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What is going on with Nikon and entry-level DSLRs?


frans_waterlander

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Heat in a mirrorless camera comes mainly from three sources - Battery, Storage, and video processing. If you eliminate the first two by (a) using an external power source (dummy battery) and (b) recording externally (e.g., Ninja V), the camera can operate indefinitely without overheating or running into a time limit imposed for tariff reasons. I keep my Sony A7xxx cameras running continuously for 8 hours or more on many occasions. I have seen no evidence of thermal image degradation.
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Yep, that's the 1500 pound elephant in the room that nobody wants to talk about.

I'm surprised no one wants to talk about it. An elephant at that weight (if male) is a little over a year old, and still very cute. Less than some horse breeds (Percheron, Clydesdale, Belgian) weigh as adults.

 

But you were writing about Nikon cameras. If you're still using your D70, don't worry about Nikon phasing out its DSLRs. Just buy a used D7200 or D7500 when your present one wears out, and it will last you a very long time, and be capable of far better photos.

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Give us your sources if you think you have any.

Google and you will find many reports of mirrorless cameras overheating to the point of shutting down, but keep in mind that noise increases all along, whether the camera heats up to the point of needing to be shut down (to prevent physical damage to the camera or user) or not.

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The only 2 things digital I've had shut down on me were my iPhone 5 left in a camera bag on a sunny English day. It was in one of those external mesh pouches facing South. My D500 was in the bag and worked fine.

 

The second was this Android tablet (im typing on now) left on a picnic table, in the Sunshine, in the Lake District.

The body is white, but was resting screen up.

 

Never had a camera even twitch, even when I've left them on the dashboard in Florida accidentally. Hot to touch, but worked fine.

 

I've just got a Z6ii but am not worried.

 

If the end of entry price Nikon DSLRs is a future worry, I think the sweetspot for DX is getting a clean 2nd hand either the D5300 or D7200.

 

D70s used to be in British speed cameras, until they were deemed obsolete 10 years ago.....;) hint...:D.

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LCD are somewhat temperature sensitive, which would apply to iPhone, iPad and cameras.

 

Silicon has a band gap of about 1.1eV, and kT at room temperature is about 0.025eV at 300K.

Hopefully your camera doesn't go above about 600K, or about 330C or maybe 500F,

which have kT about twice as much, or 0.05eV.

 

OK, first, thermal noise is only important at the highest ISO settings, as the actual

signal is much lower. That is the reason we don't use high ISO all the time.

Similarly, we don't use high speed film all the time.

 

OK, next, it depends on the time. For astrophotography, where the like exposures in minutes

or hours, the noise adds up over time. For the fraction of seconds for most photography,

that is not a problem.

 

One reason people like larger sensors, like FX cameras, is that the sensor area is larger.

More area for more photons to stay above the thermal noise. So with everything else

constant, more area is better. But everything else is hardly ever constant.

 

New sensors are a lot better. There are plenty of newer cameras, with the best prices

on used but still plenty good enough models.

 

But if you really want to keep noise down, there are professional lab cameras that

use liquid nitrogen to cool the sensor. Not so convenient for most use, though.

 

I notice that you don't mention quantization noise. Sensors can only detect whole

photons by moving whole electrons across the band gap. There is no way around

that one, at any temperature electrons are still whole.

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-- glen

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[...]

Call me a sceptic, but I'd like to see some credible test results that quantify how much degradation occurs under worst case conditions, but I'm not holding my breath.

Yes... Just like we need to see some credible test results that, uhm..., quantify how much degradation occurs under, uhm... , worst case conditions to tell us there is such a problem?

Is that the 3000 pound elephant in the room nobody wants to talk about?

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Show me your “reports.” 10 years with mirrorless and aside from high spec video recording (that DSLRs can’t do either) I’ve never even seen a camera do that. Give us your sources if you think you have any.

 

It's not difficult to find evidence of this. Here is an account of Canon R5 long exposure noise which is substantial compared to its peers.

