[madbrain]

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I just bought a Rokinon 800m mirror lens.

This is the lens there .
http://www.amazon.com/Rokinon-800M-B-EOS-800mm-Mirror-Canon/dp/B004JHY5LK/re...7821517&sr=1-6

The one I actually bought was part of a kit on ebay that included a 2x teleconverter and a Canon T-mount adapter, for $207 shipped. It is the black version of the lens, not the more widely available and cheaper white model, which I didn't like. I received it yesterday and started playing with it overnight.

The Rokinon-brand T Mount adapter for Canon that came with the kit in a separate box fits my Canon Rebel T3i perfectly with this lens, at least without the teleconverter attached. Everything feels solid. It is made in Korea, like the lens.

I bought a third party T mount adapter for Pentax on ebay for $5 . I received it last week, long before the mirror lens . It is made by Sonia and made in India.

When I mounted the Rokinon mirror lens on it and attached it to my K-r, I noticed the ring is somewhat loose on the camera side. It doesn't seem to be a very secure fit with the camera.
The outer ring is also smaller than the other one I have for Canon . This is not related to the distance - the height of the Pentax adapter is shorter by 1mm but I expect this is normal.

Where can I get a better quality T mount adapter for Pentax K ?
I would buy the Rokinon brand adapter for Pentax if I could, but I don't see it available separately from the lens anywhere.

[Bob from Aus]

I am interested in the answer as well.

I do have one and need another. But the one I do have I purchased in a camera shop on Norfolk Is in the Pacific ocean. I think the population wouldn't be more than a couple of thousand. The camera shop had been collecting stuff for years and not that many people shifted their pentax stuff. So I picked up a number of K mount bits and pieces including a great T mount and a reversing adapter.

[calsan]

Kowa?
Optics4Birding.com - SLR Camera Adapters

[madbrain]

Kowa?
Optics4Birding.com - SLR Camera Adapters

Wow, $25 for a ring ! Sure hope it's nice. It does have a screw for tightening adjustment.
I will check when I get home if there is any adjustment possible on the cheap one I got.

[RioRico]

I bought a half-dozen cheap T2-PK's last year, shipped from India, and have had no problems with any of them. Yes, it is important to tighten the screws adequately. Good luck!

[excanonfd]

I just bought a Rokinon 800m mirror lens.

It is the black version of the lens, not the more widely available and cheaper white model, which I didn't like.

Where is a cheaper and white, Rokinon 800mm lens? I don't mind the colour at all...

I've bought 2 T2-PK mount from here: T2 T mount Lens to Pentax PK adapter K-7 KM K200D K20D | eBay I had to replace the T2-PK mount on the Rokinon 500/6.3 (white) and I haven't had any issues with the replacement whatsoever.

[madbrain]

Hi,

Where is a cheaper and white, Rokinon 800mm lens? I don't mind the colour at all...

The white model is really black & white.
Amazon sells it for $199 regularly alone, without a T mount or a teleconverter. I guess that is the cheapest regular price I have found for a black & white one.

Amazon.com: Rokinon 800M 800mm F/8.0 Mirror Lens (White ): Camera & Photo

The black one seems to start at a bit more.
I haven't seen a better price than what I paid for the black + TC + t ring, but it wasn't a "buy it now" price, it was an auction. The seller was "bestpriceoptics".

I guess if you have a white K-m, K-x or K-r, the black & white one would fit better.
For my black K-r, I prefer the black lens.

This is only my second day (well, night) with the lens, it is very hard to compose any pictures with it, let alone focus. Tripod is definitely required just for composition. And even on the tripod, focus is very hard as touching the focus ring even very slightly is enough to move the position of the lens and change the composition of the entire frame. The lens does not have any tripod attachment underneath, unfortunately. It is very front heavy.

I am not sure yet if the 2x TC was worth getting, I can't imagine how much harder it will be at 1600mm than 800mm. And the combo is much less stable.
Despite all the difficulties, I have already produced one or two decent images that I could never have gotten any other way. Moon was not out last night, it is tonight, but very small tonight. It takes about 1/6th of the frame at 800mm already.

I have able to see some store signs between 3 and 9 miles away. I live on a hill at 700ft overlooking the south SF bay area, and have quite a bit choice of targets . So far night time only, maybe this weekend I will get to do some daytime shooting.

