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DSLR vs CMOS vs CCD with a $800 budget

astrophotography ccd CMOS dslr equipment
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#26 17.5Dob

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Posted 23 September 2019 - 10:58 AM

IIRC the D5100 has a Toshiba sensor where the 5300 has a Sony sensor

No, it was a Sony chip in the D5100. It was the D5200/D7100 that used that horrid Toshiba.

The biggest reason not to go with the D5100 is the inability to control bulb over USB.

 


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#27 TelescopeGreg

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Posted 23 September 2019 - 01:16 PM

No, it was a Sony chip in the D5100. It was the D5200/D7100 that used that horrid Toshiba.

The biggest reason not to go with the D5100 is the inability to control bulb over USB.

 

Ah, yes.  That's a big negative.  My D3200 has the same problem, so I use an external Intervalometer.  The advantage of that, actually, is that the images go to the camera's SD card, which is an easy way to move them to the processing computer.  But, the down-side is that I cannot do an automatic dither, since the camera and mount aren't synchronized.

 

To Bob's point about the Black Point, I'm concluding that this is a camera firmware function, not inherent in the sensor, right?  I thought raw was raw, straight from the sensor, but apparently it gets massaged a little bit along the way?



#28 Alen K

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Posted 23 September 2019 - 01:27 PM

To Bob's point about the Black Point, I'm concluding that this is a camera firmware function, not inherent in the sensor, right?  I thought raw was raw, straight from the sensor, but apparently it gets massaged a little bit along the way?

Raw is usually slightly cooked in practice. Maybe the manufacturers are worried about us contracting salmonella. :D



#29 TelescopeGreg

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Posted 23 September 2019 - 01:47 PM

Raw is usually slightly cooked in practice. Maybe the manufacturers are worried about us contracting salmonella. laugh.gif

Perhaps, yes, but it you're paranoid I suppose you could go with jpeg?  Totally cooked, if not burnt to a crisp.

 

A follow-up thought...  In Deep Sky Stacker there is a setting "Set black point to zero", which I am thinking is exactly what one would use for the D5100.  If so, perhaps the impact of the camera's black point treatment on calibration frame processing isn't quite so much of a problem? 

 

What remains, then, is the lack of computer control, which I've found to be annoying but not fatal.  To the original topic, perhaps the D5100 might not be a bad choice, if the D5300 / 5500 / 5600 isn't available or is too pricey?



#30 bobzeq25

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Posted 23 September 2019 - 03:32 PM


A follow-up thought...  In Deep Sky Stacker there is a setting "Set black point to zero", which I am thinking is exactly what one would use for the D5100.  If so, perhaps the impact of the camera's black point treatment on calibration frame processing isn't quite so much of a problem? 

 

What remains, then, is the lack of computer control, which I've found to be annoying but not fatal.  To the original topic, perhaps the D5100 might not be a bad choice, if the D5300 / 5500 / 5600 isn't available or is too pricey?

No.  The internal black point setting wipes out half your bias, _before_ DSS sees it.  It's the loss of data that's a problem.

 

Again, there are _reasons_ why people recommend the 5300/5500/5600, but _not_ the 5100.  Getting "creative" with this stuff or "saving money" leads to many mistakes here, and _wasted_ money.

 

If you already have one, it's not that bad.  If you're buying fresh, choosing it over the 5300/5500/5600 is a fairly serious mistake.  Whether or not to upgrade a 5100 is a personal choice, but I'd proceed straight to a cooled astro camera instead.


Edited by bobzeq25, 23 September 2019 - 03:40 PM.


#31 17.5Dob

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Posted 23 September 2019 - 05:08 PM

The D5100 can be computer controlled, just not through USB. You need an extra, and very expensive Serial to USB cable to allow exposure control via computer. The black point issue can also be fixed using a firmware hack that has been around for ages. With that in place, the Sony chipped D5100 will put out the most pure "RAW" of any Nikon camera.

The senor is great, but I'd get the 071 vs the D5100.

Better yet, a D5300.......same sensor as a QHY247C


Edited by 17.5Dob, 23 September 2019 - 05:10 PM.

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#32 TelescopeGreg

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Posted 23 September 2019 - 05:36 PM

The D5100 can be computer controlled, just not through USB. You need an extra, and very expensive Serial to USB cable to allow exposure control via computer. The black point issue can also be fixed using a firmware hack that has been around for ages. With that in place, the Sony chipped D5100 will put out the most pure "RAW" of any Nikon camera.

The senor is great, but I'd get the 071 vs the D5100.

