SharpCap Forums

I have tried and tried - I can focus with eyepiece on either my scopes (I'm using the 150EDX now). I can focus on a nearish tree (50m, it's all I have nearby that the mount can get to) during the day, take a photo on either camera (I'm using the QHY colour one at the moment, since it's smaller). So I believe my back focus is OK - 55mm apparently with my reducer/flattener.

When night and a clear sky comes (rarely Ireland) - I point my scope anywhere and attempt a picture - just to get a basic 'hello, there are some stars' - but NOTHING! Over and over and over again, needless to say I'm very frustrated. Can anyone suggest anything?

I'm using SharpCap Pro. I've done the sensor analysis tool, tried all sorts of exposure and gain and it just looks like noise. I have the lens cap off - you'd nearly think it was on from what I can tell - but it's definitely off.

One tree: Taken with the Starlight Xpress camera
Night time with the QHY: See black picture!

The black picture of nothing was taken using Sharp cap, on a 'live view'
[QHY5III585C]
CameraSerialNumber=73966c4797a698a7
FrameType=Light
Debayer Preview=On
Output Format=PNG files (*.png)
Binning=1x1
Capture Area=3856x2180
Colour Space=RAW16
Pan=0
Tilt=0
Exposure/Gain Shift=0
Auto Exposure Sample Area=Full Frame
Auto Gain Limit=100
Auto Exp Target=100
Auto Exposure Limit=50
Force Still Mode=Off
Enable Live Broadcast=Off
USB Traffic=0
Offset=50
Frame Rate Limit=Maximum
Gain=27
Exposure=250.0000ms
Timestamp Frames=Off
White Bal (B)=64
White Bal (G)=64
White Bal (R)=64
Contrast=0
Brightness=0
Gamma=1
CA Reduction/Synthetic Blue=Off
Mask over exposed pixels=Off
Flip (after dark/flat)=None
Trail Width=3
Minimum Trail Length=100
Trail Detection Sensitivity=9
Remove Satellite Trails=Off
Background Subtraction=Off
Planet/Disk Stabilization=Off
Banding Threshold=10
Banding Suppression=0
Apply Flat=None
Dark Scaling (Experimental)=Off
Hot Pixel Sensitivity=5
Subtract Dark=None
DisplayStretchEnable=1
NegativeDisplay=0
Display Black Point=0
Display MidTone Point=0.0011156034292466425
Display White Point=0.006591796875
Notes=
ZWO Focuser (1)=5000
Focuser Temperature=-0.6899999976158142
ASCOM GS Sky Telescope=RA=15:55:38.5,Dec=+89:59:59 (JNOW)
TimeStamp=2026-04-03T21:30:56.5922321Z
SharpCapVersion=4.1.14136.0
StartCapture=2026-04-03T21:30:56.4346420Z
MidCapture=2026-04-03T21:31:06.3174315Z
EndCapture=2026-04-03T21:31:16.2002210Z
JDStartCapture=2461134.396487
JDMidCapture=2461134.396601
JDEndCapture=2461134.396715
Duration=19.766s
FrameCount=52
ActualFrameRate=2.6308fps
TimeZone=+1.00

I'm stumped.

Can anyone give me an idiots guide to what I should do? Other easier software, exposure times, gain? I've try the usual AI bots for advice but I think expert human opinion will win out!

I get about Bortle 5 or6 in general at home.

Many thanks.

Richard

Hi Richard,

you are at the steepest part of the learning curve - you have to get the focus, camera settings and pointing of the camera all right at the same time to see anything in deep sky imaging...

You've done the right thing so far in testing the camera on a terrestrial target and being able to get an image. When you switch from that to deep sky, you need to move the camera further out from the telescope to account for the change in focus (unless the tree was like 1km+ away), along with that, set higher exposure and gain.

To be honest, the easiest way to start is using the moon as a target - it's big and bright enough that you can see the glow in the camera even if it is out of focus and a bit out of view. Use a couple of seconds exposure, high gain, and (if needed to see things) a display stretch. Once you have some light from the moon visible in the camera, turn down exposure/gain/stretch to avoid it being a white-out image, then move the telescope around to get the image brighter (closer to the moon). Continue adjusting the pointing of the telescope and turning down the exposure/gain/stretch until you've found the brightest view you can get - now pointing at the moon. You can now adjust focus (again probably turning down exposure/gain/etc as the focus gets closer) until you have a view of the moon in focus.

At this point, you know your focus is correct, so move away from the moon and set maybe 5s exposure, high gain and a display stretch - that should be enough to see stars.

