 300 2.8 in a private sale to a Pentax shooter and for the a Nikon mount 120-300 2.8 OS I could have purchased one used from a camera store in better shape and also a more current generation lens for 200-300 dollars less than what I sold the 300 2.8 for.

$1500 Canadian you can buy you 120-300 2.8 OS and all current TC work flawless on it including their new 1.4 ;)
Forum: Pentax DSLR Discussion 04-04-2020, 12:59 AM  
18% Grey?
Posted By Ian Stuart Forsyth
Replies: 33
Views: 1,827
Color matrices have nothing to do with WB

The multipliers I am speaking of can be found in non DNG files also, this is what WB is its multiplying 1 or more of the color channels to produce a white balance. The multiplying of the color channels is done independently of the profile used. and does not change when changing the Color matrices ether in a profile editor or the color matrices tab of ARC.

We can see this if we simply change the multiplier stored within the raw data regardless if it is a DNG. It only makes adjustments to the WB setting and only the WB sliders. We also know this because to use the multiplier data within the raw converter you can only use this data if your select "as shot".

Here I have used the multipliers that are measured by the camera WB settings


Here I have set them with no multipliers meaning no WB is being applied to the raw file. If you look you can see that the WB sliders have changed and this is the UniWB setting for this camera model red=1 green=1 blue=1

Every forum that I have participated in call these multipliers
Do Not Let White Balance Throw You Off-Balance | FastRawViewer
What is UniWB? | DSLRBodies | Thom Hogan
Forum: Pentax DSLR Discussion 04-03-2020, 02:53 AM  
18% Grey?
Posted By Ian Stuart Forsyth
Replies: 33
Views: 1,827
Let start from the beginning, this is not to be sarcastic.

While many find no issues with using a 18% grey as a target to set a white balance from, the problem lies with why we are doing the WB in the first place and what we mean by applying a correct WB.

The calculation of setting the WB is done by the selection of your WB target with your WB tool, many times these targets are not even a neutral target. You can see the results of the WB calc by how it has placed the WB sliders, or if done by the camera what it has done to the RGB multipliers in the raw data.

Here you can see in the As shot neutral 0.475,1,0.697( RGB) this is telling the raw converter how to multiply the 3 channels to a the desired WB for Red 2.10 times green 1 and the blue 1.43 times. This is what WB is, setting a target to white and yes this target may not even be white

This is one of the colors I like to use for much of my work as it produces a WB I use very often
#e5f0f3 Color Hex
When selected as a target it produces the warm tones I like for much of my work, A correct WB calculation will allow me to carry this over independent of the light source. When this target is shot in a different light source and I use this as my WB target it will calc a new WB setting to produce this WB. This is one of the main reason why a person would go about trying to set their WB manually.



So here I have selected the patch labeled #7, the raw converter has calculated a what it takes to create that WB. If you take a look around #7 you will see 9 other WB targets all of which are not neutral and if you notice are not 18% grey.
One of the reason of this is for the very reason as I have stated before that noise from that weaker signal will cause the user issues with obtaining good WB calculations ( noise). Just look at a 18% target that has been photographed and view it with NR turned off and see the different colors within that grey or just take multiple samples over different areas of the target and see how it adjusts your WB sliders.

The image above was taken in direct sunlight while the image below is takin in the shade and selecting the very same WB target and the raw converter has calc'd a new settings for the same WB as you can see it has moved the sliders

This is the goal for setting WB to carry how the subject appears across different sources of light

Following Jeff Schewe for sometime I have learned to trust what he says as he has worked along with Thomas Knoll

page 5
https://www.adobe.com/digitalimag/pdfs/ps_workflow_sec3.pdf

Re: What they say is:: Retouching Forum: Digital Photography Review
Forum: Pentax DSLR Discussion 04-01-2020, 01:54 AM  
18% Grey?
Posted By Ian Stuart Forsyth
Replies: 33
Views: 1,827
Never said I deceased the shutter by 3 stops but the fact remains that the signal for patch#22 18%grey was within -0.15 of the signal for patch #19 of the other photo, so they are within around 1/16 of a stop ( not the end of the world). We can see this as all I had to do was +0.15 to equal the same output lightness of 250,250,250. This drop in exposure did not even change the calculated WB setting for the 2 measured signals, as it shouldn't for where the images are taken.

