[BrianR]

BrianR I don't know what I did the first time to make then the same size . I'm going to do it again and export them again . I must have had the image size checked with a size . This last time to get the 1026x670 and 6016x4000 numbers I unchecks the image size and got the 1026x670 and 6016x4000 numbers and a big difference in the mb sizes .I'll delete the 2 photos I have there now and replace them with the new numbers and see what it looks like of flickr . I haven't figured out what export setting to use yet . If I post a photo on facebook I will make the image sizing 8x8 or 10x10 because it fills up the space on facebook . I don't know what I'm doing or why yet . Here are the new sizes _IMG6181-3 | myridevlx600 | Flickr _IMG6184-4 | myridevlx600 | Flickr one should be 1026x670 and the other 6016x4000 If its not I don't know why . I didn't resize anything . will you look at both and tell me if I did it right . I noticed on the 35mm one it doesn't enlarge it as much as the 200mm photo .

Looks right now. The size difference on your screen as first served up by flickr might not be much different (depends on your monitor), but as you've pointed out flickr lets you enlarge the 200mm one significantly more. Either way, you should be able to see far more detail in the 200mm one.

I still suggest a print test. Cropping is a compromise in quality. The surest way to find out how much of a compromise you're willing to make is with tests of your own.

[taks]

I did some quick comparison shots today. All shot RAW converted to JPEG in DXO Photolab2 No correction, except coped the sigma 18-35 to approximately match the DA50-135 at 135mm.

Sigma 18-35


DA50-135


Sigma18-35


DA50-135


Sigma18-35


DA50-135


The difference starts to increase quick even at moderate ISO.
Sigma 18-35 ISO 400


DA50-135


I hope it helps

[pentaxk3user]

I did some quick comparison shots today. All shot RAW converted to JPEG in DXO Photolab2 No correction, except coped the sigma 18-35 to approximately match the DA50-135 at 135mm.

Sigma 18-35


DA50-135


Sigma18-35


DA50-135


Sigma18-35


DA50-135


The difference starts to increase quick even at moderate ISO.
Sigma 18-35 ISO 400


DA50-135


I hope it helps

Thanks a lot Taks . I can really see the differences . I guess it really does make a difference . I think I'm just going to have to get the 50-135 The photo you took look great And the city distance is probably what I'll be doing . .I hope it wasn't to much trouble . All the numbers I got from others really didn't help. I have to see things . I was just trying to use the 18-35 as a single take along lens but I can see now its okay but just not like the 135mm . Is the 50-135 mm good for close ups of baby faces ? I didn't want to use a flash . Do you have any photos of faces close up . Not crazy close up just like a full face view ? I was trying to just take one lens back and forth and if the 50-135 is good for indoor photos I would just take it .

[Sandy Hancock]

You can't do everything with one lens.
Accept it.
Or get the 18-135 and accept that you will have to crank the ISO indoors.

[mikesbike]

The difference shown here would no doubt be even more noticeable without the limitations of the file size restriction of posting these and other photos. And Sandy is right- the one-does-nearly-all lens is the DA 18-135mm, really a good all-around lens, but not best for doing a telephoto landscape. Good for say a 24mm landscape. As he says, you also don't get the benefits of having f/2.8 aperture. I have both these lenses and use both as needed.

[bdery]

Thanks bdery what you said helped I think I see what you all are telling me .

A pleasure to help. You will find that most people here on the forum are glad to help out anyone who wishes to learn

[Serkevan]

The difference shown here would no doubt be even more noticeable without the limitations of the file size restriction of posting these and other photos. And Sandy is right- the one-does-nearly-all lens is the DA 18-135mm, really a good all-around lens, but not best for doing a telephoto landscape. Good for say a 24mm landscape. As he says, you also don't get the benefits of having f/2.8 aperture. I have both these lenses and use both as needed.

Wouldn't it technically be the DA 18-270? Of course then you're getting even more optical compromises and it's not WR.

Irrelevant details aside, you are absolutely right... if you were to actually print the crops they would look unappealing, to say the least.

[AstroDave]

Here’s pretty much the example you were asking for (except not of a building or a house!). This is very similar to the effort of taks above, with perhaps a bit more ability to compare resolution effects.

I shot one of my resolution test charts with my K-3 and the Pentax-DA 18-135mm, first at 135 mm focal length, with the chart nearly filling the frame (from around 20 feet away). Then, from that same position zooming out to 36 mm (I tried to set 35 mm, but missed by a millimeter! - that won’t make much difference here).

Then I zoomed into the middle of the chart for both frames with Photoshop Elements and cropped the same area (field of view).

Here is the full frame image with the lens at 135 mm. The blue box in the middle shows the cropped area for the next image.




And, here is the cropped area. In the original (before Forum downsizing; If you want originals, please PM me) you can easily see that the 9 resolution line pairs at top center are readily resolved all the way down to what would be 2000 line pairs if the chart was photographed at proper size. The original pixel size of this image is 1522 by 746, or about 1.14 megapixels.




Now, here is the full frame with the lens set to 36 mm (please excuse the unkempt bed sheets!). Again, the blue box shows the (much smaller!) cropped area. Not that the total size (width and height) of the crop box is a much smaller fraction of the total width/height of the frame.




And, finally, here is the cropped area from the center of the 36mm frame. Now, you can barely resolve the 9 lines at their low-resolution end (slightly more than 600 line pairs, versus the more than 2000 apparent in the 135 mm frame). The pixel size of this image is only 445 by 218 (and shown with no Forum re-sizing!), just 97 kilo (not mega!) pixels. That is a total pixel count that is only 8.5 percent of the crop from the 135 mm frame.





As has been explained above, when you zoom in to crop, you are using fewer pixels out of the original frame. Cropping does not “make” new pixels! The farther you have to zoom in, the more pixels (in a fractional sense) you loose.

[y0chang]

The only way you gain resolution by cropping is by using CSI's special computers that enhance.. ZOOM IN - ENHANCE!

You Tube

You Tube

[taks]

Thanks a lot Taks . I can really see the differences . I guess it really does make a difference . I think I'm just going to have to get the 50-135 The photo you took look great And the city distance is probably what I'll be doing . .I hope it wasn't to much trouble . All the numbers I got from others really didn't help. I have to see things . I was just trying to use the 18-35 as a single take along lens but I can see now its okay but just not like the 135mm . Is the 50-135 mm good for close ups of baby faces ? I didn't want to use a flash . Do you have any photos of faces close up . Not crazy close up just like a full face view ? I was trying to just take one lens back and forth and if the 50-135 is good for indoor photos I would just take it .

I'm happy if it was of any help Remember DA50-135 was taken at f2.8 as requested and 135mm wide open is the weakest point of the lens. Stopped down even one stop and the buildings will be sharper. I love my DA50-135 and I will never part with it ...until they bring out the DA50-135 II with a blazing fast focus motor As for faces close up, is the baby sitting yet? My experience is that when baby is laying down the minimum focus distance on the DA50-135 makes it difficult to get the shot. I think you will be happier with the sigma for sleeping babies usually in dim light. I would take both lens

[pentaxk3user]

AstroDave Thank you for doing that . I see now cropping even when you're close it still makes a difference .I thought it only made a difference when the objects were far away .
yOchang That must have been where I got the idea if you cropped bigger things didn't change in sharpness .
bdery Yes everyone here is great and very helpful . I have a lot to learn . I have got to figure out pixel sizes numbers and what they mean . I think that will help me a lot .