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01-05-2009, 11:55 AM   #16
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That was helpful :)

Ok,

is there a TC* weather sealed TC 1.4x* in the roadmap?

What is the better IQ DA*300 w/ 1.4 TC or DA*400?

the progression has been 200 f2.8, 300 f4, 400 ? [5.6] seems logical, especially for cost concerns. there needs to be a DA* 400 lens to make wildlife, sports and far action possible.

I would even take a 200-400 f4

unfortunately my price point is under $2k, maybe this happens


Last edited by rdrum76; 01-05-2009 at 11:55 AM. Reason: mistype
01-05-2009, 11:58 AM   #17
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QuoteOriginally posted by k100d Quote
if 400 5.6 is what you really need, might as well spare yourself the suspense and go to canon
that or find an overpriced F/A* 400 5.6, or the rarer Sigma's
I obtained my FA* 400mm for under $800- just saying

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01-05-2009, 01:23 PM   #18
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QuoteOriginally posted by vizjerei Quote
how big and heavy is it? don't the radius need to be much larger for it to have a fast aperture? sorry I am totally newbie on mirror lens..
Max aperture is the focal length over the diameter. 600/f4 means a 150mm objective.

The Zeiss 1000/f5.6 is 14 kg (and at least a 180 mm objective); it's also a very traditional, built-like-two-tanks, medium format lens, so I doubt I want to use its numbers to scale with!

The Celestron C5 is a 1250/f10 lens when used as a lens; it weighs under 3 kg. I would expect that 600/f4 could be done for that same 3kg. (more mirror, less tube.) Note that the FA600/f4 is 6.8 kg.

Kenko-tokina has an 800/f8 fixed aperture mirror lens that weighs 840 grammes. Doubling the mirror diameter quadruples the area (area is pi r^2; r is d/2; it's d^2/4 versus d^2 if the larger versions has 2d as the lens diameter), so 4 x 840 gives 3.36 kg for an 800mm/f4. The Sigmonster (800/f5.6) is 4.74 kg, and about 7 kUSD. Schmidt-Cassegrain telescopes with 200mm mirrors are around 1 kUSD, with an optical tube weight 6 kg. (Note that light tube weight is bad from an astronomy point of view; this is not going to be optimized by a telescope manufacturer before stiffness.)

There's always a tradeoff between cost and how clever one wants to get with the materials technology, but the Cassegrain reflector designs are inherently lighter and cheaper than refractor designs of the same capabilities. The historical problem for photography has been the fixed aperture, but I don't see why that can't be handled with rotating filters; that would not have been practical before integrated circuits, but is straightforward now.

So they ought to be able to do 800/f4 at 5kg and 2 kUSD. That would sell.
01-05-2009, 02:20 PM   #19
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The Road Map that came out in Sep 2008 has that "Super Telephoto" name in the same place as the Oct 2007 Roadmap had the DA* 300mm. If you look, the dotted line, it starts at the top of the map with "300" in lime green and still goes through the DA* 300mm photo and the "Super Tele". The photo of the 300mm was moved from the future lenses to the released lenses. In other words, a 400mm would be "off the map." Compare the 2 maps:

Pentax lens roadmap updated | PentaxLife

Pentax lens roadmap updated | PentaxLife

I hope Pentax has a super tele beyond the 300mm up their sleeve, but if they do, its not on the current map.

01-05-2009, 03:52 PM   #20
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QuoteOriginally posted by Jonson PL Quote
Then f/4.5 instead. A 400/4 would be around the same weight as a 300/2.8. I hope for a 400/4, as the reputation of the FA* 400/5.6 was not stellar. So I would prefer a new formula, like they did on the DA* 300/4.
.

No one would any longer make a super telephoto lens with a focal lenght below 600mm and a speed less than F:4. The reason is that slower lenses are better served by a zoom (eg. 100-400/5.6), and that slower lenses than F:4 cannot be used with a 1,4X teleconverter while maintaining AF something that lessen their appeal considerably. Tellingly, Nikon doesn't offer a 400/5.6 prime lens.....
01-05-2009, 03:55 PM   #21
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QuoteOriginally posted by Graydon Quote
Colour shifting isn't a problem; the mirrors cancel each other out.
Unless I missed something, the only colour shifting that happens in reflector telescopes is within the refractor components, ie the eyepiece and the Barlow lens etc. Angle of reflection isn't affected by wavelength, unlike angle of refraction.

The nice thing about a Maksutov-style mirror lens is that the lens (refractor) elements are simple and shallow concave or convex, so fringing can be less of a problem than with pure refractors. Colour fringing (which is a manifestation of the different focal lengths that lenses have with different light wavelengths) is noticeable mainly when a light ray strikes a refracting surface at a comparatively steep angle, but it always occurs in refraction and can only be compensated for (and never completely, as far as I know) by optical design.

