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Histogram


melvin

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Hi, this morning the dogs got me up at 3.30am so I decided to put into action some of the things I've learned!! about bye. But, I tried to adjust things so that the histogram showed most of the pixels in the 2nd third not all to one side (usually on the left). I changed the ISO, aperture and exposure, but no matter what adjustment I did I could not move the pixels to where they should be. Can anyone help. Probably not a bye issue but I'm hoping someone can help.

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Melvin,

 

Can you provide more information?

 

Were you shooting raw or jpeg?

What camera and scope?

What shooting mode? Manual?

What adjustments did you make? Increasing the ISO, the aperture (lower f-stop value) and/or the exposure duration should have a noticeable affect on both the image itself and on the displayed histogram.

 

I would suggest setting the f-stop 2 or 3 stops from wide open and the ISO to 800. Then change the exposure to adjust the brightness/histogram. Don't move in small amounts, like from 15 seconds to 20 seconds. Move from 15 seconds to 1 minute. Then if 1 minute is too much, you have 2 exposures on either side of where you need to be and can better decide the best exposure for the next shot.

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I would suggest setting the f-stop 2 or 3 stops from wide open and the ISO to 800. Then change the exposure to adjust the brightness/histogram. Don't move in small amounts, like from 15 seconds to 20 seconds. Move from 15 seconds to 1 minute. Then if 1 minute is too much, you have 2 exposures on either side of where you need to be and can better decide the best exposure for the next shot.

Let's add:

Set the Camera to "Bulb" mode (if your DSLR only has "Manual" mode then use that).

Set your Lens to "MF" - Manual Focus" - for Nighttime Shots (unless you have the Moon up - then use "AF" on the Moon as your Focus - then set to "MF" to keep that Focus).

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Hi the camera is a Canon 600d file type was raw/JPEG there was no scope just my 18/55 canon lens, the dial on the camera was 'm' and bulb was set on both bye and camera. I set the switch on the lens to m/f. I tried setting the shutter speed from bulb all the way down to 1.750. Quite a move along side the ISO from 100 to 6400. But as I say the histogram did not go where it should. I moved the f-stop up and down then tried for fine focus. I really am lost, I have watched and read loads today and the only thing I can glean out is that the duration should move the pixels nearer too the 2nd third.

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Melvin,

 

Bulb is not a shutter speed.  It simply means that the shutter will be controlled by the user (you pressing and holding the shutter button on the camera or remote shutter, by an interval timer, or by BYE).

 

When the shutter is set to BULB, you define the shutter speed in BYE by setting the Duration parameter.

 

The default duration is 1 second. This quite short for a nighttime image. So you may not have seen too much of a difference between that and an exposure of 1/750th of a second, especially if you are not close to focus.

 

In addition to my previous advice, you need to be close to focused.  In order to do that, you need to start with the lens focused at the stop all the way beyond Infinity and the camera aimed at a bright star. Then take short, say 10 second, Snap exposures with BYE's Frame & Focus while usihg the FWHM or HFD focus parameter to get good focus.  Then try a 60 second exposure. You should see lots of stars.

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Thanks for your time, tomorrow I shall try again and incorporate your comments. I'll keep you informed but it could take a few days of experimenting. Once again thanks for being there and helping someone who basically is pretty useless but I'll get there with your help. When I see some of the pics that are posted it makes me intent on improving.

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Hi the camera is a Canon 600d file type was raw/JPEG there was no scope just my 18/55 canon lens, the dial on the camera was 'm' and bulb was set on both bye and camera. I set the switch on the lens to m/f. I tried setting the shutter speed from bulb all the way down to 1.750. Quite a move along side the ISO from 100 to 6400. But as I say the histogram did not go where it should. I moved the f-stop up and down then tried for fine focus. I really am lost, I have watched and read loads today and the only thing I can glean out is that the duration should move the pixels nearer too the 2nd third.

OK.  Sounds like you need to Simplify.  Make sure that you are NOT changing Every Setting all at the Same Time.

Start by looking through the BYE Manual (click the "?" icon in upper right of BYE).

 

Then, perhaps it is best to simply connect your 600D to your Laptop while sitting at the Kitchen Table...  Set the DSLR on its Tripod, or just on the Table, and point it at something (anything).

Work to get it Focused (either "MF" with the Lens Focus Ring looking through the Camera ViewFinder; or using the BYE Focus Tool if you're trying the "Free Trial" or "Premium" versions).

Set the Camera to "Manual".

Now, the Camera and its Settings are controlled by BYE

 

Set the BYE Mode to "Frame&Focus".  You should be able to see what the Camera is Focused On being displayed on the Laptop Screen.

 

Now, work to get BYE to take a Picture that you can see on the Screen.

Select BYE Mode "Imaging".

Using only the 1st Line in the Capture Plan, select Shutter "Bulb" and Duration "1" and Aperture "lowest offered" and ISO "100".

Now click "Preview".  When it is done with downloading the 1 sec Exposure, you'll have an Image displayed in the "Image Center".

If that Image is Over-Exposed (Histogram far to the Right), then change the Aperture to "f/7.1", and click another "Preview".

If the 1st Image is Under-Exposed (Histogram far to the Left), then change the Duration to "2", and click another "Preview".

 

Now that you have an Image displayed on BYE that you can See...  Look at the Histogram.

That will be what a Normal "Bright" Histogram looks like...

 

Now, play with the "Duration" setting, running it to higher and lower values, and watch the Histogram change with every "Preview".

 

Next, I'd suggest that you do basically the same thing with the Camera and Laptop on a Table and/or Tripod outside After Dark - pointed at a Distant Dimly Lit Fence or Garage Door or Car Bumper.

The main difference would be to set the ISO at "1600".  And expect the needed Exposure to be 30-45-60sec or more.

 

Once you have a better command of the basic Settings and their Impacts, you'll be much more comfortable attempting AP Imaging...

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That is what I call magic info. I signed up for a beginners course on photography but before it began the local council withdrew funding so the cost shot up and I could not afford it. I keep having a go with the camera and bye, usually during the day but as the dogs woke me just after 3am the other day I decided, as the sky was nice and clear, to try out things, but as usual I did not get very far. Today I am going to follow s3igell's words. Thank you.

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