Fast Macro lenses for Astrophotography???

[Robert_T]

Hi All, I've been looking at a few fast Macro lenses - e.g single focal length 150mm F2.8 that sort of thing. I'm wondering whether these "true" macros should be equally good for astro given their mid range focal length and fast aperture or is there something particular about them that makes them only good for macro?:shrug:

[[1ponders]]

You might want to try the few bottom posts of this thread Rob,

http://www.iceinspace.com.au/forum/showthread.php?t=21245&highlight=lens

where Terry is discussing his 100 f/2.8 macro

[RB]

Depends on how much you want to spend Rob.

You can get the CANON 180mm f/3.5L Macro but that's around $1600 :(
Very sharp but a bit slow in AF for terrestrial, still a top choice IMO.

Or there's the CANON 100mm f/2.8 Macro for around $600.
It's a great macro lens, very popular.
Also good for astro work.

Then there's the wider CANON 50mm f/2.5 Compact Macro Lens for around $300.
Again it's a nice macro, gives a nice fov for wide astro shots.

The newer CANON EF-S 60mm f/2.8 Macro Lens is one I have not had any experience with yet so can't comment but suspect it would fit the bill nicely.
Only thing is, if you ever upgrade to a FF camera like a 5D then you won't be able to use this lens on it.

[space oddity]

In my younger :P days,I did full testing of all my lenses at all apertures with tech pan film under a microscope with the Patterson test cards for lines per millimeter results. My Pentax 50mm f/4 macro hit the highest resolution of all my lenses (88 lpmm) which was only a bit above the Pentax 50 f/1.4 . The macro lens started out with high resolution (56 lpmm from memory) and climbed very quickly to its peak. The 50 f/1.4 started out soft and was near its peak stopped down 2 stops(f/2.8) peak at f/6.3. Since then, I have have a Pentax 50 f/2.8 macro and a 100 f/2.8 1:1 macro, neither of which are as sharp. Macro lenses are better corrected for close up, but are better in terms of flatness of field. My sharpest lens was probably the 100 f/4 manual bellows lens which has no focus mechanism! For piggyback photography, I reckon the slowness of the macro lens would drive you nuts, given that you would still have to stop down a bit for peak optics. Another thing to check is the number of elements - the more elements, the more the light dropoff and potential for internal reflection , all the more reason to avoid zooms for astro work if possible.

[AlexN]

Im a big fan of my 200mm F/2.8L for the canon, though haven't tested it for astro work.. also the 135mm F/2L and the 100mm F/2.8L

The 135 is a great trade off between aperture and FL and stoping down that bit further than the other two 2.8 lenses means shorter exposures for equal depth images :) Can't be bad!

[rsbfoto]

Hi,

Just thinking loud which means that the word Macro says it all.

I just looked on the focusing ring of my Canon 180mm f3.5 and saw that the focusing ring is quite open when I focus in the near range eg. the numbers do take up a lot whole of the scale in the near focusing range and less in the far focusing range.

What I want to say is that it will be difficult to focus a Macro lens in the infinity region but it is easy to focus in the near range ...

Think about that ;)

regards Rainer

[RB]

umm I think there's some confusion here.
The Canon 180mm is a true macro lens but it also is a 'normal' 180mm prime lens able to focus to infinity for telephoto shots.
It can be used for astro imaging when set to infinity (or approx infinity) and aperture adjusted to almost wide open.

It can also be set to macro mode (true macro mode) and will focus up close for beautiful 1:1 life size shots.

The reason, I suspect, Robert (OP), asked specifically about macro lenses for astro is that he wants to 'kill two birds with the one stone'.
He would like to use the same lens for macro imaging and astro imaging, cutting down the number of lenses he needs to buy.

Hence why I recommended the list of true macro lenses that are available from Canon.
Unfortunately I haven't had to opportunity to try any macro lenses from other manufactures so I couldn't comment on other brands.

But you certainly can use these macro lenses for astro when focused on infinity.

The only lens I know of that can't be used is the highly specialised Canon MP-E 65mm 1:5 macro lens.

:)

[Robert_T]

Andrew - you got it in one !!:)

[rsbfoto]

Hi Guys,

I guess you missunderstood me. I did not say it does not focus to infinity. What I wanted to say is that it is very difficult to focus on Infinity with a Macro lens. That is all.

If it is already difficult to focus a 500mm f4 Canon lens on Infinity now imagine focusing with a Macro lens ...

Well it does not cost much to buy a Macro 180mm and try it ;) but afterwards you have a lot of experience and that is worth it :D

[RB]

Most people who try to estimate focus to infinity by using the ∞ on any lens find that it's difficult for astro work to get spot on.
I wouldn't recommend it.

Robert's using a 40D and probably focuses using Live Focus.
I've been using livefocus on the 20Da for years now and never had a problem.
There's also utilities to achieve perfect focus using the various astro software that most people use in the field.

Focusing a macro lens using the above methods wouldn't be any different or harder than focusing any other lens.

[Robert_T]

[quote=RB;334629]
Robert's using a 40D and probably focuses using Live Focus.
I've been using livefocus on the 20Da for years now and never had a problem.
There's also utilities to achieve perfect focus using the various astro software that most people use in the field. quote]

Thanks Fella's, I think I get the picture. I'm actually using Images PLus camera control software's focussing routine to gradually tweak and refine focus. Sounds like the Macro lens is capable of focus here, it's more a comparison between a coarse and a micro focus in terms of sensitivity or feel to achieve precise focus at infinity.

cheers,

Rob

[Dennis]

Using Remote Live View on the 40D (on a computer screen), I had little problem in focusing a 400mm F5.6 with x2 EF II Converter (efl 800mm F11) on a slender crescent Moon and obtaining a sharp photo.

However, if I had to use (camera based) Live View on the 3” LCD on the back of the Canon 40D, I suspect it might have been a little more difficult, due to the size of LCD, the bent over viewing position, etc.

A motorised focuser on the 400mm F5.6 would have been sweet!

Cheers

Dennis

[ving]

my nikkor 55mm f3.5 micro is extremely sharp at infinity...

[Robert_T]

Hi Dennis, I've been meaning to try this, but didn't think live-view would pick up many stars to focus on? cheers, Rob

[Dennis]

Hi Rob

I’ve had no problems in picking up the 4 stars in the Trapezium (M42) with Remote Live View (http://www.iceinspace.com.au/forum/showthread.php?t=28022) using the Mewlon 180 at F12.

Cheers

Dennis