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Been trying to avoid asking this but.....

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#1 AstroDan77

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Posted 10 June 2013 - 02:37 PM

Ok I'm really showing how green I am at AP but perhaps you guys can help with something I tried last night and can’t seem to figure out. I noticed that when doing 30 sec exposures at 18mm, ISO1600, F3.5 the sky looks good so, just for experimentation I kept the same settings in bulb mode and shot 30 seconds and the photo was grossly overexposed. What changes from 30 sec exposures timed vs. 30 sec exposures in bulb mode if the settings are the same? I know I'm probably missing something obvious but I'm just not seeing it apparently. :confused:

Thanks
Dan

#2 sparky123

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Posted 10 June 2013 - 04:26 PM

What changes from 30 sec exposures timed vs. 30 sec exposures in bulb mode if the settings are the same?


i was hoping to tag onto this question as well...should one be in "bulb" or "manual" setting on the camera...or is there any difference. sorry for tagging on..hopefully thats allowed

#3 rflinn68

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Posted 10 June 2013 - 04:29 PM

Was it on A/V mode?

#4 frito

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Posted 10 June 2013 - 04:40 PM

I guess the real question is how are you controlling the camera shutter?

on my Rebel XT (350d) i have to use a shutter cable to get longer than 30 seconds via bulb mode. i made a serial control cable to achieve this.

using just the shutter cable connected to a laptop running DSLR shutter i would set the camera to manual, set all settings on the camera how i want them and set it to bulb. all the shutter cable can control is opening and closing the shutter, thats it.

i now use BackyardEOS. with BYEOS i have to have a usb cable AND the serial shutter cable connected and camera set to manual mode and PC connection mode. no other setting on the camera matters as BYEOS takes over full control of all of them and i set what i want in it.

#5 DaemonGPF

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Posted 10 June 2013 - 05:25 PM

Amp glow?

#6 Momerath

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Posted 10 June 2013 - 06:27 PM

I know in the canon 60D 30 seconds is the highest you can go in manual. You have to use Bulb for exposures greater than 30 seconds. This holds true even if you use a shutter release or a wireless intervolometer while in manual.

I also know the just because you set up iso and exposure settings in manual, when going to bulb they do not transfer over. Bulb will take the settings of the shutter release or intervolometer, even tho it will show the manual settings in the camera windows. This threw me for a loop the first time i used my intervolometer. i was trying to set up a 30 second exposure and the intervolometer was set for 1 min. the camera kept taking 1 min exposures even tho the windows indicated 30 sec was set.

This may be what is affecting you. Hope this helps

#7 frito

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Posted 10 June 2013 - 06:50 PM

Amp glow?


i've had AMP glow show up in some of my images before, it shows up in the bottom right hand corner only i'm pretty sure.

#8 Darren1968

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Posted 10 June 2013 - 07:04 PM

Are you able to click on each image and look at the details for exposure length, duration, ISO, and aperature to comapre and make sure that all of the settings are equal???

To me if all is equal there should be no difference.

Let us know.

Darren

#9 sparky123

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Posted 10 June 2013 - 07:49 PM

i capture using byeos. the question just popped into my mind when I read the posters thread...Im sure I have captured in both the manual and bulb setting...just curious if there were any benefits of using one camera setting versus the other

#10 Momerath

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Posted 11 June 2013 - 07:10 PM

i capture using byeos. the question just popped into my mind when I read the posters thread...Im sure I have captured in both the manual and bulb setting...just curious if there were any benefits of using one camera setting versus the other


Only the fact that in Manual you can only take 30 second subs. If you want longer than you will have to use bulb.

#11 AstroDan77

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Posted 13 June 2013 - 01:33 AM

Anytime I shoot I use the shutter release, timed or BULB mode so I reduce random vibrations through camera interactions.

Sparky123 its fine with me if you jump in, the more I can learn the merrier.

#12 AstroDan77

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Posted 13 June 2013 - 01:34 AM

nope wasnt in AV mode and I have no idea what Amp glow is haha.

#13 AstroDan77

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Posted 13 June 2013 - 01:43 AM

momerath you may be onto something there. I set up the same way wether its 10 sec or 2 minnutes. Camera on the tripod, settings and shutter release cable so nothing ever changes there. Now for example I took night sky exposures at 30 sec, ISO 3200, F3.5 with the camera set to 30 second exposures. So I just hit the shutter release and 30 sec later the exposure is complete.

