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Telescope40

Afocal astrophotography - help ?

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Hi. Looking to start taking some piccies if possible. Moon to start and maybe planets. Bit baffled as to how to get started. I will list my kit and where I am so far stumped. Any help, advice, pointing in the right direction much appreciated. :icon_salut:

Scope - LX90 10 inch on fork mount. ( No wedge - no long exposure attempts required at this point).

Camera - Fuji S5100 DSLR - lens is not removable - 55mm adaptor ring.

T mount which does fit onto the camera. :headbang:

I'm stuck as I have a few Meade 5000 eyepieces but the t adaptor will not fit on them due to the way they are made ( integral eyepiece cover/eyecup too bit for adaptor ? ) and a standard Meade 4000 40mm eyepiece. I thought the 40 mm was prob a good place to start but am really stumped as to how to proceed. I've held the camera up to the eyepieces but cannot see anything but a small point of light on the lcd screen. Same thru the viewfinder. :cool: I'm sure I'm being really dumb but any comments more than welcome. I noted a few posts about the AFOCAL method ? Is this the route i need to take? Many thx in advance John

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If the camera lens is not removable there is no need for the t adaptor. You will be doing afocal, which basically means putting your camera to the eyepiece, so you just need maybe one of these to hold the camera in place at the eyepiece.

http://www.pulsar-optical.co.uk/prod/skywatcher/universaldigiscopingadaptor.html

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The skywatcher digicam adaptor is good and FLO is best priced.

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Hi. Thanks for the idea. The Skywatcher digicam looks the way to go. Good price as well.

Next dumb questions. This will be where the adaptor holds the camera right up against the eyepiece in use. Yeah ?

Would I have to use the viewfinder on the camera or would the Lcd screen show wots in view.

Am I gonna be limited to the Moon and bright planets (Jupiter, Saturn and Venus - Mars when close)

What about DSO's ? Will need to buy a 450 D etc as I have read a few threads about these, plus a wedge / guiescope etc, as exposure times will need to be much longer.

Thx again John

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Not dumb questions at all.

yep just as you say for question 1.

2. You use the camera just you normally would, if the lcd shows a live view, use that.

3.Yep again, you will be limited to planets and moon and maybe some clusters. This really depends how sensitive the camera chip is.

4. DSO's require longer capture times and therefore guiding and a good mount are required though not essential. Also your camera is probably not sensitive enough or does not have the required shutter settings etc, Bulb setting allows for long exposure times and is normally associated with DSLRs and not so much the compact cameras which normally only allow a max of 30sec.

I don't own a canon so can't comment, I do like my Nikon D80, though it has no live view via an lcd so focusing can be a nightmare.

Your on the slippery slope to imaging which can be hard work and frustrating but the rewards are great when it all comes together. good luck..

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I started imaging using an afocal setup, but instead of using a universal camera adapter with my camera, I used a Baader Hyperion eyepiece. If you can get the necessary rings, you can get some half decent results out of it. See here: http://stargazerslounge.com/imaging-deep-sky/56585-afocal-m42-10-12-07-new-improved.html .

Tony..

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I looked into the Hyperons, but think my f/5 newt would be too fast to get the best out of them...Hmmm

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Set several seconds shutter delay to allow time to lose any vibrations caused when you press the shutter button or let go of the release cable

Allan

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P.S. if you have a threaded camera lens I would always go the T-threaded adapter route rather than getting one those digiscoping mounts. Getting the chip square on to the focal plane is so much easier if you can just screw the eyepiece to the camera lens!

NigelM

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Hello Nigel.

I've just been reading your guide to "Afocal" astrophotography. It's very interesting indeed - particularly the sections on exposure times and "f" numbers to use. You seem to have mastered the art! Your photos are excellent. I particularly liked the 2004 Jupiter. That was a nice well focussed and naturally coloured shot.