If the moon is not co-operating by being around at the right time, you have to do it the hard way... Again maybe 5s exposure, gain near maximum, a strong display stretch and target bright stars. If you are out of focus by a long way, the star light is spread over a large, faint, disk, but with these settings you should be able to see the disks for bright stars and adjust focus to make the disk smaller and gradually get to the right focus.

Hope this helps,

Robin

Umm, Robin, I think you have the focus movement backward: if your target is further away, the light rays are more nearly parallel entering your scope (and therefore more sharply converging at the EP), rather than diverging as they do on a closer object, so you need to move the camera closer to the OTA, not further away.

The rest is good advice: start with something very bright, like the moon or one of the very bright stars like Capella, Vega, etc. I like Sirius, but that may be hard to see from Ireland, so you can tell if it's in the FOV even if it's waaaaay out of focus. That was a big problem I had when I was first starting in this hobby: I couldn't see anything, but it was because I was so far out of focus that nothing was visible.

Ah yes, you are quite right - move the camera closer to the telescope as you move from 'near' to infinity focus. Sorry about that.

Now and then you get situations where you might struggle to get the camera close enough in to the telescope to actually get to infinity focus - I've seen that happen with small reflectors (ie 130mm or so) and DSLR cameras. It's not usual for it to happen with dedicated astro cameras, but it's worth being aware of.

cheers,

Robin

Success!

Good news - I got stars!

I think my back focus was off as well - I needed 55mm and after much messing around with adapters and my newly acquired digital calliper (really useful for me) I got what seemed 55mm, found Capella in the finder scope, fired up Sharpcap with some general parameters you all suggested and after 10 or 15 exposures of about 5 secs at all the focus points (I used 2000 step size on a ZWO EAF) - I almost imagined some stars, moved down to 1000 step size and a bit of in/out focusing and hey presto!

I may have some more of a journey to go (as seen from the picture!). But's it's a start. Thank you all.

Pic and setting added in case anyone reads this thread and finds it all as useful as I did.

The community really is like the old days of the internet, nice, helpful and informative.

[QHY5III585C]
CameraSerialNumber=73966c4797a698a7
FrameType=Light
Debayer Preview=Force RGGB
Output Format=PNG files (*.png)
Binning=1x1
Capture Area=3856x2180
Colour Space=RAW16
Pan=0
Tilt=0
Exposure/Gain Shift=0
Auto Exposure Sample Area=Full Frame
Auto Gain Limit=100
Auto Exp Target=100
Auto Exposure Limit=50
Force Still Mode=Off
Enable Live Broadcast=Off
USB Traffic=0
Offset=26
Frame Rate Limit=Maximum
Gain=108
Exposure=4.865s
Timestamp Frames=Off
White Bal (B)=64
White Bal (G)=64
White Bal (R)=64
Contrast=0
Brightness=0
Gamma=1
CA Reduction/Synthetic Blue=Off
Mask over exposed pixels=Off
Flip (after dark/flat)=None
Trail Width=3
Minimum Trail Length=100
Trail Detection Sensitivity=9
Remove Satellite Trails=Off
Background Subtraction=Off
Planet/Disk Stabilization=Off
Banding Threshold=10
Banding Suppression=0
Apply Flat=None
Dark Scaling (Experimental)=Off
Hot Pixel Sensitivity=5
Subtract Dark=None
DisplayStretchEnable=0
NegativeDisplay=0
Display Black Point=0
Display MidTone Point=0.0011156034292466425
Display White Point=0.006591796875
Notes=
ASCOM GS Sky Telescope=RA=04:49:21.2,Dec=+51:19:27 (JNOW)
TimeStamp=2026-04-09T22:04:31.6570464Z
SharpCapVersion=4.1.14136.0
LastPlateSolveData=Plate solve result was RA=05:24:41.3,Dec=+46:15:45 with mount at RA=04:49:20.5,Dec=+51:19:27, FOV 0.788x0.446 degrees, up is 11.00 degrees East of North

Hi,

glad to hear that you are now in business It's also good to see that you are getting successful plate solve results, as that makes finding your targets much easier (especially when you have a relatively small field of view).

As you've probably already noticed, the stars in your posted image are still a bit out of focus - they are visibly uniform discs, rather than being sharp points. However, now that you are close to having good focus, it's much easier to dial it in to spot on. You can either do that manually, or with the assistance of the focus tools in SharpCap (Multi-Star FWHM would be best for your situation).

Anyway, hopefully you will get some more clear skies soon to continue your astrophotography journey

cheers,

Robin

PS. I know what you mean about the early days of the internet - Usenet groups in the mid-1990s were very similar - you asked a question and got helpful, sensible answers