I've bought 2 T2-PK mount from here: T2 T mount Lens to Pentax PK adapter K-7 KM K200D K20D | eBay I had to replace the T2-PK mount on the Rokinon 500/6.3 (white) and I haven't had any issues with the replacement whatsoever.

Thanks.
The one I bought was this one :
NEW T Mount Adapter for PENTAX K Metal MX K1000 | eBay

[madbrain]

RioRico,

I bought a half-dozen cheap T2-PK's last year, shipped from India, and have had no problems with any of them. Yes, it is important to tighten the screws adequately. Good luck!

Just checked, and the only adjustment screw my Sonia T mount for Pentax has is one on the side of the lens. None on the side of the camera. I would say there is about 0.3 to 0.5mm of play. I don't think the camera or the lens are in danger of falling, but it makes stabilization much more difficult for pictures even with a tripod.

The Rokinon T mount for Canon has screws on both the lens and camera sides.

[excanonfd]

Hi,



The white model is really black & white.
Amazon sells it for $199 regularly alone, without a T mount or a teleconverter. I guess that is the cheapest regular price I have found for a black & white one.

Amazon.com: Rokinon 800M 800mm F/8.0 Mirror Lens (White ): Camera & Photo

The black one seems to start at a bit more.
I haven't seen a better price than what I paid for the black + TC + t ring, but it wasn't a "buy it now" price, it was an auction. The seller was "bestpriceoptics".

I guess if you have a white K-m, K-x or K-r, the black & white one would fit better.
For my black K-r, I prefer the black lens.

This is only my second day (well, night) with the lens, it is very hard to compose any pictures with it, let alone focus. Tripod is definitely required just for composition. And even on the tripod, focus is very hard as touching the focus ring even very slightly is enough to move the position of the lens and change the composition of the entire frame. The lens does not have any tripod attachment underneath, unfortunately. It is very front heavy.

I am not sure yet if the 2x TC was worth getting, I can't imagine how much harder it will be at 1600mm than 800mm. And the combo is much less stable.
Despite all the difficulties, I have already produced one or two decent images that I could never have gotten any other way. Moon was not out last night, it is tonight, but very small tonight. It takes about 1/6th of the frame at 800mm already.

I have able to see some store signs between 3 and 9 miles away. I live on a hill at 700ft overlooking the south SF bay area, and have quite a bit choice of targets . So far night time only, maybe this weekend I will get to do some daytime shooting.

Thanks for the link, I have just placed an order for a white one for 198.00 plus 6.95 for shipping. I don't have a white camera body but paying less for mere cosmetics suit me just fine.

You are finding it difficult to focus with this lens, that's not surprising. I have the Rokinon 500/6.3 and looking at the pictures of the 800/8.0, I can see the same shortcoming on the 800 that's present on the 500; short focus throw. Just guessing, I'd estimate the focus throw to be about 100 degrees, on the other hand my Tamron SP 55B 500/8.0 has focus throw of about 345 degrees. Turning the focus ring in one direction then the other minutely on the Rokinon just don't work as well as it does with the Tamron but when I do manage to nail the focus, I would say the Rokinon 500/6.3 is as good as any mirror lens, including the Tamron. I am hoping the 800 would deliver the same sort of performance as the 500, despite the difficulty in focusing.

You should get yourself a lens hood for the 800. Here is a Sonia 105mm lens hood: Sonia Metal 105mm 105 Tele Telephoto Lens Hood Shade | eBay The only problem is that this lens cannot be reversed over the lens when not in use, making the whole assembly bulky to store and transport. There are aftermarket lens hood for the 800 that will reverse over the lens when the lens is not being used but they typically cost about 4 times more: Samyang 105mm Tele Lens Hood for 800mm f/8.0 Mirror Telephoto Lens | eBay I went with the Sonia 95mm lens hood for my 500 and with the hood left on the lens, the lens is as bulky as my P6x7 SMC Takumar 300/4.0. If the 800 turn out to be a keeper, I may opt for the hood that can slip over the lens when it's not in use - sure would be a lot easier to carry around.

[madbrain]

Hi,

You should get yourself a lens hood for the 800. Here is a Sonia 105mm lens hood: Sonia Metal 105mm 105 Tele Telephoto Lens Hood Shade | eBay

Thanks for the links. I bought the lens primarily for night use. Moon is the #1 intended target. But I will certainly will try others. The bulk of the hood doesn't really bother me, I don't think I will take this lens on any faraway trip anyway where I would have to carry it for an extended period of time. $50+ for a hood does seem a bit much, though. 105mm front filters are very expensive too. The front of the lens rotates with the focus ring, so filters would rotate too. Not great for polarizers. But I think rear filters can be used too. I wonder about using a rear polarizer filter.

