Hi guys, I've had my Canon 400D for a while now, and have overall been very pleased with the results
However, when using the 400D for astronomy purposes, the trouble has always come with focusing. My question is what is the most suitable lens to use when photographing the sky with a 400D? I bought the camera with the twin lens kit (standard 18-55mm lens + 75-300mm lens) but these two so far seem unsatisfactory for photographing the sky. Are there any lenses that are specifically made for astrophotography?
Regards,
Andrew
edit: Feel free to move this over to Cameras and Imaging equipment discussion
Ahhh yesss......the search for the perfect astro lens
You might want to have a bit of a read of this thread Andrew "Which widefield lens on a budget". Lots of useful info and experience offered in that thread.
Personally, if I wasn't already married I think I'd marry my 135mm lens
Andrew I agree with Paul, and I love mine as well, the 135mm F2.0L Canon Lens that is, it is a killer of a unit, and you will not be disappointed, however it is not real cheap, but you will not want for another wide field lens again.
Hi Andrew, firstly a couple of questions.
What sort of FOV are you looking for, how much sky do you want to image, wide field or deeper DSO.
Also what sort of budget are you looking at ?
Generally prime lenses perform better but you're limited to that FOV and they usually cost more.
Zooms generally suffer from a bit more chromatic aberration but give you the flexibility of variable FOV.
I love the Canon 10-22mm EF-S for wide fields.
The Canon 135mm f/2 and 200mm f/2.8 are very sharp/excellent lenses.
I'm definitely looking at wide-field. As for budget.....less than $1500 is preferable.. The main incentive is to take a step up from the standard lens kit that came with the camera, as it doesn't seem appropriate for astrophotography.
I'm definitely looking at wide-field. As for budget.....less than $1500 is preferable.. The main incentive is to take a step up from the standard lens kit that came with the camera, as it doesn't seem appropriate for astrophotography.
generally speaking kit lenses are less than desireable.
on a budget i suggest the 85mm f1.8, 100mm f2 or 200mm f2.8L
if you have extra to burn then i suggest the 135mm f2L (I paid bout $1700 for it, new).
in my limited experience the Canon L lens is the best and the wider the aperture the better.
Any difference with IQ using the zoom lenses. Say a 70-200 f2.8 IS at say 200mm f2.8 and with IS on instead of the 200mm at f 2.8. zoom creep is controlled using the rubber band on the lense body.
BTW is AF sufficiently accurate otherwise how to focus.
So sorry if too many questions. A newbie here experience limited to unguided short exposures. Learning how to stack pictures and looking for which GEM to buy.
Just last night I was testing couple of lenses I have for some time with my new 400D...
So far the best behaved is Russian-made Tair 11A, 135mm, F2.8, I used a lot with my Praktica... (I just found one on ebay for US$45 + postage). Some tests claim over over 74 lps/mm ( line pairs/mm), wide open (http://forum.manualfocus.org/viewtopic.php?pid=64397).
Even with iris fully opened, there is very little SA distortion at the frame edges. At f4 the images are perfect throughout the image area (this lens was designed for full frame 35mm format, so there are less problems with smaller CCD that 400D uses).
It is rather heavy though (it is made of brass... ideal material for lenses, but forgotten recently because of this cheap but light and adequate (for most purposes) plastic materials..). So I am thinking of mounting the lens on the equatorial platform and then attaching the camera to it, instead of other way around, as it is at the moment.
As far as focusing is concerned, this is another story. Since it is not a Canon lens, and since Canon disabled the focus confirmation for non-canon lenses, I have built right angle viewer with 10x magnification (see the thread in ATM section, http://www.iceinspace.com.au/forum/s...ad.php?t=23756 ). It is a great help (still there is some ambiguity due to the fresnel lens used as a matte glass in the camera), but all really depends on how precisely the camera diagonal mirror is adjusted. So there are still some tests to be done to find the best focus by taking pictures of a bright star and to record the position of the lens focuser ring. Once this is done, I will fix the position of infinity focus on the lens and never I will have the focus problem again. Of course, that means this lens will be used with that particular camera only.
This was done last night with Tair-11A (full apperture), through Melbourne light pollution....... This was all I could do with it (M6 & M7).
I hope the results will be much better next weekend when I plan to go to darker area (if weather permits, of course)