How to shoot in Bulb mode

[tsk1979]

Great info. Tanveer... Thanks for the share. BTW, can you please suggest suitable exposure times for relevant scenes like city nightscapes, star trails (with / without moon etc), traffic trails etc.... I guess I mean to say, how do we decide or predict the suitable exposure time for a shot in Bulb mode... do you have any bench marks or its hit and trials and then learning as you shoot...

Its always good to take a test shot at high ISO to get a feel of it.
there is no exact math.
On a very dark night with light pollution, you need to take minimum 15-20 minutes exposure at ISO 200 F5.6

With moon, even a 4-5 minute exposure at ISO 200 can be enough.;

So experiment.
Even if you take twice the exposure, you still have to recover just one stop!

 

[oriole12]

I agree. There is no magic formula or set exposures. Trial and error is the best way. In fact, what I like about digital cameras are their ability to show results instantly and to teach me like no trainer can.
For star trails, it is better to shoot at intervals, using an intervalometer, discussed elsewhere in this forum or by using the camera's built im programme. Take at least 30 images at intervals and stack them together in a programme like Image Stacker or Starstax. ( Here is a great guide Your Complete Guide For Photographing Star Trails | DIYPhotography.net)
Some of the advanced cameras have long exposure Noise Reduction settings, but if the noise is an issue, it is better tackled during Post Processing using specialized Noise reduction programmes. BTW, the noise reduction and stacking capabilities of the Photoshop CS5 are impressive too!

 

[hensil]

Great info. Tanveer... Thanks for the share. BTW, can you please suggest suitable exposure times for relevant scenes like city nightscapes, star trails (with / without moon etc), traffic trails etc.... I guess I mean to say, how do we decide or predict the suitable exposure time for a shot in Bulb mode... do you have any bench marks or its hit and trials and then learning as you shoot...

Dheeraj,
Even though my response is late, I'd like to give you a tip to calculate the shutter speed for bulb mode.
These days all DLSs have ISO in excess of 6400. First keep your ISO to 6400. Then use your 50mm f/1.8 lens just for calculation. Keep it at f/2 for simple calculation. Later you may want to shoot at f/5.6 with other lens. Keep your camera on aperture priority and take a sample picture. Suppose your camera gave shutter speed of 10 secs.
Now, turn your ISO to 100. That is straight away 6 stops slow shutter speed and when you reduce the aperture to f/5.6 you have lost 3 stops. Now calculate your shutter speed 9 stops (6+3) from your original 10 secs, that is approx 85 mins. I hope my maths is right.
Henry

 

[oriole12]

...
Now, turn your ISO to 100. That is straight away 6 stops slow shutter speed and when you reduce the aperture to f/5.6 you have lost 3 stops. Now calculate your shutter speed 9 stops (6+3) from your original 10 secs, that is approx 85 mins. I hope my maths is right.
Henry

Very interesting way of going about. Must try this out some day soon! Thanks Henry.

 

[Roadie..]

Wow thats a lot of science in it!
I had a query.. Although My Sony APS-C does great with long exposures giving almost noiseless pics with long exposure NR turned on but when theres not enough time and ISO has to be pushed up, there is considerable noise.
That becomes the only need to do post processing which I generally dont feel like applying in normal well lit pics which are are just great.
Please help

 

[tsk1979]

Wow thats a lot of science in it!
I had a query.. Although My Sony APS-C does great with long exposures giving almost noiseless pics with long exposure NR turned on but when theres not enough time and ISO has to be pushed up, there is considerable noise.
That becomes the only need to do post processing which I generally dont feel like applying in normal well lit pics which are are just great.
Please help

If you crank up ISO, there is noise. No getting around it. Whether you have a 1000$ camera or 10000$ camera, noise is a part and parcel of high ISO shooting. How much noise? Well that depends on your camera (eg cams with lower pixel density give better high ISO results).

 

[oriole12]

Tanveer, not only high ISO, but long exposure also adds to the noise. The method of calculating suggested by Henry is worth trying. I just donot seem to get away to a nice spot for some startrail and light painting!

 

[tsk1979]

Tanveer, not only high ISO, but long exposure also adds to the noise. The method of calculating suggested by Henry is worth trying. I just donot seem to get away to a nice spot for some startrail and light painting!

Long exposure noise is still controllable
1. You can use long exposure dark frame reduction
2. Noise is mostly RGB pixels scattered here and there, and its easy for noise reduction programs to get rid of it.

However, high ISO noise is a totally different beast.

But your point is very valid for P&S where there is not enough sensor cooling, and long exposures often lead to very high noise. Even in DSLRs crossing 20 minutes or so can give AMP glow if (greenish tint around edges) if the ambient temp is not very low.

 

[Roadie..]

If you crank up ISO, there is noise. No getting around it. Whether you have a 1000$ camera or 10000$ camera, noise is a part and parcel of high ISO shooting. How much noise? Well that depends on your camera (eg cams with lower pixel density give better high ISO results).

Thanks.
Surely noise is a part of high ISO, but I was wondering that if any certain setting of the camera may help in producing less noisy pics in high iso. Pixel density of Sony APS-c is good at 16 MP thats why I didnt go for 18 MPs or 24 Mps in entry level SLRs.
I feel noise from 3200 and above.
Also may you suggest any good free editor for sony ARW file, I think GIMP doesnt support ARW.

 

[tsk1979]

Thanks.
Surely noise is a part of high ISO, but I was wondering that if any certain setting of the camera may help in producing less noisy pics in high iso. Pixel density of Sony APS-c is good at 16 MP thats why I didnt go for 18 MPs or 24 Mps in entry level SLRs.
I feel noise from 3200 and above.
Also may you suggest any good free editor for sony ARW file, I think GIMP doesnt support ARW.

Try RAWTHERAPEE. Visit their forums and download experimental version
rawtherapee.com ? View topic - Latest builds - test the latest, bleeding-edge version of RT -> Bleeding edge with advanced noise reduction features etc.,