Better yet, a D5300.......same sensor as a QHY247C

Thanks, very informative.



#33 TelescopeGreg

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Posted 23 September 2019 - 05:59 PM

No.  The internal black point setting wipes out half your bias, _before_ DSS sees it.  It's the loss of data that's a problem.

 

Again, there are _reasons_ why people recommend the 5300/5500/5600, but _not_ the 5100.  Getting "creative" with this stuff or "saving money" leads to many mistakes here, and _wasted_ money.

 

If you already have one, it's not that bad.  If you're buying fresh, choosing it over the 5300/5500/5600 is a fairly serious mistake.  Whether or not to upgrade a 5100 is a personal choice, but I'd proceed straight to a cooled astro camera instead.

{sigh}  Not looking to get arbitrarily creative, just trying to understand.  I truly don't care what others recommend, regardless of their reputation, if they don't tell me why.  Every decision is a balance of tradeoffs, and everyone has their own objectives and constraints to consider.

 

Can you walk me through the "wipes out half your bias" part?  E.g., where did "half" come from?  Just trying to understand how this stuff works, in support of the OP's question about what options might be worth looking at, and why.



#34 bobzeq25

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Posted 23 September 2019 - 10:17 PM

{sigh}  Not looking to get arbitrarily creative, just trying to understand.  I truly don't care what others recommend, regardless of their reputation, if they don't tell me why.  Every decision is a balance of tradeoffs, and everyone has their own objectives and constraints to consider.

 

Can you walk me through the "wipes out half your bias" part?  E.g., where did "half" come from?  Just trying to understand how this stuff works, in support of the OP's question about what options might be worth looking at, and why.

Sure.  Bias is basically a bell shaped curve.  There's a central peak called the zero point.   If you set the zero point at zero ADU, half the curve is negative numbers, and the camera electronics ignores that data.  It doesn't affect terrestrial photography, just astrophotography.  Canons have had the zero point set at 600 ADU for a long time.  Nikon moved it up there with the 5300.

 

I quite agree that you shouldn't listen to any one person, regardless of their reputation.  But _many_ people here recommend the 5300/5500/5600.  And that's a completely different story.


Edited by bobzeq25, 23 September 2019 - 10:18 PM.

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#35 TelescopeGreg

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Posted 23 September 2019 - 10:47 PM

Sure.  Bias is basically a bell shaped curve.  There's a central peak called the zero point.   If you set the zero point at zero ADU, half the curve is negative numbers, and the camera electronics ignores that data.  It doesn't affect terrestrial photography, just astrophotography.  Canons have had the zero point set at 600 ADU for a long time.  Nikon moved it up there with the 5300.

 

I quite agree that you shouldn't listen to any one person, regardless of their reputation.  But _many_ people here recommend the 5300/5500/5600.  And that's a completely different story.

Ha.  Thanks, I just learned something.  I had understood / assumed that the zero point was below the bell, not at the peak.  So putting it at the peak would definitely be a problem.  Makes sense now.

 

Listening to recommendations is like being handed a fish.  I'd rather learn how to fish...



#36 bobzeq25

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Posted 23 September 2019 - 11:32 PM

Ha.  Thanks, I just learned something.  I had understood / assumed that the zero point was below the bell, not at the peak.  So putting it at the peak would definitely be a problem.  Makes sense now.

 

Listening to recommendations is like being handed a fish.  I'd rather learn how to fish...

There's a marvelous book called "Stumbling on Happiness" by the noted neuropsychologist Daniel Gilbert.   He spends most of it detailing how we create mental illusions about what will give us happiness in the future.  Then this:

 

"At this point my friends are ready to kill me and demand the answer to the problem.  I tell them I have it, but they won't like it, and won't do it.  It's to see what made other people happy in the past.  For:

 

The thing about most people is that they are like most people.  The other thing about most people is that they think they are not."

 

<grin>

 

The reason it applies more in AP of DSOs is that this business is so unintuitive.


Edited by bobzeq25, 23 September 2019 - 11:33 PM.


#37 TelescopeGreg

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Posted 24 September 2019 - 12:27 AM

The reason it applies more in AP of DSOs is that this business is so unintuitive.

Yep, we're all above average, don't you know.

 

DSO AP is only unintuitive until you know just a few of the basics about what's going on.  You need some sort of framework, then it's easy, or at least a lot easier.  Folks think (aided and abetted by the major telescope suppliers who only do visual and planetary without explaining any of it) that they want a big long telescope, until you tell them DSO objects can be bigger than the Moon and are really really really dim.  Then the rest of the short-fat-refractor-on-a-beefy-mount puzzle starts falling into place. 

