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08-04-2009, 06:55 PM   #1
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Difference between Pentax DA and FA lens

Hi all;

I am trying to buy a zoom lens which is about 300mm. I have a pentax k200d

Can a good soul please tell me the main difference these two types? I was looking around and the FA lens seems to be cheaper than the DA lens.

I am looking for a lens for wildlife photography please.



Thanks

CJ

08-04-2009, 07:27 PM   #2
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The difference between a FA and a DA is THE PRICE!!!But seriously,the FA series were made for film cameras,like the MZ cameras etc around the 1990's to early 2000's.If you put say for example a FA 50mm on your digital camera,it would be a 75mm because of the 1.5x crop factor.The DA series are completely designed and used for digital cameras only.If you need to look at the different type of FA or DA's,have a look at Lens Reviews in this forum.
08-04-2009, 07:49 PM   #3
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^The same holds true if you were to put a DA lens on your camera. And to clarify for the OP's benefit... there is no magnification. Your 50 doesn't really become a 75mm with the 1.5 crop factor. The field of view now equals that of a 75mm lens. A 300mm lens is still a 300mm lens.

The main difference between the DA and FA series lenses are that DA series lenses don't have an aperture ring. I would also suggest reading the reviews. You'll find terrible lenses in any series.

Last edited by JHfwp; 08-04-2009 at 07:57 PM.
08-04-2009, 08:01 PM   #4
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wait, i thought all lens focal lengths are the same, and based on 35mm. So even though a 50mm DA won't work on a FF DSLR or SLR without vignetting if it even fits, the result would be 50mm and not 33mm FOV.

e.g. 50mm DA and 50mm FA are both 75mm FOV equivalent on a APS-C Pentax and how 14mm lenses on Oly 4/3rds are 28mm FOV equivalent, and P&S cameras say something like 6mm but are really like 30+ mm FOV equivalent.


Last edited by Eruditass; 08-05-2009 at 12:24 PM.
08-04-2009, 09:05 PM   #5
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It's important to note the difference between 'reach' or magnification and APS-C equivalent FL.
A 50mm lens gives you 50mm in reach, just as described above, no more, no less under any circumstances. The APS-C crop factor means that in the same magnification, the image is just cropped - but does NOTHING to add more reach.

I also fell into that marketing hype - don't be fooled by it all...

DA lenses have no aperture ring (no longer needed as it's all controlled electronically), and perhaps slightly different coatings optimised for digital cameras.
FA lenses have an aperture ring to be able to set manually if needed on the old film SLRs that require it.
08-04-2009, 09:17 PM   #6
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Are you talking about the FA 100-300 and the DA 50-300? They're lenses of different leagues. The DA 50-300 is much better.
08-04-2009, 09:23 PM   #7
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DA lenses have the information to allow CA and distortion correction on the K-7. Most have Quick-Shift Focus. Some have SDM.
08-04-2009, 09:46 PM   #8
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Not this discussion again!

"Reach" has no meaning that I can see when considering the lens only. A 50mm lens on digital produces the same image as a 75mm lens on film in an way that would be apparent to the naked eye without pixel peeping (or printing and then breaking out a magnifying glass). So whatever "reach" is, it must be something you only measure by examing both images with a magnifying glass. So I'm guessing it must have something to do with which of the two apparently-identical images has more detail when examined under a magnifying glass. And then, the answer would depend entirely on specific 75mm and 50mm lenses you used in your comparison, as well as the specific film you used and the resolution of your digital camera. You simply cannot assume the 75mm lens on film than the 50mm lens on digital just because 75mm is a longer focal length.

If there is some other definition of "reach" that has meaning in this context, then, it must be something you can not see wither with the naked eye or with a magnifying glass. Meaning I don't see why anyone would care about it.

Anyhow, whether a lens is FA or DA has nothing to do with this. A 50mm lens is a 50mm lens, whether FA or DA. When used on a digital camera with 1.5X crop factor, *either* will provide the same FOV (and therefore the same "reach" in any practical sense visible to the human eye) as a 75mm lens would have on film. If you don't use film camera, then that fact is not relevant for you, and you can forget you ever heard about crop factors.

Anyhow, most of the specifics about DA versus FA here are true. To summarize, DA is designed in some way for digital. In most cases, that means it won't work with most film cameras - it won't cover the whol film rectanlge (meaning the corners will be left dark) plus there is no aperture ring, so you can't control the aperture with older film cameras. There might be other subtleties in the design of the DA lenses that them work better with digital than FA lenses, all else equal. But as I've said before, all else is rarely equal. There are plenty of FA lenses that produce better results on digital than most DA lenses do.

As for price, they are all over the map. Some FA lenses are much more expensive than the closest DA counterparts, and sometimes it is the other way around.

