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From: Paul Furman on 23 Apr 2010 12:17
infiniteMPG wrote:
> Was looking for a inexpensive fair long length lens to use with my
> Sony Alpha A-100 DSLR camera. Ran across this and was thinking it
> might not be a bad deal for under $300. Anyone have any experience
> using a Rokinon 650-2600mm Telephoto Zoom Lens with a DSLR camera???
>
> Oh yeah, I do know it's a 650-1300 with a 2X adapter.

I've got a Century 500mm f/4.5 Teleathenar if you're interested. It's
non-telephoto meaning not a compact design so is huge and heavy with
slow stiff focus. It was something like a $2,500 lens new in the
70's/80's but has a bit of gunk on the front. T-mount so can be adapted
to any camera. You'll need a very sturdy tripod. Front element is 110mm,
more than 4 inches. $200 I guess... I got it with a huge tripod that I
want to keep. My 300mm f/2.8 is a little better with teleconverters
(although a tad slower) but the 300 cost more. The out of focus
rendering is much nicer than a mirror lens, check out the 'donut bokeh'
on those first.

--
Paul Furman
www.edgehill.net
www.baynatives.com

all google groups messages filtered due to spam
From: infiniteMPG on 27 Apr 2010 17:20
> I've got a Century 500mm f/4.5 Teleathenar if you're interested. It's
> non-telephoto meaning not a compact design so is huge and heavy with
> slow stiff focus. It was something like a $2,500 lens new in the
> 70's/80's but has a bit of gunk on the front. T-mount so can be adapted
> to any camera. You'll need a very sturdy tripod. Front element is 110mm,
> more than 4 inches. $200 I guess... I got it with a huge tripod that I
> want to keep. My 300mm f/2.8 is a little better with teleconverters
> (although a tad slower) but the 300 cost more. The out of focus
> rendering is much nicer than a mirror lens, check out the 'donut bokeh'
> on those first.

Hey Paul,

Thanks for the offer but that's a beast of a lens. Saw some pictures
of it on the web and I think I would rather try to clean up issues
with the mirror lens before I try to haul this out to an eagle nest
site. I have a nice Tamron 18-250 Dii that does good but I really
want to jump up to get close on some stuff. That's why I was looking
at 800-1600. Tried to use my double with the Tamron but for some
reason I can't even manual focus with that setup.

Thanks again.
From: Ofnuts on 27 Apr 2010 17:58
On 27/04/2010 23:20, infiniteMPG wrote:

>
> Thanks for the offer but that's a beast of a lens. Saw some pictures
> of it on the web and I think I would rather try to clean up issues
> with the mirror lens before I try to haul this out to an eagle nest
> site. I have a nice Tamron 18-250 Dii that does good but I really
> want to jump up to get close on some stuff. That's why I was looking
> at 800-1600. Tried to use my double with the Tamron but for some
> reason I can't even manual focus with that setup.

A teleconverter on a zoom with that kind of range won't give good
results. A TC requires a prime lens, or a zoom designed to work with it.
And it's usually a 1.4x TC, becaise the 2x TC requires an even higher
quality lens. And keep the following in mind:

- 400mm is not that easy to keep steady, 800mm is quite impossible.

- unless you have a very effective focusing screen, the manual focus
accuracy won't be enough for the shallow depth of field you get wit
these focal lengths (in other words, you will get a lot of focus misses).

- AFAIK, on the sensor-stabilized cameras such as the Sony, the subject
moves a lot in the viewfinder, so the manual focusing is going to be
difficult, even with a tripod, unless the latter weighs three times the
camera and lens combined.

- it's better to have a sharp picture that requires cropping than a
full-size fuzzy/blurry eagle.

I'd start with a 400-ish zoom (for instance the Sigma 120-400), or if
the AF is still working a 500mm with your camera, the Sigma 150-500, and
once I get suffiently proficient with the setup, add a 1.4x TC to it.
--
Bertrand, with a Canon 450D, a Sigma 120-400, and an underused 1.4x TC.
From: Remmy Martin on 27 Apr 2010 20:27
On Tue, 27 Apr 2010 23:58:55 +0200, Ofnuts <o.f.n.u.t.s(a)la.poste.net>
wrote:

>On 27/04/2010 23:20, infiniteMPG wrote:
>
>>
>> Thanks for the offer but that's a beast of a lens. Saw some pictures
>> of it on the web and I think I would rather try to clean up issues
>> with the mirror lens before I try to haul this out to an eagle nest
>> site. I have a nice Tamron 18-250 Dii that does good but I really
>> want to jump up to get close on some stuff. That's why I was looking
>> at 800-1600. Tried to use my double with the Tamron but for some
>> reason I can't even manual focus with that setup.
>
>A teleconverter on a zoom with that kind of range won't give good
>results. A TC requires a prime lens, or a zoom designed to work with it.
>And it's usually a 1.4x TC, becaise the 2x TC requires an even higher
>quality lens. And keep the following in mind:
>
>- 400mm is not that easy to keep steady, 800mm is quite impossible.
>

For pretend-photographer trolls like you perhaps. I recall seeing a sharp
hand-held shot done with a 2100mm lens.

>- unless you have a very effective focusing screen, the manual focus
>accuracy won't be enough for the shallow depth of field you get wit
>these focal lengths (in other words, you will get a lot of focus misses).
>

True. Any DSLR is abysmal when it comes to using long focal-lengths,
especially for wildlife photography where their direction of travel or
motions might be hard to predict. The DOF with DSLRs is so shallow that you
can rarely get all of your main subject in focus no matter what method you
use.

>- AFAIK, on the sensor-stabilized cameras such as the Sony, the subject
>moves a lot in the viewfinder, so the manual focusing is going to be
>difficult, even with a tripod, unless the latter weighs three times the
>camera and lens combined.

If only you would type about things with which you have any firsthand
knowledge whatsoever. But then this would only limit you to information
about the keys on your keyboard and that chair, sofa, or bed that you live
in and on.

>
>- it's better to have a sharp picture that requires cropping than a
>full-size fuzzy/blurry eagle.
>
>I'd start with a 400-ish zoom (for instance the Sigma 120-400), or if
>the AF is still working a 500mm with your camera, the Sigma 150-500, and
>once I get suffiently proficient with the setup, add a 1.4x TC to it.

But then what would a pretend-photographer troll like you know about these
things when it comes to reality. Keep on dreaming.

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