10-01-2017 07:39 PM
BTW, it translates to about 15 seconds on your new T7i with the same 24mm lens.
10-01-2017 08:11 PM
You need to learn the 500 Rule. It is similar to the Sunny 16 but for astro-photography.
Here’s the 500 Rule:
500 Divided By the Focal Length of Your Lens = The Longest Exposure (in Seconds) Before Stars Start to “Trail”
For example; let's say you're taking a shot with a 24mm lens on a full frame camera. 500 / 24 = 21 seconds, which you can round to 20 seconds.
IMHO, it really sounds like you need to get into post editing before you buy anymore gear. Great photos are made in post not in the camera. Look at Lightroom and/or Photoshop. Possibly Photoshop Elements.
I would agree with the suggestion that you become familiar with shooting as RAW, not JPEGs, and using post processing software. Canon makes their Digital Photo Professional 4, DPP4, software available with the camera. While it is not the most sophisticated application of its' type, it is fully featured enough to do a fairly decent job.
In a nutshell, when you set the camera up to save photos as JPEG files, you are using the camera much like an old Polaroid instant camera, which spat out a print that took up to a minute to develop. When you shoot RAW, you are asking the camera to create the equivalent of a digital negative. The DPP4 software is your digital darkroom to convert the RAW digital negative files to JPEG output files, which you can share with others in our digital world.
The Adobe application Lightroom is a far more powerful and sophisticated digital darkroom application. I would suggest learning the concepts of post processing with DPP4 before making the immediate leap to Lightroom. Photoshop and Photoshop Elements, which is less sophisticated version of full blown Photoshop, take image processing in a different direction, allowing you to make edits of the actual image itself. This is an essential part of creating astrophotography images. While it is not absolutely mandatory for wide angle shots of the night sky, it does improve the images immensely.
10-01-2017 08:34 PM
10-01-2017 09:19 PM
10-01-2017 10:35 PM
I have seen the RAW file typeIs the Photoshop program a reasonably intuitive application to work with in your opinion?
I may be in the minority in this group, but I would say no. Photoshop is a very powerful editor, but most people who use it don't actually need it. Take Waddizzle's advice and become proficient in Digital Photo Professional V4. If and when you find that you need a capability that DPP doesn't have, look into other editors like Lightroom and Photoshop to see whether one of them is what you need.
10-02-2017 07:51 AM
10-02-2017 11:44 AM - edited 10-02-2017 12:08 PM
One other thing that I have been considering is a star tracking device I have not seen any questions on this forum about them, should I start a new topic or is it proper to bring that up here?
The two most popular tracking heads are:
1) The "Star Adventurer" by Sky Watcher
2) The "SkyTracker Pro" by iOptron
The Star Adventurer was the beefier system and could handle heavier loads and costs a bit more... but I noticed that NOW Sky Watcher offers a "Star Adventurer Mini" (a lower cost version that handles less-beefy loads) and conversely iOptron now offers a "SkyGuider Pro" which is a more expensive version to handle beefier loads. So both companies are definitely trying to cross-compete both on load capacity and price.
These devices tend to be in the $300 price range (give or take a bit).
The Earth spins from west-to-east which gives us the illusion that we remain still and the sky moves east-to-west. The tracking head spins east-to-west and while it has selectable speeds, the main speed for tracking stars ("sidereal rate") rotates at 15 arc-seconds (angular rotation) per second (of time).
If the rotating axis of the tracker is exactly parallel to the axis of the Earth, then the rotation of the device cancels out the rotation of the planet and any objects in the sky are exactly held in place ... you can take nice long exposures with tack sharp results.
The shot below used a 135mm lens and an 8 minute exposure!! The lens was set to f/10. This isn't the exposure I actually used when imaging the area but it was nice to test the tracking accuracy (the real exposures used a much lower f-stop and much shorter exposure times.) ...but you get the idea. A nicely aligned tracking head will eliminate the star drift problem and not only let you shoot longer to capture more detail... it'll also let you use longer lenses for more detail on parts of the sky.
These heads all come with some type of alignment aid to help you get a pretty close polar alignment.
I do strongly suggest a quality beefy tripod. You may want to hang a weight from the center post to help stabilize the tripod. Adding weight helps reduce vibration.
I think the iOptron might include the equatorial wedge but I think it's sold as an accessory for the Sky Watcher brand head. Regardless... you want one. The head gives you fine adjustment control for carefully dialing in your accurate latitude and azimuth for accurate alignment. It can be done with just a simple ballhead or pan-tilt head... but it's tought to do that accurately.
Both have an optional counterweight bar and weight ... which would be for use with longer/heavier lenses. This allows the weight of the camera & lens to be balanced by the counterweight so that the tracking motor isn't running slower when "lifting" the camera and faster when "lowering" the camera.
The narrower the angle of view of the lens, the more critical it is to have accurate alignment and tracking.
10-02-2017 12:05 PM
10-02-2017 01:32 PM