Skip to main content

Typical Field of View

18 posts / 0 new
Last post
Typical Field of View

Hello All,

I realize that the answer to this is not straightforward, but I'm trying to determine what a typical CCD field of view (FOV) is within the AAVSO observing community.  I know in principal it can vary based on a lot of factors, but i'm just looking for a ball park number (e.g. minutes, tens of minutes) . It would be useful to me if a few people could comment, at least on their FOV, if the answer isn't easily generalizable. Thanks in advance.



Bert Pablo

Staff Astronomer, AAVSO

Typical Field of View

Hi Bert,

23 x 17 minutes


res's picture
Typical Field of View


dks's picture
Typical Field of VIew

Hi Bert,

14' x 14' and 18' x 13'

I wonder how many people have filled out the Equipment section in their profile. That might be useful to data-mine if you don't get many responses.


HBB's picture

Great reminder Shawn

sfra's picture
Typical FOV

C14 with STL1000e camera, 20'x20'

CMJA's picture
Typical Field of View

16' x 11'

Meade 0.4 m f/10 with f/7 focal reducer.and QSI 516 CCD

Eric Dose
Eric Dose's picture

35' x 23' from my C14 + focal reducer + 6303E

Ed Wiley_WEY
Ed Wiley_WEY's picture

C11 HD w/reducer (ca F7) and Moravian G2-1600 (9x9, 1536x1024): 24'x16'

ldj's picture
C14+ST8+compessor which gives

C14+ST8+compessor which gives 21.4' x 14.3. I think if you have about 12-15 minutes FOV, it is large enough for photometry (good range of comp stars) in most cases.

--- Dave

Bikeman's picture
f=1000 mm , ZWO ASI 178mm (3000 x 2000 pixels)

...which results in ca 25 x 17 arcmin .

For the benfit of the casual reader, not the OP:

I think the reason why so many answers here are in the same ballpark is this (as a crude rule of thumb): The typical angular resolution of our amateur equipment is already limited more by the atmosphere than by the equipment, so it willl rarely be better than (say) 1 arcsec. When covering your field with pixels, a bit of oversampling is ok, but undersampling isn't making that much sense for most applications, as it risks blending of sources. We amateurs tend to use single CCD/CMOS sensors, not sensor mosaics, so the FOV is defined for many of us by chosing an affordable-enough sensor that will give you arc-second-ish pixel resolution for your partiular type of 'scope.  

Many dedicated astro-cameras have rather huge pixels (and in total on the order of 1000 x 1000 pixels), so we are now roughly in the 15 .. 30  arcmin FOV territory.

I think this is just fine to get enough comparison stars for almost all fields of interest, with the exception perhaps of single-digit-magnitude, and thus very bright stars, but that's where one  could switch to DSLRs and telephoto lenses to get wider FOVs with minimal (if any) additional investment.

Hope that helps


JBD's picture

ST-7 + ES127mm =

Size : 24.8 x 16.6 arcmin
Radius : 0.249 deg
Pixel scale: 1.95 arcsec/pixel

Check on

spp's picture

23' X 23'    C14 with STL1001e       1.34 arcsec/pixel

also, piggyback

80' X 54"   C80FL with ST10xme     2.19 arcsec/pixel

PVEA's picture

FOV = 35.5 х 35.5 arcmin

Working configuration: Ritchey Chretien Astrograph, D = 300 mm (12”), f/5 with focal reducer, FL = 1 470 mm, CCD camera sensor active size 2048 x 2048 px, pixel size 7.4 mk, Image scale = 1.04 arcsec/px

Hey All,

Hey All,

Thanks a lot for the information. I am pretty imprssed that while almost every single FOV is different they all fall in roughly the same range. The reason shouldn't be that surprising as HBE pointed out, but it is very useful to know. Thank you all for your help. I really appreciate it. 

If you were wondering why I was asking, I have been asked a few times by astronomers creating alerts for specific sizes to their FOV. They may be looking for particular comp stars or have multiple targets, etc. In order to help them, I need to know what is reasonable  and this helps immensely.

Thanks again,

Bert Pablo

Staff Astronomer, AAVSO

HBB's picture

My CCD FOV is 26 x 26 arc-mins

ARJ's picture

29 X 20 arc-min

C11HD with Optc .62 reducer.  SBIG ST 10

HQA's picture
field of view

With the NOFS 1.0m, we used 11x11arcmin and 22x22 arcmin FOVs.  With the BSMs, we use 2.2x1.4 degree FOVs.  In general, the size of the field corresponds to the faintness of the object you wish to observe.  At 13-17mag (NOFS), you had plenty of comp stars in the field, even at 11x11 arcmin.  For 5th magnitude stars with BSM, you needed several degrees of field to find a comp star.

That said, the trend is towards larger fields as the sensors get larger.  With the Mittelman 0.95m telescope, we're using 31x31arcmin FOV with the 4kx4k CCD.  With the Epsilon-180 astrographs in the new BSM systems, we're currently at 1.5x1.0 degrees, but could easily get to 4x3 degrees with the new IMX-455 60Mpix sensors that are becoming available in $5K cameras.

I think the numbers given by many posters, plus the information in the equipment sections of the observer profiles, will give a Bert good indication of the current setups, and things will only get larger in the future!


Log in to post comments
AAVSO 49 Bay State Rd. Cambridge, MA 02138 617-354-0484