 

Canon EOS R5 Image Quality

 

The noise could be related to sensor heating or other components heating (which is well-known for this camera during video reporting) and may be related to the in-camera stabilization preventing effective removal of heat from the sensor. Also the sensor is on for the LV and EVF use (which is not the case for DSLR viewfinders).

 

Sony mirrorless cameras are known to use algorithms to reduce long-exposure noise, this is called the "star eater" algorithm and apparently it cannot be turned off and Sony have been unwilling to remove it or allow users to turn it off. This has been reported to remove some fainter stars from astrophotographs. I have seen a comparison between two models, one with IBIS and one without, and the latter was better in long exposure noise, and I think this could be one of the reasons why some mirrorless cameras have increased long-exposure noise.

 

I can find more links about the issues but I don't think it's necessary, the information is easy enough to find.

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OK, next, it depends on the time. For astrophotography, where the like exposures in minutes

or hours, the noise adds up over time. For the fraction of seconds for most photography,

that is not a problem.

But, Glen, the reasoning goes that these sensors in cameras without an optical finder are 'hot', i.e. on, for much longer than the faction of a second that takes to record the image that you want stored on a memory card.

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The movements needed for IBIS may mean the heat is not as effectively dissipated from the sensor. Nikon Z7 doesn't seem to have this problem to the same degree which could be due to a better design of the stabilizer or simply because in the Nikon to get 45MP you need only 45MP, whereas Canon need a 90MP sensor to get 45MP images with dual-pixel autofocus (which means they need to read and process twice as much data, generating more heat). But the Z7 has banding and striping which Canon do not. Anyway, swamp here and ditch there, different companies try to get around the problems using different approaches.
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Seems that claims are a bit inflated on both sides of this conversation. No, mirrorless cameras do not have superior high-ISO performance. And over-heating is likely not a problem for typical use cases.

 

I'm still waiting for a EVF that I like for shooting sports. And I'd rather not pay the inflated prices for Z-mount lenses. So I'll continue shooting DSLRs.

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But, Glen, the reasoning goes that these sensors in cameras without an optical finder are 'hot', i.e. on, for much longer than the faction of a second that takes to record the image that you want stored on a memory card.

 

Thermal noise is a current, so the effect depends on the length of the exposure.

-- glen

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Yep, that's the 1500 pound elephant in the room that nobody wants to talk about. Mirrorless sensors heat up, even to the point where the camera needs to be powered down to avoid physical damage to the sensor and other electronic circuits and there are plenty of reports on that phenomenon. So what happens before the camera shuts down? The sensor heats up anyway and image quality suffers. How much does it suffer? Nobody wants to say, not the manufacturers, not the reviewers, not the test houses.

Call me a sceptic, but I'd like to see some credible test results that quantify how much degradation occurs under worst case conditions, but I'm not holding my breath.

That elephant is certainly not in my room. I've used a wide range of mirrorless cameras sometimes for intensive shooting at motorsports. Sensor heat up has never been apparent on any of them.

 

It might become an issue if you leave the camera on endlessly without shooting - but I didn't do that with my DSLRs so don't see the need to with mirrorless cameras. 10 minutes left on isn't a problem.

Edited by petrochemist
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Google and you will find many reports of mirrorless cameras overheating to the point of shutting down, but keep in mind that noise increases all along, whether the camera heats up to the point of needing to be shut down (to prevent physical damage to the camera or user) or not.

This isn’t a Q-anon board, you can’t just make shit up. You persist in making this claim but have no evidence that supports it. Every single person here with actual experience says you’re wrong. The burden to provide evidence is yours. “Google it” is not evidence, it’s a way of saying you have none.

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It's not difficult to find evidence of this. Here is an account of Canon R5 long exposure noise which is substantial compared to its peers.

 

Canon EOS R5 Image Quality

That’s not a mirrorless problem. DSLRs also get long exposure noise. In this case the R5 had more long exposure noise than a Nikon or Sony mirrorless or an older model Canon mirrorless - it’s about the R5, not evidence that mirrorless cameras have an inherent heat problem.

