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Oct 21, 2022 14:02:02   #
with my pentax dslrs there is the green button which when pressed closes the aperture down to that selected and adjusts the shutterspeed to suit. Some manual lenses have a lens code that describes the maximum and minimum aperture and the aperture lever movement is proportional to the required f-stop. not all lenses will stop down correctly these you need the green button. There are different options for focus some you can swop out the focus screen but with pentax at least the centre spot focus always works adjust till the green hexagon is filled you may then recompose. On canon to m42 adapters often you get an adapter ring with a chip on it which is faking an ef50 which beeps when focus is detected you must manually stop down and lie to the camera so it thinks you are shooting wide open. otherwise it will over expose as the body meters wide open and calculates the shutter speed based on how many stops down you are telling it you are using e.g 2 stops down will end up with 2 stops over exposed. So with manual lenses it depends on the camera and lens combination. Pentax also has a focus method where the shutter only fires in focus, Sometimes you might use this to wait for your subject to reach your preset focus point but you can also use it to rotate the focus ring and when it sees focus it will fire. Other methods already discussed may apply. It depends on the camera but i've even used enlarger lenses with a helicoid adapter and tubes.
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Oct 7, 2022 19:59:35   #
selmslie wrote:
At all ISO settings the camera's meter places middle gray for a 14-bit at a raw value of between about 1000 and 2000 (the range is 0-16383) depending on the model. That leaves about 3 stops of DR above middle gray.

The light reaching the sensor below middle gray has less noise at low ISO because the exposure is greater.

This can be seen in the earlier post from therwol from the DxOMark results. As the ISO is increased, the noisy part creeps up (or the DR drops) as the ISO increases and noise becomes more visible in the shadows.
At all ISO settings the camera's meter places midd... (show quote)


"That leaves about 3 stops above middle gray" The DXO chart doesn't show that, it's purely a plot of dynamic range against ISO. It's not telling you where that dynamic range is, The chart for the Bmpcc 4k is and yes the lower iso does bring out more shadow detail at the expense of highlight detail.

What happens when you increase iso by one stop to keep the exposure the same we reduce the shutter speed by one stop which means half the quantity of photons come in. So lets say just for numbers sake that on the first exposure for middle gray we recorded say 4000 photons and that we had 3 stops above middle gray available 4000 8000 16000 32000 photons (we are essentially saying that 32,000 photons is the max we can record before blowing highlights. how much shadow detail can we record in terms of photons 2000 1000 500 250 125 65 Ok so our imaginary camera has 10 stops of dynamic range. Then if we half the exposure then each part of our sensor gets half the light we basically changed the multipier for our iso so what was 32,000 photons recorded becomes 16,000 and what was 65 becomes about 32 and our subject is recorded from 2000 photons instead of 4000, our sensor is still capable of recording 32,000 so effectively we are getting an extra stop of highlights for the loss of 1 stop of shadow detail as it disapears into the noise.

An over simplification but the bmpcc4k range chart seems to show this increase in highlight range and decrease in shadow range as ISO increases. The DXO chart lacks that detail, you are assuming that the distribution of dynamic range doesn't change and that you just lose a stop each time you increase ISO by a stop. The DXO chart is showing much less of a loss of dynamic range as iso increases (up to a point) before decreasing rapidly. My chart is saying increased highlight detail at the expense of shadows the DXO chart doesn't say.

Our eyes are ok with seeing more highlight detail and less shadow detail with brighter light..
need better eyes ...

i'm not saying my imaginary camera is accurate but its the kind of trend which makes sense.
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Oct 7, 2022 18:50:12   #
Rongnongno wrote:
Actually, this is a poor concept. The DR is divided equally (as far I know). Using the base ISO basically kills a good part of the camera DR capabilities, as the sensor is unable to capture below a sensitivity that needs to be determined by experimenting. I use a D850 and a D500. The D850 needs ISO 800 to get an optimal DR (14DR) the D500 overs between ISO 800 and 1000. To check, I use a Black Grey White target. Then I check the color noise in the black, then in the grey. That is why I mentioned earlier to use a dynamic range that starts at ISO 800. This number, of course, depends on your camera capability to capture the dark.

When testing I use ACR I do three things first:
► Optical correction
► Aberration
► Defringe
 Then I reduce the color noise to 0 and check the darker grey areas for visible noise (600% magnification and above). If the noise is minimal (acceptable) I have my lower ISO for the range.

When I PP a capture, I do the exact same thing, but I adjust the slider to remove the color noise, usually around 10~12. ACR over corrects. (see samples)

 
Actually, this is a poor concept. The DR is divid... (show quote)


Perfect, so your experimentation has pointed you towards ISO 800 on D850 for maximum dynamic range. It will be interesting to see how using your post processing steps can improve my own images.

