[aslyfox]

If you look at the 15 thread and the DA 21 samples thread ( Pentax DA 21mm f/3.2 AL Limited samples - Page 3 - PentaxForums.com ) you'll want both.

well

you are right, when you can't decide between the two, buy both

I have bought my lottery tickets, a total of $ 5 down the drain but who knows

last time I spent $ 4 and won $ 5

[Saltwater Images]

DA 21mm is kind of wide, but it is very useable. It is not awkwardly wide. It can be used for almost anything, but portraiture and architecture might not be the best choices because of the distortion. Nature, landscapes, travel photos, street photos, indoor would be great. I don't have DA 15mm, but I have another 14mm lens. That FoV is really wide. It is not fisheye, because it has some correction. Fisheye means that lines are not straight. When using fisheye lenses there is actually the danger that the tips your own feet will be in the shot. With non-fish UWA lenses, the lines might be bent a little, but not too much (and this can be fixed with lens profiles, in-camera or on computer).
IF you are not doing much wide photography, the DA 21mm might be more useable. DA 15mm has a FoV that is approaching extreme, so it has fewer uses, but it produces more stunning results when you get it right.
If you buy used you can sell it at a minimal loss, but I doubt you would regret it. They have the "limited" look - great colours, contrasts

The HD DA 21 is a wide normal and is very usable in a wide range of shooting situations. The 15 is an ultra wide - it needs to be deployed with much more thought usually with a very specific purpose in mind. Ultra wide lenses pull the foreground closer and push the background further away that's why they don't offer the versatility of a normal lens. In the HD DA series, I feel the 21 is a wide normal, the 35 is normal, the 40 is a tight normal. The 15 is an ultra wide and the 70 is a short tele.

[aslyfox]

The HD DA 21 is a wide normal and is very usable in a wide range of shooting situations. The 15 is an ultra wide - it needs to be deployed with much more thought usually with a very specific purpose in mind. Ultra wide lenses pull the foreground closer and push the background further away that's why they don't offer the versatility of a normal lens. In the HD DA series, I feel the 21 is a wide normal, the 35 is normal, the 40 is a tight normal. The 15 is an ultra wide and the 70 is a short tele.

that is how I would classify the lenses

if I was using them on a full frame film SLR

yet, with the smaller filter of the K 3 and K 3 II

the " field of view " of the lens is not the same as the " field of view " you get with the same lens on a full filter found on the full frame K 1

if I understand it correctly

so are the " classifications " the same?

[MrB1]

Generally, most descriptions of wide lenses seem to be related to the size of the sensor -
Full frame (36x24mm) - a wide-angle lens is below 36mm focal length and a super-wide is below 24mm. Similarly,
for APS-C (24x16mm) - a wide-angle lens is below 24mm focal length and a super-wide is below 16mm.
So, in that scheme of things, the DA 21 Ltd is a wide-angle lens and the DA 15 Ltd is a super-wide.

[Saltwater Images]

that is how I would classify the lenses

if I was using them on a full frame film SLR

yet, with the smaller filter of the K 3 and K 3 II

the " field of view " of the lens is not the same as the " field of view " you get with the same lens on a full filter found on the full frame K 1

if I understand it correctly

so are the " classifications " the same?

Normal on APS-C includes focal lengths between 28 and 35 mm. 21 is a moderate wide angle (I would call a wide normal because the lens renders a scene much the way we see it). 15 is ultra wide - ultra wide lenses have a focal length that is shorter than the short side of the sensor (the K-3II sensor is 23.5 x 15.6mm). Short telephoto lenses usually have a focal length between 67mm and 100mm on full frame. The HD DA 40 on APS-C is a 60mm equalivent do it is still technically a normal lens. The HD DA 70 on APS-C is a 105mm full frame equalivent so it is a short telephoto. Does that make sense?

[aslyfox]

Normal on APS-C includes focal lengths between 28 and 35 mm. 21 is a moderate wide angle (I would call a wide normal because the lens renders a scene much the way we see it). 15 is ultra wide - ultra wide lenses have a focal length that is shorter than the short side of the sensor (the K-3II sensor is 23.5 x 15.6mm). Short telephoto lenses usually have a focal length between 67mm and 100mm on full frame. The HD DA 40 on APS-C is a 60mm equalivent do it is still technically a normal lens. The HD DA 70 on APS-C is a 105mm full frame equalivent so it is a short telephoto. Does that make sense?

don't ask me

I'm a confused newbie

but that is the way I understand it

the only way I can even begin to understand is that you take a photo captured by a lens of a certain focal length on a full frame sensor

then you " crop " the photo by the equivalent size of the smaller sensor losing the top, sides and bottom of the photo and thus you see what you get

this is what I am attempting to explain:

Full Frame Sensor vs Crop Sensor: Which is Right For You?

https://digital-photography-school.com/crop-factor-explained/

[Alex645]

the only way I can even begin to understand is that you take a photo captured by a lens of a certain focal length on a full frame sensor

then you " crop " the photo by the equivalent size of the smaller sensor losing the top, sides and bottom of the photo and thus you see what you get

Actually this is very common for anyone who started with 35mm film photography. There is now a generation that knows natively the fov for focal lengths on APS-C. Of course, I have to 'shift gears' everytime I work with 645 medium format and folks like Ansel Adams that started with 4x5" and 8x10" large format had to think of his transition to 6x6cm (2.25x2.25") Hasselblad as a major crop adjustment.

