Are these any good ?

[Alpha_7]

They look dodgey to me, just wondering if these are any good ? Looks like its wacking a dodgey telescope on the front of your camera.

http://cgi.ebay.com.au/NEW-500mm-f-8-telephoto-lens-for-all-Nikon-SLR-cameras_W0QQitemZ7570051639QQcategoryZ3343QQrdZ1QQcmdZViewItem

[Steffen]

Not too sure, really. A 500/f8 is a mighty slow lens, hence not too versatile, but I wouldn't be surprised at all if it compared favourably with Nikon's mirror lens. I suppose the biggest potential fault is CA (a discipline in which the mirror lens should perform very well in theory). Apart from that, it should give *much* better contrast than the mirror and better bokeh of course.

I've had some good experience with Russian optical engineering. For example, my Intes Maksutov telescope beats the shiny midnight-blue Meade and Celestron mob hands down, by a big margin, at less than half the price.

I'm not sure whether this one is Russian or Chinese, but I guess it wouldn't hurt bidding a dollar or ten. If it's no good you can always use it as an offensive weapon If you're in the market for a really long lens you might as well add it to your watch list...

Cheers
Steffen.

[Steffen]

Errm, forgot to mention, this lens may not be too much fun on a D70, seeing that it is obviously no CPU lens. Unless you're planning on adding a D200 or D1/2 to your bag it's probably not worth it.

Cheers
Steffen.

[Steffen]

Just reading on what the ad says... The lens mounts via a T-mount adapter, so there will only be stop-down metering at best with any Nikon SLR. The optics would have to exceptional to justify the hassle. Maybe it's usable for astro-photography, though.

Cheers
Steffen.

[Sheetshooter]

Craig,

Even if I were to accept the previously stated limitations of this lens I would be wary of the fact that there is no description of the optical configuration in terms of how many elements and how many groups. This may be just a very simple two-element design with the glass cemented together in one group right at the front. Even though Leica also made long lenses like this in the old days, they seldom worked exceedingly well.

The speed and fabrication along with the possibility of misalignment through the adapter would indicate the value of giving this number a wide berth in my opinion.

Cheers,

[gstark]

Maybe it's usable for astro-photography, though.

F/8 on a D70?

Only if you're shooting the sun, I'm afraid.

Focussing will be a challenge under all circumstances ...

[Steffen]

Actually, f/8 is considered pretty fast in astronomy. Most people shoot with f/10 or slower telescopes. Mine is f/12. Of course, you don't expose for just 1/125s...

Not sure what the long time exposure capabilities of the D70 sensor are, though.

Cheers
Steffen.

[Alpha_7]

Thank you all for the feedback, I am currently watching a few Mirror lens and in my browsing I saw this lens as well, but I was pretty skeptical.... one of the great benefits of the forum is getting a few other opinions before jumping into an rash decisions.

[sirhc55]

Opteka - in a word ’opeless

[avkomp]

nikon made/make a 500/f8 mirror lens and a 1000/f11 mirror lens
I still have my 1000/f11 which I have put on a d70. you have to guess the exposure by sunny 16 rule of thumb and it does work.
I tried it on a d2 series body and you can use the metering with it.
Mighty magnification but very hard to wield hand held and even on a tripod you can see the image in the viewfinder jump with mirror slap.
Ok if you have mirror lockup.

not sure why I got it now, but it produces ok shots within limits
ie you use fast iso, you use a tripod etc.

the image in the viewfinder of my film slr was so dark that the standard focus screen produced a dark semicircle on one of the split image focus screen.
I use a type d focus screen which is just a flat ground glass, no circles etc.

Steve