Getting back into astronomy - astrophotography related

[Jasp05 (Aaron)]

Hi guys,

After quite a lonnggg.. hiatus, I've decided to get back into astronomy.

A little bit of background on me, I live in Rockhampton QLD (Anyone else from there, let me know, would be keen to catch up with some like minded ppl).

My first telescope was a 114mm reflector on a very shaky EQ mount. But it still got the job done and definately helped peak my interest in space.

Unfortunately said reflector has seen better days and had to be retired. (Although I have repurposed the mount for my DSLR).

I have however been out and about throwing my hand at some astrophotography with just a 1200d Dslr and a small tripod.

I've found just taking a few second snaps of the constellations and trying to stack and edit the photos to be quite fun even though I have not had a lot of success. Although I am still quite happy with the photos I have gotten and how they've turned out, they can be better. I have snapped the pleaides, M42, the cluster M41 and even the andromeda galaxy.

Now my reason for this post is to get some sage advice on astrophotography and what is possible on a budget.

I am looking for a scope but seen as I've had a taste of a small scope, a nice big 10-12 inch dob sounds like that is the next step for me. However astrophotography also grabs me as something I'd like to try. (If only for the purpose of having some way to record what I see and show my kids who are 2 & 4 years old. My daughter loves coming out to the see the stars and I would like to be able to show her alot more of what is actually hiding in the sky.

So I am in the market for a telescope (If any one is selling let me know) and any advice around what would be best for viewing or photography or a mixture of both.

But I would also like to know what kind of objects would be good targets for photographing with just the DSLR in the mean time. I've tried to look at lists based on magnitude of the DSO's, and just going after the brightest objects. Mag 5 & higher. The camera is a 1200D with the standard 18-55m lens F3.5. so I don't get alot of magnification.

What lens would you recommend for a beginner in this field to get some half decent shots of the brighter objects?

Also what would be the faintest objects you would attempt to photograph? Bearing in mind, my mount is not able to track. (At this stage anyway. I;m working on a little project to try and motorise it currently. one of my other many hobbies

Anyway, this post has gotten a bit out of control but would appreciate any feedback on the above. Thanks in advance.

[ZeroID (Brent)]

Hi Aaron and back to the madhouse.
You obviously realise that visual and photographic requirements are not necessarily good partners.
Visual and the big DOB is the usual recommendation for most newbies and is an easy and excellent way to see lots and learn star lore.
Astrophotographry requires the EQ mount and usually a smaller refractor plus other hardware and a lot of trials and patience to get it working for DSO objects.

I'd suggest starting with the big DOB as it is probably the one scope that almost everybody has and never gets rid of because bang for buck it will give you and your family viewing pleasure for a long time. It is possible with short exposures and a bit of persistence and patience to get astro pix of fainter objects with it, it has been done. It is certainly possible to do stacked video or even single frames of lunar views and planetary pix and these are good practice in moving on to later equipment upgrades.

Photographically if you can motorise your small EQ mount and balance it with the DSLR you can take surprisingly good widefeild shots. I started exactly that same way and still have it for trips away to dark sites. (I use a UPS to provide the 240v 50 hz it needs ). A lens upgrade is easy but you will find the alignment and tracking accuracy it requires will be a bit problematic. There are commercial camera EQ mounts available but weight capacity can be a limit and if you grow further then you need bigger gear. After that it an EQ5 or better an EQ6 ( or similar ) and a small APO.

It really comes down to budget and time. With a young family to entertain I'd go with the big DOB to start with to get their buy-in. Long term it would pay off. There is always some pretty good deals here in the For Sale section and you will get excellent support and probably a few extras and pointers from them all. Enjoy !

Keep us all posted, we love spending other peoples money.

[geolindon (Lindon)]

G day Aaron

there are a couple of other AAs around Rocky that i know off, must be others tho - surely?

i agree with the dob recomendations; aperture for $$, and kid proof. some IISers are getting good images using dobs with video and equatorial platform tracking.

i'll be in Rocky in next coupla days - hopefully we can catch up.

L

[sil (Steve)]

Jasp05, others will give you scope advice, I'll give you something different. Orion make a very nice 100mm tabletop dob and i can highly recommend you grab one to keep your daughter occupied while you are busy with your other scope. She can explore the sky as she sees fit with ease and its a very good scope. I use mine while my camera is clicking away and it gives amazing views.

DSLR astrophotography is my hobby and I mostly now stick to a 70-200 f2.8 lens and shoot off tripod. As you've found, its all about the processing to account for the capture limitations. Still there is much you can do with just a camera. (see my astrobin gallery in my signature link for some examples).

