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06-07-2011, 05:23 PM   #1
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Pentax smc DA*135-270mm f/2.8 ED [IF] SDM

Well I thought of this new lens for a number of reasons. I put it up on the POLL on where to put R&D money to in bringing out new lenses for Pentax. The poll: https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/146454-wich-le...r-d-money.html can still need your attention.

This new lens should have a new thread, just to talk about it and see what use it can be and if there is enough interest for.

My thoughts:
It should be in the DA*-zoomrange and adding up to the two current zooms DA*16-50mm/f2.8 and DA*50-135mm/f2.8. This because I was looking for some time now for a lens longer then current in Pentax line-up with fast aperture f2.8. At the time only DA*200mm/f2.8 is available. I use these fast lenses mainly for sports and for some occasions having f4 and even with K-5 and his great high-iso-performance isn't the best thing to have. For sportsarena's (indoor) and swimarena's I could really use a f2.8 lens. Options I looked at are FA*300mm/f2.8 and A*300mm/f2.8 (also the sigma 300/2.8). I was at a swimmingevent and you really need 300mm to get a picture off the lanes 3 and 4 (that is where the fast swimmers are, it was a 10 lane olympic sized pool of 50 meters). So scoring a Sigma 70-200 or a Pentax FA*80-200 would help some, to my current DA*50-135mm, but not enough. With the upcoming Sigmalens 120-300mm/f2.8 I think there is a great lens in the line. Only thing is that that is not a Pentax lens.

Why this range:
Well the Sigma is going to weight almost 3 kg and since I rescently bought a DA*60-250mm as my long range for this summer I know what weight means when you are walking all day. So when Pentax should make a new lens it should also give a new range, not to much competing with current lensline. Making some compromise on length would make this lens lightweight as is with making it APS-C only instead of a Full Frame compatible lens. Making it only a 2x times zoom would simplify the design in the way off optics. And there you have my idea, making it DA*135-270mm/f2.8.

This is a big lens, make no mistake about that. It weights 2 kg easily. It should also be a topdesign in optics and image quality since it will be very expensive (compared to current Pentax lenses). I expect it to be twice the price of DA*60-250mm.

Reach:
Well it is 135-270mm on our APS-C body so it will give a very nice telerange (206-412mm/f2.8 to FF range). When there is also a 1,4x TC (wich makes a lot of sence to buy with this lens even when it will cost 450 euro) you have a reach of 189-378mm/f4 wich is a very strong telelens (289-578mm/f4 to a full frame camera). It is on the short side for birding, but it is 26 % longer reach then the current longest lens the DA*300mm/f4. With no light loss and a more versatile tool then a prime.

Question:
Is it possible to design? How big would this lens be? How expensive is this lens? Would you be interested? Do you have any ideas about such a lens or something alike?


Last edited by RonHendriks1966; 06-19-2011 at 03:34 AM.
06-07-2011, 05:31 PM   #2
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A prime lens of this telephoto focal length? f/2.8 is conceivable. The 300mm f/2.8s are testament of that.
But a zoom of that focal range? I cannot say if it's impossible but I'd wager that it would be very difficult for Pentax to develop and keep it in line with its product ethos, and be of a specialist lens caliber and availability, like the 250-600/5.6 or 600/4.
Very ambitious, and I'm not sure I'd buy it, purely from a financial point of view.
06-07-2011, 05:49 PM   #3
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That is quite interesting. I personally wouldn't buy it from a financial and focal length perspective. A 260-420 f2.8? or f4 for that matter.... now we're talking
06-07-2011, 05:50 PM   #4
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QuoteOriginally posted by Ash Quote
A prime lens of this telephoto focal length? f/2.8 is conceivable. The 300mm f/2.8s are testament of that.
But a zoom of that focal range? I cannot say if it's impossible but I'd wager that it would be very difficult for Pentax to develop and keep it in line with its product ethos, and be of a specialist lens caliber and availability, like the 250-600/5.6 or 600/4.
Very ambitious, and I'm not sure I'd buy it, purely from a financial point of view.
I suspect it would be physically twice the size of the FA* 250-600/5.6. I don't think I could afford to buy which is the reason I don't have a FA* 600/4 or even an FA* 300/2.8 for that matter.

06-07-2011, 06:07 PM   #5
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QuoteOriginally posted by RonHendriks1966 Quote
Question:
Is it possible to design? How big would this lens be? How expensive is this lens? Would you be interested? Do you have any ideas about such a lens or something alike?
Possible but highly unlikely. Hardly anyone would buy it. It would be very expensive. Try $10 000.
In addition this sortof speed isn't needed in this focal length range anymore. 300/2.8 lenses is from a time when 100 ISO was max for quality work and/or make it usable with converters. Converters aren't that usable anymore either as you can crop a digital image and get similar (or even better) image quality than with a converter in spite of fewer pixels. The Limited DOF at max aperture and focal lenght is a problem 99% of the time.
It will also weigth in excess of 2kg ensuring that it will stay at home when the novelty wears off. This is in fact why these kind of lenses change hands rather often. A 2kg 135/2.8 lens is in addition a useless piece of shit.
It is one thing dreaming about lenses; the reality is often different :ugh:
06-07-2011, 07:47 PM   #6
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You know if anyone go to eye doctor for new glasses. If anyone want to cheap glaSs with glasses but glass is too thick and heavy it worth cheap $$ if anyone want nice thin glass with nice glasses that expensive $$$$
06-07-2011, 08:20 PM   #7
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Most ppl have a problem understanding APS-C designed focal length lenses as it is.
50-135mm vs 70-200mm, most ppl opt for the longer and bigger
Esp. if it has Canikon written on the lens.