The tripod you need for this lens is much bulkier than the hood anyway. The tripod I have used so far, a Manfrotto MKC3-H02 , is just not good enough. Whenever I turn the ball to lock the camera into position, it ends up moving the camera too much and changing the view. I have another tripod, a Quantaray, which I will try next. It has a bent handle.

The only problem is that this lens cannot be reversed over the lens when not in use, making the whole assembly bulky to store and transport. There are aftermarket lens hood for the 800 that will reverse over the lens when the lens is not being used but they typically cost about 4 times more: Samyang 105mm Tele Lens Hood for 800mm f/8.0 Mirror Telephoto Lens | eBay I went with the Sonia 95mm lens hood for my 500 and with the hood left on the lens, the lens is as bulky as my P6x7 SMC Takumar 300/4.0. If the 800 turn out to be a keeper, I may opt for the hood that can slip over the lens when it's not in use - sure would be a lot easier to carry around.

Thanks for the hood links too. I bought the lens primarily for night use. Moon is the #1 intended target. But I will certainly will try others. The bulk of the hood doesn't really bother me, I don't think I will take this lens on any faraway trip anyway where I would have to carry it for an extended period of time. $50+ for a hood does seem a bit much, though. 105mm front filters are very expensive too. The front of the lens rotates with the focus ring, so filters would rotate too. Not great for polarizers. But I think rear filters can be used too. I wonder about using a rear polarizer filter.

The tripod you need for this lens is much bulkier than the hood anyway. The tripod I have used so far, a Manfrotto MKC3-H02 , is just not good enough. Whenever I turn the ball to lock the camera into position, it ends up moving the camera too much and changing the view. I have another tripod, a Quantaray, which I will try next. It has a bent handle.

Here is a picture I took of my cat, indoor, last night. This is at 800mm, ISO 100, 1 second exposure. Taken at somewhere between 15-20 feet back, I think. I have a very big room but still had to move way back against the wall to be able to fit his head into the frame. My cat was very tired, I can't believe he didn't move for one entire second. Sorry, the lens was on my Canon T3i at the time

[madbrain]

Here is another shot with the K-r last night. This is downtown San Jose from my balcony. About 7-8 miles away I think.

[pete-tarmigan]

Have you heard of Pentax's adapter, called PF-CA35? It's marketed for spotting scopes, so I'm not sure if it's suitable for your needs. It costs around $420.00 USD. I use between my K-5 and my Pentax PF-80ED spotting scope.
PENTAX - PENTAX PF-CA35 K-Mount SLR Camera Adapter

Specifications:
http://www.pentax.jp/english/products/binoculars/scope/pf-ca35/spec.html

Forum member 'falconeye' described it as a 2X teleconverter with a T mount:

https://www.pentaxforums.com/forums/pentax-news-rumors/173969-pentax-560mm-23.html

[excanonfd]

Have you heard of Pentax's adapter, called PF-CA35? It's marketed for spotting scopes, so I'm not sure if it's suitable for your needs. It costs around $420.00 USD. I use between my K-5 and my Pentax PF-80ED spotting scope.
PENTAX - PENTAX PF-CA35 K-Mount SLR Camera Adapter

Specifications:
PF-CA35 : Spotting Scopes : Binoculars / Spotting Scopes | PENTAX RICOH IMAGING

Forum member 'falconeye' described it as a 2X teleconverter with a T mount:

https://www.pentaxforums.com/forums/pentax-news-rumors/173969-pentax-560mm-23.html

I saw this setup on the marketplace, out of which the PF-CA35 got sold first - I hadn't realized the camera adapter for the spotting scope would be so costly. When you add the cost of a spotting scope, it becomes little too rich for me to stomach.

Hi,

Thanks for the hood links too. I bought the lens primarily for night use. Moon is the #1 intended target. But I will certainly will try others. The bulk of the hood doesn't really bother me, I don't think I will take this lens on any faraway trip anyway where I would have to carry it for an extended period of time. $50+ for a hood does seem a bit much, though. 105mm front filters are very expensive too. The front of the lens rotates with the focus ring, so filters would rotate too. Not great for polarizers. But I think rear filters can be used too. I wonder about using a rear polarizer filter.