Until recently, Pentax offered a super-telephoto mirror lens (2000/f13.5?), at a suitably astronomical price, if I remember correctly.
01-05-2009, 04:20 PM   #22
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QuoteOriginally posted by m8o Quote
A 400/5.6 would be superfluous if the 1.4x SDM TC is shipped coupled to the DA* 300/4 that we already have. I'm firmly in the "it better be 400/4 or longer and/or faster else it's pointless" camp.

With that said odds are higher than I'd like that it's a 400/5.6 that we see because it is like integrating a TC into an already existing design. :ugh:
Except that you can *also* use the 1.4x with the 400/5.6 to get a 600/8. And I bet the 400/5.6 would be sharper wide open than the 300/4 and TC combination. A 400/4 would be a big and expensive lens, with very small potential sales. A DA*100-400/5.6 would also be large and expensive, but probably more desireable. I bet that's a lens that would actually sell, especially to nature photographers attracted by the weather sealed package.
01-05-2009, 04:58 PM   #23
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Nikon doesn't, but canon does

Canon still makes 400mm 5.6L. I read alot of good things about it and at the price, $1,099, for a new lens even I consider it from time to time. Supposedly Canon is coming out with a new designed 500mm 5.6L IS later this year. They do not road map product but 500mm/5.6 is new info on popular rumor site just posted last week. May or may not happen, but sounds intersting and likely under $2,000.


Canon | 400mm f/5.6L USM Autofocus Lens | 2526A004 | B&H Photo


QuoteOriginally posted by Pål Jensen Quote
No one would any longer make a super telephoto lens with a focal lenght below 600mm and a speed less than F:4. The reason is that slower lenses are better served by a zoom (eg. 100-400/5.6), and that slower lenses than F:4 cannot be used with a 1,4X teleconverter while maintaining AF something that lessen their appeal considerably. Tellingly, Nikon doesn't offer a 400/5.6 prime lens.....


01-05-2009, 05:34 PM   #24
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QuoteOriginally posted by RobA_Oz Quote
The nice thing about a Maksutov-style mirror lens is that the lens (refractor) elements are simple and shallow concave or convex, so fringing can be less of a problem than with pure refractors. Colour fringing (which is a manifestation of the different focal lengths that lenses have with different light wavelengths) is noticeable mainly when a light ray strikes a refracting surface at a comparatively steep angle, but it always occurs in refraction and can only be compensated for (and never completely, as far as I know) by optical design.
I believe that's true for constant index of refraction materials; it may not be for variable index of refraction materials, which are starting to get downright common in higher-end eyeglasses.

My limited understanding of the matter is that you can, and most designs do, manage to select the refractive elements of a Cassegrain design (Schmidt or Mak) to function so they reverse on another on the colour fringing, and that you can get away with this because the primary focusing is being done by the mirrors. (Focus moves the rear mirror; the refraction, particularly in a Schmidt-Cassegrain, is not much involved in focusing the light.)

Certainly the sample shots from the 1000/f5.6 at Pentacon Six: 1000mm lenses and Pentacon Six:1000mm lenses Pt2 show "a total absence of colour fringing", and looking at the sample shots, if there were going to be any, I'd expect to see it; building crane lattices against a bright sky.
01-05-2009, 06:50 PM   #25
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QuoteOriginally posted by GaryM Quote
Except that you can *also* use the 1.4x with the 400/5.6 to get a 600/8.
That 1.4x on a 400/5.6 is very unlikely to provide AF in anything but EV14-16.
QuoteQuote:
And I bet the 400/5.6 would be sharper wide open than the 300/4 and TC combination.
Folks say that. Yet I find the 1.4X on my sigma 300/2.8 is pretty much invisible which I've heard others echo. If I'm losing rez, it's nothing I miss.

I hear what you're saying, and it'll probably end up the case. It's super tough to find used old long fast Pentax glass; when I was shopping for my 1st DSLR & Lens buying for a safari trip the B&H salesman warned me Pentax was never known for long fast lenses but I thought that was just a ploy to talk me into Cankon. The glass strategy will probably stay a commodity approach, especially given the global depression. I'd give my Sigma 300/2.8 up for their 120-300/2.8 if they made a Pentax version so I could make use of it more; or instead of a zoom, weather sealed would make it worth while too. But still, 400/4.5 would be the slowest I'd want to see to make it worthwhile to me. There were many times when even a 300/2 would have been what I needed. A 400/5.6 would be too slow for me. Pentax once did make that cannon of a 500/4.5.

