IN Sky Safari 5 Plus, how do I show the field of view, if I am NOT using a telescope, but instead using a DSLR camera (Canon) and a telephoto lens? I'm using an Ipad.
Thanks
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15 comments
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Keiron Smith Hi Dan,
What is the DSLR mounted on?
Thanks!
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Keiron Smith Hi Dan,
I'm assuming you want to use SkySafari to control your EQ5 mount even though it has only the DSLR mounted on it.
So...
In Settings >>> SetUp >>> ScopeType >>> Orion Atlas (this only applies if you have a telescope control solution; i.e. SkyFi 3)
In Settings >>> Display >>> Fields of View >>> Custom Field of View <<< define a FOV that matches your DSLR
In Settings >>> Display >>> Fields of View >>> Field of View Display Options >>> Show Even if Not Connected to Telescope <<< checked ON.
Now...
You can connect and control your mount (if you have a telescope control solution) and show the FOV for your DSLR.
Thanks!
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Dan Bjarnason hi kelon ...
im not trying to control my mount with sky safari ... what i want to do is for sky safari show my what the field of view will be if i have my canon 70D dslr camera, with a 300 mm lens, mounted on a tripod. i want some representation of what the camera will see.
i know how to do it for telescopes and eyepieces, but i cant figure out how to do it with just a camera and a lens.
thanks
dan
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Keiron Smith Hi Dan,
What is the FOV of your 300mm lens attached to the Canon 70D?
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Dan Bjarnason hi again jeiron
i havent been able ot figure that out. and canon's web site is no help. sorry.
dan
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Mario Wolczko -
Dan Bjarnason great mario. many thanks.
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Keiron Smith Thanks, Mario!
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John Fisanotti Hi Dan:
I've done it and it is not that complicated. Besides knowing the focal length of the lenses you intend to use with the camera, you also need to know the size of the camera's sensor. I looked it up on-line and a Canon 70D has a sensor which is 22.5mm x 15mm.
Now go to Settings>Equipment>Add Camera. There are five fields to fill out but you only need to fill out the first three: In your case, "Camera Name" would of course be Canon 70D, "Sensor Width" would be 22.5 and "Sensor Height" would be 15. You can leave the two "Offset" fields at zero (0).
Now tap "Equipment" to back out of that and then tap "Add Telescope". I add everyone of my camera lenses as if it were a telescope. There are three fields to fill out but you only need to fill out two. Under "Scope Name" I list the lens (e.g. 135 mm f/2.0), you can leave the "Aperture" field at zero (0), and in the "Focal Length" field enter the focal length of the lens (e.g. 135). Do this for every lens you intend to use for astro-photography.
Now that you have entered the parameters of your equipment you can select them to display the field of view: Go to Settings>Display>Fields of View and then select the camera and the lens combination you plan to use and select "Show Even If Not Connected to Telescope". That should do it. Also notice the "Field Rotation Angle", which is right under "Show Even If Not Connected to Telescope". Because the sensor is a rectangle, your field of view is a rectangle and you can use this to rotate the box to figure out which orientation of the camera will frame the subject best
I hope this helps.
John Fisanotti
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Dan Bjarnason wonderful. thanks john.
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Tim Campbell The lens and camera have to be added separately.
First add the lens... go into "Settings" -> "Equipment" then in the "Telescopes" section tap "Add Telescope" (even though it's a lens).
It will ask you for three things:
1) A name - any name you want (e.g. "300mm f/5.6 lens" for example)
2) The aperture ... you'll do a quick bit of math.... the aperture (in millimeters) is simply the focal length of the lens (e.g. 300mm) divided by the focal ratio (e.g. 5.6). So in this example, 300 / 5. 6 = 53.57. I'd round that to 53.6 and key that value in.
3) The focal length (e.g. 300mm)
With the lens in the database (as a telescope) you also have to add your camera.
Go into "Settings" -> "Equipment" and in the "Cameras" section tap "Add Camera"
The camera wants to know 5 pieces of information.
1) The name ... any name you want (e.g. I have a "Canon 60Da" on my list)
2) The sensor width and (this is important) this must be entered in MILLIMETERS (some users confuse this for the camera resolution... it wants to know the physical dimensions of the image sensor to calculate the field of view). My particular camera has a 22.0 mm wide camera sensor.
3) The sensor height (again, in millimeters). Mine is entered as 15mm.
4) The sensor x-offset in millimeters (typically this is just 0 - more on this in a moment)
5) The sensor y-offset in millimeters (also typically just 0).
About those "offsets"... some telescope imaging setups have both an "imaging" camera and a "guiding" camera operating at the same time and they may use a technique called "off-axis guiding". In that setup, the guide adapter allows two cameras to connect to the same telescope... one camera (typically the main imaging camera) is at the back and has the largest field of view through the center of the scope. But the adapter has a tiny prism on the edge called a pick-off mirror... and this bounces light out at a 90º angle to a second camera (the guide-camera). The field of view for this camera isn't in the center of the telescope's optical axis... it's off to the side. So this "x" and "y" offset data allows you to position the field of view of the camera so that it isn't actually in the center of the telescope's optical axis -- it's offset by some amount (so that two different cameras can look through the same telescope at the same time.)
If you aren't doing this type of work, then just enter the "x" and "y" values as 0's (which means the center of the camera's field of view in in the center of the telescope's optical axis.)
Now you've got the equipment entered... but no field of view.
Go into "Settings" -> "Display" and you'll notice Sky Safari offers 5 different "Fields of View" which you can configure on/off.
Tap a row near the right edge (where you see the ">" arrow) and this will let you configure which telescope & camera (or telescope & eyepiece) combination will be used for that field of view.
