MicrostockGroup

This entire series was denied by DT due to "Poor optical performance due to low lens quality, such as lens fringing, chromatic aberrations, uneven sharpness in focus area."  I now know DT does NOT allow discussion of denials on their boards. :- )

Anyway, I'd greatly appreciate if someone could help me see it. Another image taken with the same lens was approved. Of course that's neither here nor there. I'm not objecting, I'm really new and just learning, but I can't very well correct or prevent something I'm not seeing.

Thanks!

http://www.flickr.com/photos/rlboston/4005704108/#sizes/l/in/set-72157617553107197/

agreed, it is really hard to see what the image looks like without a 100% view, but you should be able to see good detail in the corn stalks if the image is OK.

One problem that is visible however is the blown out highlights in the corn.  On all the corn cobs (or husks) there is a highlight and it is completely white with no detail.  It looks like you might have increased the contrast too much while editing (unless the camera did that by itself) .... or actually it looks like the image was shot overexposed a bit, then you edited it so the image was more correctly exposed but they highlights were still blown out.  If there is no information in the highlights you can't 'bring them back'

I don't agree.  Background images can sell quite well on microstock.

Its a Powershot A590 IS - I agre with your comments, except not sure what you mean about the large lens opening - on a compact camera with a 1/2.5 sensor that has a "crop factor" of about 6 -  f5.5 will be equivalent of about f33 on a a 35mm... you can't really stop it down!

I was surprised to discover that the A590 doesn't stop down any further than that; its aperture only goes from F/2.6 to F/5.5.  That puts the maximum F-stop at F/16 on a 35mm.  Not much room for creative DOF.

Most of what I have in microstock was taken with a A620. It has limitations, butit is a decent camera, and I expect the A650 to be the same.  One limitation is noise (present in sky even at ISO50), which is perhaps worse if the A650 produces larger images - A620 is 7Mpix and sometimes I downsize for micros because of their picky standards (I have upsized for Alamy with no problems).  Another limitation is chromatic aberration, especially at larger apertures.

I don't understand holgs calculation about aperture.  A620's minimum aperture is f/8 and it doesn't mean infinite DOF...  At f/5.6 I get a limited DOF, depending on the distance.  I use f/2.8 to f/4 in many of my shallow DOF images.

Well I'm confused as to why the Flickr infor page says "Canon PowerShot A590 IS" - the aperture calculations were based on that model's sensor size giving it an effective focal length multiplier of 6 - a 1/1.7 sensor will give you something like a 5 times multiplier when comparing to full frame - so an effective aperture of something like f/13 to f20 in the aerture ranges you quote. This isn't infinite aperture, so if you want to limit depth of field, its still possible, but probably more likely on macro and close-up subjects where you have a high level of magnification than when doing portraits.

The camera that's being quoted now looks to have a 6* zoom range with 12MP sensor. That's a lot of compromises in a small camera, and I think even with re-sizing and post processing you'd be pushing it to get these files accepted.

"Poor optical performance due to low lens quality, such as lens fringing, chromatic aberrations, uneven sharpness in focus area." has nothing to do with sensor quality. I own Canon 30D and it is 8MP. But I use 2.8 L lenses. Just stay at 100 ISO and you will do fine all over microstock world.

I was not following the thread very well. I just wanted to say that you do not need a 10MP camera as long as you stay at 100 ISO.

A couple of final points; Holgs is correct, my bad, it's a 590. My default iso is 80 and noise is still a huge problem so I take two things from this discussion:

1) A DSLR ASAP.

2) I need to invest some time training my eyes to see these issues which my assumption means looking at lots and lots of pictures on this board and others like it.

Thanks again everyone, for taking the time!