Need some advice with wide field imaging setup

[SteveA]

All my imaging over the last 3 years has been via my 10" newt which is permantley setup in my garden observatory.

My garden is fairly limited.. in that large areas of the sky are obscured by trees and houses and I can't get anywhere near the Eastern or Western horizons.

With some notable comets coming up this year and some trips planned to darker sky locations I'm looking at putting together a portable rig.

I've already got a Canon 350D which I have in the past attached to the 10" newt.

I'm considering getting an Astrotrac to mount the camera on, hopefully will pick one up at Astrofest next month.

I've only got the standard lens that came with the Canon, so was wondering what would be an effective lens for wide field work, including capturing some good images of this years comets..

Any suggestions?

Cheers

Steve

[Matt Scunthorpe]

For some widefield shots of parts of the sky that i do, like constellations, i just use the standard 18-55 lens that came with mine. More experienced people may be able to tell you of better ones though im sure

[kenny k]

The canon 'Nifty fifty' lens gets good reviews for its price for widefield AP !

On my next items list:)

[tommo b]

2nd the 'nifty fifty'. I've had decent star-trail results with both this & the 17-85mm.

Just a bit of trial & error with the iso settings......

[Andymac79]

What kind of budget do we have to spend...? And how wide?

Older manual focus lenses maybe worth thinking about, choose wisely and you will get a fine prime lens for not much money, the build quality of them is generally very good.

Other wise the 50 is a good lens, a pig to focus properly due too the cheapness, or maybe my shaky hand.

Going way up in price the Canon 200L, it aint cheap but does deliver fine results.

[Ulysses]

I'd also recommend the Canon 50mm f1.8. It's a brilliant lens and I've managed some good stacked fixed tripod shots with one. Used wide open, you will get lens aberrations, but the centre is pretty sharp! If you can track, then stop it down for sharper results, Paul

[SteveA]

Thanks for the pointers chaps....

I'm certainly not looking to spend a fortune......at least not after getting the Astrotrack!

I have played with some imaging using the standard 18-55mm lens and found the focusing a real pain, but then it was a pain also with camera attached to my telescope...so I guess that's just one of the facts of life with DSLR's.

Is there any particular advantage in using a fixed focal length lens over a zoom lens?

Steve

[stem1989]

i have the 50mm 1.8f, should be able to find at around £65 very nice wide field shots.

[ollypenrice]

Primes are far better on stars than zooms. The Samyang 85 is a fast 85mm prime at a very reasonable price though it won't give clean stars wide open. It does need to be stopped down. I used it for this CCD mosaic, six panel marathon.

http://ollypenrice.smugmug.com/Other/Best-of-Les-Granges/i-V9SQcqS/0/X2/ORION%2085MM%20LENS%20HaOSC%206%20PANEL-X2.jpg

The Canon L series primes are superb. I've just parted with my 200 which is an absolute classic.

Olly

[Andymac79]

Thanks for the pointers chaps....

I'm certainly not looking to spend a fortune......at least not after getting the Astrotrack!

I have played with some imaging using the standard 18-55mm lens and found the focusing a real pain, but then it was a pain also with camera attached to my telescope...so I guess that's just one of the facts of life with DSLR's.

Is there any particular advantage in using a fixed focal length lens over a zoom lens?

Steve

Steve, I bought a 50mm but the problem is you already have that focal length in the 18-55, sure the 50mm is better but its not, in my view, worth the extra spend.

I would say a 200mm is a very usefull length, lots of great targets too keep you going a long while. If you dont want to afford an L series then £50 on ebay or ABS will get a decent older M42 fit lens.

I know Gina on here is pleased with their results, as I am. Some makes too keep a look out for are Jupiter, Takumar (SMC), Pentacon (I Have all Pentacon lenses, very cheap and soooo well built).

They will suffer a little with CA and multi defraction spikes on stars (due to the manual iris shutters for adjusting f stop) but even this can be overcome by using a mask over the front while keeping the lens wide open. (Thanks Olly !)

Where as the 18-55 focus ring is very difficult to fine adjust, these old metal lenses are very easy. I think with the quality of the Astrotrac they will give you very nice results

So they are not perfect but they are cheap and we all know how expensive glass can get.....

These two were taken with Pentacon 200mm f4 that cost £25, broken iris lever but works ok. You can see the effect of the iris blades on the stars. M45 is cropped a fair bit

Now these were 120 sec unguided and Im not over the moon with them, just an example of what £25 can get you.

