Best lens for astrophotography.

[Coastliner]

Hi,

I have a Canon EOS 450D which I intend to mount on a Skywatcher Star Adventurer EQ mount, with the intention of photographing the Milky Way ( to start off with!). I have the kit lens for this camera, an 18-55mm f3.5. Can anyone recommend a budget lens that would be better suited to astro? I'm not necessarily looking for a particular manufacturer, just the generic optimum specs for such a lens. If a particular lens can be specified so much the better.

Or, given the kit list, what would be the optimum settings in terms of exposure time (bearing in mind that I will be tracking), f number, iso etc?

Many thanks,

Neil.

[iksose7]

Its easier if we know what lens is being used before deciding on settings. But if tracking, i personally would go for 5-10 minute subs, ISO 800 and choose and aperture that suits the lens (usually stepping the lens down will produce better star shapes towards the edges) this all depends on your sky conditions also.

As for the lens, it depends on what sort of field of view you want to shoot the Milky way in. The 18-55mm @ 18mm is not too bad if heavily stepped down. If on a budget its hard to find a lens wider that 18mm cheaply. I know there are some fairly cheap fish eyes but i'm not sure how they preform. What is your budget?

If you want to go for some mosaics and get some nice detailed images, i as well as everybody else recommend the 50mm 1.8. Its usually £50-80. If you spend a little more you could get the pancake lens at 40mm. I wouldnt mind getting my hands on it. 

[hobsey]

The kit lens tends to be quite slow but as it will be tracked then you can get away with an iso800 'I think' not to make too much of a noisy image.

A cheap and cheerful lens a lot of people have been trying recently is a canon 50mm 1.8, its quite fast. Also know as the nifty fifty.
 

[Coastliner]

Thanks both, as it happens I own the "nifty fifty" but never considered it for astro as the fov is so narrow. Mosaics are one of the many techniques I haven't tried yet. And, as you say, it is a nice sharp lens. I'll be googling "pancake 40mm" straight away!

By "stepping the lens down" do you mean closing up the aperture to something like f11 or thereabouts?

[iksose7]

The nifty fifty is an excellent lens for astro! Good job you have one lying around. I usually stop it down to around f4 i think, heres the last image i took with mine as an example: http://stargazerslounge.com/topic/220617-scutum-star-cloud/

Yes, stopping down is closing the aperture. I wouldnt go as far as f11 though, that would make it very slow. I've not experimented with the 18-55mm too much but i think i've tried it at f7 and it wasnt too bad. Remember that zoom lens will always be the worst when it comes to astrophotography as they tend to reveal their flaws more, go for a prime any day.

[Alien 13]

I have the is version of the 18-55mm kit lens and found it very good for astro better than my nifty fifty (i did use it with the in camera CA and edge reduction) and could be used wide open the Samyang lenses often get very good reviews for AP use but i have not personally tried one.

Alan

[Coastliner]

Thanks both, I will do some experimenting with the lenses I have first the. Iksose7, that pic of yours is certainly an inspiration!

Neil.

[jgs001]

The kit lens suffers from a bit of blue CA wide open at 18mm, maybe stop it down to f/4, or f/4.5. The 50mm is actually very good, if you stop down to f/4 to f/4.5 and tracked that's not really an issue. I use an unmodded 450d for my astro imaging and with 5 minute exposures on an astrotrac, I pick up quite a lot of Ha.

I've picked up the 40mm f/2.8 pancake lens after seeing some results wide open, surprisingly good. It seems the killer lenses for astro are surprisingly Macro lenses... They are designed to have a very flat field, and with some image analysis this has been proved with my 150mm f/2.8 wide open.. so I was picking up faint Ha (the band behind the horsehead) with 2.5 minute exposures and I only got 13 of them before clouds stopped play, however, macro lenses are not cheap.

[hobsey]

 It seems the killer lenses for astro are surprisingly Macro lenses... They are designed to have a very flat field, and with some image analysis this has been proved with my 150mm f/2.8 wide open..

Get a 2x teleconvertor and you will have something that would probably be able to compete up against the really expensive refractors.

[Coastliner]

Hobsey, 'scuse my ignorance, are you talking about using a teleconverter with the 18-55 kit lens or the 50mm prime?

Neil.

[hobsey]

Hobsey, 'scuse my ignorance, are you talking about using a teleconverter with the 18-55 kit lens or the 50mm prime?

Neil.

Thats cool.

I was on about the 150mm macro lens of Johns that I had quoted in my post.

It was my fault for going off topic ever so slightly.

[Coastliner]

Ouch - just looked at the price of 150mm f2.8 Macro. Methinks I'll defer for now!

[jgs001]

I did say macro lenses weren't cheap . It's worth keeping an eye on the second hand retailers though... Bargains can be had. Check out mpbphotohraphic.

You can't typically use TC's with EFS lenses. I'm not sure 300mm at f/5.6 would be worth it, although I do have a 2x.

