Photoclubalpha

I recently purchased this lens for my A-700 and wasn't wild about it (not very sharp) but decided to keep it anyway for event shooting (I like the 18-250mm range). I also was using it to shoot portraits (using green chromakey background), and could not figure out why I was getting a dark outline around my subjects (in clean line areas like clothing). I fooled with the "FX Photokey2" software for several days and shot numerous tests and could not get the dark outlines out. I then decided to switch to my old kit Sony 55-200mm lens and the problem disappeared having excellent image definition around my subjects. Also tried my Sony/Zeiss 16-80mm and has similar good results (although the Sony kit lens still performed better).
Fortunately, Amazon will give me a full refund but - not end of story.
Question - what good lens can I replace this with which will have a similar range. I would like to try the "Sigma 70-300 APO DG Macro", (from Sonolta's post) but do not care to switch lens's in the middle of shooting unless I really must.
Any proven winners out there ??

Videoguy

Sigma's 18-250 is said to run circles around the Sony/Tamron design. It uses larger filters, though.

Sigma 18-250mm new OS design. It's a better lens but much bigger and heavier, and fairly expensive. You get what you pay for, it also has HSM focusing which is a big improvement over the 18-250mm Sony mechanical focus (not all that much faster - slightly so, and more responsive). The downside is no DMF manual focus over-ride is possible.

I do not undersrtand why you have got what you see as dark outlines. Do you mean colour fringes?

David

Here are three samples (I had to reduce the files quite a bit). You can see that they are not color fringes but outlines. The photo captions explains which lens used. They were not corrected, and all had the same processing in the FX software. The Sony kit lens did the best job with having clean edges.
thanks David
videoguy

videoguy, I have the Sony 18-250mm and I have never seen that strange black outline like in your photos. Your second photo really shows it very strongly. Can you post a 100% crop of just a section of the woman's shirt on the right side of the photo so we can see the outline full size?

If you seriously overexpose an image and then use Adobe Camera Raw to process it with AUTO adjustment, RECOVERY can create grey outlines from colour-clipped data which is on the verge of being pure white. I can produce this effect only with massively overexposed raw files - where the white backdrop would be for example lit to 3 stops over the main exposure instead of just 0.5 to 1 stop over clipping level.

DRO+ in camera can almost certainly produce a similar effect with greatly overexposed images. Whatever, I know for sure this is an artefact produced by a recovery process which is affecting channels on the verge of clipping and replacing strongly overexposed chromatic fringes with neutral grey. Sharpening setting will also affect this. Turning sharpening off entirely will reduce the chance of it happening. Turning RECOVERY back to zero in auto-set ACR conversions (or Lightroom) will also remove the effect.

David

Yes I do tend to make things too bright in PP, Sonolta (who has a great thread) has pointed that out to me, and I'm working on it. Attached is an underexposed and untouched pic, shot JPEG Fine, standard DRO, and did not go through photoshop (as with the other samples). But I think you are on to something there, as I see it mostly in white and lighter areas, and in this case on only one side of the pic. However,
in the "animal" models (I'm hard up for models) you can see the edge difference between the 18-250 lens and the kit kens in the blue blanket. I'm not sure what is going on here, but it sure looks like the lens makes the difference.
Looking for help,

videoguy

are you using IDC to convert the RAW?
if so IDC gives me the penciled outline in high key images all the time.

You are right about IDC, it has some kind of odd "edge enhancement" even if sharpening is set to the lowest possible setting, one area I noticed fairly quickly.

bfitzgerald wrote:You are right about IDC, it has some kind of odd "edge enhancement" even if sharpening is set to the lowest possible setting, one area I noticed fairly quickly.

this is what it does to me even with 0 sharpening on the RAW file.....



notice the penciled edges? especially on the arms on the left!
Does not happen in ACR, LR or C1.

I think you can control this by using the Undershoot and Overshoot settings with no sharpening.

The almost solid black line is something different, not just a sharpening artefact. I am a bit concerned that it should appear in DRO Standard, but reading the manuals it seems that DRO Standard may even have an effect on raw file data - which DRO+ and +Manual do not. I found this when studying the A900 and A850 manual PDFs and it needs more investigation.

They state that if you shoot RAW only, the effect of DRO+ can not be seen when viewing the image on the camera in magnified views, but the effect of DRO Standard can be seen.

I'm sure that a combination of settings can solve this problem and it is not lens-specific.

David

I just shot this (using my non union models) with DRO OFF, using the Sony 18-250mm lens, with a not blown exposure, and viola!! Clean edges all around.
Glad to see all the reply's !!
videoguy

looks like the pic didn't load the first time.

videoguy

Follow up. This sample is using the Sony 55-200mm Kit lens, shot with DRO Off. This shows that the lens does make a difference. Here you can see the blanket edge detail much more clearer than in the other samples (with DRO Off). Lesson learned - when shooting against a green or blue chromakey backdrop, and you need a natural but defined edge around the subject, shoot with DRO OFF, and see how well your lens defines the edges.

videoguy

ps - I sent the Sony 18-250mm back. Not as sharp as I expected for the price. I'll look into the Sigma 18-250 OS HSM next.

You can find a couple of 18-250mm full size examples via:

http://www.photoclubalpha.com/2009/08/0 ... -big-view/

I will post a review of this lens next (may be two or three days' time). It is pretty exceptional.

David