Andy

[laser_jock99]

I've only got the standard lens that came with the Canon, so was wondering what would be an effective lens for wide field work, including capturing some good images of this years comets..

Any suggestions?

Cheers

Steve

Personally I'm hoping these comets turn into bright objects with really long tails. To cover that you'll need a fish-eye or at least very wide angle lens. Maybe consider some like the Sigma 10-20mm zoom which I have found usefull both in 'normal' and astro work. The last comet with a long tail visible from the UK was Hyakutake in 1996 with a tail of almost 80 degrees long, that needed a 24mm wide angle lens to cover it. I'm hoping ISON will be better yet.

[PeteC]

I've used the standard EOS zooms for wide field. They aren't really designed for manual focussing - they're flimsy and too easy to knock back out of focus accidentally - but do a reasonable job if you get it right. As everyone says, a prime lens will always beat a zoom. Old manual focus lenses are solidly built, silky smooth to focus and cheap on ebay. You can get a dirt cheap one and stop it down a bit to counteract the aberrations or pay a bit more for a good quality one. M42 fit will give you the most variety, along with a M42 to EOS adapter ring.

On tracking, I was going to get an Astrotrac but decided on a Vixen Polarie instead. What won it for me was the compact size (stick it in a pocket going through the airport) and the ability to track at half sidereal rate for doing nightscapes.The downside is a max load capacity of only 2kg, but that's OK if you don't plan to use a jumbo lens. I've not tried it yet, only just got it from FLO, but I'm off to hopefully clearer skies in a couple of weeks for a test drive.

Good luck

Pete

[SteveA]

Thanks everyone....some very useful advice here..

I think I'm going to keep an eye open for some second hand lenses...though the nifty 50 seems affordable new. Looks like a selection of affordable second hand prime manual focus lenses is going to be the way I go...

Thanks for the hint on the Vixen mount, I'll certainly look into that before forking out any money...

Cheers everyone..

[laser_jock99]

Thanks everyone....some very useful advice here..

I think I'm going to keep an eye open for some second hand lenses...though the nifty 50 seems affordable new. Looks like a selection of affordable second hand prime manual focus lenses is going to be the way I go...

Thanks for the hint on the Vixen mount, I'll certainly look into that before forking out any money...

Cheers everyone..

I'm hoping a 'nifty fifty' won't be wide field enough for these upcoming comets! But they are a usefull astro lens none the less.

[SteveA]

On tracking, I was going to get an Astrotrac but decided on a Vixen Polarie instead. What won it for me was the compact size (stick it in a pocket going through the airport) and the ability to track at half sidereal rate for doing nightscapes.The downside is a max load capacity of only 2kg, but that's OK if you don't plan to use a jumbo lens. I've not tried it yet, only just got it from FLO, but I'm off to hopefully clearer skies in a couple of weeks for a test drive.

Pete..Pete...Pete what have you done!

This was going to be an easy purchase....ie. buy an Astrotrack... Now I'm in a dilema! The Vixen Polarie looks like a really neat piece of kit and and now I'm faced with a decision...

I was vaguely aware of the Polarie but having spent some while this afternoon looking into it and viewing some of the videos on YouTube I've realised its a serious contender here.

The load capacity is probably going to be a deciding factor for me and although I wasn't planning anything more than using it with a DSLR at this stage...I may well want to do more in the future.....but it does look really simple to use/setup and a definate advantage is its small size if travelling.....hohum....what to do??

[PeteC]

Sorry to add to your dilemma Steve! If you search the forums on here for Vixen Polarie I think there has been quite a bit said about its pros and cons versus Astrotrac and other portable tracking mounts. I think someone said that Vixen in the States had rated its load capablity at 3kg, but the user manual that came with mine says only 2kg. It was a bit of a no brainer for me when I found that it could track at half sidereal rate because I want to get more into doing nightscapes, and this means I should be able to do longer exposures while still keeping both the stars and foreground objects fairly sharp. As well as that, I don't intend using anything heavier than a 135mm tele. If I was doing wide field astro only and wanted the possibility of using a short focus refractor on it I would have gone for the Astrotrac.

I haven't tried it yet but it certainly looks and feels a well-engineered piece of kit. I bought it cos I'm off to La Palma in a couple of weeks and decided you can't go somewhere like that with a reputation for quality dark skies without taking some passable imaging kit.

Pete

[SteveA]

And now...having started looking into this in more detail I find a whole load of portable tracking mounts...they certainly seem to be becoming an popular accessory these days...

I'm hoping I'll be able to compare a few of these devices in the "flesh" at Astrofest in a few weeks time....

Steve