Sent from my GT-I9300 using Tapatalk

[lensman57]

Hi,

For AP you'd need a lens that is well corrected for CA and quite fast so you'd be able to keep the exposure lenght low. All this means that for Canon it needs to be an L lens and for Nikons ED which all together equates  to big money. One of the SGL members produces superb images with a Canon DSLR and a 500mm F4 IS lens. This lens costs more than a Takahashi  FSQ 106. I use a 200 F2.8L IS with Atik CCDs but even this lens ( costs about £750.00 new ) has to be stopped down to F4 to control the CA, I use a front aperture mask of 52mm for this. I guess what I am trying to tell you is that if you already have a lens then give it a go see how it fares but IMHO it is not worth buying an expensive DSLR lens just for AP you might as well save a little more and buy a decent Apo or ED scope of about 80mm, F6.

SW 80mm Equinox is a very capable scope for a little more than £500.00 if budget allows.

Regards,

A.G

[wxsatuser]

There is an open box EF 200mm L f2.8 on WEX for £549, bargain. 

http://www.wexphotographic.com/buy-used-canon-ef-200mm-f2-8-l-usm-mkii-lens/p1557297

[jgs001]

MPB have the Sigma 105 macro for £199, the 150 in Nikon fit for £299 (non OS which is the one I have). They also have the Canon 200 L for £479.

Here's a couple of examples with my unmodded 450d

Here's my first results with the Sigma 150, 13x 165 seconds, ISO800 @f/2.8

Orion's Belt and Sword

As you have the 50, start with that.. f/4.5, 300 second exposures at ISO800 (I'd wanted a lot more exposures, but the weather had other ideas so only got 19)

Cassiopeia Widefield

Orion (all of it) is quite a nice fit at 50mm.

[hobsey]

That Orions Belt is a crack shot.

[Coastliner]

John, excellent shots. I can't wait for the nights to draw in a bit now to give my 50mm a go. I also need to try out my sparkling new SW Star Adventurer, I only hope I can get it to track accurately enough to get 300 sec exposures.  Talking of the 50mm, I am amazed that one can get such good shots with such a cheap lens. It is also nice to see the pics taken with the unmodded 450D, which is what I have.

Thanks for all the replies guys, keep 'em coming. I know I'm not replying to all the posts individually, but they are all being read and notes taken - lensman57, I like the idea of the Equinox 80, I think my best bet is to try some shots with the kit I have first and then start talking nicely to my wife. I doubt that flowers and chocs will cut it!

Neil.

[jgs001]

You could try using the 50 a bit wider than 4.5... but at f/3.2 the nifty suffers from coma around the edges (I had to crop about 30% of my first image with it, all of Orion to remove the coma)... I was using the 50 f/1.4, and that suffers from Ca in the middle at f/3.5 (which is quite odd) but at f/4.5 this is all gone (I have a very similar framed image to the above with the 50 at f/3.5 if you want to see it... I really ought to try it at f/4 and see how the f/1.4 behaves then. 

At 50mm, tracking for 5 minutes is relatively easy, as long as you've polar aligned quite well, you should be good, although I've no knowledge or experience of that mount. I do know the HEQ5 and the Astrotrac both work perfectly for 50mm and 5 minutes.

[Knight of Clear Skies]

The 50mm is a lot of fun, I've been playing with mine for a few weeks now. I don't really know what I'm doing, especially with regards to processing, but here are a couple of my first attempts:

Both are about 35 minutes of data with the lens stopped down to f4. Tracking is very forgiving at 50mm, I'm consistently getting 2 minute subs and that's just sighting on Polaris through the mount without a polar scope.

One problem I have with my 50mm is that the focus ring is quite loose and can drift out of focus over time. I was using a rubber band to hold it in place, but I'm now using a couple pieces of blu tack!

Here's my first results with the Sigma 150, 13x 165 seconds, ISO800 @f/2.8

Interesting to see the result with the macro lens. Might be something to consider further down the line, as I could also use it for its intended purpose. I'll give my M42 lenses a try first and see what I can get out of them.

[Coastliner]

 I have a very similar framed image to the above with the 50 at f/3.5 if you want to see it... I really ought to try it at f/4 and see how the f/1.4 behaves then. 

Yes please - I'd love to see the image.

[Coastliner]

The 50mm is a lot of fun, I've been playing with mine for a few weeks now. I don't really know what I'm doing, especially with regards to processing, but here are a couple of my first attempts:

Both are about 35 minutes of data with the lens stopped down to f4. Tracking is very forgiving at 50mm, I'm consistently getting 2 minute subs and that's just sighting on Polaris through the mount without a polar scope.

One problem I have with my 50mm is that the focus ring is quite loose and can drift out of focus over time. I was using a rubber band to hold it in place, but I'm now using a couple pieces of blu tack!

Interesting to see the result with the macro lens. Might be something to consider further down the line, as I could also use it for its intended purpose. I'll give my M42 lenses a try first and see what I can get out of them.

I'm absolutely knocked out by these images and the others taken with the 50mm. I need a couple of very late nights very soon!

[jgs001]

Here you go... 

Widefield Cassiopeia

And the orion with the Nifty

Orion Widefield

[frugal]

I find that 50mm on a crop frame DSLR is a bit too tight to get a whole constellation in. I have just splashed out on a Canon 28mm f1.8 lens (which works out at about 50mm on a full frame camera) for constellations and wide field. More expensive than a nifty fifty, but more practical for my purposes. So far it is looking to be a cracking lens.

[wxsatuser]

Not wide wide but I tried my Sigma 105mm f2.8 Macro last night and it does quite well at f4.

Here is an hour on the North American area.

Canon 60Da....12x300secs at f4  ISO 1600