Can the new D90 take acceptable time exposures?

JerryinToronto · Oct 4, 2008

Hi, I used to do time exposures using a Minolta X-700 with a multi-function back and Kodachrome 100. But it's a real hassle to get that film processed in Canada. I know that the DSLRs have a problem with noise when doing low light scenes. Does the new D90 eliminate it, or at least significantly reduce it? I am thinking of doing multiple exposures as well.

Jerry

goodoneian · Oct 4, 2008

on digital slr's if you keep the iso low (200 or less i'd say) you shouldn't really have too much problem with noise. how long of exposures are you talking about though? with my d40 and d300 i could easily do 30 second exposures at iso 200 and would only have little if not any noise. i'm not sure if the d90 has it, but some nikons have long exposure noise reduction which also helps keep the noise to a minimum, even though it extends the time to record the image to the memory card.

JerryPH · Oct 4, 2008

If your exposures go beyond 5 minutes and up, believe it or not, good 'ole film will kick any digital camera's butt quality-wise. Not only that, but, you end up slowly overheating your sensor and burning out pixels WAY faster than if you did not do this.

As a general rule, if I cannot do it in 30 seconds with my D200, I do not feel I need it that badly... lol

JerryinToronto · Oct 4, 2008

I am thinking between 15 to 60 seconds. Just looking at doing some street time exposures to get the feeling of movement from the lights of street traffic.

goodoneian said:
on digital slr's if you keep the iso low (200 or less i'd say) you shouldn't really have too much problem with noise. how long of exposures are you talking about though? with my d40 and d300 i could easily do 30 second exposures at iso 200 and would only have little if not any noise. i'm not sure if the d90 has it, but some nikons have long exposure noise reduction which also helps keep the noise to a minimum, even though it extends the time to record the image to the memory card.

JerryinToronto · Oct 4, 2008

No, about a minute would be it. I think the D90 would be good. The local camera store is willing to giving a loaner, against a deposit, for a day or so. Trouble is they sold out of their 5 D90's in 2 days!! I'll have to wait until they get one. Must be a good camera.

Bifurcator · Oct 4, 2008

JerryPH said:
If your exposures go beyond 5 minutes and up, believe it or not, good 'ole film will kick any digital camera's butt quality-wise. Not only that, but, you end up slowly overheating your sensor and burning out pixels WAY faster than if you did not do this.

As a general rule, if I cannot do it in 30 seconds with my D200, I do not feel I need it that badly... lol

I'm always wondering why camera designers don't add a cooling system of some kind. I think it's kinda lame that they don't... I mean for the bucks they ask for these things.

JerryPH · Oct 4, 2008

Because so few people do it, it is not worth their time to invest R&D and costs for this.

Garbz · Oct 5, 2008

That and peltier + heatsink makes for quite the large camera.

JerryPH · Oct 5, 2008

lol... no kidding!

Early · Oct 5, 2008

JerryPH said:
If your exposures go beyond 5 minutes and up, believe it or not, good 'ole film will kick any digital camera's butt quality-wise. Not only that, but, you end up slowly overheating your sensor and burning out pixels WAY faster than if you did not do this.

As a general rule, if I cannot do it in 30 seconds with my D200, I do not feel I need it that badly... lol

Shoot! This should be added to the "Advantages of film" thread floating around here somewhere.

Bifurcator · Oct 5, 2008

Well it wouldn't need to add any space. I know you guys are just having some fun with me but there is existing tech that could cool a CCD or CMOS and not add more than about 2mm to the size, then there's good old fashion air-flow, there's lots of things they could do... Hell, they even modify the firmware to operate the chip at lower temperatures with no space at all.

And Jerry, did you ever think that the reason "so few people" try it is because it's simply not available in any modern camera? When I 1st got into film photography I guess 10% or more of all the shots I thought were cool were looooong exposures.

So nya-nya...

Tiberius · Oct 5, 2008

Bifurcator said:
then there's good old fashion air-flow

Sensors attract dust like no other; air cooling is definitely a no-go.

Hell, they even modify the firmware to operate the chip at lower temperatures with no space at all.

It's not that simple at all. You can't just tell the sensor to operate at a lower temperature, just like your car's computer can't suddenly tell it "keep accelerating but use less gas".

Garbz · Oct 7, 2008

Well you can, but that requires running a lower voltage, which causes ADC compliance issues, loss of sensitivity, etc, and is likely to put you back into square one issue of more noise.

Bifurcator · Oct 7, 2008

Tiberius said:
Sensors attract dust like no other; air cooling is definitely a no-go.It's not that simple at all. You can't just tell the sensor to operate at a lower temperature, just like your car's computer can't suddenly tell it "keep accelerating but use less gas".

Well if we're daft and unclever then we can't do much at all - sure... That's true about anything.

But there could be a chamber in back of the sensor sealed off from the mirror box all together (so no dust) that allowed airflow to cool the sensor. Additionally ports in the sensor's ceramic cradle could by built in place. Air flow in either could be achieved with an electrostatic membrane requiring almost no space and consuming very little power. And those are just the lame ideas >I< can think of. I would hope chip and camera designers are as smart or smarter than I.

Also you can actually tell the sensor "to just operate at a lower temperature" .

Garbz said:
Well you can, but that requires running a lower voltage, which causes ADC compliance issues, loss of sensitivity, etc, and is likely to put you back into square one issue of more noise.

What about applying a regulated pulse width of some breadth across the circuit and using collection in an off sensor buffering system? We're only talking about looooog exposures here anyway so why not? That's a firmware mod only (for the most part) and could increase exposure lengths by 4 or 5 times bringing it up to an hour or so. We'd need to test all these fantastic theories but I think it might even improve IQ and reduce overall noise. And again, that's just what I can think of at first. With a salary and a nice test site like I'm sure exist at Canon or Nikon more could tried.