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Moderate fast and cheap tele lens for astro photography?
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PostPosted: Wed Aug 15, 2012 1:12 pm    Post subject: Moderate fast and cheap tele lens for astro photography? Reply with quote

Hello!
I'm looking for a fast tele lens for astro-photography with a focal length between 100-200mm.
It has to be sharp wide open and needs to have at least F2.8
Price limit should be around 50€, maybe a lot more if it's a really great lens.

I thought about Porst 135/2.8 - which seems to be promising and is generally very cheap.
Do you have any other recommendations?


PostPosted: Wed Aug 15, 2012 1:23 pm    Post subject: Reply with quote

Well, I don't have any recommendation for astrophotography, never have done that. But if you are looking for a good 135/f2.8 under 50 Euros, I have 4/4 Minolta MD 135/f2.8 exactly for 50 Euros. I would be extremely surprised if it's not better than Porst.

Last edited by fermy on Wed Aug 15, 2012 1:24 pm; edited 1 time in total


PostPosted: Wed Aug 15, 2012 1:23 pm    Post subject: Reply with quote

An apo version should be very useful to you. And pay a lot of bucks can be right. By the way, Apo lieca R 180/3,4.


PostPosted: Wed Aug 15, 2012 8:24 pm    Post subject: Reply with quote

Cheap and astrophotography just doesn't fit together. Cheap lenses at f2.8 are commonly just plain awful. Astrophotography is the ultimate lens test for sharpness at infinity focus.
Very rarely a lens will give very good results at f2.8...Even famous lenses like Canon 300mm and 400mm f2.8L fail wide open for astrophotography on a full frame....Based on tests I read one of the best should be Nikkor ED 180mm f2.8 (should be sharp on a full frame with acceptable chromatic abberation - on a test it outperformed Leica APOs!).
If you are not very picky about chromatic abberation I know a cheap and useful lens in this range could be pentacon 200mm f4. Carl Zeiss Sonnar 135mm f3.5 is a very good one, on APS-C sharp wide open from edge to edge, with quite controlled chromatic abberation.

But still, if you are a beginner, you can have a lot of fun with a cheap lens Smile


PostPosted: Wed Aug 15, 2012 9:19 pm    Post subject: Reply with quote

looks to me a bit short focal length. Carl Zeiss Sonnar zebra 135mm f3.5 can fit into budget and beat most 135mm cheap lens.


PostPosted: Wed Aug 15, 2012 9:30 pm    Post subject: Reply with quote

Thanks!
The 135/3.5 Sonnar sound's good, even if slow. Does anyone know how much better it is compared to the Minolta MD 135/2.8?


PostPosted: Wed Aug 15, 2012 10:57 pm    Post subject: Reply with quote

ForenSeil wrote:
Thanks!
The 135/3.5 Sonnar sound's good, even if slow. Does anyone know how much better it is compared to the Minolta MD 135/2.8?


IMHO they have similar rendering. Perhaps the CZJ gives more saturated colors, but in sharpness both are OK. I prefer the 4/4 MD Rokkor. But it's only a personal preference, not objective and greats diferences.

Rino.


PostPosted: Thu Aug 16, 2012 12:18 am    Post subject: Reply with quote

I've been looking for good manual focus astroimaging lenses for years, especially in the 85-200mm range. The best I've found so far for each focal length are:

85mm -- Contax (Carl Zeiss) 85mm f/2.8 (too short for you, but perhaps the best lens among all these) --
300% crop at f/2.8 : http://www.flickr.com/photos/s58y/6252516710/sizes/o/in/photostream/

105mm -- Nikon 105mm f/2.5 AIS --
300% crop at f/2.8 : http://www.flickr.com/photos/s58y/6252514376/sizes/o/in/photostream/

135mm -- Contax (Carl Zeiss) 135mm f/2.8 --
300% crop at f/2.8 : http://www.flickr.com/photos/s58y/6252515128/sizes/o/in/photostream/

180mm -- Leica APO-Telyt-R 180mm f/3.4 (too slow for you) --
Old test at 100% full frame:http://www.flickr.com/photos/s58y/4792309546/sizes/o/in/photostream/

180mm -- Nikkor 180mm f/2.5 AIS (ED) (not as good as the Leica, but does f/2.8 ) -
300% crop at f/2.8 :http://www.flickr.com/photos/s58y/6252515920/sizes/o/in/photostream/


Last edited by s58y on Thu Aug 16, 2012 12:42 am; edited 1 time in total


PostPosted: Thu Aug 16, 2012 12:37 am    Post subject: Reply with quote

For 50 euros, It's the Canon 135/2.8 FDn.

There's better if you wanna triple or quadruple your budget tho. Smile But not by much, the FDn 135/2.8 is one crisp customer!


PostPosted: Thu Aug 16, 2012 12:56 am    Post subject: Reply with quote

sammo wrote:
....Based on tests I read one of the best should be Nikkor ED 180mm f2.8 (should be sharp on a full frame with acceptable chromatic abberation - on a test it outperformed Leica APOs!).
...


The Nikkor 180/2.8 AIS ED is decent, but when I tested it at f/3.4 against the 180mm/3.4 Leica Apo-Telyt-R, I thought hte Leica was better. The Nikkor I tested had better star shapes out at the corners, but had "horrible" chromatic aberration (red focus was out). The Leica I tested was great for chromatic aberration, but had blueish flare around bright stars, especially away from the center. The Nikkor also had loose focus that would not stay put when pointed straight up -- I had to add friction using flexible rough plastic strips and rubber bands.