Last edited by m8o; 01-05-2009 at 06:55 PM.
01-05-2009, 07:37 PM   #26
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A 400mm f4 with a matching TC would be nice (hoya does make glass)
That would by a good crop equivalent to the 600mm f4
01-05-2009, 10:11 PM   #27
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QuoteOriginally posted by Graydon Quote
... sample shots from the 1000/f5.6 at Pentacon Six: 1000mm lenses and Pentacon Six:1000mm lenses Pt2 show "a total absence of colour fringing", and looking at the sample shots, if there were going to be any, I'd expect to see it; building crane lattices against a bright sky.
Fascinating. I wasn't aware of this mirror lens, and I imagine there weren't too many made.
01-05-2009, 10:26 PM   #28
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QuoteOriginally posted by borno Quote
A 400mm f4 with a matching TC would be nice (hoya does make glass)
That would by a good crop equivalent to the 600mm f4
This is exactly what I’m hoping for. That they continue the philosophy of making APS-C crop lenses of previous Film Format lenses. Like :

(24) 28-70/2.8 -> 16-50/2.8

70-200/2.8 -> 50-135/2.8

Macro 50/2.8 -> Macro 35/2.8

85/1.4 -> 55/1.4

50/1.4 -> 35/1.4 (pending)

300/2.8 -> 200/2.8

600/4 -> 400/4
I just hope that a DA* 400/4, also would be useable on a future FF camera, (though it may be far, far away). But as I understand it, it would be likely to work that way with extreme-telephoto primes.

The supertele are the last Pentax needs for a complete line-up, and they know this. They could just make them built-to-order, so things would be less costly for them.

What is happening now, is that loyal users with big lens line-ups, who start to investigate e.g. getting a hold of FA* 600/4, find out that it is simply too cumbersome, and they go Canon instead. Just like Walter did, when he needed more fps, and Pentax couldn’t give; (and others before him) :

“You are right. I got an unbelievable deal to shoot with Canon. I am not into brands, I think I can shoot with any brand (everybody can do that). I did shoot with the Pentax 600mm (the one Mousehill is having now) and I shot with the Sigma 500mm F4.5 [non DG version]. When pentax is coming tomorrow with an 600 or 500 SDM lens and a new K30D with an exceptional offer I am back .
I did shoot with the K20D and the Voightlander 125mm and I was very happy with it. Great combo and also the K20D with the Sigma 500mm is a good combo. Pentax does have very good glass and they are lucky changing them over to SDM (and it was time to do so).”
This is what you must see but read the warning!!!! [Page 4]: Pentax SLR Talk Forum: Digital Photography Review



QuoteOriginally posted by rdrum76 Quote
is there a TC* weather sealed TC 1.4x* in the roadmap?

the progression has been 200 f2.8, 300 f4, 400 ? [5.6] seems logical, especially for cost concerns. there needs to be a DA* 400 lens to make wildlife, sports and far action possible.

I would even take a 200-400 f4

unfortunately my price point is under $2k, maybe this happens
I don't know if the TC is gonna be weathersealed.

Ron just got the Sigma 400/5.6 APO Tele-Macro, and it seem a good lens :
http://forums.dpreview.com/forums/readflat.asp?forum=1036&message=30582669

Last edited by Jonson PL; 01-06-2009 at 01:40 AM.
01-06-2009, 05:44 AM   #29
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QuoteOriginally posted by GaryM Quote
Except that you can *also* use the 1.4x with the 400/5.6 to get a 600/8. And I bet the 400/5.6 would be sharper wide open than the 300/4 and TC combination. A 400/4 would be a big and expensive lens, with very small potential sales. A DA*100-400/5.6 would also be large and expensive, but probably more desireable. I bet that's a lens that would actually sell, especially to nature photographers attracted by the weather sealed package.

"No one" would want to use a 600/8 lens. It is close to impossible to focus due to a dim viewfinder and AF won't work. A 400/4 would be expensive (cheap high quality supe telephotos don't exist), but will also give a very useful 560/5.6 lens of high quality. A 100-400/5.6 won't cost more than a 400/5.6 cause it will have 10 times the salesvolume.
01-06-2009, 05:46 AM   #30
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QuoteOriginally posted by Samsungian Quote
Canon still makes 400mm 5.6L. I read alot of good things about it and at the price, $1,099, for a new lens even I consider it from time to time. ]


The Canon 400/5.6 is a very old lens and will almost certainly see no replacement. Most Canon user prefer the 300/4 + 1,4X converter or the 100-400/5.6 IS.
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