Which DSLR?

[CowsonConcrete]

Hi,

I have a 130p ds and a newly acquired EQ5. I use am Olly e pl1 which takes great terrestrial pictures but when attached to a scope or Ep (via t adapter) I always get slight trailing. The amount of trail is the same between 1 and 15 seconds (anything after that I would presume comes from celestial movement. The amount of trail is also only marginally better than I had using the EQ2 which makes me think there's movement in the camera (I use a timer when I take the pics).

Do I need a new camera? A web cam isn't an option as I don't have the finds for a lap top. I don't want to spend my money on syncscan motors now if I'll still have this problem using this camera so what's the best used DSLR body I could buy. It would be used for Astro work only.

Thanks

[happy-kat]

By chance do you have an android phone or tablet?

[happy-kat]

Can you use a remote shutter release with your existing camera?

[RikM]

Forgive me if this is a stupid question, but you do have a motor drive for your EQ5?

Other than that, could you be seeing coma in the images? Stars trailing out towards the corners?

I don't think it can be anything to do with the camera unless you have a loose mounting and you are getting some shutter-shake. Does your camera have mirror lock up facility?

Failing any of that either a used 450D, 1000D or 1100D would be my preference. There is not much to choose from between them.

[CowsonConcrete]

Thanks for the response.

Yes, I have a phone.

no I don't have a remote shutter I use timer

And no I don't have a motor drive. My camera is a micro four thirds so has no mirror. The trails all look to be through a shake rather than star movement and I wouldn't expect to see star trail at the short exposure time using the afocal method.

I'm in the market for a syncscan but want to make sure I don't need to use a different camera.

Thanks again.

[happy-kat]

A remote shutter release and built in introvolemetre would be a useful thing to have if your camera supports a remote shutter release cable. These are approx (£15) on Amazon.

Do the trails go right across the image or only in some parts of it?

My Nexus 7 running KitKat 4.4.4 with an OTG cable (£3) and an app called USBWebcameras (free) will run a compatible webcam. Which is why I asked. I bought a cheap (£3.49) webcam to try it out and it worked it will save video and take stills and has full gain and contrast support so next time the Moon comes round I am going to have a go.

[happy-kat]

Have you tried this camera in prime imaging mode seeing as you have that nice 130P-DS?

[RikM]

Your camera has 4.3micron pixels, at 650mm with the camera body connected to the telescope at prime focus you are looking at 1.36 arcsec/pixel. Stars move at 15arces/sec so a 1sec exposure with out tracking motors a 1pixel star would be 11pixel long. To get your star within the seeing, assuming typical 3arc/sec seeing you would be looking at about 1/3sec exposure time. If you are connecting to an eyepiece or Barlow this will increase the effective focal length and reduce your exposure time even further.

A simpler way of looking at is is with the 500 rule. 500 / (focal length x crop factor) = max exposure time before visible trailing assuming you don't zoom in and further crop your image, nor look too closely at it.

500 / (650x2) = 0.38 sec exposure time.

For deep sky AP with a telescope you need a driven mount. You don't need Synscan but you do need a motor drive at minimum.

[tingting44]

a picture speaks a thousand words, have you got a sub to post?

[uhb1966]

rikm nailed it ... BUT you might try to go a little bit longer, say 0,5 sek, take 50 pics+50 flats and stack them in dss... that should give you a start to play around with until youve saved for a motorized mount ... i did sth similar

[CowsonConcrete]

Thanks again for all your responses.

I do have pictures but won't be at my pc until Monday so can't show them till then.

Happy-kat: loving the cheap webcam idea, love to see how that pans out.

Rikm: thanks for the math. I think I'd heard that before but didn't want to believe it ;-).

Given a clear night next week, when I'm home, I'll try again and post the pics on this thread.

I did question buying motors first and then a syncscan but don't want to spend £90 now and then £300 in a few months time.