Imaging with telephoto lens

[Allsopl51]

Are there any dsos that are feasible to image using just a canon 60da-200mm f2.8 or 300mm f4 lens and lp filter on a static tripod and stacking software.

I usually head for Winchelsea beach for astrophotography of the milky way,still a begginer in this subject but looking to find other objects to try.

[houston]

Hi, check out forrest tanaka on youtube. He gets a decent m31 with a tripod, 300mm lens and stacking software. Good luck!

[kalasinman]

I get an identifiable M6,7,8 with a 150mm @3secs, so you should do well with that. :-)

Only problem is the exposures to stack will be absurdly short to avoid trails. 1-2 seconds, I'd guess.

That's why I'm getting a Skyguider.

I took 60 lights and darks @3 secs with bias and flats f/2.8 (DSS).

Not the best job, just an example

[Knight of Clear Skies]

It's worth a go but don't expect great results. To eliminate trailing at 200mm you are probably looking at 1-1.5 second exposures. Here's a couple of my efforts from a fixed tripod using a 50mm lens.

Orion's Belt and Orion Nebula.

Pleiades.

(I took about 70 3.2 second exposures, but could have maybe pushed it to 5 seconds.)

Open clusters are probably your best targets, a browse on Stellarium should show you what's in the sky at the moment.

[Allsopl51]

Hi All

Thanks for replies.I have seen Tanakas youtube posts.Have looked into subject and realise very short exposures with zoom lens.

Will be purchasing a tracker soon,just a mount for dslr not really looking to going into telescope in foreseeable future.

Maybe I-optron sky guider,anybody using that ?

How hard is it to actually find dsos in the night sky ?

[Allsopl51]

I'm impressed with the images guys.

[jgs001]

As a rough rule of thumb, the exposure time for static tripod shooting, is 400/f.l in seconds (for a crop sensor camera, which the 600d is), so in your case with the 200mm f/2.8, the maximum exposure time is 2 seconds, you may find you need shorter exposures to be on the safe side. If you wanted to try the 300 f/4, then you're looking at about 1.3 seconds, and what with the lens being one stop slower, you'd actually need to double the exposure time to get a comparable exposure to the 200mm. 

You can give it a go, but you're really not likely to get any faint detail, I didn't when I was checking a FOV with my 150mm f/2.8 at f/2.8 with 1.5second exposures. 

[kalasinman]

I'll order an Ioptron Skyguider next week. Of course it's rain season now, so who knows when I get to try it.-Jack

[farunj]

I have a question. How do you stack the images taken using a static tripod? Or more properly, how do you keep the object centred in the DSLR? Because after some shots, the object moves?

[Knight of Clear Skies]

DSS (Deep Sky Stacker) will handle that for you, it works out the offsets and rotation between each frame and aligns them.

[Giray Gencaslan]

I get an identifiable M6,7,8 with a 150mm @3secs, so you should do well with that. :-)

Only problem is the exposures to stack will be absurdly short to avoid trails. 1-2 seconds, I'd guess.

That's why I'm getting a Skyguider.

I took 60 lights and darks @3 secs with bias and flats f/2.8 (DSS).

Not the best job, just an example

How you take bias and flat frames?

Would you help?

[jgs001]

Bias frames - fit the lens cap, set the fastest shutter speed, the same ISO and fire of at least 20 frames.

Flats are more complicated... You need even illumination down the lens, St the Cabrera to Av mode and fire off 20 or so frames.I use notepad on a laptop screen.

The DSS help filesgoI into some detail and are helpful.

Sent from my GT-I9300 using Tapatalk

[ronin]

This one over on another section was took with a 14mm lens, it had tracking for the length of the exposures but seems you can get good results without a scope just a lens.

http://stargazerslounge.com/topic/219938-dont-see-it-like-this-all-the-time/#entry2363856

[StuartJPP]

Not tracking with any focal length is limiting, but it is still possible to get something pretty decent, it really depends on your expectations. Obviously the wider you go the better and as long an exposure as you can go without trailing.

However, once you get any form of tracking mount things change considerably. At the minute I am quite content with my collection of lenses and I have no desire to get a telescope. Maybe in time I will but it will only be once I have exhausted all avenues with my current glass, though with the rubbish weather we are having for what seems like ages means it will take a long time for me to reach that point.

Best bet is to get out there and start practising, no matter what kit you have got.

How hard is it to actually find dsos in the night sky ?

Finding DSOs in the sky can be a bit tricky at times, I tend to use Stellarium and star hop from something identifiable, but it will come with time.

[kalasinman]

For flat frames I modified the t-shirt method. I place a white t-shirt over the lens, keeping it wrinkle free, then hold it a meter or so away and aimed at a white painted which which has no shadows or marks. The reflected light seems to give nice, even illumination.-Jack

[farunj]

DSS (Deep Sky Stacker) will handle that for you, it works out the offsets and rotation between each frame and aligns them.

But then won't the object change? For instance suppose I am imaging M31 with a 50mm lens and no tracking. Then as M31 moves from the field of view of my camera, the objects captured by the camera change. Will DSS have a problem with this? Or then will I have to periodically alter my camera to point approx at M31?

[Knight of Clear Skies]

Not a big problem, DSS looks at the positions of the stars and matches them up. You then use 'intersection' mode when stacking so that the final image only covers the areas that overlap (otherwise the edges might look a bit strange). You can re-centre, but with a 50mm lens it will take quite a long time for your target to wander away from you.

[happy-kat]

Then there is a barn door you can make to increase your exposure times

[nicks90]

at 50mm you dont need to worry about aiming too much. I did Lyra last time i was out and just snapped away merrily for a while. When I noticed albireo creeping in to the bottom left of my image previews, I nudged the tripod to the right a bit and carried on.

DSS crops out anything that doesnt appear in all the pictures and only seems to stack the continuous overlap. At least i think it does this automatically, as my picture output seemed to be a smidge less than the field of view i was getting from each individual frame!!!

I would imagine doing 300mm focal length would require a bit more care though and more frequent nudging to keep everything more or less centred. Also the exposure time will vary depending on where in the sky you are pointing. Low on the horizon due south - the stars positively gallop along. Pointing north you might be able to get a bit more without noticeable star trails.

[lensman57]

Of course it is, here is one did earlier, just click my link.http://www.astrobin.com/102819/, I used a modded 1100and a Canon 200 F2.8 L ISII @ F2.8.

Regards,

A.G

[Knight of Clear Skies]

Of course it is, here is one did earlier, just click my link.http://www.astrobin.com/102819/, I used a modded 1100and a Canon 200 F2.8 L ISII @ F2.8.

Regards,

A.G

I think you misread the question I'm afraid, the OP is talking about from a static tripod.

[farunj]

Not a big problem, DSS looks at the positions of the stars and matches them up. You then use 'intersection' mode when stacking so that the final image only covers the areas that overlap (otherwise the edges might look a bit strange). You can re-centre, but with a 50mm lens it will take quite a long time for your target to wander away from you.

Thanks that seems to have cleared it up. Just waiting for clear skies now!

[happy-kat]

Wow 360 images, looks great though.

Oh I read it as 6 x 360 images.

36 * 60 / 360 gave 6 seconds per image hence I thought it was that way round.

[leeseafish]

some useful ideas on a DIY barn door here - http://www.bencooper.karoo.net/AstronomyMountsBarn.html