The Way to Pick an astro camera to match your imaging needs
Component 1- Guidelines for Choosing the Best camera to your telescope and observing conditions:
As an introductory note, T actually wrote this article a few years back when CCD cameras mled the roost. At the request of a colleague, I have taken a fresh look at the issues and updated my recommendations based on ct lease CMOS camera models. Many oftbe concepts apply equally well to CCD and CMOS cameras however I am more famar with QHYCCD products now so that I shall use examples of our CMOS versions to illustrate a few points in the article.
It1 Component I I outline a number of the basic issues one should cons ider whe n making a camera choice: Price, size, field of view, sens itivity and resolution. Component 2 comprises concerns of cooling, sound daccesso ries.
·Price / Size
The best camera for you isn’ t always the biggest or most expensive. A costly camera with pixels which are too large can be a waste of excellent mooey. A cheap camera with lots of little pixels may not be appropriate for your telescope and may suffer with poor sensitivity, again wasting money. A camera that is too big or too small for your scope and mount will result in A camera that’s too large and heavy can tax your mount. One that’s too smaJJ will not offer you much satisfaction.
Take some time to consider directing you i.ntend to use your camera and to find out about the numerous factors that can affect its performance for your intended usage. As a very general guideline, astro cameras cost more the larger they are.
So, the longer you pay, the larger the detector and the bigger the area of view it is capable of capturing in a single framework. Modern CMOS cameras
Now offer large sensors (generous field of view) with relatively s mall pixels (high resolution) and great sensvity (large QE and reduced sound ) at prices that are significantly lower compared to mature CCD based cameras. Very good low noise, high QE cameras sell for less than
$ I000. When J rst wrote tl1is article, cameras
With 小 e KAF-8300 were ground-breaking. 8 Megapixels, decent sized sensor and all for about $2000. QHYCCD still makes a camera using this detector, however it’s definitely been eclipsed by 小 e latest plethora of c.ameras using Sony and oilier CMOS sensors One popular example is the QHY 163M, a 16- megap ixel camera using a 4/3-inch sensor concerning the same dimensions as the older 8300 that sells for about half the price of an 8300 based camera.
And concu rrent with this upgrade. We are about to release the QHY492M that a back-illummated
4/3-mch monochrome camera wtth even higher resolution, greater QE and lower sound than the 163M. The new 492M will probably be priced well under $1500.
Following the general size of tiJe senso r, au else being equal, price is usually detem1ined by the amount of pixe ls and sensiti vity of this detector. That is, between 2 sensors of the Exact Same size,
Kind d sens iti vi ty, the sensor together with the larger number of pixels will normally cost Conve rsely, involving two sensors of the
Same dimensions, type aud variety of pixels, sensor with the greater sensitivity will normally cost more. Na turally, then, a I ge detector with lots of pixels and large sensitivity prices tl1e most and since the sensor itself is frequently tbe most expensive component in a camera, the more expe nsive the sensor, the more expensive the camera
[direct you intend to picture primaly planets or bright objects or large areas of view through comparatively fast optical systems, then sensit iv ity might not be so significant a factor as the magnitude of the detector and tbe resolution. If, however, you intend to im age little faint objects via a long focal length range or if you want to utilize narrowband or photometric filters, then the higher sensitivity of among the 11 fra me sensors may be an important factor in your
Our guidance to obtain the best balance of these factors is to set a budget to your camera system aod then, based oo your major interests.
Buy a camera win tbat budget which has the des ired balance of senso r size, sensitivity
And resolution to match yotir telescope. Remember to add tbe price of y accessories you intend to include l ike autoguider, filter wbeels, etc..
Some important sensor para.meters are discussed in detail under Note that this has nothing to do with the amount of pixels. A detector which includes 5 I2 x 512 pixels that are 20 microns square is going to have exactly the same field of view for a sensor with 1024 x 1024 pix.els that are 10 microns square even though the latter sensor bas four occasions as mauy pixels. T _s is also why binning 2×2 or 3×3 influences resolution but does not affect the field of opinion of the senso r.
Larger sen.sors have larger fields of view at a given focal length. You can chge the field of view of a sensor only by altering the focal length of 小 e telescope. Using a focal reducer you shorten the effective focal length of the telescope and increase the field of view (and make the picture brighter in the
Process). By using a barlow or eyepiece projection you effectively lengthen the focal length of tbe telescope 1d decrease the field of view (and also make the picture dimmer in the procedure )
In order to Find out the field of view for a given sensor, oote tl1e se nsor’ s lengtl1 and width dimensions (or diagonal) in millimeters and use the formula to detem1ining the field of opinion for that detector through any telescope as follows:
(135.3xD)/L=Field of View at afcmm utes