When you're in that section, you'll see a couple of lists... first is a list of telescopes, binoculars and finders... you should see your new camera lens on that list. Tap it to select it. You should see a checkmark next to your selected piece of equipment.
Scroll down further and you'll the list of "eyepieces & cameras". You should see the camera you just added on that list. Tap it to select the row and confirm that you get a checkmark on the row indicating it has been selected.
At the top of the panel, tap "< Display" to save your configuration and return to the previous menu (if you tap "Done" then it will save but return to the main Sky Safari display (you'll have to go back into "Settings" again).
Now you should see your newly configured Display choice... but it's likely toggled off. Just tap the toggle to turn it on.
Before you tap "Done", gaze down to the bottom of the screen and notice there's a setting for "Field Rotation Angle". Tap that and it'll take you to a preview window which shows the current area of the sky, with a slider along the bottom that lets you rotate your field of view.
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Dan Bjarnason thanks tim. much appreciated.
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Dan Bjarnason thanks everyone. all the help is much appreciated. i get it now.
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Sumon Islam I finally decided to upgrade to DSLR, but I'm not sure if Canon t3i or Nikon D3200. Can anyone provide some clarity? (both cameras look pretty similar to me)Also, should I get a couple of lenses, or is the 18-55 mm fine? I will use it just to take pics of my kids, family events, and vacations. Thanks in advance!
Deqto -
Tim Campbell Yes - big difference in those choices.
I'm normally not one to say go with brand x over brand y. Loads of professional photographers shoot both systems and get great results. BUT... for astrophotography there are some major differences you'll want to know about.
Short version: Get the Canon
Long version:
In astrophotography, when doing focus (especially if putting a Bahtinov mask on the front of the lens or telescope) it helps to brighten the exposure so that you can actually see the diffraction spikes. Canon supports something called "exposure simulation" in live-view mode. Very few Nikon cameras have that feature (they introduced it for the D810a and a few models after that have it ... but most of the product line does not). On the Canon, just crank the ISO to max and crank the shutter speed to 30 seconds (these are not the settings you'll use when you image) but that will brighten the display to help you focus ... then return your exposure settings to something reasonable for the actual imaging.
When imaging the moon, there's a similar problem on the Nikon ... the camera will notice all the blackness of the background and tries to auto-brighten the display ... but this just creates a bloated while blob where the moon should be. I once had a camera club visit the observatory ... and the instructor had a Nikon and so all his students also got Nikons. They really struggled to focus anything through the telescope.
Canon has historically been extremely good about opening up their software development kits to public developers. For this reason, it's easy to find lots of software that supports Canon cameras. Nikon hasn't been as good about this AND ... the support varies by model. If you get a D5xxx series body, they have better SDK support. But for a D3xxx series body, they do not.
If you look at popular image acquisition software (such as Backyard EOS & Backyard NIK) you'll see that while they support pretty much every Canon model produced in many years ... on the Nikon side they do not have any support for any D3xxx series body.
A friend of mine does have a Nikon D3xxx series body (modded for astrophotography) and reported that he cannot control the shutter via the USB cable... he HAS to use a wired remote control (so there are some software based apps that use a dongle to control the wired shutter release port). I was really surprised by this. He says he can download the images after they're captured, but he can't control the camera via the USB port on a D3xxx series body.
There's a little more...
On the Nikon, they use a Sony ISO-invariant sensor. Shooting at, say, ISO 800 is no different than shooting at ISO 100 ... and then using post processing software to amplify the image data by 4 exposures stops. But when you do this with a digital image, you end up clipping some dynamic range.
On most Canon models, they use a combination of "upstream" and "downstream" gain to boost ISO. "upstream" gain, is any gain applied to an image before it goes through analog-to-digital conversion (ADC). It is analog amplification of the data before it is digitized. "downstream" gain is mathematical gain applied to the digital data (in other words multiply the value in each pixel by some multiplier).
Since both Nikon and Canon cameras have 14-bit sensors (when shooting RAW ... and you should only ever use RAW for astrophotography), dark values will be mathematically increased ... but already bright values (such as bright stars in your image) will "clip" as they are multiplied above the 14-bit limit. This results in the star just appearing as a white dot ... instead of showing some true star color (such a blue or yellow or red color cast that reveals the temperature of the star).
On most Canon models prior to the T5i (basically any Canon camera that has an 18MP sensor), the magic ISO is ISO 800. Up to ISO 800 the camera sensor applies analog gain (which results in very little loss of dynamic range). Beyond ISO 800, any additional gain is "digital" (downstream gain) where there's a loss of dynamic range. This means on any Canon camera with an 18MP sensor, you don't want to operate at anything higher than ISO 800 (I do for framing & focusing testing ... but once I'm capturing real data, I return the camera to ISO 800 or lower for actual image captures).
Since most Nikon models use ISO-invariant sensors, it's all digital gain (all "downstream" gain) and you start losing dynamic range as soon as you come off base ISO (ISO 100). The good news is that Nikons tend to have slightly higher overall dynamic range as compared to the Canon. So you can stand to lose a tiny amount of DR and still get good data ... you just don't want to take it too far.
Canon is the most popular DSLR used for astrophotography (by far) *because* of the software support ... the fact that Canon has made their Software Development Kit (SDK) freely available to any third party -- and has been for years and years -- has resulted in a market where just about any application you can think of designed to do astrophotography with a DSLR will support Canon models ... but only *might* support other models.
While this is true in the astrophotography world... if you want a DSLR for other purposes (sports/action, family life, portraits, weddings, landscapes, and on and on and on) then it really doesn't matter which brand you go with. Both companies make outstanding products that serve professionals extremely well. It's just that astrophotography is this niche field where Canon has a huge advantage over everyone else.
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