Some people think of photography as just pressing a button when the composition looks good and yes thats important, but there is a whole lot more to crafting the capture that you want. Aperture and Shutterspeed are fairly obvious choices as is the choice of lens focal length. ISO has been the poor relation primarily being used as light compensation, and as you started this thread IS or VR is also being used to compensate for lack of light on the subject and clearly it's not appropriate when your subject is moving and you want them to be sharp in the frame.

This is a pretty good thread, I must admit to abusing the VR function in camera and I aim to make better choices in future, i never really thought of it other than as a crutch for poor light.
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Oct 7, 2022 17:47:31   #
I thought i would share an interesting chart with you. This is for the blackmagic 4k cinema camera which is a dual base iso camera. It's a little different from most dynamic range charts which normally show that at base iso you get maximum dynamic range and as iso goes up dynamic range goes down. This is similar to the last third of the chart given here.

What makes this different is the distribution of the dynamic range. if we look at the first iso range. iso 100 gives 2 stops of detail above middle gray and 11 below. at iso 1000 its 5.3 stops above and 7 stops below. from 1250 to 6400 iso you are into the 2nd native iso range which has 0.8 stops less dynamic range but performs similarly. From 8000 to 25600 its more familiar with dynamic range decreasing with 4.7 over and losing shadow detail.

On a sunny day the sky is likely to be the brightest thing in frame so to keep that from blowing out you are better at say 800 or 1000 Iso to preserve highlights at the cost of less shadow detail on an overcast day the highlights can be lower compared to your subject and you can choose to capture more shadow detail instead e.g iso 100. The Blackmagic cinema camera having dual iso has the extra trck that you can move into the second range, usually for shooting at night and get a cleaner capture by using the 1250 to 1600 second iso range, which most cameras do not have. Finally it moves into the range where dynamic range decreases as iso increases.
With a camera like the BMPCC 4K you tend to shoot at a low frame rate that on a typical day and a wide aperture would blow the highlights without the use of an ND filter, photographers can just raise shutterspeed to compensate.

This dynamic range distribution that is shown here, does it apply to your camera? I don't know but you can shoot a scene changing the iso and maintaning the same exposure to see which iso is best for the scenes dynamic range. If the results are as interesting, using as low an iso as possible might be replaced with use the best iso for the contents of the scene rather than compensation for not enough available light.


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Oct 5, 2022 21:48:35   #
VR = Vibration reduction (Nikon term) Canon calls it image stabalisation.
It's designed to reduce camera shake while handholding the camera.
VR and IS systems are able to handle vibrations only in certain ranges.The frequency range of interest is about 0.3 Hz to 30 Hz.

IS and VR systems are designed to ignore very low frequencies of vibration because these systems would mistake panning or reframing for vibration, and would try to work against us as we tried to shoot.

Frequencies higher than about 30 Hz aren't particularly important. Our muscles don't wiggle faster than 30 Hz, and external vibrations at higher frequencies are filtered by the combination of our bodies and the mass of the camera.

So it's only compensation for the movement in the hands of the photographer , not the subject.
So it's best for stationary rocks and sutch. Which kinda leads on to what do you want to be sharp it probably will not be everything. shorter focal length lenses have a wider field of view than telephoto lenses which effectively means the subject will move over fewer pixels while you are exposing the image, higher shutter speeds give less time for the subject to move , flash gives even less time, panning with the subject also helps and probably a fast aperture (less in the frame will be in focus but thats to be expected.

Iso helps reduce the light needed for the shot but it can be interesting how it moves the dynamic range of the camera. Exposing a middle gray subject at say iso 100 gives more dynamic range to the shadows and less to the highlights. Higher ISO will push the dynamic range towards the highlights making for less details in the shadows. which depending on the scene may make a higher iso a better choice. More so on a sunny day where the range of highlights would tend to cause blown highlights. Kinda counter intuitive to our use the lowest iso instincts.
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Sep 27, 2022 07:48:47   #
I was a big fan of arca swiss clamps but these days I find these are much more useful.

Often I will take one of these with me and maybe some tripod legs rather than a tripod with a head attached. It gives quite a decent footprint attaches easily to any 1/4 or 3/8ths thread. plates are automatically captured. the locking lever is spring loaded which lets you reposition if you don't have a full turn possible due to what you have mounted. There is even a couple of 3/8th and 1/4 threads on the side which come in handy at times. I have some very short and light tripod legs that i sometimes use with this. Sometimes i will adapt arca swiss for this as well an arca swiss clamp can be attached to the plate and even an arca swiss plate can attach underneath the clamp. The plates are long enough in themselves to hold a camera and a fair size lens flat on a surface. I probably have around 5 of these as i use them for different setups sometimes not even with cameras.