08-05-2009, 01:44 AM   #9
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FA is an earlier version of an autofocus lens before the DA. good thing about the FA is the aperture ring which makes it compatible with film cameras, if you dont mind using film these days. as for DA, they are digitally enhanced, though there are lenses that suck from both versions. if you want to get an idea if the lenses on those versions are any good, please visit the review section of this forum. it is very helpful in determining which lens to buy and which ones to avoid.
08-05-2009, 01:49 AM   #10
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THanks for all your comments. So what I understand is that I need to get a DA lens for the k200d isnt it?
08-05-2009, 02:22 AM   #11
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QuoteOriginally posted by chaminda_jay Quote
THanks for all your comments. So what I understand is that I need to get a DA lens for the k200d isnt it?
No, you can use FA lenses on your K200D, through some may be less ideal considering some optical artificats because the coating was not optimised for digital sensors. For many of them, it wont matter, or you will have to shoot in very difficult light conditions to see the difference. Understandably, they got you confused when they got into this crop and reach fighting rather than answering your question. If you have the K200D and no film SLR lacking apperture ring will not matter to you. Generally, the DA's are better built than the FA's and easier to manual focus, and they have the quick shift focusing. But there are many good FA's that simply have no corresponding DA. If you specifically compare the DA55-300 and the old F/FA80/100-300mm lenses, the DA is way better, as someone pointed out. But that has to do with optical design, not weather it is a DA or FA/F lens.
08-05-2009, 02:57 AM   #12
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QuoteOriginally posted by JHfwp Quote
^The same holds true if you were to put a DA lens on your camera. And to clarify for the OP's benefit... there is no magnification. Your 50 doesn't really become a 75mm with the 1.5 crop factor. The field of view now equals that of a 75mm lens. A 300mm lens is still a 300mm lens.

The main difference between the DA and FA series lenses are that DA series lenses don't have an aperture ring. I would also suggest reading the reviews. You'll find terrible lenses in any series.
You wrote that a 50mm doesn't really become a 75mm with the 1.5x crop factor. I always thought that if you put a 50mm film lens on a digital camera,it would equivalate to a 75mm on a 35mm film camera because of the 1.5x crop factor????
08-05-2009, 05:22 AM   #13
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QuoteOriginally posted by chaminda_jay Quote
THanks for all your comments. So what I understand is that I need to get a DA lens for the k200d isnt it?
You can choose a DA series and FA series lenses for your K200D. I have a few of both and both work just splendidly on my K10D. If ever in the future, Pentax develops a FF digital camera, I know my FA's will work on them with no problem...my DA's, not so much. (No, not trying to drag this thread into a debate, just a statement being made)

Jason
08-05-2009, 06:28 AM   #14
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QuoteOriginally posted by Barnster Quote
The difference between a FA and a DA is THE PRICE!!!But seriously,the FA series were made for film cameras,like the MZ cameras etc around the 1990's to early 2000's.If you put say for example a FA 50mm on your digital camera,it would be a 75mm because of the 1.5x crop factor.The DA series are completely designed and used for digital cameras only.If you need to look at the different type of FA or DA's,have a look at Lens Reviews in this forum.
Please, no more crop factor, you will just confuse the hell out of someone.

There is no difference AT ALL between how an image will look with a 50mm FA lens vs a 50mm DA lens.

focal length is focal lenght.

The real differences between DA and FA lenses will be
- the application of an anti glare coating on the rear element to stop glare and contrast reduction caused by reflections off the sensor, as it is more reflective than film was,
- light hitting the film / sensor plane. Digital sensors are sensitive not only to the level of light but the angle light hits them. This causes vignetting if the angle is too far from perpendicular, hence DA lenses are designed to have th elight hitting the sensor at closer to perpendicular
- the image circle FA lenses are designed to cover a 24mm x 36 mm frame, DA lenses are designed to cover a 16mm x 24 mm frame, and may not cover a film frame, although this varies on a lens by lens basis
- FA lenses have an aperture coupling, and can be used on any MF film body all the way back to the K1000, DA don't and need to work on cameras after the pentax Program Plus (I.e. KA mount bodies). Note there is a varient of the FA lens, FA-J which don't have aperture couplings.
08-05-2009, 06:50 AM   #15
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QuoteOriginally posted by Lowell Goudge Quote
Please, no more crop factor, you will just confuse the hell out of someone.

There is no difference AT ALL between how an image will look with a 50mm FA lens vs a 50mm DA lens.

focal length is focal lenght.

The real differences between DA and FA lenses will be
- the application of an anti glare coating on the rear element to stop glare and contrast reduction caused by reflections off the sensor, as it is more reflective than film was,
- light hitting the film / sensor plane. Digital sensors are sensitive not only to the level of light but the angle light hits them. This causes vignetting if the angle is too far from perpendicular, hence DA lenses are designed to have th elight hitting the sensor at closer to perpendicular
- the image circle FA lenses are designed to cover a 24mm x 36 mm frame, DA lenses are designed to cover a 16mm x 24 mm frame, and may not cover a film frame, although this varies on a lens by lens basis
- FA lenses have an aperture coupling, and can be used on any MF film body all the way back to the K1000, DA don't and need to work on cameras after the pentax Program Plus (I.e. KA mount bodies). Note there is a varient of the FA lens, FA-J which don't have aperture couplings.
Lowell covered it well. The image circle difference is a show stopper if you'll ever use the lens on a full frame camera. I don't know how important the rear element coating is; anybody have data?
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