Lens for Wide angle

[Kenza]

Hi! I want to shoot wide angles of the milky way and the sky. What properties does a lens need to have (apart from being a wide angle lens)? Do I need Image Stabilizer since I will be shooting from a tripod and piggyback. Is it better to get a prime lens or zoom lens?

Canon only!

[spacebloke]

Hi Kenza,

Prime lenses are always better than zoom lenses as they provide better image quality. Image stabilization is not needed seeing as it's on the tripod.

I use a canon 100mm macro f2.8 on my Heq5 and it's pretty good. I even had a focus mask made for it.

[Keiran]

I would recommend the Nifty Fifty.... 50mm F1.8, normally under £100 New.

[michael.h.f.wilkinson]

50mm lenses are great for this kind of work. Stopping them down a bit is recommended to improve image quality and create a more even illumination.

[Keiran]

Yes, stopping it down is recommended, if you can afford it they do a 50mm F1.4 USM as well, but this is a little bit more pricey. They also do a 40mm f2.8 pancake lens and a 35mm F2.0, but you are looking at around £200 for these. I would stick with a prime lens, unless you are buying a L zoom lens, and you wont need IS either, i thank that cause more throuble when used on long exposures.

[jgs001]

Define wide ?? I've read good things about the Samyang 8mm, that has a huge field of view. The 50mm primes are excellent, but unless you can track, the exposure lengths are going to be really short (about 8-10 seconds with the 50mm).

[Kenza]

Hi Kenza,

Prime lenses are always better than zoom lenses as they provide better image quality. Image stabilization is not needed seeing as it's on the tripod.

I use a canon 100mm macro f2.8 on my Heq5 and it's pretty good. I even had a focus mask made for it.

I have the 100mm Canon Macro, but I thought that for shooting the milky way you need a wider angle lens.

[Kenza]

Define wide ?? I've read good things about the Samyang 8mm, that has a huge field of view. The 50mm primes are excellent, but unless you can track, the exposure lengths are going to be really short (about 8-10 seconds with the 50mm).

I can track, I have an EQ6. I have found 3 lenses which cought my eye:

1) http://www.usa.canon.com/cusa/consumer/products/cameras/ef_lens_lineup/ef_50mm_f_1_4_usm

2) http://www.usa.canon.com/cusa/consumer/products/cameras/ef_lens_lineup/ef_20mm_f_2_8_usm

3) http://www.usa.canon.com/cusa/consumer/products/cameras/ef_lens_lineup/ef_17_40mm_f_4l_usm

[jgs001]

In that case, not a problem. At 50mm, my HEQ5 can handle 5 minutes with ease, without guiding. I have the f/1.4 and have used the f/1.8. I don't think there's a lot between them for Astro use, I upgraded to the f/1.4 for the USM, for some very low light stuff I was shooting.

[michael.h.f.wilkinson]

I tracked comet Hyakutake for 12 minutes with an 85mm F/1.4 lens stopped down to F/2.0 without guiding on a Vixen GP mount without guiding, so a properly aligned HEQ5 should be able to do more than 5 minutes. The result of my tracking (scanned print of slide, so loss of quality) is this:

[Kenza]

So as I see it, the best lens for AP is one with larger focal length and smaller f-ratio so in the end the aperture is bigger, since FL/f-ratio= aperture. Right?

[Catweazel]

Hmmm...this is interesting; I have the 50mm F1.8 II Canon lens, but have never tried it for AP. When you say stop it down, what would you recommend stopping it down to? Also, when you say tracking, will RA & Dec motors do? Thanks

[portedGoblin]

I use the Nikon 50mm 1.4, so pretty similar. It has very bad quality if used at f/1.4, stars at the edges looks like bats (no joke). Also the vignetting is pretty bad, at least on my full frame Nikon. This is an image stopped down to f/3.2. 26x5" exposures, ISO 1000 I belive. As you can see it is almost overexposed due to the stacking. My next try would be f/4 at ISO 800.

http://www.astrobin.com/26566/

It can also give you an idea of the FOV. This image is only slightly cropped at the edges witch turn to mush due to non tracking stacking. 50mm is pretty good focal length for getting a constellation in frame.

[Catweazel]

Thanks portedGoblin, that's a fantastic image!, what length exposure was it? I will have to have a try with mine next time I get clear skies

[Xlracer]

Been using a canon efs 10-22 zoom, excellent but cannot use an astronomik clip in light pollution filter as it fouls. Have just bought a SIGMA 14MM PRIME ON E BAY, AND HOPE TO TRY THA SOON. Gave also used the cacon ef 28 f2.8 which is goog, and a SIGMA 600MM MIRROR LENS FOR SMALLER TARGETS, ALL ON AN ASTROTRAX, ALBEIT MODIFIED TO REDUCE PLY.

[allcart]

kenza, you need shorter focal length and wider aperture. 50mm or less and a lens that opens up to F2 or f2.8 is good. I mostly use a Canon 20mm 2.8, but you can get some sigma (third party lenses ) that wil do a decent job as you are manually focusing. I had a Sigma f1.4 that couldn't hit a barn door with auto focus, but was great with manual focus.

I also have a 15mm fisheye, but can't use that at home because I get half the house in the frame.

[Kenza]

kenza, you need shorter focal length and wider aperture. 50mm or less and a lens that opens up to F2 or f2.8 is good. I mostly use a Canon 20mm 2.8, but you can get some sigma (third party lenses ) that wil do a decent job as you are manually focusing. I had a Sigma f1.4 that couldn't hit a barn door with auto focus, but was great with manual focus.

I also have a 15mm fisheye, but can't use that at home because I get half the house in the frame.

thanks I think I'll go for the Sigma 20mm 1.8. Seems ok for the job

[Catweazel]

How easy is it to focus? Do you use the same method as with a scope; Bahtinov masks?

[JamesF]

I usually do it by eye using live view in APT, but I'm told APT will actually do the focusing for you (unless the lens is manual).

James

[Catweazel]

I usually do it by eye using live view in APT, but I'm told APT will actually do the focusing for you (unless the lens is manual).

James

Thanks James, I have the 50mm f1.8 Canon lens, and it does have auto focus. I never knew that about APT, but will certainly give it a try; I wish it could auto focus a scope

[jammo]

I use a Sigma 10-20mm lens, one of there EX range, stopped down to f/5.6 its pretty good, there is a bit of distortion at the 10mm end but you can get 30 second exposures with out noticeable elongation of the stars, maybe more is the photo is un-cropped

[melsky]

I find the Sigma 15-30mm excellent even at full aperture.

Mel

[allcart]

I usually do it by eye using live view in APT, but I'm told APT will actually do the focusing for you (unless the lens is manual).

James

Strange though it may be James, but I have been using APT to focus my canon lenses while they have been set to manual focus. It seems to work for me.

It means I don't have to go back out and touch the lens after focusing.

[JamesF]

Strange though it may be James, but I have been using APT to focus my canon lenses while they have been set to manual focus. It seems to work for me.

I had in mind completely manual lenses, but I had no idea it worked for auto focus lenses in manual mode. That's handy to know.

James

[allcart]

Ah, I haven't got any manual lenses in my collection, only autofocus. I also tried eos utility to focus with the laptop but you do have to have the lens set to autofocus for that to work. Or take the laptop out to the scope and adjust visually.