I'm still struggling with my Canon A570IS digicamera. My single shots are a bit hit and miss. My greatest problem is achieving a sharp focus and getting the right exposure. My planet shots come out all colours!. I'm going to try "sealing" the gap between the eyepiece and camera lens. Also to use only "ISO" 80 or 100. And of course focus to infinity. (When I focus on a planet, and then lock the telescope focus, my photos still come out blurred? The only way I can achieve any kind of sharpness is to set the timer on a 10 or 15 second setting, press the shutter and with the camera counting down, I try to adjust the telescope focus whilst looking at the image on cameras screen.

Here are a couple of single shots, (using "Picasa to clarify and lighten the shots).

Regards,

philsail1

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I rapidly decided the only way to focus was to fix the camera on infinity and take trial shots with the telescope focus in different positions. I then take the card out of the camera whilst leaving the camera in position and examine the shots on the computer the in the house for best focus. Then I trot back out and try and remember which shot corresponded to which focuser position!

This is obviously easier if the camera is fixed to the eypiece. I also have a helical focuser on the 8.5" which makes judging the focus position really easy, as it corresponds to camera angle! On the 4", which is rack and pinion, I use an electronic focuser and try and judge position by looking at the angle of the screw head that holds the focus knob in place.

NigelM

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Thanks for that advice Nigel.

I think I will have some difficulty with my Canon A570IS, as the card slot is underneath the base of the camera. Can't get at it when it's fitted to the camera bracket. But, I'll look closely at figuring out some easy way of adjusting the focus on the scope.

Regards,

philsail1

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Doesn't the A570IS have a threaded lens adapter (LA-DC52G)? I would get one, plus suitable T-thread to fasten to the eyepiece.

NigelM

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Hello Nigel,

Yes! that's something I never thought about utilizing!!!

I bought a fitting + adaptor and a "Telephoto" lens for the camera some time ago. I only use it when photographing wildlife.

Do you think I can obtain an adaptor to screw into the end and then attach to an eyepiece?

What would this gain me though - as the adaptor would push the camera's lens further away from any eyepiece and cause vignetting?

I need your advice here Nigel.

Regards,

Philsail1

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Hmm - asssuming the Canon adapter is a 52mm thread (thats what is says on the web), Astro-Engineering appear to do a 52mm to T2 stepper ring (Adap-T ST52) and a T2 eyepiece adapter (AC530). You need the latter if your eyepiece is not threaded at the top (doesn't fit all eyepieces, as they need to have a groove at the top under the rubber eyecup, you need to check).

Whether it will cause vignetting or not is impossible to say without trying it - the arrangement will probably only add a 1mm or so to the length of the adapter, so you could fake it by holding the camera + adapter that far from the eyepiece and seeing what happens.

NigelM

p.s. there are two kinds of vignetting - there is the sharp circle which is just the image of the aperture stop of the eyepiece, which is what people normally moan about with afocal imaging. This can be minimised by zooming and isn't really a problem anyway (so you lose some pixels at the edges, who cares). However, there is also real optical vignetting, where the image of the sky fades towards the edges of the field - this is caused by the exit pupil of the eyepiece not being at the entrance aperture of the camera. You want to avoid/minimise this if you can, but it is often difficult.

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Thanks for that Nigel. I'll try my camera with the existing bracket attached, against various eyepieces on my scope - to see if there is any appeciable vignetting.

I think I have suffered both of the vignetting types you mention - but again, I think I've managed to eradicate both types simply by firstly ensuring the camera is as near to the eyepiece as possible, and by "zooming" the camera a little.

Sometimes, I've left the "field stop" type of vignetting in the original photo, then simply "cropped" the image to get rid of it.

I use a simple bracket to connect the camera at present - have to be careful that I loow for "zooming" as sometimes the camera lens has pushed against the eyepiece and the camera has "bleeped" a fault and swithed off. (Luckily, no permanent damage has occurred).

If I'm undestanding correctly, an eyepiece adaptor would prevent this by allowing the camera's lens to extend unrestricted inside the barrel of the eyepiece adaptor?

Regards,

philsail1

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