Recommendations for fast f/ratio lenses for 300D

[[1ponders]]

I'm ready to bite the bullet and purchase my first serious lense for astrophotography. I currently have three zoom lenses:-

the 28-90mm f/1:4-5.6 that came with the 300D

an Ultrasonic 80-200mm f1:4.5-5.6

and a 35-80mm Starlight f/1:4-5.6 that came with my EOS500 film SLR.

I also have a Kenko C-AF1 2X Teleplus converter.

First question. I know what f/4.5 means but what does f/1:4.5 mean?

Second question. I'm looking for a lense somewhere in the range of 50 to 80 mm for wide field shots with an f/ratio of around f/1.8-3. Does anyone know of any that are good for the job i want to put them to and not require me to get a second mortgage. (I want to save that for when I upgrade my telescopes :D )

Third question. Do you think that my desired range of lenses would be suitable. If not what would you recommend. Remember they need to be 300D compatible. For canon lenses that is the EF and L series. I'm not sure about other brands.


My bank manager awaits :)
thanks

[gbeal]

Hi Paul,
OK, two thoughts.
First. Try what you have, you may be surprised, but I doubt it.
At the expense of sounding snobbish, I have always believed that optics is money driven. Sure there will be a bargain out there, and if you are not tooooo fussy you can use lenses of lesser quality, but........
Astro imaging demands good gear, sorry. If I was gearing up in your case I would look only at the "L" series, and these are not cheap. Try to find a few older "Press" lenses, ones that newpaper pros have replaced, and as long as the glass is scratched they will give good results. My preferrence would be a good 85mm, and maybe a 200mm. This is partly the reason I was happy to stay with Nikon, as most any older Nikkor will give decent results with the D100.
Try one of your current zooms, and let us see whether you need to splurge.

[[1ponders]]

I'm going to keep my eye on ebay and check out some of the local pawn shops etc, Gary. I just need a good idea of a range of lenses to look at. From what I can find the Ultrasonic is a fairly good lense but a bit slow for me to get images like John Ds getting.

[gbeal]

Paul,
sorry just re-read what I said, and maybe I should have suggested "L" series PRIME lenses. I have always shunned zooms, old school sorry. OK, maybe the L series zooms, but at worst maybe a couple of battered (read Cheaper) primes, 85mm and 200mm. Thease are normally f2.8 or better, and sharper than a shower of $^%@.
JD is using a Sigma f2.8 zoom, and I too have used a Nikon 80 - -200 F2.8 zoom. Both were OK, but again I like primes.
The Ultrasonic part I believe is just the focussing system.

[acropolite]

Paul, this link might help you. If you want a fast 50mm Lens the standard canon 50mm f1.8 is very good for the price. I've seen lots of favourable comment on this lens and because it's fixed focal length it has less elements than a zoom and hence it's sharper and has less chromatic abberation. The 50mm is quite refined because it was the workhorse lense for 35mm SLR's for years and makes a great portrait lens as well on a digital. (Equivalent to a 70mm on a 35 mm camera). Bear in mind that the lower the f number the shallower the depth of field (focus) is.
For reviews and testing have a look at this link.
http://www.bobatkins.com/photography/digital/10d300dlenses.html and
http://www.bobatkins.com/photography/reviews/tamron_28_75c.html

[rowena]

my next lens will be a 50mm f1.8 its around 150$ aus.

otherwise if you wanted to do astro photos anything with a low f no. but the lower the f no. the more the $'s :(

the lower f no means the less exposure required, which is good for digital.

[[1ponders]]

Hopefully I'll get to see a few of these sort of lenses in NZ. then I'll be able to decide.

Beware SE Qlders. there could be more wet weather on its way

[Jonathan]

In my opinion price = quality when it comes to lenses. Most lenses that come with an SLR camera are pretty ordinary. I think it's worth spending a fair bit on lenses because they last a lifetime and they bring out the best in the camera. I'd stay away from zoom lenses unless you're prepared to spend big $'s. There are some good older Canon lenses that are reasonably cheap, but I don't know if they fit the new DSLR's. I've stuck with Nikon gear myself so I can't really help with any specific lenses to look out for.

[MiG]

If by older Canon lenses you mean FD mount then no. The DSLRs take EF mount.

[trufflehunter]

Some great advice here! Paul, to answer your first question: there is no difference between the terms f4.5 and f1:4.5... just two ways of saying the same thing!