kit lens or older lens?

I have purchased the K200 with the kit lens 18 55m SMC Penax DA. I also have an older lens SMC Pentax FA 28 - 80 (not digital size) I am wondering if this older lens is a better quality lens than the kit lens that came with camera?

It's interesting that you say "not digital size". Actually a 28-80mm lens provides a focal length of 28-80mm on digital as well as film, so you won't get such a wide angle with it as you will with the 18-55mm. (Pentax Digital cameras need a shorter focal length to get the same angle of view as you would with a 35mm film camera).

Generally, older zoom lenses aren't as sharp as modern zoom lenses, but I don't know if that's true for this specific case. I suggest using both lenses and seeing for yourself. The extra telephoto reach of the 28-80 will be useful sometimes anyway, and you may prefer it if you don't do much wide-angle photography.

Umm I am a bit confused I thought you used a conversion factor of roughly x1.5 to digtal lens sizes to get the 35mm equivlant. Therfore my digital kit lens which is 18-55 would be equivlant to 27 - 82mm and thus both lenses would be almost covering the same range?

No. Focal length is focal length. There is no such thing as a digital focal length, or a film focal length.

So both need to be multiplied by 1.5 to produce the same angle of view as you would get if using film.

A "digital" lens is one which has been optimised for use with digital sensors, which require the light to hit the sensor at close to a right-angle. Some "digital" lenses will also be designed to fit the (small) digital sensor, and will not cover a full 135 film frame.

G

No. Your SMC Pentax FA 28 - 80 would turn out a 42 - 120 (1.5 crop factor incl) on your Dslr.

Martin.

Aghh so my 80 - 320 smc would be 120 - 480mm on my digtal SLR ?

Thanks very much for the help

Johna

It would. Advantage on cropped Dslr's is the use of tele lenses. Disadvantage used to be the wide angle lenses.. Not anymore though, since every manufacture has solved that problem by now.

martin.

Hello all,
I am new to all this stuff and have gone out and got myself a k20d and a couple of kit lens 18-55 pentax 2 and a sigma (dg) 70- 300 with macro switch and I have been using them just fine (well happy emoction).
Now I have some older len's manual, a tamron 90mm macro and a 28mm PK unknown make.

The question is I'm getting confused on this x or devide by 1.5 thingy.
So when I mount the len I get a input focal length what should it be ?

28 x 1.5 =42 or 28 / 1.5= 18
90 x 1.5 =135 or 90 / 1.5=60

many thanks in advance for an answer I can understand

You don't have to multiply or divide anything when entering the focal length for the Shake Reduction.

For your 90mm lens, enter 90.

It produces a different view from what you get with a film camera, but a 90mm lens still has a focal length of 90mm on digital.

Im buy june Pentax K200D + DA 18-55mm f/3.5-5.6 AL + DA 50-200mm f/4-5.6 ED !
The 18-55 kitlenses my vote:6/10, and 50-200 kitlenses my vote: 8/10!
Have saturdays my friends Sigma 105mm f/2.8 EX DG Macro!
Hmmm.....fantastic lenses!
Best Buy!!

Sorry the wrong english,but im littlebit speak english!

For newbies to all this, the various answers have been a bit confusing, so perhaps a bit of clarification might help.

The focal length of a lens is the focal length of the lens, whatever camera you attach it to. Thus, a 100mm lens is a 100mm lens.

BUT, the angle of view that lens gives you depends on the size of the image the lens is creating (actually, how much of that image you are using). Thus, with a full plate camera (6.5 x 8.5 inch image) a six inch lens (c. 150mm) is a wide angle lens.

Many photographers, however, started and extensively used 35mm film cameras and got used to the idea that 50mm = standard lens, 28mm wide angle, 135mm medium telephoto etc. and instinctively knew which lens to go for. When switching to digital with its smaller sensor, a rough rule of thumb in terms of converting the angle of view was to multiply the lens length by 1.5. Therefore, a 50mm lens on a digital camera gives approximately the same angle of view as a 75mm lens on a 35mm camera, a 300mm lens on a digital gives roughly the same angle of view as a 450mm lens on a 35mm camera and so on.

Of course, the 1.5 rule depends on the size of the sensor. If you are using a camera with a full frame sensor, then the angle of views are the same. I have no idea what it would be for the four thirds system.

The interesting wrinkle in this, is that the other aspects of using various focal lengths remain the same. Thus, a 500mm telephoto will have the same flattening effect on an image as it always did, and the same depth of field. Thus, if you are using a specific lens for the effect it has on the look of the image, not just the difference in the angle of view, it remains the same across the board.

As an example, 80mm lenses were regarded as the ideal portrait lens, partly because you could be a little bit away from your subject, but partly for the slight flattening and flattering effect the lens has. If you are shooting digital, a 50mm lens will give you almost the same angle of view, but not the slight flattening effect. On the other hand you can pick up a F1.7 50mm lens for next to nothing on ebay (or the lovely F1.4 for slightly more) and the wide aperture allows you to shoot more easily in low light and have a narrow depth of field to throw the background out of focus.

I could go on but this message is too long already!

Best wishes, Kris.

Nicely explained, but just a tweak perhaps to the issue of DOF. A 500mm lens, to take your example, will indeed have the same DOF as any other 500mm lens, but on digital now it is much longer, in effect a field of view of 750mm. This means a super-telephoto will the DOF of a slightly less telephoto, which leads us to smaller format = more DOF, for a given field of view.

This could get very complicated, but I'll just mention that for a given magnification then all lenses at a given aperture will have the same DOF. You can get rounf this idea with a simple macro lens example, with a subject at say 1:1 magnification. If a 50mm macro is say 5 inches away, then to get the same image with a 100mm macro it will need to be 10 inches away. The DOF will be the same for both. However, as we have moved our viewpoint the perspective will be different.

I hope that helps and doesn't confuse...

Thanks, John, for clarifying the DOF field issue, and far better than I could have done!

Best wishes, Kris.

Another Newbie. I acquired a Sigma 70 - 300mm lens and the only way I can use the lens is by turning the F-stop at the camera end of the lens to A. ( I take it that that is for automatic ) Without that on what ever setting or menu I use I get a flashing "Av--" Why can't I use different F-stops in manual mode without getting a flashing "Av--" I have used a Pentax Spotmatic F for years and developed my own rules of thumb and taken fair shots using wide angle, macro, normal and telezoom previously.
Am I getting dementic or am I just doing something wrong.
I would like to blurr the background with a telephoto with wide aperture and secondary shutter speed or some times get greater depth of field with long exposures and small f stop (f22)with strong light.
Problem is I do not understand the menu's on the digital Pentax K100D

Welcome to the forum.

1: This should be a separate topic, not tagged on to somebody else's.
2: You are doing nothing wrong, that behaviour is by design. Why do you want to set the aperture on the lens when you can do it more easily on the body?

Most new Pentax lenses do not have an aperture ring.