A camera as guider?

[LewisM]

I have a spare Canon 40D - was going to go the full modding, but decided against it.

Was thinking, how could I get it to respond to PHD guiding and act as a guider? Would it be hard to write an interface driver??? Or is there a preset in PHD already for this that I cannot see? Like tricking it into being a WDM webcam, or an ASCOM camera?

I have ALL the adaptors, cables etc, just need a way to make it into a guide camera.

Or am I just farting against thunder?

[peter_4059 (Peter)]

Sounds like a whole lot of pain for no gain. Also heavy, too many pixels so slow to download and bayer matrix to reduce sensitivity. Buy a mono QHY5.

[LewisM]

Yeah, probably. Already have an Orion SSAG, but it's nowhere near sensitive enough for the OAG I have been TRYING to use with it - won't see ANYTHING, even Achernar or Canopus.

[naskies (Dave)]

Originally Posted by LewisM

I have a spare Canon 40D - was going to go the full modding, but decided against it.

Was thinking, how could I get it to respond to PHD guiding and act as a guider? Would it be hard to write an interface driver???

DSLRs aren't really designed for continuous, rapid full-frame shooting since the shutters will wear out - although some last a surprisingly long time. The bigger problem as previously mentioned would be the slow download times.

However, the more recent Canon DSLRs (including the 40D) have LiveView - which would probably be reasonably effective as a guide camera.

It wouldn't be technically difficult to write the driver at all - it would just be a simple bridge utility between the Canon EOS SDK and ASCOM. The tool would connect to the camera in LiveView mode (much like what the EOS Utility already does), capture a stream of live frames, and pass it along to client applications via ASCOM.

You may potentially run into overheating problems (though I've used LiveView to record Jupiter for many hours on end with no problems on my 5DmkII) and managing the extra weight on the OAG could be tricky.

Originally Posted by LewisM

nowhere near sensitive enough for the OAG I have been TRYING to use with it - won't see ANYTHING, even Achernar or Canopus.

Sounds like either you're not getting them onto the SSAG chip (pointing problem), or it's a focus issue. Have you tried attached the QHY5 on axis as the "main" camera?

I have an Orion mini guide scope + QHY5 (same as the SSAG, different firmware), and an SBIG OAG-8300 + ST-i guider. The ST-i won't come into focus on the Orion without an extension tube, and the standard nose piece of the QHY5 is far too long for the OAG.

If my QHY5 can pick up bright stars fine with short exposures on a piddly little 50 mm guide scope, then your SSAG can certainly image them fine on a proper imaging scope!

[Peter.M]

In my experience using a ssag and an oag it is plenty sensitive enough. Make sure you are using a 2-3 second exposure and make sure PhD has the autodarks. Then if theres still no stars its a focus issue. I would just slew to a star rich part of the sky and adjust it, trying to put a named star on an oag chip with a portable setup is a nightmare.

[LewisM]

Peter, I believe that is the issue. Focus is fine (tested during the day with stopped down cover over the objective), autodarks etc. Just doesn'tseemto see anything at night, regardless of what I am aimed at (short of trying the moon!)

I'll try again as soon as we get an even SLIGHTLY clear night... that may be winter next year at this rate.

[pluto (Hugh)]

You can get your dslr to work as a standard webcam using a program (for windows) called extrawebcam http://extrawebcam.com/
I've used it with my 5DmkII and sharpcap (and a couple of other things) and it's not bad. Not sure about PHD but it should show up in anything that supports a standard windows usb camera.

[naskies (Dave)]

Originally Posted by LewisM

Focus is fine (tested during the day with stopped down cover over the objective)

That sounds like a pinhole camera...? If so, you'll be able to capture sharp images regardless of your camera's position because the depth of field of a pinhole camera is virtually infinite... but stars through a scope are definitely not!

[2stroke (Jay)]

Don't be a girls blouse and mod the 40D lol, theres no way i know to use phd and a eos for guiding. Really though it wouldn't be all that hard though due to the cannon sdk for the phd writters to do, though not practical due to the weight and size. Just get a dsi pro or a dmk mono for the job, they work and there cheap. You could also get a toucam and mono mod and RAW that for a real cheap cam.

[Marke (Mark)]

Originally Posted by LewisM

Peter, I believe that is the issue. Focus is fine (tested during the day with stopped down cover over the objective), autodarks etc. Just doesn'tseemto see anything at night, regardless of what I am aimed at (short of trying the moon!)

I'll try again as soon as we get an even SLIGHTLY clear night... that may be winter next year at this rate.

Do you have the OAG prism far enough into the light path and properly
focused - you may need to add or remove extentions as well . The orion
should be able to pick up brighter stars but a Lodestar would be much better
and trying to use a dlsr is not worth the effort if it works at all imho.