A 35mm normal prime on APS-C=
50mm on FF (or 35mm film)=
75mm on 645 (film)=
100mm on 6x7 (film)=
155mm on 4x5" (film)=
350mm on 8x10" (film).

PS. Everyone that wants to now post "focal length is focal length" please revisit those posts for your debating pleasure

[jddwoods]

between lusting for a SMC DA 21 limited and the SMC DA 15 limited

although if the price is right, I might choose the HD versions

as noted I don't really have a wide angle lens when the ASP- C camera bodies are considered

however I am not a fan of the " fish eye " look

any thoughts

can any one confirm the field of view I would have with those lenses on my K 3 and K 3 II

and thoughts about whether to go with the SMC or HD versions

Realistically you will need to get both. As soon as you get one of them, you will most likely want the other. They complement each other.

[UncleVanya]

don't ask me

I'm a confused newbie

but that is the way I understand it

the only way I can even begin to understand is that you take a photo captured by a lens of a certain focal length on a full frame sensor

then you " crop " the photo by the equivalent size of the smaller sensor losing the top, sides and bottom of the photo and thus you see what you get

this is what I am attempting to explain:

Full Frame Sensor vs Crop Sensor: Which is Right For You?

Crop Factor Explained

Just remember that the da15 on a k-3 gives a wider angle of view than a 35mm film camera using a 24mm but narrower than a 20mm. The da 21 on a k-3 is closer to a 30mm on a k1000 in perspective. The 35 on a k-3 is near a 50-55 on an LX. The 40 on a k-5 is tighter than a 55 on a MX. The 70 on a k-3 gives a view like a 105 nikon on an F2.

[iheiramo]

Realistically you will need to get both. As soon as you get one of them, you will most likely want the other. They complement each other.

Got the 21ltd recently. Don't feel any pull towards 15. 21 is already pushing my limits and reserved for occasions when I can't step back or need anti-flare feature, so at the moment I have no desire to go any wider. I rather stitch a panorama if I need wider view.

[ffking]

Got the 21ltd recently. Don't feel any pull towards 15. 21 is already pushing my limits and reserved for occasions when I can't step back or need anti-flare feature, so at the moment I have no desire to go any wider. I rather stitch a panorama if I need wider view.

There are other factors, of course - the dof at a given aperture gets greater as the angle of view gets wider, and lenses of comparable speeds (other than dedicated macros) focus closer - so wide angle is all about changing the relationship between foreground and background and works best not for getting more in but for giving something near to the camera greater prominence in the photograph but also keeping it in the context of its surroundings (ie getting a lot of recognisably sharp surroundings in the frame)[COLOR="Silver"]

[Rondec]

don't ask me

I'm a confused newbie

but that is the way I understand it

the only way I can even begin to understand is that you take a photo captured by a lens of a certain focal length on a full frame sensor

then you " crop " the photo by the equivalent size of the smaller sensor losing the top, sides and bottom of the photo and thus you see what you get

this is what I am attempting to explain:

Full Frame Sensor vs Crop Sensor: Which is Right For You?

Crop Factor Explained

Don't worry about naming and crop factors and things like that. To me, a lot of that stuff is semi-useful if you are shooting multiple different size sensor formats, but otherwise it doesn't help. The important thing is more to think about angle of view for a particular lens and let it go at that. The wider the lens, the more things sort of get stretched and distorted at the corners. You may not notice it too much in nature (although trees begin to lean towards the middle and things like that), but if there are people in the image, they begin to look pretty odd if they are at the edges of your image.

As far as crop factor, you are right. That explains why focal lengths have a more narrow angle of view on APS-C than on full frame cameras, but as I said before, I don't think it is particularly helpful for most folks to think about it if they are only shooting APS-C.

[iheiramo]

There are other factors, of course - the dof at a given aperture gets greater as the angle of view gets wider, and lenses of comparable speeds (other than dedicated macros) focus closer - so wide angle is all about changing the relationship between foreground and background and works best not for getting more in but for giving something near to the camera greater prominence in the photograph but also keeping it in the context of its surroundings (ie getting a lot of recognisably sharp surroundings in the frame)[COLOR="Silver"]

Yes, but personally I rather like to keep background meaningful or remove subject from it's context. Plus what Rondec said:

The wider the lens, the more things sort of get stretched and distorted at the corners.

I guess I'm just not ultra wide kind of guy.

[aslyfox]

. . . The important thing is more to think about angle of view for a particular lens and let it go at that. The wider the lens, the more things sort of get stretched and distorted at the corners. . . . As far as crop factor, you are right. That explains why focal lengths have a more narrow angle of view on APS-C than on full frame cameras, but as I said before, I don't think it is particularly helpful for most folks to think about it if they are only shooting APS-C.

There are other factors, of course - the dof at a given aperture gets greater as the angle of view gets wider, and lenses of comparable speeds (other than dedicated macros) focus closer -. . .

" angle of view " was the term I was trying to remember when I wrote " field of view "

[Saltwater Images]

One thing this thread has made me realize is that there is a gap in my bag of 6 primes from 15 to 100 mm. That gap is 28mm which would be the focal length providing a true normal on APS-C. I'm willing to bet a HD DA 28 f/2.8 wouldn't be an engineering challenge and would sell quite well....just a thought....