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Sep 27, 2022 06:16:42   #
rjaywallace wrote:
Blackest - Take a look at the latest lines of rolling packs and backpacks at Tenba.com. Their most recent designs incorporate thoughtful features and excellent materials. Good luck. /Ralph


My most recent bag is the tenba 32L black. Main reason the long central compartment which is long enough to hold a zeapon slider and a dji rs2 bag and still have a good bit of space.
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May 17, 2022 06:57:41   #
Well yesterday i picked up an m50 mark 1 with the 15-45mm f3.5 to f6.3 kit lens for 425 euro with a case and a couple of batteries and a charger (one battery is 3rd party) It doesn't seem too bad. I also have adapters for pentax pk and m42 mount lenses as well as the a viltrox EF to M mount adapter. So i have a good number of lenses for it mostly manual.

It seems almost toy like in size compared to most of my other cameras and i have to keep reminding myself that it's a 24 Mpix aps-C sensor so a 50mm has a field of view of 80mm slightly longer than the 75mm fov of my Pentax aps cameras.

Looks like its quite a nice little camera, it should be fun :)
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May 12, 2022 09:58:40   #
Hi anyone using this camera?

Seems to be a pretty reasonable aps C camera for the price along with some reasonable video modes. i'm kinda tempted but it will not be my only camera, I already have ef-to m mount adapter as well as m42 and pk mount so i have quite a few lenses that should work well including the sigma art 18-35 the classic helios 58mm f2 and others.

It seems to be the best m series canon

what do you think
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May 1, 2022 11:41:15   #
lamiaceae wrote:
Personally I have tried placing colored contrast filters that I have had since my film days over lenses on my digital camera. Nothing useful came from this. About as horrible as a similar filter used with Kodachrome Film. The only "pigmented" filters I use for digital photography are Infrared passing ones for IR photography using an non-converted digital camera. I also have a IR converted cameras where the needed filters are installed over the sensor directly. Digital cameras seem to go crazy when trying to white balance non-RGB data. Note, a yellow filter is minus blue light. Magenta minus green, and so forth. Not sure that your laser glasses are even removing polarized light like sky glasses are. There is something else going on that I do not know. But I know many even low-power laser light can damage your eyes as well as digital cameras.
Personally I have tried placing colored contrast f... (show quote)


Yes in davinci resolve the scopes show the red and green channels have a full scale range and the blue channel values are much reduced which may mean the effect could be reproduced digitally. it's kind pf similar in a way to false color Infrared photography. different materials have differences in opacity to some wavelengths. Some trees go from blending into the others to really standing out from the crowd. In video it's kind of similar to a wes craven film. On a cold gray rainy day it becomes light and warm.
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Apr 29, 2022 08:06:25   #
The best idea i have come up with so far is a cokin filter adapter good bit of surface for taping glueing the lens.
I think making a screw in filter would be quite tricky.
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Apr 29, 2022 07:52:21   #
Hi all,
I recently picked up some orange UV ski goggles which are mostly orange but rather interestingly make the greens pop, I tried to replicate this with an orange filter but i guess unsurprisingly it pretty much makes everything orange.

The effect of the glasses seems to increase sharpness and contrast and the greens are different grass is more emerald green and horse chestnuts a lime green. Makes everything a bit brighter too.

I managed to find on Amazon a pair of laser safety glasses which is designed to filter UV and blue light very similar to the first pair. It's a polycarbonate material but now I need to mod this to fit a lens.

Any ideas?
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Apr 29, 2022 07:38:56   #
I don't touch film these days but with a smart bulb I turned my enlarger into a smart lamp it's around a 9 watt multi colour led. just needed an E27 to gu10 adapter.
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Mar 2, 2022 21:21:45   #
Sidus link is primarily mobile software for controlling aputure lights of many sizes and outputs.

The app is free and on Android and IOS. It has some useful features that even without one or more of their lights are useful.
It does a pretty good job of measuring color temperature as well as picking out colors to match.

Because it uses your phone camera, pointing it at the light source isn't a great idea as it will tend to blow out. instead point the camera at some white card and get the reading from there for my aputure rgb lamp this can match up with another rgb source really well.

dedicated color meters tend to be very expensive and this may not be as accurate, but it gives usable readings.
It's worth taking a look
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Feb 22, 2022 09:47:50   #
The background was shot a couple of weeks back while the foreground was shot in front of a green screen. I set the key light to F5.6 fill and hair light to F4 for basic 3 point lighting.
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