Here is a picture I took of my cat, indoor, last night. This is at 800mm, ISO 100, 1 second exposure. Taken at somewhere between 15-20 feet back, I think. I have a very big room but still had to move way back against the wall to be able to fit his head into the frame. My cat was very tired, I can't believe he didn't move for one entire second. Sorry, the lens was on my Canon T3i at the time

This lens isn't going to used hand held too often, though I am sure we'll try - often. Tripod will be a requisite equipment but yours is far too light for this. I have an 055 with 410 Junior Geared Head or the Dolica CF with 488 ball head. For absolute stock still shot, I will use the former but the reduced size and weight of the latter set up is good for hiking, although the shortness of the legs are problematic for my back. At the minimum, I will be carting around the 679B monopod to shoot with this lens.

That's a very good shot of your cat - so far, I am impressed by what this lens can do.

[madbrain]

Hi,

Have you heard of Pentax's adapter, called PF-CA35? It's marketed for spotting scopes, so I'm not sure if it's suitable for your needs. It costs around $420.00 USD. I use between my K-5 and my Pentax PF-80ED spotting scope.
PENTAX - PENTAX PF-CA35 K-Mount SLR Camera Adapter

Specifications:
PF-CA35 : Spotting Scopes : Binoculars / Spotting Scopes | PENTAX RICOH IMAGING

Forum member 'falconeye' described it as a 2X teleconverter with a T mount:

https://www.pentaxforums.com/forums/pentax-news-rumors/173969-pentax-560mm-23.html

No, I had not heard of this. It's fair to say that this is way above my budget. Considering I am using a $200 mirror lens, buying a $420 adapter is out of the question .

I am sure the included teleconverter is way better than the Rokinon tmount 2x teleconverter I got as part of my package. I tried it last night but really didn't have much luck getting any sharp pictures with it. At 1600mm, the TC makes it so much harder to focus than it already is at 800mm. 800mm is already plenty.

[madbrain]

This lens isn't going to used hand held too often, though I am sure we'll try - often. Tripod will be a requisite equipment but yours is far too light for this. I have an 055 with 410 Junior Geared Head or the Dolica CF with 488 ball head. For absolute stock still shot, I will use the former but the reduced size and weight of the latter set up is good for hiking, although the shortness of the legs are problematic for my back. At the minimum, I will be carting around the 679B monopod to shoot with this lens.

Thanks for the tripod links, I will definitely consider something better.
I tried my Quantaray QSX-9502 last night, and it is a lot more stable. However, I also tried with the TC, and couldn't get any sharp pictures
It is really hard to figure out the subject and focus when all you see with your naked eye is pitch black with a bunch of dots for lights. The right angle finder eyepiece is really critical. Focusing with live view doesn't really work well enough in those conditions unfortunately, even with the magnification option. You would need to have ISO 25600 enabled for the live view preview which doesn't appear to be possible. The K-r also has quite a delay in the live view, compared to the T3i.

I have attached a few handheld shots taken today.
The first five are were taken from my balcony. The bridge is the Dumbarton bridge over the SF bay, 21 miles away bird's eye view.
There was a lot of sun, not a cloud in sight. Probably too much. A hood might have helped.
There was rather a lot of wind which interfered with my ability to stand still, let alone hold the camera still. But I used ISO 1600 and very short exposure times.
I also have a handheld shot of the back of a car with a very clear license plate from about 150-200 ft way, but didn't want to post that one for privacy reasons. Not something you could ever read with your naked eyes.
As you can see all those shots are rather washed out. I only spent about 15 minutes trying, will have more time over the weekend. I am sure I can do a lot better with a tripod, not sure without.
Edit: I am not sure, but I think that I may have had the 2x TC on the lens when I took these handheld shots from the balcony. That would certainly explain much of the reason for the softness.

Starting with the paper which was taken indoor, the shots are from my office campus, all outdoor. These are at 800mm, without the TC.
It took 3 tries to get the bricks in focus, but I am amazed as the sharpness I was able to get when I succeeded. It looks good even at 1:1.

That's a very good shot of your cat - so far, I am impressed by what this lens can do.

Thanks ! I actually have about a dozen shots of him which all came out very fine, just posted the one I thought was best.