It ends up as my spoting -scope: The auto focusing of my Sigma 50-500mm f4-f6.3 tele-zoom stopped working after 5 years moderated use. It costs $300-$400 to fix it. I decide not...

wingclui44 Loc: CT USA

The auto focusing of my Sigma 50-500mm f4-f6.3 tele-zoom stopped working after 5 years moderated use. It costs $300-$400 to fix it. I decide not spending more on a old lens. I am planning replacing it with the Nikon 80-400mm AF-s ED G lens. It's expensive but it's Nikon quality, I even pay attention to the new Tamron 150-600mm, but I doubt about it's durability plus the sharpness and the AF speed at the long end.
So I have some decision to be made.

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joer Loc: Colorado/Illinois

wingclui44 wrote:

The auto focusing of my Sigma 50-500mm f4-f6.3 tele-zoom stopped working after 5 years moderated use. It costs $300-$400 to fix it. I decide not spending more on a old lens. I am planning replacing it with the Nikon 80-400mm AF-s ED G lens. It's expensive but it's Nikon quality, I even pay attention to the new Tamron 150-600mm, but I doubt about it's durability plus the sharpness and the AF speed at the long end.
So I have some decision to be made.

Great way to repurpose a malfunctioning lens.

Peterff Loc: O'er The Hills and Far Away, in Themyscira.

wingclui44 wrote:

The auto focusing of my Sigma 50-500mm f4-f6.3 tele-zoom stopped working after 5 years moderated use. It costs $300-$400 to fix it. I decide not spending more on a old lens. I am planning replacing it with the Nikon 80-400mm AF-s ED G lens. It's expensive but it's Nikon quality, I even pay attention to the new Tamron 150-600mm, but I doubt about it's durability plus the sharpness and the AF speed at the long end.
So I have some decision to be made.

Recycling is a wonderful thing. I have an old Canon FDn 100 -300 with an eyepiece that gets used in similar ways...

Indi Loc: L. I., NY, Palm Beach Cty when it's cold.

wingclui44 wrote:

The auto focusing of my Sigma 50-500mm f4-f6.3 tele-zoom stopped working after 5 years moderated use. It costs $300-$400 to fix it. I decide not spending more on a old lens. I am planning replacing it with the Nikon 80-400mm AF-s ED G lens. It's expensive but it's Nikon quality, I even pay attention to the new Tamron 150-600mm, but I doubt about it's durability plus the sharpness and the AF speed at the long end.
So I have some decision to be made.

Would it be possible to outline the parts and steps you used to do that?
I lost my 8" telescope in Sandy, probably just needs a new mirror, and I'd like to use my 150-500 like that...if it's not permanent.
BTW what might this setup be equivalent to compared to a telescope?
Thanks.

wingclui44 Loc: CT USA

Indi wrote:

Would it be possible to outline the parts and steps you used to do that?
I lost my 8" telescope in Sandy, probably just needs a new mirror, and I'd like to use my 150-500 like that...if it's not permanent.
BTW what might this setup be equivalent to compared to a telescope?
Thanks.

As seeing in the picture, you may find several parts added to the lens mount. Those are 1-1/4"eye-piece; 45 degree diagonal; 2X borrow lens (used to achieve the focusing on a Nikon mount lens, if you have another mount type of lens, you may not need it), it will double the focal length to max. 1000mm, and also reduces the f-stop to f12.6 from f6.3 originally. That why it's only good for using in bright day light out door observing! Using an eye-piece not less than 25mm, so you can have a bright image of 40X. not bad.
I used a Nikon rear lens cap with a 1-1/4"hole cut to fit the diagonal with three set-srews to secure it.
By comparing to a real APO refracting telescope which will have flatter field across the view and less CA (chromatic Aberration) and faster F stop.

RWR Loc: La Mesa, CA

wingclui44 wrote:

As seeing in the picture, you may find several par... (show quote)

Or you could simply use a Nikon Lens Scope Converter, which would give you a 5~50X scope, albeit not 45°.

Indi Loc: L. I., NY, Palm Beach Cty when it's cold.

wingclui44 wrote:

As seeing in the picture, you may find several par... (show quote)

Well, I have some of those items, but how sturdy is drilling and mounting to the rear lens cap?

