What astrophotography can my gear manage?

[Dara]

I don't currently own a telescope, however I do own some decent photography gear. I'd like to try taking some pictures of things 'up there', but I don't know enough to know whether I'd be wasting my time shooting unsuitable subjects. At the moment my interests are varied, moon, planets, DSOs, although with practice I may come to prefer one category - I just don't know which yet.

I'm fortunate enough to possess a Canon 600mm f/4 lens which is usually used for wildlife (especially bird) photography, and is sometimes pressed into service as a terrestrial telescope. This has a 6 inch front element diameter, and combined with 2x, 1.4x converters and a 7D body gives a combined focal length of 2688mm. Given the usual photographic rule of 50mm is 1 x magnification, then this adds up to 53 x magnification.

It sits on a Wimberly head on a tripod - this is very convenient for changing the direction it points, but that's the only good thing about it for astrophotography.

Would I be correct in assuming that this gear is relatively useless for anything other than single, short exposure, images?

It would appear to be the case that, as with ordinary photography, the support the camera/telescope sits on is key.

What I had considered doing is acquiring a tracking or guiding support on which to mount the lens, which would serve me for the short-medium term. Later on (once the bank balance - and more critically the accumulated brownie points - had recovered) then it would be time for a proper telescope to sit on the previously acquired support.

I've got shorter lenses suitable for wide field imagery, but even there a capable support would be a big step-up.

Am I barking up the wrong tree? In fact, am I barking in completely the wrong forest?! :)

[russ]

I bet that weighs a fair bit? Do you not have a wide angle lens you can use? Using a 28mm, or even a 50mm with the 7D, you could start with some constellation images on the tripod.

But to get going with the 600mm telephoto, you will need a good equatorial mount to track the sky. I would forget the teleconverters, the 600mm alone will be enough.

[Demonperformer]

A 600mm f/4 lens is like attaching your camera to a 6" f/4 telescope and so has potential for some astropics. My guess is that you would need a solid equatorial mount, with an RA motor drive, to achieve its full potential. However, you have nothing to lose by getting outside under the stars and seeing what you can achieve from your tripod. You could certainly get some widefield shots if you have a shorter (standard) lens.

EDIT: Russ beat me to the response again! At least we more or less agree.

[russ]

Sorry John

But at least we were singing from the same hymn sheet

minimum requirement .... EQ mount with RA drive, such as secondhand EQ5/CG5.

[Herishi]

See the below two pics, nothing that great but it'll give you an idea, the moon was taken with a 1000d sigma 70-200mm F2.8 and 2x MC7 doublers, counting the crop factor then it would be 1280mm at about F6.3.

the orion area pic I think its M42 (please excuse my lack of knowledge at the mo) is just using the 70-200mm lens.

[E621Keith]

Here is a site with some information about using camera lenses for astrophotography

Lenses for Astrophotography

and a review of Canon 400/2.8, not quite 600/4 but it's the closest I can found.

Canon EOS EF 400mm f/2.8 L USM IS Astrophotography Tests

and one from dpreview using Nikon

D3X and D3S team up to nab a Nebula

A 600/4 weights around 6kg, I guess you will be using an 1D which will add a further 1.5kg. That exceeds the recommended imaging load capacity of a GP mount or its clone (CG5/EQ5), so you will need a HEQ5 or an EQ6.

[Dara]

Thanks for the advice.

It's a 7D I've now got, not a 1D (for 6 years I used only a 10D with the 600!). Lens + body + grip + 2 batteries + 2 extenders + extension tube will be in the area of 8kg total.

Here's a moon image I got a while ago with a 1.4 extender on (for a total of 1344mm)-

I've also managed to see some texture on Mars, but the photos are hiding from me at the moment and they're pretty poor anyway.

I will be trying some widefield shots, but I'm presuming those great stacked multiple exposure shots that get posted won't be possible for now. I've a Sigma 10-20mm (so 16mm at widest with the crop body), which unfortunately is relatively slow but I'll see what I can come up with.

But it does look like my idea of mounting the telephoto on a 'proper' mount and then getting a proper telescope later will actually work.

By the way, can these mounts be fitted with 'Quick Release' systems? I use Arca-Swiss plates on all my gear and being able to attach one of their baseplates onto the mount would make life much easier and quicker.

So, an HEQ5 or EQ6 (without GOTO as I'd be using a laptop, if that's right?).

All I need now is to do some research and acquire a large bunch of flowers...

[samir_ansari]

is there a way to stick a camera straight onto an eq5 or heq5 without piggy backing it onto a telescope?

[Herishi]

Thanks for the advice.

It's a 7D I've now got, not a 1D (for 6 years I used only a 10D with the 600!). Lens + body + grip + 2 batteries + 2 extenders + extension tube will be in the area of 8kg total.

Here's a moon image I got a while ago with a 1.4 extender on (for a total of 1344mm)-

I've also managed to see some texture on Mars, but the photos are hiding from me at the moment and they're pretty poor anyway.

I will be trying some widefield shots, but I'm presuming those great stacked multiple exposure shots that get posted won't be possible for now. I've a Sigma 10-20mm (so 16mm at widest with the crop body), which unfortunately is relatively slow but I'll see what I can come up with.

But it does look like my idea of mounting the telephoto on a 'proper' mount and then getting a proper telescope later will actually work.

By the way, can these mounts be fitted with 'Quick Release' systems? I use Arca-Swiss plates on all my gear and being able to attach one of their baseplates onto the mount would make life much easier and quicker.