Note: If you are doing narrowband H-alpha imaging, chromatic aberration is not always bad, as long as the deep red can be brought into sharp focus by adjusting the focus ring. This is sometimes easier said than done, with a DSLR.

I don't think you can pick up either of these lenses for 50 Euros, though. IIRC , the Nikkor was about $300 and the Leica was about $600, quite a while ago. These two may be more expensive now, especially the Leica.


PostPosted: Thu Aug 16, 2012 7:16 pm    Post subject: Reply with quote

s58y, thans for some great input.

s58y wrote:
The Leica I tested was great for chromatic aberration, but had blueish flare around bright stars, especially away from the center.


That was exactly the reason why the nikkor was considered better that 10x expensiver leica. As I remember it was a lot worse at 2.8 that on your photos with Telyt.


PostPosted: Thu Aug 16, 2012 7:31 pm    Post subject: Reply with quote

I'd be happy w/ a 180mm/2.8 nikkor ED AIS if I can get my hands on one but the prices have gone up again this yr. It would pair up nice w/ my canon or even my mono CCD.

Here's an image I processed w/ Erik Larsen's data last yr....

Erik Larsen NGC 7000 hubble pallet by jsigone, on Flickr


Erik Larsen NGC 7000: green from RGB, OIII as blue, Ha as red by jsigone, on Flickr

Here's some more of his work he's done w/ the 180 wide open on a Canon 500D

M8/M20 HaRGB by Erik N Larsen, on Flickr


Sadr-Deneb-NA False RGB by Erik N Larsen, on Flickr


PostPosted: Thu Aug 16, 2012 11:47 pm    Post subject: Reply with quote

Wooooooow, that's more than you should ever expect from me Smile
21x10min exposure is I think much more than what I wan't to try with my setup. There I would need some better mechanics and maybe a motor etc.

I have an offer for Takumar 200/4 for 49€
I heard it's sharp wide open and has very good CA control. Can somebody confirm that?


PostPosted: Fri Aug 17, 2012 2:53 am    Post subject: Reply with quote

ForenSeil wrote:
Wooooooow, that's more than you should ever expect from me Smile
21x10min exposure is I think much more than what I wan't to try with my setup. There I would need some better mechanics and maybe a motor etc.

I have an offer for Takumar 200/4 for 49€
I heard it's sharp wide open and has very good CA control. Can somebody confirm that?


Over at the Cloudy Nights forum (also called "Cloudy Nights Telescope Reviews"), there's a guy that uses Takumar Telephotos for DSLR astroimaging. You might join and ask this question over there.

I've tested a few Takumars using artificial stars, and the 135/2.5 (2nd type) under real stars, but none of them were very good for astro. I don't know about the 200/4, though.

For 10 minute exposures, your best bet is probably a tracking mount that supports autoguiding. With autoguiding, you can be a little sloppier on polar alignment, and get away with it, without trailing.

For most camera lenses (including the 200mm), an inexpensive mount (less than a few thousand dollars) will do.


PostPosted: Fri Aug 17, 2012 5:22 am    Post subject: Reply with quote

IMO anything over 50mm on a crop sensor will need a tracking mount. Longer you go on the focal length the more demanding the tracking has to be.

I have a super tak 200/4...not a good AP lens. Wide open it has bloated stars, corner looked pretty bad. Even stopped down to 5.6 the corners get better and no more bloating. F6.2 would be better but at point its pretty darn slow to gather data and I didn't get much color even w/ 5-6min subs. Daytime pics w/ it are pretty awesome though. Some guys on cloudynights are using the faster taks 105/2.5 lens but they are using them under narrowband filters so the stars won't bloat at all. Look around on Flickr for some images as well.

Narrowband imaging will require longer subs like 10min range to gather enough data to soak the sensor. You'll be battling noise and camera heat. I used a lunch box cooler to get cleaner 10min subs at iso1600 w/ my canon.

Camera cooler_01 by jsigone, on Flickr


Camera cooler_03 by jsigone, on Flickr

first image results from 35-40*F cooler raw image, chip temps went from low 90's 10min subs to mid 50's under same hot summer night conditions. About 3 hours worth pf data, 731mm F4.8 mak-newt lens and modded 1000D w/ LP and Ha filters, 5min color subs and 10min Ha subs both at iso1600. Shot from my backyard in San Diego's light pollution.

HaRGB M8 Lagoon Nebula 185min Final by jsigone, on Flickr


PostPosted: Fri Aug 17, 2012 8:28 am    Post subject: Reply with quote

at anything approaching 100mm you are going to need a driven equatorial mount of some description, otherwise lens quality will be irrelevant.....


PostPosted: Fri Aug 17, 2012 12:45 pm    Post subject: Reply with quote

martyn_bannister wrote:
at anything approaching 100mm you are going to need a driven equatorial mount of some description, otherwise lens quality will be irrelevant.....

I have acces to a tripod with such a thing but without any motor or fine adjustment screws (30-60s exposures are doable with that by hand, but 21x10min tracking by hand would hurt a lot in the arms and the brain Wink)
I did a very first deep sky try some nights ago, and found my Minolta Macro Rokkor 100/4 to be a bit limiting for my technique http://forum.mflenses.com/viewtopic,p,1253180.html#1253180 (next I would do it much better anyway)
And you can make also make great pics with short exposures by stacking.


PostPosted: Fri Aug 17, 2012 4:02 pm    Post subject: Reply with quote

there are some really nice stuff that just came out this past yr for AP lens users w/o having to drop big coin to get started into the hobby. Losmandy has a version out for about $6-800 then iOptron came out w/ this lil gem at only $400

http://www.optcorp.com/product.aspx?pid=278-17967