Maybe I'll save my Amazon Rewards for the Nikon Lens Scope Converter. :-)

wingclui44 Loc: CT USA

Indi wrote:

Well, I have some of those items, but how sturdy is drilling and mounting to the rear lens cap?

Maybe I'll save my Amazon Rewards for the Nikon Lens Scope Converter. :-)

I drilled and tapped 8/32" holes for the 8/32" machine screws. I even have same set screws for securing the rear cap to the lens mount too, because I can not lock the cap to the lens mount like a real lens with the lock button on the camera!

speters Loc: Grangeville/Idaho

wingclui44 wrote:

The auto focusing of my Sigma 50-500mm f4-f6.3 tele-zoom stopped working after 5 years moderated use. It costs $300-$400 to fix it. I decide not spending more on a old lens. I am planning replacing it with the Nikon 80-400mm AF-s ED G lens. It's expensive but it's Nikon quality, I even pay attention to the new Tamron 150-600mm, but I doubt about it's durability plus the sharpness and the AF speed at the long end.
So I have some decision to be made.

Good decision to go for the Nikon (the Sigma makes for a good paper weight).

Indi Loc: L. I., NY, Palm Beach Cty when it's cold.

wingclui44 wrote:

I drilled and tapped 8/32" holes for the 8/32" machine screws. I even have same set screws for securing the rear cap to the lens mount too, because I can not lock the cap to the lens mount like a real lens with the lock button on the camera!

Another favor...can you provide a picture where the eyepiece is shown inserted and mounted into the rear lens cap? If you get a chance.
This is not a permanent attachment whereby I wouldn't be able to use the lens, is it?

wingclui44 Loc: CT USA

Indi wrote:

Another favor...can you provide a picture where the eyepiece is shown inserted and mounted into the rear lens cap? If you get a chance.
This is not a permanent attachment whereby I wouldn't be able to use the lens, is it?

No, this is not permanent attachment! As shown here in the picture, it holds the the borrow lens with three set-screws only, and can be removed easily.
The mount is made with two parts, one was the lens rear cap, another one was a inner tube inserted in the cut hole of the cap. The tube then was set with three more set screws to hold the borrow lens and the diagonal.

(Download)

wingclui44 Loc: CT USA

speters wrote:

Good decision to go for the Nikon (the Sigma makes for a good paper weight).

Yes, I won't buy any Sigma lens anymore, I will stay with Nikon!
:)

Uuglypher Loc: South Dakota (East River)

wingclui44 wrote:

The auto focusing of my Sigma 50-500mm f4-f6.3 tele-zoom stopped working after 5 years moderated use. It costs $300-$400 to fix it. I decide not spending more on a old lens. I am planning replacing it with the Nikon 80-400mm AF-s ED G lens. It's expensive but it's Nikon quality, I even pay attention to the new Tamron 150-600mm, but I doubt about it's durability plus the sharpness and the AF speed at the long end.
So I have some decision to be made.

Look again at the Tamron...and don't skim over that Tamron 6-year warranty!
Thrie service is unbeatable.

wingclui44 Loc: CT USA

Uuglypher wrote:

Look again at the Tamron...and don't skim over that Tamron 6-year warranty!
Thrie service is unbeatable.

I will wait and see a little longer to know more user report about the Tamron's new 150-600mm. But I don't really like the short end at 150mm, I prefer 80mm like the Nikon. I shoot with both FX and DX body, I did like the range of the Sigma, 50-500mm, but I won't buy it again!

Indi Loc: L. I., NY, Palm Beach Cty when it's cold.

wingclui44 wrote:

No, this is not permanent attachment! As shown here in the picture, it holds the the borrow lens with three set-screws only, and can be removed easily.
The mount is made with two parts, one was the lens rear cap, another one was a inner tube inserted in the cut hole of the cap. The tube then was set with three more set screws to hold the borrow lens and the diagonal.

OK, final question (hopefully.) Where'd you get the inner tube with the set screws?

Did you mean "Barlow Lens?" (sorry, that's 2 final questions.

BTW, thanks for taking the time to do this. It cleared up a lot.