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08-30-2007, 09:39 PM   #76
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QuoteOriginally posted by k10dbook Quote
I don't really want to argue about the technicallity of this, my point is that I hate to have to interpolate effective lens equivalency based on 35mm cameras. It's not a 35mm camera, it's a different format...APS-C.
It is a new format (as is the Canon 1.6x crop sensor) but the difference is that it's a legacy mount not an outright new format like 4/3 so there will always be this type of discussion as it's impossible to ignore the heritage of the mount. Even Pentax remain confused, see the lens FL vs field of view pics at the top of page 22 in the following new Pentax lens brochure:

http://www.pentax.co.jp/japan/catalog/pdf/35_lenses.pdf

08-30-2007, 09:45 PM   #77
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QuoteOriginally posted by k10dbook Quote
The equivalent "normal" lens FL for the current Pentax sensor (based on 50mm for a 24x36mm frame) is 32.7mm so that's effectively the new arbitrary magic FL under which it WA and above which is tele ;-)

You say 32.7mm I say 30mm. I can do the exact calculations as well. In practical terms, the normal lens for the APS size should really be 30mm. It's close enough. In the 135 format, normal lens is anywhere between 45mm and 55mm.

I don't really want to argue about the technicallity of this, my point is that I hate to have to interpolate effective lens equivalency based on 35mm cameras. It's not a 35mm camera, it's a different format...APS-C.[/QUOTE]

All debate aside, I suspect it is not accident that the pentax lens road map includes a 35mm macro prime, and a 35mm general purpose prime.
08-31-2007, 01:39 AM   #78
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QuoteOriginally posted by k10dbook Quote
The problen began when camera companies decided that the new DSLRS should be able to use 35mm lenses. It all started with an APS-C sized sensor. That is an entirely different format. Lenses should have been made specifically to that format, without factors. The dumbest thing is that companies using the APS-C sized sensor are now making lenses specifically for them and specifically say that these lenses will not work correctly on 35mm cameras. Hello...why didn't give the correct mm size that these lenses have with the smaller sensor? Why that comparison with 35mm format all the time? Medium format users did not have to put up with a factor to compare their lenses to the 35mm format. 35mm cameras users did not use medium format lenses and say this is a 45mm in medium format cameras! It's the same with Large format cameras!

Now, back to full frame sensor. I think it makes a lot of sense. All 35mm lenses will work at their described focal length. Wide angles will be wide angles again. As for telephotos, since the sensors are now much bigger (in size and in megapixels that is) you can still crop the image and get the same results as far as 1.5 factor to telephotos, except at around 6 to 8 megapixels, which is still very good indeed. The noise will be reduced a lot with larger sensors, especially if they use CMOS sensors. They will all use CMOS soon as the prices have gone down, except of course if new technology takes over....like maybe the foveon sensor.

To compensate, most companies have produced super-wide angle lenses, that with the magnification factor still give reasonable equivalent of 20MM in 35mm format. At the end of the day, everyone has been fixing the lens problems with bandaids. What will happen when technology makes much larges sensors available at a reasonable price. You will now have all cameras sensors the size of todays medium format cameras. 35mm lens factor will not work at all then.

Yvon Bourque
Focal length is focal length is focal length.

A 50mm lens that projects a 10mm x 10mm object on a sensor - will project a 10mm x 10mm object on a 135 format sensor, AP-S sensor, 4x5 sensor, 6x6 sensor, 126 sensor, 110 sensor or super 8 sensor - ok will super 8 just might not be large enough to resolve an object that is 10mm x 10mm.

You are confusing Field of View with focal length. Focal length is designed into the lens - it does not "change" due to the size of the sensor (film or digital - it does not matter). In order to get the same Field of View (FOV) of my FA 50mm f1.4 on my K10D (17x23mm sensor) on my SF-1 (24x36mm sensor) I would have to use a 75mm lens. However, if you measure the object --- on the sensor --- produced with my 50mm FA 1.4 it is 10mm x 10mm, regarless of camera body.

The use of 135 format to describe the realationship between FOV and focal length comes from almost 80 years of 135 film usage. Notice that when you see these "conversions" they are refering to equivalent FOV - not focal length.

