Trying to image M82 with 6" and 350d...frustrating

[bradfrankshaw]

Hi everyone - needs some tips for imaging the M82 supernova. I found the two galaxies easily but swapping to the camera its impossible to see anything in the viewfinder - no live view

I tried to achieve focus on Jupiter then slew back to M82 but my synscan always brings the scope a couple of degrees off target and I have to jig a little to centre. Unfortunately M82 is too dim too see in the viewfinder.... any thoughts or pointers?

Thanks

Frank

[LouisJB]

ahh that's tricky. I think you need to fix your goto, are you polar aligned and 3-star aligned? Can you not use your finder to nudge the scope to the right place?

Another idea.

Probably I'd slew to Jupiter, focus the DSLR, measure with a ruler the focuser position. 

Now slew back to M82, swap to low power EP and centre. Put the camera back and move the focuser to the measured position.

Now, take short, say 15s shots at highest ISO and see what you get, adjust the focus slightly if necessary, try again. It's going to take a while but you might be able to get focus fairly well.

You really need live-view and/or goto and both is best.

Using the finder would be the best bet though if goto is go-near, have you got a magnifying finder, M81 and M82 show up in a 9x50

Fix your goto, it's so useful, almost essential I've found for AP.

[davefrance]

I have no idea whether this is possible with the 350d but can you not link via USB to tablet, phone, laptop to give you a live view to help you find and focus? I am sure some Canon owners will chip in and  confirm or rubblish.

[WaveSoarer]

I find this to be quite tricky and I don't have a go to mount. It's important that you nail the focusing and I use a Bahtinov mask to do this. It's easy to use and it just requires a few test exposures (with the telescope pointing at a reasonably bright star) to achieve this. The tricky bit is that you need to slew the telscope to a bright star to achieve focus and then try to get back to where you were when you were viewing through the eye-piece. I do my best to note the position of the finder scope cross-hair relative to stars close to the object ,before slewing the telescope to a star to focus the camera, and I then try to get back to the original position. I then take some long test exposures to tweak the positioning so the object I'm after is placed correctly. My 200p has sufficient aperture that I can actually see M81 and M82 (just about) in the view finder so I haven't needed to adopt this approach top capture the supernova. Other dimmer DSOs do require a few test exposures, however.

[lensman57]

Hi everyone - needs some tips for imaging the M82 supernova. I found the two galaxies easily but swapping to the camera its impossible to see anything in the viewfinder - no live view

I tried to achieve focus on Jupiter then slew back to M82 but my synscan always brings the scope a couple of degrees off target and I have to jig a little to centre. Unfortunately M82 is too dim too see in the viewfinder.... any thoughts or pointers?

Thanks

Frank

Hi Frank,

You are doing it all wrong mate, focusing on Jupiter and then turning the scope through  30 degrees to M82 is not going to work with budget equipment. Once you have done your PA and either  a two or three star alignment command the Synscan to go to Dubhe, this is brightest major star near to M81 and M82. You do this by pressing the button Named Star and then scroll down. Once the mount finds Dubhe and beeps press the escape button once and then again and hold it down untill you see the message " centering Dubhe" flashing on the hand set. Use the direction buttons to slowly center the star and try not to overshoot and having to correct. Now the hand set has applied a PAE algorithm to the sky map for about 5 degrees around the star. Do all your focusing on Dubhe and get it as best as you can. I use FWHM in APT. Once the focus is achieved then gently lock the focus and then command the handset to go to M81 or M82 , with a DSLR size sensor they should both be on the sensor. Do a test exposure of about 60s at the highest ISO of your camera to make sure you have got them and good luck.

Regards,

A.G

[andre808]

A crude way i have used, is focus camera with mask. Lock the focuser, remove camera and replace with eyepiece. Sliding the eyepiece in focuser to achieve focus, then lock eyepiece in place with lock screws, Find object. Replace camera. Got a Telrad finder now, which seems to make finding stuff easier. 

[Sandancer10]

I focus my DSLR on Jupiter's Moons (using the maximum zoom) and then use Stellarium to check that Jupiter and the scope are showing exactly matched. If I am slightly out I unlock the gears and manually adjust the scope until it is spot on Stellarium. I find then I can goto any object and it will be centered.

[LouisJB]

I focus on _anything_ bright in the sky (that isn't a planet) at the time then slew to the target, even if it's over the other side of the sky. If goto is working and you're aligned I find the HEQ5 slews perfectly around the sky all night. However maybe different mounts behave differently, but the largest error is likely to be initial setup I'd have thought.

Also, get a magnifying finder. This is one of the main advantages, once aligned to your main scope then you'll be able to confirm and make adjustments to centre in the finder without live-view etc.

I find it useful as a double check and to keep an eye on the sky conditions. M82/M81 show up in a finder from where I am, unless you've particularly bad skies they should for you too. The 9x50 RACI is particularly useful for this as you can always find a way to look in its eyepiece without having to contort and potentially knock the rig. 