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Seems that claims are a bit inflated on both sides of this conversation. No, mirrorless cameras do not have superior high-ISO performance. And over-heating is likely not a problem for typical use cases.

 

I'm still waiting for a EVF that I like for shooting sports. And I'd rather not pay the inflated prices for Z-mount lenses. So I'll continue shooting DSLRs.

I find for most of my shooting mirrorless suits me better, but as my cameras are all older models I've certainly found EVFs are slightly less comfortable for motorsports & so I still use my DSLRs for that.

Any of my mirrorless cameras are still usable for motorsports (even the ancient G1) and I've never been able to determine exactly what it is with the DSLRs that's preferable - viewfinder lag has not been an issue for me. It could just be that I don't have good native AF super telephoto lenses for my mirrorless cameras...

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That’s not a mirrorless problem. DSLRs also get long exposure noise. In this case the R5 had more long exposure noise than a Nikon or Sony mirrorless or an older model Canon mirrorless - it’s about the R5, not evidence that mirrorless cameras have an inherent heat problem.

 

These image quality issues are not strictly mirrorless-bound but they are related to technologies commonly used in mirrorless cameras (and not strictly speaking needed on DSLRs). DSLRs don't need dual-pixel sensors (leading to requirement for twice as many pixels in the sensor than can be utilized in the final image, which can lead to increased heat and noise) or OSPDAF sensors (which can cause banding and striping when light comes in at certain angles) unless live view and video AF are prioritised. Nikon and Canon DSLRs use in-lens optical stabilizers to provide accurate viewfinder framing (instead of in-camera stabilizers). In-camera stabilizers mean the sensor heat is not as efficiently transmitted to the rest of the body. Increasing pixel count to double (or quadruple if they decide to make cross-type sensors) can increase heat and noise. R5 introduced Canon's first in-camera image stabilization and that combined with the 90-MP sensor may be one reason why it has this long-exposure noise issue to greater degree than their previous cameras (which had fewer pixels and no in-camera stabilization). A7R II has IBIS and A7R does not, and I've read tests showing there is increased long-exposure noise for the A7R II. Sony remove some of the long-exposure noise with the algorithm known infamously as the "star eater" as it removes some stars along with the noise.

 

Of course DSLRs have noise at long exposures as well but in a design where there is no sensor stabilizer, the noise can be lower than that in mirrorless cameras with sensor stabilizers. Some DSLRs have dual-pixel or on-sensor PDAF and these have similar issues as mirrorless cameras with those features, but it's not necessary for a DSLR used for still photography to have those features, thus these artifacts are avoided or reduced in magnitude.

 

The Z7 is a newer camera than the D850 yet the data show the former is behind the latter in midtone SNR at ultra-high ISO settings:

 

Nikon D850 vs Nikon Z7 vs

 

Also dynamic range at both low and ultra-high ISOs is worse for the Z7 than D850:

 

Nikon D850 vs Nikon Z7 vs

 

Tonal range and color sensitivity also show the D850 is somewhat better at the extended ISO range.

 

Although the long-exposure tests show good results (at least side by side with the R5), Nikon still can't get the mirrorless camera sensor to perform as well the closest DSLR version. The differences may not be all that large but they are there.

 

However, this isn't the reason I don't use Z cameras. I simply prefer the optical viewfinders. I also find that many of the lenses I'm most keen on aren't available for mirrorless cameras as native lenses. Mirrorless cameras have their own advantages as do DSLRs. I am not at all suggesting that mirrorless cameras shouldn't be made. I use some of them for work although I don't own any of them personally at present.

Edited by ilkka_nissila
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“Dual pixel” af was first used in Canon DSLRs. And it’s not used in all mirrorless. And there’s no reason to think it’s the cause of that guy’s camera having long exposure noise. Three out of four mirrorless cameras he tried did not produce significant long exposure noise, which is evidence that Frans’s hypothesis does not pan out in real world use.
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