 

Now, back to our regularly scheduled program... 

 

I've not seen any on-line references to what cameras are stunted by a zero black point.  I presume could be buried somewhere in various reviews, but they focus on terrestrial photography where it's not a significant topic.  Is this another word-of-mouth sort of spec that's never written down?  If someone had a random camera, how would they know without testing it?



#38 bobzeq25

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Posted 24 September 2019 - 09:25 AM

Yep, we're all above average, don't you know.

 

DSO AP is only unintuitive until you know just a few of the basics about what's going on.  You need some sort of framework, then it's easy, or at least a lot easier.  Folks think (aided and abetted by the major telescope suppliers who only do visual and planetary without explaining any of it) that they want a big long telescope, until you tell them DSO objects can be bigger than the Moon and are really really really dim.  Then the rest of the short-fat-refractor-on-a-beefy-mount puzzle starts falling into place. 

 

Now, back to our regularly scheduled program... 

 

I've not seen any on-line references to what cameras are stunted by a zero black point.  I presume could be buried somewhere in various reviews, but they focus on terrestrial photography where it's not a significant topic.  Is this another word-of-mouth sort of spec that's never written down?  If someone had a random camera, how would they know without testing it?

There is some general knowledge.  Canons don't have the problem.  Nikons before the 5300 generally do, after, generally not.  If you use something else (Sonys, for example, which have their own issues) you'd need to do some research.  But people who go elsewhere typically are less serious, may ignore the issue.  It's not devastating. 

 

The test is not all that hard.  Shoot a bias, load it in a program that doesn't mangle the histogram (IRIS is my choice), and look at it.  Again, people who use oddball cameras and/or fly by the seat of their pants, generally just won't do that, even if someone recommends it.  BTDTGTTS.

 

Yet another example of how following the crowd and using something standard can make life easier.  When I needed a lightweight upscale mount, because of physical issues, the Vixen SXD2 was an attractive choice.  But the lack of a significant user base here sent me to the CEM60, instead.  Which worked out well.


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#39 TelescopeGreg

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Posted 24 September 2019 - 12:56 PM

There is some general knowledge.  Canons don't have the problem.  Nikons before the 5300 generally do, after, generally not.  If you use something else (Sonys, for example, which have their own issues) you'd need to do some research.  But people who go elsewhere typically are less serious, may ignore the issue.  It's not devastating. 

 

The test is not all that hard.  Shoot a bias, load it in a program that doesn't mangle the histogram (IRIS is my choice), and look at it. 

So what would one look for in the Bias image? I have a sample loaded in IRIS, but don't see where the Black Point is displayed.

 

My D3200 camera pre-dates the D5300 by about a year, so based on your dates, it is more likely to have the problem than not.

 

Yet another example of how following the crowd and using something standard can make life easier.  When I needed a lightweight upscale mount, because of physical issues, the Vixen SXD2 was an attractive choice.  But the lack of a significant user base here sent me to the CEM60, instead.  Which worked out well.

Yeah, but sometimes one can experience more (more fun,  learn more) by not following the crowd.  Depends on what your goals are.  Robert Frost, and all that...



#40 bobzeq25

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Posted 24 September 2019 - 01:16 PM

So what would one look for in the Bias image? I have a sample loaded in IRIS, but don't see where the Black Point is displayed.

 

My D3200 camera pre-dates the D5300 by about a year, so based on your dates, it is more likely to have the problem than not.

 

Yeah, but sometimes one can experience more (more fun,  learn more) by not following the crowd.  Depends on what your goals are.  Robert Frost, and all that...

Look at the histogram of the bias.  The peak is the black point.  If your peak is at zero, half the curve will be missing.



#41 Stelios

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Posted 24 September 2019 - 01:34 PM

Look at the histogram of the bias.  The peak is the black point.  If your peak is at zero, half the curve will be missing.

I think you guys (Bob and Telescope Greg) should start a different thread or take it to a PM. Please don't highjack the OP's thread.


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#42 TelescopeGreg

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Posted 24 September 2019 - 01:48 PM

I think you guys (Bob and Telescope Greg) should start a different thread or take it to a PM. Please don't highjack the OP's thread.

Just clarifying the characteristics of a suitable DSLR...



#43 bobzeq25

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Posted 24 September 2019 - 03:47 PM

I think you guys (Bob and Telescope Greg) should start a different thread or take it to a PM. Please don't highjack the OP's thread.

Done deal.




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