It won't help with dimmer objects but often there's some reference stars in a wide-field finder view you can use to orientate with too. Especially if you look with bins first and cross-ref against a sky-map or Stellarium.

[PorkyB]

A crude way i have used, is focus camera with mask. Lock the focuser, remove camera and replace with eyepiece. Sliding the eyepiece in focuser to achieve focus, then lock eyepiece in place with lock screws, Find object. Replace camera. Got a Telrad finder now, which seems to make finding stuff easier. 

I made an eyepiece to focus in the same place as my camera using a parfocal ring (from Alan at Sky's the Limit http://www.ebay.co.uk/itm/Skys-the-Limit-Par-Focal-Parfocal-Telescope-Eyepiece-Ring-1-25-/161124310561?pt=UK_Telescope_Eyepieces&hash=item2583c1de21) and an eyepiece extension tube (to lengthen the EP's nosepiece) which I made by taking a hacksaw to a cheap barlow.  Now I can focus the camera on something bright, lock the focus.  Put my ep in and slide it up and down until it's in focus, then lock the ring.  Then I can swap between the camera and the eyepiece to find and frame stuff up.

[Tiny Small]

Probably I'd slew to Jupiter, focus the DSLR, measure with a ruler the focuser position. 

Now slew back to M82, swap to low power EP and centre. Put the camera back and move the focuser to the measured position.

 This is a good idea. A set of vernier calipers should get you dead on.

I'll give it a go next time I'm out as I don't have goto either.

[starnut]

I'm fairly new at all this so sorry if this sounds stupid “would a flip mirror diagonal do the trick”

[LouisJB]

I like the parfocal ring idea. However when my camera is focused I don't want to touch it, it's very sensitive to movement to be in exact focus. Some combination of goto and finder works without touching the camera. Can you maintain precise DSLR focus after swapping the camera for EP and back again? With a crayford, is your camera very small/light?

[mallorcasaint]

Using a programme such as Backyard EOS on your laptop and focus using a Bahtinov mask on a bright star ( Dubhe good in this case ) is an excellent way to achieve good focus points.

[andre808]

yes i use a cheap barlow with the lens unscewed off it, to extend the eyepiece to focus. I have a 130pds which has a dual speed crayford. All seems solid when its locked, but am careful not to knock anything out of adjustment. 

[andre808]

Oh and the camera is a Cannon 350d.

[Hawkeye]

Hi Frank,

you don't say if you are using a laptop or not and if you are what software your using..

If you do have a laptop, why not use EQAscom to control the mount and Astrotilla to centre M82 in the centre of the camera sensor?..

this is what I do and never put an eyepiece in at all.. Once the camera is focused just select the object in Stellarium or CDC, let the mount slew to the target, click on the solve button in Astrotilla and wait.. within a minute your target will be centred on the camera sensor........

If your not using a laptop.... follow the advice above with the parfocal eyepiece..

Cheers

Paul

[Hawkeye]

Sorry, read Astrotilla as Astrotortilla 

[Dave_D]

If you do have a laptop, why not use EQAscom to control the mount and Astrotilla to centre M82 in the centre of the camera sensor?..

Astrotortilla is brilliant. i don't use synscan at all now. every time i've used astrotortilla, it's put the object dead centre frame with just 1 pass.

[Hawkeye]

 i don't use synscan at all now. 

TBH I'm not even sure where my syncscan handset is now... 

[Pete Presland]

i use a canon 350, i focus on what ever target i am imaging, when i take an image it downloads to my PC (EOS utility) and i check the focus of the image and adjust as needed.

[bradfrankshaw]

Hi everyone - quick reply, more later - thanks for replies so far; I do have a win 7 laptop I use in conjunction with my ToUCam for planetary imaging but not used with my DSLR at all nor for slewing/finding/focussing/tracking etc.

Would upgrading to a Live View available camera help at all?

thanks

frank

[PorkyB]

I'm fairly new at all this so sorry if this sounds stupid “would a flip mirror diagonal do the trick”

A flip mirror would work with a Mak or a refractor as long as you have enough focus travel.  My Newts are very tight on focus travel and in any case a flip mirror would leave the camera or eyepiece at a strange angle.

I like the parfocal ring idea. However when my camera is focused I don't want to touch it, it's very sensitive to movement to be in exact focus. Some combination of goto and finder works without touching the camera. Can you maintain precise DSLR focus after swapping the camera for EP and back again? With a crayford, is your camera very small/light?

Once I've locked the focus it stays put pretty well.  I always re-check the focus between targets but most of the time it is still good.  My camera is a Canon 1100D with a coma corrector attached, so it's not particularly lightweight.

[Hawkeye]

Frank,

Try the software option first, All the software is free so won't cost you anything (or maybe a few pounds on a lead).. then you can always change the camera at a later date..

Cheers

Paul

[bradfrankshaw]

Cheers all - I'll have a go at the software option tonight (cloudy tonight and my cable release broke last night ) and see what happens!

[Hawkeye]

How are you getting on with the software option Frank?

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