I will further add that for the image it was taken using a modified EC for ETTR and placed 18% grey at 155,155,155 for this color space it should be closer to 100,100,100. and white 9.5 should be at 237,237,237
Forum: Pentax DSLR Discussion 03-31-2020, 08:23 PM  
18% Grey?
Posted By Ian Stuart Forsyth
Replies: 33
Views: 1,827
Nothing was measured incorrectly I metered off of the grey patch increased the exposure so that the signal from patch #22 was the same size of signal coming from patch #19 from the previous image, This was done by decreasing the shutterspeed.
This was to show that when the noise component was removed from the WB calculation by increasing the signal from the surface you are trying to set your WB you will calculate a more accurate WB.

Using 18% grey because the lower signal you will be applying WB multiplier with a larger component of noise giving you a less accurate WB, and if you are trying to reproduce or carryover any color accuracy between different light conditions it is best to use a WB multiplier calculated using the least amount of noise.

My sample images above was to show when the same signal was used to calculate a WB for that scene that it was near constant at 8700 +29, once we used a target for WB with a lower signal the WB changed it went from 8700 +29 to 9700 when measured using the %18 grey patch under the same light and this is what caused the color tint we see in that WB setting and I will state it again it was the noise that was being used to set the WB that caused this tint.

---------- Post added 03-31-2020 at 08:47 PM ----------



If we remove WB from the raw file converter there will be no recognisable image from a standpoint as we see it in photograph and color, we will be left with this.

zero WB

The software is WB while using color profiles to create our images you cannot have one without the other.

Image 1


image 2


Image one was using the same setting on the same photograph with the same color profile as was image 2 the only difference was that image 2 was set using 18% grey and like I said the software is both WB and the color profile.

If nothing has changed other than the target used for the WB calculation and we see color tint it should be clear that it was the target used for WB that changed the color tint of the image. And when we increase the signal for that target we lose that tint it then should be clear that there was something else that was contributing to that color tint in the raw conversion. Noise from the lower signal using 18% grey target
Forum: Pentax DSLR Discussion 03-29-2020, 09:20 PM  
18% Grey?
Posted By Ian Stuart Forsyth
Replies: 33
Views: 1,827
Sure it does as white balance is a software related item, most importantly for you is that it calculate a WB for a selected area, the software will measure the signals for that area and apply a multiplication to those signals to achieve a white balance ( making those channels equal in lightness). If I take readings for grey and for white and they multiply the channels differently ( meaning that they will measure a different WB setting for those areas) you will see a tint to the processing in your image and all resulting color within that image. And as I stated before the difference in this is related to a noise component because of the lower signal from that 18% patch while the patch with a larger signal has a lower noise component most notably the red channel.


Never said it was, but however it plays a relationship to how the colors are mapped into a working color space via the converter. Different WB different color tint to the mapped image

The examples that was shown was not about color calibration, it was to show that



and as you can see from my examples that we have calculated a different WB setting for both the white are and the 18% grey area resulting in a color tint even thou we have WB the same image in 2 different areas.





The second part was to show that when you use a signal from a adequate source, (this not being a grey card as this introduces noise based inaccuracy's in the WB) that the accuracy of WB can be carried over from daylight image to an image taken in the shadows with very little to no issues color reproduction using the same color profile for both images.

Again this has nothing to do with color profile, the target was only used to show that just using the 18% patch and the white patch as a target of calculating the color channel multiplier to achieve a correct WB setting is different for both targets.

You may say this really doesn't prove anything but if we remove the noise component from the equations by taking a image of that same color checker grey target but the only difference is that we increase the signal (with a longer shutter speed ) coming from the 18% grey target and match it to the signal from the white patch from previous image like so.

calculated WB setting 8700 +29
Increase the signal and remove the noise component of the WB calculation

We have a very similar multiplier to signal with a similar WB setting, 8700 +28
All I have done is increase the signal, removed the noise component to the calculation of the WB setting


Here is the comparison of the calculated WB with the weaker signal
This calculated WB setting is 9700 and this is what has introduced the color tint to the resulting image in the raw conversion.
Forum: Pentax DSLR Discussion 03-28-2020, 08:59 PM  
18% Grey?
Posted By Ian Stuart Forsyth
Replies: 33
Views: 1,827
Has nothing to do with the issue for WB I was only referencing the color checker card so that one can see what the differences are when selecting the wrong target to WB on.

