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Occasional Contributor
Posts: 5
Registered: ‎02-25-2018

Re: Problem with startrails on the edges. EOS 700D.

How can I send it to you?

Esteemed Contributor
Posts: 3,485
Registered: ‎06-11-2013

Re: Problem with startrails on the edges. EOS 700D.

The easiest way is to use Dropbox or Google Drive.  Both offer a limited out of storage and it's free.

 

I started with Dropbox ... they only give you 2GB of free storage (they give you more if you refer friends, etc.)  

But Google Drive gives you 15GB free (much better).

 

You can find them at:

 

drive.google.com

dropbox.com

 

If you already have any Google services or a Google login, then you already have Google Drive and just don't know it.  

 

You can upload the file to their cloud and share the link to it.  You can set permissions for who can see each file... just set the permissions so that anyone with the link you provide can access the file.   You can also share files (or entire folders) to named individuals, but to do that they also have to have a Google (or Dropbox if you prefer them) account and you have to know their login name (email address they use to log in).  

 

Both Dropbox and Google offer to let you install an agent on your PC/Mac... but it's not required.  All the agent does is let you pick a folder on your computer... where anything in that folder will automatically be sync'd to the cloud drive.  If you don't want to install the agent, you can just use the web interface to upload the file.  (I use the agent to sync files between the observatory where I do some imaging work... and my home computer.  As I capture images, they go to the local folder, the agent "syncs" that folder to the cloud drive, and my computer back home has an agent that also monitors the cloud drive and downloads any new files to a local folder.   So "in effect" I take a photo at the observatory (20 minutes from my house) and the images show up on my home computer a few minutes later because both computers are syncing the contents of the same shared cloud drive.

 

You could also use photo-sharing services such as Flickr... but the "catch" is that Flickr is specific to photos so the file has to be a photo type they recognize and they don't support RAW files.  (Google and Dropbox don't care what kind of file it is.)  But it would still work as long as the image was uploaded in full size (don't let it reduce the image size) and not stripped of the EXIF data (exposure settings and other meta-data such as the camera, lens, date/time, etc.)  

 

If the image is reduced in size, then much of what we'd need to inspect will be too small.

 

 

Tim Campbell
5D III, 5D IV, 60Da
Occasional Contributor
Posts: 5
Registered: ‎02-25-2018

Re: Problem with startrails on the edges. EOS 700D.

Didn't have many pictures in RAW atm, it's not the best picture but illustrates my problem.

https://drive.google.com/open?id=1iK-qTJuDB6zfyE0prbTvAnmMztLphoQ9

Exposure: 2 sec
Iso: 800
Tripod: Velbon DF 50
Remote trigger.
Aparture: 2.0
Esteemed Contributor
Posts: 3,485
Registered: ‎06-11-2013

Re: Problem with startrails on the edges. EOS 700D.

I had a chance to look at the image.  I see the Hyades (Taurus) and Pleiades in the image which means the star direction would have been moving toward the lower right (your camera was pointed roughly toward the southwest).

 

I see the various optical aberrations in the image and they don’t match the direction of star travel... so they aren’t caused by a long exposure (also your exposure time appears to be very short).

 

I see lots of optical issues ... the stars look like they aren’t quite focused, but the de-focused stars are giving odd shapes and it looks like more than one issue — and I suspect de-centered optics as well.  I say this because the stars in the center actually don’t look good to me... the stars a bit right of the center look a little better (all of them look a touch soft). 

 

Normally when you manually focus for night photography, you would turn on live-view and crank the ISO to max and crank the shutter speed to 30 seconds ... because the camera supports “exposure simulation” when using live-view.  This will brighten the stars to make them easier to focus.  Find the brightest star you can find (but it should be a star... not a planet.  Currently Sirius is the brightest star in the sky (it’s the brightest star apart from the Sun).  To find it, follow the 3 stars of Orion’s “belt” toward the left (east) and the brightest star you come upon is Sirius.  It doesn’t matter if you plan to image a different section of the sky... once anything is focused, everything is focused (unless there’s a problem with the lens).

 

Get the star roughly close to focus (you can adjust the focus ring to infinity to be close), then use the LCD zoom feature (the magnifying glass icon with the “+”) to zoom in to 10x ... then very carefully adjust focus to get that star to a pinpoint as best as possible.

 

A focusing aid such as a SharpStar 2 (Lonely Speck makes it) will help.  It creates diffraction spikes on the stars which will converge at a common center point only when the focus is perfect... so it’s easy to see when you’ve nailed the focus.)   Take a test shot of a few seconds with the focus aid on the lens because this will create much bigger diffraction spikes than you can see in Live-View mode ... and confirm that your focus is bang-on accurate.

 

Once focused, return the exposure to sane settings and point the camera to the part of the sky you want to image (being careful not to touch the focus ring).

 

MOST lenses will give some optical aberrations when shooting wide-open (even high quality lenses).  You can greatly reduce them by stopping down a touch.  But you should have pretty even focus across the entire image field with only a tiny degradation near the corners.  If you are still getting de-focused stars... the lens has optical problems.

 

 

 

Tim Campbell
5D III, 5D IV, 60Da
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