Small Magellanic Cloud with Canon 100-400 F/4-5.6 IS L

[rogerg]

While my LX was busy taking shots of IC 5150 last night I spent the whole night playing with my portable setup in preparation of an upcoming astro camp this coming weekend.

I was testing out my partners Canon 100-400 F/4-5.6 IS L lens, to see if it would be suitable for astronomy and allow me to easily guide through the Megrez while imaging through the lens. The lens seems to have horrible distortions of stars until it's inperfect focus, then it is excellent, probably better than my 70-200 F/4 L.

This is the only barely nice looking image I ended up with from the night: Small Magellanic Cloud (http://www.rogergroom.com/rogergroom/esh_rog_item.jsp?Item=653)

Full image is about 1mb.

I'm still disapointed with what my 350D gives me as compared to Provia 400F used to give me. Missing out on all that red really hurts the images. So as I guess I should expect, this image looks very much like a DSLR shot, from an unmodified camera.

If I try the SMC next weekend it'll probably turn out better because here I am in light pollution so am missing some contrast to start with.

Roger.

[Dennis]

Hi Roger

That is a fine image. It looks sharp right to the edges, with nice round stars everywhere. I sympathise - it’s a pity about the (lack of) red sensitivity of modern DSLR’s. Looks like a very useful and competent lens.

What was the issue with stars inside/outside of focus? Did you use manual or auto focus?

Cheers

Dennis

[leon]

Like Dennis said a great image, I have actually never imaged this object, yet i see it all the time, have done it's big brother, but not the smaller one. :shrug:
Must try it one day.
Leon :thumbsup:

[h0ughy]

well go back to film then - but on second thoughts don't. As with any new toy it takes time to get to know the beast - maybe a modified camera with a nice filter in it to get the details out (Ha etc) could be the fix

[jase]

I like the composition Roger. Indeed, its a shame about the red sensitivity. The LMC and SMC have many knots of HII structure which looks a little strange when the image does not portray this. Keep at it.:thumbsup:

[iceman]

I can see what you mean, Roger. The image is still very good and I'd be happy with it!

Was that at 100mm?

To get 10 min exposures unguided is excellent!

[rogerg]

Thanks all, I didn't expect so many replies for such a boring old common object :lol:

h0ughy, you're right - I need a modified DSLR. But it's a tossup for me - Do I spend $1500 on a modified DSLR now, or spend $8000 later on something like a ST10XME :rolleyes:

Right now, I'm saving for the latter instead of getting the DSLR. But this inability to do nice wide fields is a bit of a pain :shrug:

I did go back to film not long ago, but the real problem now is that there's no Provia 400F available, and that was the only film I used for astornomy with good success. :(

Mike - It was at 150mm actually. I tried it at 400mm earlier in the night but decided to zoom out when all the objects applicable to the 400mm focal length were behind trees or the LX (the LX was blocking most of the western sky from where the portable setup was sitting. I ended up getting sharp results at 400mm also. Oh, and the exposures were guided - through the Megrez using my QuickCam Pro 4000 using GuideDog.

Roger.

[rogerg]

It was just a case of getting the focus spot on. I found I needed to focus on a bright star in the centre, then do more focus on a fainter star nearer the perimeter of the FOV. Doing a combination of that I ended up with a sharper focus.

This lens is very hard to focus for astronomy. It is a push-pull style zoom with a lock which locks both the zoom and the focus. So to stop the zoom sliding down you need to lock the lens a little, but that makes the manual focus more grippy and harder to make minor adjustments with. It also means if you want to change the zoom you need to tweak the focus because it's near on impossible to slide the zoom without rotating the focuser slightly at the same time.

But it does give me 400mm without the hassles of a 6 point ring system on the guide scope. So there's pluses and minuses.

[h0ughy]

Roger I am telling you that you will not be disappointed, as a matter of fact you will probably wonder how you ever lived without it;):D It is the type of thing that you can get a result in next to no time - why look at this one single image for 5 minutes taken with the camera for the first time from SPSP (http://www.iceinspace.com.au/forum/attachment.php?attachmentid=25863&d=1176760299) - or this one which is a stack of 9 1 minute shots (http://www.iceinspace.com.au/forum/attachment.php?attachmentid=25864&d=1176760299) not world beaters by any means, but the potential is there to do a lot with. That was the very first time I used the camera, the second was at Qld astrofest where I got shots like this (http://www.iceinspace.com.au/forum/attachment.php?attachmentid=30741&d=1187352945). so what if it add 12 months to your saving plan - its a worthy diversion:thumbsup:;):whistle::D

[rogerg]

hOughy, what've you done! I read your post about 3 hours ago and I can't stop think'n ... ohhh, nice modified DSLR, only $1500.... Mmmmmm... can I afford it ....

Nooooo! :help::sad::scared:

[h0ughy]

summer heat cool it down from a balmy evening 25degrees to about 7 degrees, far far less noise....... www.centralds.net :whistle: go on I know you want to.:whistle:
:help::help::help::help: think - those lovely results - in an instant...... why not check out his filters light response curve.... (http://www.centralds.net/en/products-x.htm) scroll on down to the graph look at it - love it;):thumbsup:

Now don’t go blameing me for you having to agonise and think about this hard decision you have already made – if in doubt buy a second hand camera and get that converted, much cheaper. I bought mine new – used it for 11 months then sent it over to the doctor. Never looked back. When you order it, get the 12 volt power supply and battery adapter for the camera – allows you to use it in the field off a battery porta pac. But who am I to merely put these type of suggestions to such a seasoned and hardened professional such as yourself.

Also theTC-80N3 timer is a great choice, as too a nice L series lens – such as the dedicated f2.8 200mm one or the 135mm. RB talked me into the first one! I use a 4 gig card with mine LOL.

I also have a regulated power supply that can supply the voltage to use with 240V mains.
:)

[Lee]

Thanks for the link Houghy - VERY tempting!

Nice pic Roger - SMC/47Tuc is an awesome area....