So, an HEQ5 or EQ6 (without GOTO as I'd be using a laptop, if that's right?).

All I need now is to do some research and acquire a large bunch of flowers...

Wow thats an amazing image, makes mine look a bit feeble.

How did you manage to focus sharply? I had all sorts of problems, I had the camera on a tripod and was connected to my laptop the EOS live view utility and even tried using the "zoom" button to get a close up to try to improve however the view wobbled so much when I touched the focus ring that I couldnt tell if I was making it better or worse :-) also the moon moves out of view (or we spin away from it a bit I cant quite work that out totally in my head yet) really quickly, admittedly my tripod is not a great quality one, should be better not I have the EQ3-2 mount rather than a camera tripod.

Steve

[Zakalwe]

Thats a helluva lump of glass you have there, Dara.

Get an EQ mount like an EQ5 (would an Astrotrac carry that much load? Its rated at 15Kgs). You would be able to get some stunning nebula shots with that kit. No reason why you couldn't stack multiple images either.

[DrGui]

You don't need need anything more than what you have to get some nice pics. Try this.

Using a 400 mm lens set your ISO to 1600 and and take a series of 2 second shots . Download DeepSkyStacker (its free) and stack your images. Keeping your exposures short you prevent star trailing, and the more frames you shoot the more detail you can detect. Just a suggestion eh.

[Dara]

How did you manage to focus sharply?

If I remember correctly I was focussing manually. It will definitely have been with a remote release, but I don't think I used mirror lockup for that one.

(And, to be honest, I was a bit hesitant about posting it because I didn't think it was all that sharp! I'm my own worst critic. )

[Glider]

Dara, the EQ5 can carry 9Kg, the HEQ5 can carry 15Kg. You would be in with the kit you have on an EQ5 but you'd soon want to add more kit and go over.

Samir_ansari, yes you could simply attach the camera to a piece of dovetail bar using the standard 1/4" thread hole on the base of the camera. This is what I've done. You'd need to drill a clearance hole in the bar for a bolt with the right length, and counter sink the head of the bolt.

Obviously, there are other, better, more expensive options!

[Dara]

Download DeepSkyStacker (its free) and stack your images. Keeping your exposures short you prevent star trailing, and the more frames you shoot the more detail you can detect. Just a suggestion eh.

The short exposures would prevent star trailing, but what about what's in the shot moving between frames? Would I need to manually adjust where the camera was pointing to keep the field of view (approximately) the same?

[Demonperformer]

DSS can handle objects not being in exactly the same position on each frame, but the closer they are to the same spot the more of every frame ends up in the finished image, producing a better result. You also have to consider how long an object is going to take to pass through your entire fov, travelling at one degree every four minutes. I think you will find manual adjusting becomes v tedious v quickly. Just my 2p ...

[E621Keith]

Dara, the EQ5 can carry 9Kg, the HEQ5 can carry 15Kg. You would be in with the kit you have on an EQ5 but you'd soon want to add more kit and go over.

I'm skeptical about the 9kg rating for EQ5, because the Vixen GP is only rated 7kg. Skywatcher quote their mounts for visual load, imaging load is often 50% less.

Putting it into perspective, that 600 f4 lens weights about the same as a C8 SCT. After adding all the camera and accessories, it weights about the same as a 200p.

My 120mm f8 (f1000mm) refractor on EQ5 is ok for visual, but not stable for imaging. I can only guess the EQ5 will perform worse with the heavier 600/4 @f1344mm.

HEQ5 should be the minimum requirement for long exposure imaging.

On the other hand, Dara, if you want to image moon and planets, your camera and lens aren't very suitable for the job. They are much better for deep sky wide field imaging. Instead a Skymax 127, EQ5 and a hacked webcam should you better results on moon and planets and cost less than a HEQ5 syntrek.

[ollypenrice]

Your big lens should be fabulous for astrophotography but, as has been said above, it is a full blown telelscope, in effect. I would suggest an EQ6 mount and autoguider. You can't do long unguided exposures successfully by just relying on the accuracy of the drives.

I would start with Steve Richards's book Making Every Photon Count, available from FLO above.

There are some camera lens shots on the deep sky section at the moment, Prokyon's stunning Sword of Orion (Canon EF200L) and my own Orion constellation mosaic (Samyang 85).

Olly

[Dara]

You also have to consider how long an object is going to take to pass through your entire fov, travelling at one degree every four minutes. I think you will find manual adjusting becomes v tedious v quickly. Just my 2p ...

Pretty much what I was thinking - which brings me back to the tracking mount again!

[Dara]

if you want to image moon and planets, your camera and lens aren't very suitable for the job.

Is that because of the comparatively low magnification, and therefore small result in a large frame, compared to a webcam?

[E621Keith]

Is that because of the comparatively low magnification, and therefore small result in a large frame, compared to a webcam?

Yes, you got it right on. The other reason is webcam or astro video cam can take videos. Individual frames in a video can be stacked to correct for atmospheric turbulence using free software such as Registax. Stacking a VGA video is easier on the computer than stacking a HD video.

[Herishi]

Stacking a VGA video is easier on the computer than stacking a HD video.

Is this purely a CPU / GPU related benifit? as in if you had a super computer it would be better to use HD?

[Dara]

The 7D (and I'm assuming other bodies) can capture in lower resolution, 640 x 480 for example. But that still wouldn't solve the issue of needing greater magnification. Plus there would possibly be the extra step of converting the file to a format the stacking software can work with.