I then did the exact same thing except the ONLY difference was that I was in bulb mode and I timed 30 sec on the stopwatch (yes it was 30 sec hah) and that single change resulted in a completely overexposed photo of the sky. So perhaps what you were saying about even though I had settings, BULB mode didnt use them for whatever reason. And if that is the case how the heck do you set your camera for longer exposures if it ust does what it wants.

By the way great info everyone, I appreciate it and keep it coming. I like learning!

#14 Footbag

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Posted 13 June 2013 - 09:54 AM

Is it possible the LCD screen was left on for one of the exposures?

When I accidentally leave my screen on, it gives me a glow like amp glow.

#15 Momerath

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Posted 13 June 2013 - 10:42 PM

If you are sure the sub lenth is the same and the iso settings are the same then the only other thing I can think that could affect exposure is apature lock. It could be you have your aparture locked to a specific f stop when in manual and then you go to bulb it does not use the apature lock.

Have you tried changing the sub length and and iso settings when in bulb? can you achieve a decent exposure or does it always overexpose?. Also you should cover the view finder with the cover that comes with the camera. (that little thing that is usually on the camera strap. it will help prevent light from going thru the view finder and over exposing the image.

#16 AstroDan77

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Posted 14 June 2013 - 07:04 AM

Unless my stop watch counts 30 sec wrong its 30 sec, and yes the LCD was not on. It only comes on for a couple seconds to display the photo I just took. Well, its SET to ISO 3200 weather the camera uses it or not is up for grabs. Although that poses another question, it only goes to 3200 so if anything shouldn't the photo be darker if it's not using it?

I will have to take 2 pics and post them here for an example. its gotta be something simple I'm just not seeing.

#17 Ratchet

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Posted 14 June 2013 - 02:51 PM

Look at the exif data. Something will be different.

#18 sullij1

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Posted 14 June 2013 - 10:50 PM

How did you process? Did you watch the histogram? Did you stretch the image to reveal the details? Stretching can be accomplished in the Canon utility software. On my humble 1000D the raw image always appeared overexposed (pure pink or red) until I used software to to correct the exposure.

#19 sullij1

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Posted 14 June 2013 - 10:53 PM

Read this thread for more info:
http://www.cloudynig...5917546/page...

#20 sullij1

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Posted 15 June 2013 - 12:50 AM

Here is a good tutorial if you have photoshop. Canon utilities also has similar functions that help get the red out. Can you post your raw image so folks can see what you are talking about?

#21 sullij1

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Posted 15 June 2013 - 01:09 AM

YOU SAID THIS “Now for example I took night sky exposures at 30 sec, ISO 3200, F3.5 with the camera set to 30 second exposures.”

I just noticed the “ISO 3200” is way too high! Back the ISO off to between 800 and 1600 and try again. I like the way ISO 800 worked for me. Stack and adjust levels and histogram to 1/3 and you should be good to go.

Clear skies.

#22 AstroDan77

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Posted 16 June 2013 - 07:27 AM

OK just had the 1st chance all week to test it out. 2 shots 30 sec, one in bulb that I times for 29.8 sec (my bad) and one with the camera set for 30 sec, ISO 3200, F3.5 @18mm.

What I found was that in the data was that when I have the camera set for 30 sec the data reads ISO-280 NOT 3200 like I have it set in the camera. Now when I shoot BULB it uses exactly what I had set thus, it was overexposed due to the high ISO.

So now my problem is why even though my camera is set to manual does it use its own ISO when set to timed exposures? Wow, that blows me away because I normally don't look at the data and I thought I have been shooting in 3200 when I haven't been.....well that's frustrating hah.

#23 AstroDan77

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Posted 16 June 2013 - 07:29 AM

Tonight when I go back out I'm going to shoot the same settings in BULB with ISO at 280 and theoretically it should look the same as the internally timed photo.

#24 AstroDan77

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Posted 16 June 2013 - 07:35 AM

Here's the 30 sec with internal timer.
ISO-280 though its set for 3200
f3.5
18mm

Attached Files



#25 AstroDan77

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Posted 16 June 2013 - 07:36 AM

Same settings in bulb mode but it actually used the ISO-3200 as I have it set.

Attached Files








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