The focal length of the lens - does not change from camera to camera with different sensor sizes. What changes is the FOV.

Edit - Oh and FF means that you use the whole frame (hense full) FF does not imply 135 format - on my 4x5 FF is not 24x36mm.

PDL

Last edited by PDL; 08-31-2007 at 01:46 AM. Reason: bunch of pontificating
08-31-2007, 04:49 AM   #79
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QuoteOriginally posted by rvannatta Quote
You say 32.7mm I say 30mm. I can do the exact calculations as well. In practical terms, the normal lens for the APS size should really be 30mm. It's close enough. ....

28,26.......

10-10-2007, 01:44 AM   #80
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QuoteOriginally posted by cygnet Quote
Ok, so I recently entered digital shooting with a K10D, and after reading through this thread the one thing I didn't see was a reference to the depth of field difference to FF. I got a 70mm DA F2.4 lens to use for portraits, and even with it cranked all the way open to 2.4 I don't find it as shallow as I would like. I used to shoot portraits with an Olympus OM1 with a 100mm Zuiko lens, and loved the look. Are y'all just used to this, or is there something I need to do to get more critical depth of field control.
You would probably prefer the 77/1.8 then.

Mskad, from testing, found that in actual terms, the DA 70/2.4 was more of a f/2.8 lens
Digital SLR and Lens Review: By popular demand: Pentax DA 70mm Limited compared to FA 77mm

Else possibly look for the K 85/1.8 or M 85/2, they should be affordable.
Pentax Short Telephoto Prime Lenses
Maybe Sigma, Tamron, Tokina, etc. also have some fast short tele primes for Pentax, but I donít know about them.

I have a 50/1.2 lens that Iím very fond if. It comes in a K version and an A version. That is what I use at the moment as portrait lens.

I might be using the DFA macro for portraits, when I get it in the new year :
Pentax DFA 100mm F2.8 Macro short review | PentaxLife

One of the best lenses, also useable for portraits, was the A* 200/4 Macro ED :
Pentax SMC A* Macro 200/4 - photo.net


QuoteOriginally posted by cygnet Quote
The other reason I would appreciate FF is the fact that my favorite lens on the old Olympus was a 28mm, where with the 18 I'm using now on the K10d, I'm not getting quite as wide a view, but I'm getting more edge curvature of straight lines. I could give a hoot about more pixels, but the way this works with the lenses would be my reasons.
The 18-55 is a consumer lens, but a good one at that. If you used a prime 28 mm on your Oly, it should be able to beat the kit lens.
Go for the 18 mm prime :
K 18/3.5
one of the 20 mm lenses, or maybe (if it is not a bit too long) the 21 limited :
Pentax SMC-DA 21mm f/3.2 AL Limited - Photozone Review / Quick Test Report

Else consider the excellent 16-45 lens :
One more K10D review from Impress Watch | PentaxLife
Pentax K10D vs Canon 1D mark3 | PentaxLife
10-10-2007, 01:50 AM   #81
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IMO, FF is primarily a marketing gimmick.

Photo-editors of major fashion magazines, thought that Benjikan had been using Medium Format, when he turned in his K10 photos.

Film cams were delivering outstanding work, in the pre-DSLR days. Now DSLR have reached a level, where they can meet and exceed a lot of what was done in the film days.


The Eos 5D is the affordable FF option for the enthusiastic amateurs, and a backup cam for working Pros. I can understand the notion of going for it, since you can just continue what you already knew, and how you worked, with 35 mm film format.

It is all down to the choice of what is right for you. Many will be conned into the idea that one needs FF, to get the full potential of your work. And the machinery of PR is working.


I rarely used beyond 24 mm in the film days. And the praised DA 12-24 mm lens, could take care of my need in the wide-angle section; (this would be 18 mm effective focal length). Most likely the DA 14 mm would more than suffice for my needs.

I donít like the smearing and loss of detail and texture that CMOS sensors inhibits. I hope Pentax goes CCD with four-channel readout, to achieve 5 fps.