I don't really ponder much over APS-C equivalent. I have a F*300/4 and I just know that it gives me a certain real usage reach. If its not enough, I pull out my M42 mount Enna Tele-ennalydt 400mm.
Long story short;
I'd certainly welcome a 100-300/4; 400/5.6; 500/5.6
Long when long is needed; not astronomical in price and not too big and heavy to make it too much of a chore to bring out.
On the K5, I do think the slower aperture is liveable.
Maybe its affordable enough for more ppl to actually buy them too.
06-07-2011, 08:30 PM   #8
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I'd suggest it would end up the size of a tank. I'm no lens engineer, but I have to assume it's why the 60-250 is an f/4...
From a completely selfish standpoint (I admit), I'd only be interested if it wasn't the size of a tank

06-07-2011, 09:38 PM   #9
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My guess would be 3kg and cost $8,000. Not something I'd buy.
06-07-2011, 09:56 PM   #10
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The OP mentioned the Sigma 120-300mm f2.8 in his post, a lens that has already existed for quite some time, and while big and expensive, it is certainly not a $10,000 tank. I believe a 135-270mm f2.8 could be easily designed at a size not much larger than a 70-200mm f2.8 in a $2000-$3000 price range (still bloody expensive, but comparable to similar lenses)
06-07-2011, 10:47 PM   #11
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The barrel would need to be around 4.5", minimum, to accommodate a 4" front element needed for 1:2.8 @ 270mm, and it would need to be about 11" long to handle the internal focus and zoom. Close to 4lbs and probably $4K minimum would be my speculative guesstimate.
06-08-2011, 01:33 AM   #12
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Well I see some dome thinking. I don't think it is large as a truck or as expensive then some guess.

When I look at Pentax 300mm/f2.8 they had 112mm frontlens and the Sigma 120-300 uses a 105mm. So there is some option of having it smaller then 100mm (in the range of 90-100mm and that would be the same as with a new DFA*500mm/f5.6) frontglass.

The Sigma costs overhere in pre-order 2299 euro and the DA*60-250mm costs 1249 euro. So expecting twice the price of the 60-250 makes it 2499 euro wich is expensive but not like a tank. Give or take maybe a few hundred extra because of the design and low numbers to be sold. So definitly under 2999 euro.

A design like 50-135mm where there is not only IF but also internal zooming is preferred. Making the lens bigger. Would it make a big difference when the lens would extract out when zooming? Designwise, weight, costs and quality?

Someone mentioned the 250-600mm but that is totaly different in size, weight and cost. Only thing in common is an almost identical frontglasssize due the difference in focallength and max aperture.

Someone who would use this if it was at your doorstep and what would it be fore?

This lens brings some new things to the range: 35 % longer reach at f2.8 then DA*200mm/f2.8 or any 70-200/80-200 lens and 26 % more reach with a TC then the current longest lens in program, the DA*300mm/f4.

A little compromise would be to make it DA*135-270mm/f3.2 so just a notch less fast, but only if that would make a difference in design or expensis.
06-08-2011, 01:40 AM   #13
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QuoteOriginally posted by RonHendriks1966 Quote
The Sigma costs overhere in pre-order 2299 euro and the DA*60-250mm costs 1249 euro. So expecting twice the price of the 60-250 makes it 2499 euro wich is expensive but not like a tank. Give or take maybe a few hundred extra because of the design and low numbers to be sold. So definitly under 2999 euro.
.
Look at the cost of a Canon/Nikon 300mm f4 compared to the f2.8 version. Then factor that to the cost of the 60-250 plus some as the reach is more.

Canon f4 = 1350 f2.8 = 5,000

Pentax 60-250 f4 = 1500 so ~6k for a 2.8 version?? + $1k or $2k for the extra reach?? Maybe more because zooms more complex than prime?
06-08-2011, 03:59 AM   #14
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QuoteOriginally posted by Super A-wesome Quote
The OP mentioned the Sigma 120-300mm f2.8 in his post, a lens that has already existed for quite some time, and while big and expensive, it is certainly not a $10,000 tank. I believe a 135-270mm f2.8 could be easily designed at a size not much larger than a 70-200mm f2.8 in a $2000-$3000 price range (still bloody expensive, but comparable to similar lenses)
Sigma will have about 50X the production volume of a similar Pentax lens as they sell the lens in "all" mounts.
Most Pentax exotic lenses in the past were loss leaders (I wonder how many 400/2.8 and 1200/8 they sold: the latter probably less than 10 samples!). That time is past; all lenses nowadays must make a profit for getting the go ahead I suspect....
06-08-2011, 06:20 AM   #15
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QuoteOriginally posted by Pål Jensen Quote
Sigma will have about 50X the production volume of a similar Pentax lens as they sell the lens in "all" mounts.
Most Pentax exotic lenses in the past were loss leaders (I wonder how many 400/2.8 and 1200/8 they sold: the latter probably less than 10 samples!). That time is past; all lenses nowadays must make a profit for getting the go ahead I suspect....
That is true, it is not a hobby for Hoya, there has to be a return on investment, and that is a good thing for saving Pentax brand for the future.

Then again there are things that add to the brand or just bring money in. My guess is that the latest lens, the DA 35mm/f2.4 is selling like cupcakes and therefor is a good investment, only the profit wont be very high on a single lens.

Question for such lenses is: How big are the initial costs for design and to make the first testingcopy's? How big are real productioncosts? What is the margin on sales and what is the expected salesvolume over the next 5-10 years? Is this lens making the brand more popular and thus attracting new users (like I think a 200mm/f4 macro will do, or maybe for a small part on this lens bringing a new option in the lensline for specialty use). Having answers to those questions can make discissions to every new lensdesign.
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