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

["Wil Milan" <wmilan@airdigital.com>]

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

Jim Barclay wrote:

>Wil,
>
>Hi mate, in regards to your 300/2.8 lens, does this lens give a flat field
>at 2.8,  or do you have to stop down a bit to get a sharper image at the
>edges. There may be a time I will need to print the entire neg, hence the
>question.

I don't have the 300 f/2.8, but rather the 400mm f/4. The 400mm is very flat
all the way to the corners. Under high magnification (50x under a
microscope) there is some chromatic aberration visible in the extreme
corners, but it is not visible in any print I've had made.

>I am looking into the options of this size lens since I missed out on the
>Pentax 800/4 sale.

I think I mentioned this at that time, but I'll mention it again: I've been
very happy with my Pentax 400mm f/4 for my 6x7.

>And if you ever think of coming Down Under one of these days for some Sth
>sky shooting, let me know, as I have a dark rural site at my Stuart Range
>Obserevatory where naked eye is at least 6.5. It is here, I will be setting
>up a GT-1100 mount within the next few months, along with a C11 and an ISDN
>line of 30 channels. This gives a bandwidth of 2 megs.

Jim, I may just take you up on that in a couple of years. I'm working my way
through all the shooting for a color sky atlas, and though the first volume
will only cover the northern hemisphere, afterwards I'd like to continue
with the southern hemisphere. Thanks for the invitation.

Wil M.



>
>Best regards,
>
>Jim
>-----Original Message-----
>From: Wil Milan <wmilan@airdigital.com>
>To: astro-photo@nightsky.com <astro-photo@nightsky.com>
>Date: Tuesday, 22 September 1998 17:01
>Subject: Re: [APML]: 300mm F2.8 lenses..which brand?
>
>
>>The Astro-Photography Mailing List
>>------------------------------------
>>
>>Philip Perkins wrote:
>>
>><< 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. >>
>>
>>Philip:
>>
>>My 400mm f/4 Tamron also exhibited some slop. It turned out to be loose
>>screws near where the tripod collar mates to the lens. I tigtened them and
>>have had no problems since. It might be worth checking if that's all it is
>>on yours.
>>
>>
>>Wil Milan
>>
>
>
>