Re: [APML]: 300mm F2.8 lenses..which brand?

["Jim Barclay" <cosmos@fan.net.au>]

The Astro-Photography Mailing List
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Phil,

Thanks mate for your input re above.

I was not aware that Nikon >did< vignetting for that that lens..mmmmmm
...this make s me wonder whether the Sigma may be he way to go...for a lens
to vignet means it is not fully illuminating the edges and I would hazard at
a guess, that it also suffers from some SA  and that to me for a huge layout
in dough, is risky.

I will now re-consider my options re this lens. ITMT I will look around for
some other lens system maybe the Sigma range as mentioned
earlier...mmmmm.....let me see what I can find over here.....

BTW if u ever decide to come on Down for  holiday, u know u have a
contact/mate that can show u around and let u obs/shoot the sky from my dark
site, here at Ellesmere, 30 kms south of the rural township of Kigaroy, 250
kms west of Brisbane in Qld.

Whats it like over there...do u find looking for a dark site harder now?

Over here....it is so easy to get a dark site..and we have millions of acres
not being used.!!..

see u soon mate,

Jim
-----Original Message-----
From: Philip Perkins <philip@astrocruise.com>
To: astro-photo@nightsky.com <astro-photo@nightsky.com>
Date: Saturday, September 19, 1998 12:28 PM
Subject: Re: [APML]: 300mm F2.8 lenses..which brand?


The Astro-Photography Mailing List
------------------------------------

> To those who responded to my last posting re the Pentax 800/4 lens,
thankyou very much for your help and input. Unfortunately, the lens was sold
before I had a chance to check out.So to this, I have >
> I have seen many beautiful images taken with these big 'guns' but which
has the flattest field at max.aperture?

Jim

I have used both Tamron and Nikon 300mm f/2.8 lenses. The Nikon does have
the edge on resolution, especially at the edges, where the Tamron has some
colour fringing.  However I was really surprised by the amount of vignetting
from the Nikon lens, even when stopped down to f/4. I think I would have to
stop it to f/5.6 to reduce vignetting to an acceptable level. I took plenty

of photos with the Tamron at f/4 and saw no sign of vignetting (I did not
try it seriously at f/2.8).  I was not prepared for this vignetting and I do
not recall anyone bringing it up as an issue before I bought mine.

I do not think it is an issue with this particular lens because my Nikon
400mm f/3.5 vignets in just the same way.

This problem has had me rethinking my plan of investing wholeheartedly
in Nikon lenses. In fact I may sell the 300mm f/2.8 because it gets used so
little and it was a very expensive investment. It cost me three times more
than the Tamron.

The big problem with the Tamron is the slop in the Adaptall mounting
system. This is a potential killer and means that the camera body really
needs mounting too.  In portrait format, this can be a big problem.

So whatever lens replaces the Nikon 300mm, it will have to have a native
Nikon fit.  I am even thinking of trying the Sigma range, which is highly
regarded.  They do a 70-200mm f/2.8 zoom which is highly regarded by
professional photographers over here.  I know that zooms are not considered
optimum but this one is supposed to be exceptional.  The zoom range would
give valuable flexibility and in my experience the field coverage of 200mm
is proving to be more useful than 300mm.  The other potential 300mm targets
are actually covered better with my 400mm.  It seems that I can cover the
range better by skipping 300mm and going with 200mm and 400mm.  There is
only one target I can think of that appears optimum for 300mm, and that is
the Antares - Rho Ophiuchi region, but I would cover that with 200mm.

Regards
--Philip

Philip Perkins  --  philip@astrocruise.com
51 27'N 1 36'W  --  Wiltshire, UK
43 54'N 5 32'E  --  Luberon, France
Astrocruise     --  http://www.astrocruise.com