Sure I wouldnít mind having useable Iso 3200 for low light, but I donít want it at expense of lost Shake Reduction feature. I donít know if APS-H would be possible to incorporate, but 24 x 36 was chosen, back in the day, a bit by coincidence for film. I donít see why it has to be the perfect set for DSLR as well. I would never be able to afford a 600 mm lens, but I could afford a 400 mm someday; and that could work wonders with the crop factor.
(Several of the DA lenses, also work on film bodies; so they could probably function on APS-H crop as well.)

FF will always be expensive, and Canon and Nikon wanna keep it that way, so people will have to lay a bundle. ďOhh, your pictures didnít come out the way you thought ? Thatís because you need the plus 1.000 $ L glass to go with itĒ, and so on.


I use my camera a lot for travel, and like that I get a more lightweight package with K10 compared to FF. (Around a thousand US, was also a little steep for me, in regard to getting the K10).

It is funny how easily scared people are. Even with more FF cameras out, my K10 can continue to take great picture for me, several years from now.

These discussions are not particularly important to me, since weíve seen them before. But Iíve used them to pick up information along the road. And there are a lot of good posts in this thread too.

If I really needed a 15 mm shot, I would grab my old Z-1P and scan some slides from it. (It is also possible via software to de-fish a fisheye lens, with digital one could grab the Sigma 8 mm FE). But I respect other peopleís choice. Each has to find the system that works for them. A good friend of mine uses the 5D, and has been very satisfied.


If Pentax can continue to bring out sensible and well thought through products, there will always be a market for brands, other than the big two C&N. Prices for the old FA* lenses have skyrocketed along with the demand, so it does seem Pentax is on the right track.
You need to do the homework, in order to discover Pentax. But it seems a certain percentage of shoppers donít just buy into the sales talk of the clerk behind the counter, but want to find out for themselves what will suit them the best.
Pentax had a revival with the MZ/ZX series. And it seems they have struck a cord with the K series digital as well. Many new SLR users have entered, and they seemed fond of having discovered the old Asahi company.


Many Proís only use 2GB cards, in order not to loose too many images, in event of failure. They then bring a handful of cards, and transfer to laptop, when back inside.

Iíve had times, when the lighting was exceptional, but we had been hiking for many hours in the rain and fog; and I couldnít care to bring out my big film SLR to take the pictures. Now with the weatherproof K10 and a pancake lens, Iíll be more likely to make the effort.
10-10-2007, 02:19 AM   #82
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marketing gimmick, I dunno about that.....
If FF is a marketing gimmick then MF is also a marketing gimmick. Of course, if it was then pros would not be paying 30000 USD for MF backs.
You can argue if APS-C is good eanough or not, for many/most it is, but FF is better.
10-10-2007, 03:00 AM   #83
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QuoteOriginally posted by and Quote
marketing gimmick, I dunno about that.....
If FF is a marketing gimmick then MF is also a marketing gimmick. Of course, if it was then pros would not be paying 30000 USD for MF backs.
You can argue if APS-C is good eanough or not, for many/most it is, but FF is better.

Maybe I should have put a smiley. 5D and 1Ds Mark II are awesome cameras. But the whole notion of Full Frame, puts the seed in people, of why they should have less; when they could have the Full Frame. (And the Canon white pages goes to lengths, as to how much of the ďframeĒ you loose by going for crop sensors).
When the truth is that APS-C and APS-H have distinct qualities, a smaller weatherproof package. In-camera IS. Smaller and lighter lenses, etc.
(Before I looked into it, I was sure that the day I went digital, I was gonna go for FF).

My point is that Phil found the D2Xs a better value than the 1Ds Mark II. And the D200 a camera above the 5D. But IMO, Nikon couldnít help but loose, because the wealthy consumers, would feel that they got a lesser deal with Nikon.
Hence from a Marketing perspective, Nikon had to go FF. When in reality, the D2Xs was a formidable camera, and more than most amateurs could handle.

Medium Format was always the name for the 645, etc. So nothing special there.
But it was a masterpiece of PR, to name the 1Ds MII and 5D Full Frame. APS-C was there first in digital SLR, so they could have called 24x36 format, for 0.83 crop

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