Looking forward I can see you building a good AP setup as time and funds allow. I can recommend step one is get yourself a good GOTO mount. Probably an EQ6 or EQ8 as no matter what scopes/cameras you buy if you have a poor tripod/mount your AP will always be limited. You could buy a GOTO EQ mount today, pick up a dovetail plate the attaches to your camera tripod mount so it can be attached to the EQ mount and you will be able to start taking 30sec exposures with ease and up to several minute exposures and that will step up drastically your AP capabilities, galaxies and nebulae. You can easily star align a GOTO mount using live view on your camera. I would suggest an EQ8 but others will offer their suggestions (I have a CGEM-DX, but can't use it at the moment). A mount capable of taking a heavy payload means no worries about performance with whatever size scope you want to put on it, but balancing the load does become critical especially for unguided subs, I've never used a guider but setting up all my gear and pointing it to the area of sky i intend to image and balancing it all in that position as precise as i could always gave me good tracking (nice round point stars) with my goto target dead center of shot even though i couldn't see the target in any single shot it was there once stacked. This is just with a camera/lens (looking pitifully tiny ) on the mount. I never got around to attaching my DSLR to my scope (an 11" SCT) but did use a ZWO cam for video capture of planets through it. Deep sky stuff I stuck to camera and lens pretty much. I didnt progress into filtered imaging for health reasons but thats where you should end up.

[CatznStars (Ed)]

+1 for 100mm tabletop dob. So easy for the young ones (and not so young) to use.

[Jasp05 (Aaron)]

Thanks for the replies guys. I had thought of the 100mm table top dobs. I did wonder if they were worth it. I definately think I'll grab one as there pretty cheap.

One thing I've also learnt is that the faster a lens is then generally the better for astrophotography. How much of a hard rule is this? Like I can pick up some 70-250mm lenses for around $100 second hand. But they are F4-5.6 or something. I'm assuming these will still be ok for AP?

Or should I just save the money and buy something closer to an F2.8 or faster lens?

Learning to photograph M42 or the Pleaides will keep me plenty busy for a while as there is a lot to learn and as im finding takes a long time to take enough pics to stack and edit later. Would a lens like that allow you to capture much nebulosity? Or at least give enough magnification to be able to distinguish what is nebulosity rather than just stars?

[sil (Steve)]

The Celestron First scope is a 76mm tabletop dob and just not worth the money. But my 100mm orion is fantastic, the included eyepieces are actually not complete garbage and the scope responds well to using my Baader Hyperion eyepieces. I first eyeballed Neptune with it, took 30min of star hopping and chart checking but I found it.

Slower lenses are ok but older lenses much less so for astrophotography.
On tripod the faster lens give you more photons therefore more signal in your shots to work with when processing ince you are still limited by exposure duration. On an astromount your have tracking so you can use a slower lens and may need to expose for longer to get the signal you want but since dslr capture is mostly about processing the captures there is little difference between f2.8 and f5.6.

The HUGE difference though is unrelated to aperture, its lens quality. Modern lenses are actually slightly different in construction to provide better image quality with digital sensors. Older film lenses work fine generally but there are technical differences. The biggest issue specific to dslr astrophotography is chromatic aberations and coma effects, basically distortion from the optics in the lens. Older lens suffer noticably from chromatic aberation but modern slow lenses not so much.

However as a photographer lenses are never an identical sharpness throughout their aperture range and rarely (if ever) when at their fastest aperture. To get cleaner rounder stars stopping the aperture down will improve matters but of course you then need to compensate by increasing exposure time and/or iso. Its all a balancing act so best advice is a quality (pricey) lens is basically worth paying for. Avoid the cheap kit lenses and ignore brands, research the lens itself online first (eg Tamron only ever made crap lenses but in recent years they are making some good ones for the price, so buying you need to research the lense model revision itself or you risk getting stuck with dud version). That said I'll repeat dslr astrophotography is mostly about the processing and you can AP with any lense/camera. So if you cheap out on your lense quality there is little you can do to fix that in post. Garbage in gabage out as they say.

Nebulosity needs exposure time, its generally large enough for whatever lense you have. But the built in filters in cameras kills some of it which is why some people mod their cameras and of course ultimately you want a well colled monochrome camera and filter set. As for taking a long time to take enough pics to stack, this is a constant no matter what your gear as it depends on capturing photons to build the picture, only aperture size helps here but still it is slow, even Hubble was exposing for months to gather enough photons so don't bother thinking you can buy something and just press a button and take a photo. I just uploaded M31 to my astrobin gallery (see my sig link) which was taken with a dslr at 200mm on a regular camera tripod only. nothing special needed or used, its just capturing enough frames and processing them to tease out the signal.

[stefang (Stefan)]

+1 dob
+1 small refractor.

At the end of the day, the best scope is the one you use. Same goes for cameras. Perhaps buy a good second hand modded EOS and T Ring adapter, experiment until aperture / gadget fever sets in and you find yourself trying to explain to your wife why a NP127is and 10k + in SBiG / FLI CCD'S , filter wheels, astrodons etc etc etc really is a long term investment in your marraige.



Stefan