As I said above it has to do with how we capture the light data to preform a WB, for this we want to use the largest signal just shy of clipping. Not doing this will result in using data (mostly in the red channel ) with noise to create a WB for you image. When you apply this WB to your image you are affecting the colors and introducing colorcasts into that image.

Every

https://www.adobe.com/digitalimag/pdfs/ps_workflow_sec3.pdf
I would go even further and say to sample not the sample that is closest to clipping for the best results

While you can use it much of the time you are introducing color cast to your image WB using the noise from a lower signal


So here is white balance done to sample 1


Here I have done white balance using sample 3 not even 18% and you can see a colorcast that has been introduced into the color found elsewhere in the image

---------- Post added 03-28-2020 at 09:49 PM ----------



I don't know what to say



Here is a image shot in the shadows requiring WB 8700 +30

Here is another in mid day light



Only thing done is WB 4750 +11



Here is the difference in between the 2 with only WB applied and using the same camera profiles

If we look here setting your WB when we are not using the best signal we see a greater variance in color cast



Like I said I don't know what to say? the reason why you are maybe seeing WB setting as a blunt tool is that maybe using 18% grey for setting WB is not a very accurate way of setting WB if you need accuracy.
Forum: Pentax DSLR Discussion 03-28-2020, 07:15 PM  
18% Grey?
Posted By Ian Stuart Forsyth
Replies: 33
Views: 1,827
One of the problems is that when WB on 18% grey you are balancing it to that grey and not to a neutral white target . This seem like it would be doing the something but they are not, if you are using 18% you are WB to a target that is only reflecting only a fraction of the total light the sensor is able to store.

This seems like nothing much but a large component of that data you are setting your WB to is noise, more importantly the red channel so any WB will contain a lot of data based on the noise within the red channel.

One only has to photograph a color checker and apply a white balance to the varying neutral color patches and see the resulting changes to the color values of the remaining patches, simply using a 18% card can introduce color casting if you are trying to produce a accurate WB in colors that you are trying to capture.
Forum: Pentax News and Rumors 03-28-2020, 03:37 PM  
Ten more lenses in the pipeline.
Posted By Ian Stuart Forsyth
Replies: 329
Views: 36,092
It depends on the end user as to what constitutes as lightweight super teles, for some it could be a 500mm lens that is less than 10" long and less than 3.5 pounds

Or for another it could be a 400mm lens that is less than 8" long and 2.5 pounds. It is even more true when you compare these lenses to a 500mm that is 6.8 pounds and is 15" in length those lenses are compact and lightweight :)
Forum: Pentax SLR Lens Discussion 03-28-2020, 12:23 PM  
Pentax 70 - 210 vs Tamron 70 - 210 | Lens Review
Posted By Ian Stuart Forsyth
Replies: 113
Views: 6,582
I hope you are not talking about me, I don't think I am famous thou I might be infamous. Its a good thing you bring this up as the D500 is 20 mp not 24.



I am glad you bring this up at this is the very thing that many Nikon users have said that the difference you see in between 24mp and 20 mp is barely noticeable.

And this is they very same for me with the small difference we see in between a 16mp crop and a 24mp crop, I am much more interested in the flexibility a 36mp FF camera has over a cropped 24mp camera and this is even more true when you are not FL limited.
Forum: Pentax DSLR Discussion 03-24-2020, 10:10 PM  
Basketball and Soccer Sports Photography Camera Body Recommendation
Posted By Ian Stuart Forsyth
Replies: 57
Views: 3,810
Funny you should say this, how can I provide any better data as the very data they have published there is no in setting up the camera as to how they have described setting the camera for there testing? I don't have to puff my chest all I have to do is pointing this out and it really should tell the reader maybe they should question to as what are they really testing?



I don't have to be a professional tester to just look at my camera, see that there is no way to test a camera with a setting they described, that cannot be found within the limits of how you can setup the cameras AF system.





