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900mm mirror lens?

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happyjack View Drop Down
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Post Options Post Options   Quote happyjack Quote  Post ReplyReply Direct Link To This Post Topic: 900mm mirror lens?
    Posted: 05 April 2016 at 11:33
Has anyone seen this - or even tried it?
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neilt3 View Drop Down
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Post Options Post Options   Quote neilt3 Quote  Post ReplyReply Direct Link To This Post Posted: 05 April 2016 at 11:55
Looking at the pictures , it seems to be the same external size ( diameter) as a 500mm reflex , a 900mm f/8 would need to be proportionately larger all around ..
The lens design could show a built in teleconverter .So at 900mm effective focal length , it wouldn't have an f/8 true aperture .
They don't really anyway due to the central obstruction .
I would imagine this lens would be a very poor performer , even at that price .
Personally , I would avoid it .
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Blutengelnouta View Drop Down
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Post Options Post Options   Quote Blutengelnouta Quote  Post ReplyReply Direct Link To This Post Posted: 05 April 2016 at 12:27
Pretty certain that is the Samyang 800mm f/8, which is sold in an uglier look branded as Vivitar, Opteka and what not sometimes. http://www.amazon.com/Vivitar-800mm-Mirror-Lens-V-800MR/dp/B008G7ZPKE

As for the image quality, it's extremely soft and simply not a good lens in any way. I did a comparison against the Samyang 500mm f/6.3 (which is pretty decent all things considered) once and the 500mm would yield better results by cropping. Not that any of them would make much sense when you have the 70-400.
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Pirate View Drop Down
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Post Options Post Options   Quote Pirate Quote  Post ReplyReply Direct Link To This Post Posted: 05 April 2016 at 14:00
Originally posted by happyjack happyjack wrote:

Has anyone seen this - or even tried it?

Ahoy!

You might find this Dyxum thread for Minolta MC/MD mirror lenses of interest, though you can see them here.

I would guess they're of superior quality to 3rd party mirror lenses, but don't quote me on that.
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sybersitizen View Drop Down
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Post Options Post Options   Quote sybersitizen Quote  Post ReplyReply Direct Link To This Post Posted: 05 April 2016 at 16:25
Originally posted by neilt3 neilt3 wrote:

Looking at the pictures , it seems to be the same external size ( diameter) as a 500mm reflex , a 900mm f/8 would need to be proportionately larger all around ..

It is much larger all around. Look at the relatively small size of the rear T-mount...



I'll also point out that even though the lens is large, we can be sure that its T-number is not 8 ... probably close to 11.

Originally posted by Blutengelnouta Blutengelnouta wrote:

Pretty certain that is the Samyang 800mm f/8, which is sold in an uglier look branded as Vivitar, Opteka and what not sometimes. http://www.amazon.com/Vivitar-800mm-Mirror-Lens-V-800MR/dp/B008G7ZPKE.

Indeed. You can even see where the 800mm engraving was changed to 900mm!

Another example here:

http://www.bhphotovideo.com/c/product/885034-REG/Vivitar_v_800mr_800mm_Mirror_Lens_for.html

This is a lens to avoid, as most of the user reviews confirm.

Edited by sybersitizen - 05 April 2016 at 16:52
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balacau View Drop Down
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Post Options Post Options   Quote balacau Quote  Post ReplyReply Direct Link To This Post Posted: 10 April 2016 at 19:19
I'm honestly surprised they were allowed to get away with that, changing the 800mm to 900mm, false advertising and all that. I do believe the penalty for that is a user's account is suspended although I don't think that'd stop someone from just making another one.

The first generation Samyang lenses (such as the 800mm mirror lenses amongst others) weren't known for their sharpness and that's probably why you see so many on eBay at crazy low prices. Even the Sigma 600mm F8 mirror lens was double the price...and that's not crazily sharp either. So yes, I would avoid the auction as well.

Its only relatively recently that Samyang have pushed the boat out and been hitting high scores for image quality and lens build.    Perhaps their 300mm mirror lens is an exception to that then? I have not heard much good feedback about that one either.
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sybersitizen View Drop Down
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Post Options Post Options   Quote sybersitizen Quote  Post ReplyReply Direct Link To This Post Posted: 10 April 2016 at 19:29
Originally posted by balacau balacau wrote:

Its only relatively recently that Samyang have pushed the boat out and been hitting high scores for image quality and lens build. Perhaps their 300mm mirror lens is an exception to that then? I have not heard much good feedback about that one either.

Some 300mm reviews and sample images are out there ... but Samyang says there is no A-mount version: 'Available mounts: Sony E Mount, Fujifilm X, MFT (Micro Four Thirds).'
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Miranda F View Drop Down
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Post Options Post Options   Quote Miranda F Quote  Post ReplyReply Direct Link To This Post Posted: 11 April 2016 at 09:19
The lens does look very similar in appearance to the Opteka 500mm mirror I had, so maybe that was a Samyang design too? It was commendably small and light, but it certainly wasn't much good optically. It's absolute resolution (at a given lens-subject distance) wasn't any better than my Sony 55-200mm zoom, and the contrast was very low. In exposure it was roughly f11, and was noticeably smaller in the front element (and everywhere else!) than the Tamron 500mm mirror.
The best thing about it was the way you could get some querky bokeh-related images with what was just about a pocket-sized lens.
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balacau View Drop Down
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Post Options Post Options   Quote balacau Quote  Post ReplyReply Direct Link To This Post Posted: 11 April 2016 at 17:22
Originally posted by Miranda F Miranda F wrote:

The lens does look very similar in appearance to the Opteka 500mm mirror I had, so maybe that was a Samyang design too? It was commendably small and light, but it certainly wasn't much good optically. It's absolute resolution (at a given lens-subject distance) wasn't any better than my Sony 55-200mm zoom, and the contrast was very low. In exposure it was roughly f11, and was noticeably smaller in the front element (and everywhere else!) than the Tamron 500mm mirror.
The best thing about it was the way you could get some querky bokeh-related images with what was just about a pocket-sized lens.


Hi Miranda

Yes, the Samyang/Rokinon/Opteka/Falcon lenses are one and the same. While I love playing around with a Sigma 600mm F8 mirror lens, its not wonderfully sharp either. The Minolta/Sony 500mm F8 seems to have better feedback on reviews.

I have always been curious to know just how good the old Minolta super-sized mirror lenses actually were in terms of image quality.

Best regards

Gavin
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Miranda F View Drop Down
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Post Options Post Options   Quote Miranda F Quote  Post ReplyReply Direct Link To This Post Posted: 11 April 2016 at 22:22
I think both that and the Tamron were reckoned to be about as good as an f8 refractor, not quite so sharp as an f4 tele. I certainly noticed that the Tamron has an amazingly high contrast for a mirror lens - most of the time I don't notice any difference between it and a normal lens, which isn't true for some mirror lenses! Can't speak of the Minolta, though. It's stil on my to-get list.
Miranda F & Sensorex, Sony A7Rii, A58, Nex-6, Dynax 4, 5, 60, 500si/600si/700si/800si, various Sony & Minolta lenses, several Tamrons, lots of MF primes and *far* too many old film cameras ...
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