I have early when I first started here, besides there are many way to contribute to a community than a dollar amount. Take several post I make here are link off of this site directing traffic to this site, giving honest feed back to users with problems such as this very thread and point out that findings from other sites to reflect my on use of the equipment. I also gave away custom profiles to users here for any camera's that I had profiled, I no longer do so around here as there is now a feeling like Goodfellas club here more than ever.

The funny thing you say us Pentax owners as I have pentax cameras and several so should my voices weigh any different to the other Pentax owners just because if find another brand of camera better for some applications.




Funny how pointing out that my own opinions differ from that of yours and they very testing review of other brands you brought into the discussion as a backhanded insult to a brand and its users, this is why you can never have a civil conversation about the limitations of a product here. It now becomes personal to the user of that equipment for GOD sakes its a camera and not one of your children, your wife or your sister.
Forum: Non-Pentax Cameras: Canon, Nikon, etc. 03-22-2020, 09:24 PM  
Sigma 150-600 sport vs $4400-$8000 lenses
Posted By Ian Stuart Forsyth
Replies: 33
Views: 6,092
I just got done profiling the sigma 150-600 and with the 1.4 converter for use on the D810, for the first time out shooting some moving targets I do see an improvement in some areas.

The first would be with the D800 about ever 50 frame when first going to acquire AF lock there could be a stutter but with the D810 it is mostly gone.

I also notice is that it is much faster when tracking, so much so that when panning as a car is going by it would try and lock onto the object that even when its passing by in the frame at less than 1/10 sec it would focus on it.
With the D800 and this lens there was not much need to use AF hold for this kind of situations, but with the D810 I need to set the AF hold as it on a very regular basis shifted focus


Here we are tracking normally

here shifts focus

and again

With the addition to group AF points there is a much added benefit at the lens and camera can track much better than I have experienced with the D800, this is mainly at the very close distance where I would see the camera tracking much better with very little times that the camera would lose lock.

Here is start to finish all the shots taken when everything was setup
https://isfphotography.smugmug.com/frame/slideshow?key=JQMBcf&autoStart=1&ca...25&clickable=1
slide show

All the shots of the day
Work - isfphotography
Forum: Pentax DSLR Discussion 03-22-2020, 08:29 PM  
Basketball and Soccer Sports Photography Camera Body Recommendation
Posted By Ian Stuart Forsyth
Replies: 57
Views: 3,810
No I completely get the point, we are here to take with undying faith of a test ( for Nikon you can not even set the setting to how they have published their test) and believe it as fact and not be given into questioning such testing.

These test don't reflect what others have been doing without any problems for 1/2 a decade and we are to believe them and take them as gospel.

When we point out that this testing has no real bearing in real life uses its impolite and that we should be banned for this, when this day comes the forum will cease to a forum and will be lowered to a fanboy blog with no critical thinking as to what Pentax is.

If the day ever comes that Pentax did reach the level of AF performance as other companies we would see a great deal of threads about how much of an improvement this next generation of camera has over the previous model.

We see it every time a new model comes out " wow its soooooo much bettttteeeerrrr than the last model" but this time we would see the improvement that we see from other companies their should be a great deal of people eating crow as to how bad the older models are. And should be banned from buying such camera ;)

One of the problems is you cannot sanitise down AF into a very simple test, it only really comes from repeated use over time as to come to a conclusion over an array of different uses.

Here is a very simple AF test anyone can do, take a photograph of a subject that is off in the distance and as quickly as you can take a photograph of a target with a slant edge near MFD, give us the raw file or out of camera jpg so that we can see the time and the accuracy of the camera.

This should not be difficult for someone like you to provide. I will do the same test and then we have some data to compare. With Pentax their is not a camera that I have had access to that can come close to what I can with another brand of camera, even with a tc added to combo the outcome remains the same.

I am wait for you to publish your results ? you can do so in the Non-Pentax forum as not to contaminate where this maybe offensive to some users.

I always welcome these discussions as they shed light into issues I observe and would rather discuss them and test them without the sanitisation of Fanboyism unless this is what you want.

Not saying this is you but their are a few that would push this discussion until things get banned, deleted or closed. I would rather that the discussion be allowed to continue and to deal with the individuals and to simple be blocked from the discussion.

Million dollar question would be, can this happen

Sadly here I don't think it would happen. \_(ツ)_/
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