Yesterday I covered the different microstock sites and my opinions of them, and why not to use Shutterstock. :) Today I will briefly cover what the microstock sites are looking for to provide guidance for those wondering whether their photos will be accepted and sell.
First, IStockPhoto probably has the best information and what is acceptable and what is not. If you sign up with them you have to go through 'training' where they will show you what they are looking for. Below is what I have found from my experience.
First, the technical details.
Noise - all of the microstock sites hate noise. Shutterstock is probably the worst here. IStockPhoto seems to take noise into account vs. the saleability of the shot but in general all microstock sites will reject for noise. The easiest way to avoid noise is to shoot at low ISOs. My general rule of thumb is to always shoot at ISO 100 unless I am forced to move up. If I can keep ISO 100 by using a tripod, I do so. In cases where I need to stop motion in darker areas, then I am often forced to move above ISO 100. The second way to help with this is to use a noise removal program such as Noise Ninja. This has dramatically improved my acceptance rate.
Focus - Obviously your shots must be in focus, but they must 'really' be in focus. What looks good on a print or on your monitor is not sufficient. I generally blow up my shots to 200% on my 24" monitor. If the focus still looks decent then, I submit it. At the very least your shot should be very sharp at 100%. Make sure you zoom in on each shot because I have accidentally submitted shots OOF because they looked fine on my monitor and others in the series were in focus on closer inspection.
Framing - The general rule of thumb is your shot should not look like a snapshot. Be extra careful when you frame and make sure that you do not accidentally put a tree, side of a building, or something else on the edge of the frame so as to make the shot look more like a snapshot. Shutterstock is more forgiving here but IStockPhoto will reject the shot quickly. Framing is especially important for vacation shots.
Lighting - Your shot must be properly exposed in all areas. Actually a great way to learn about lighting is by submitting to IStockPhoto because they are extremely critical here, but they will tell you exactly what is wrong. If you use a flash or artificial lighting be very careful that the light does not reflect back into your camera and lead to areas of overexposure. Shutterstock is more lenient than IStockPhoto when it comes to lighting but they can also be unpredictable here (sometimes they reject, sometimes they accept).
Dust spots - It is common, especially in macro photography, to get dust spots in your shots. Make sure to remove all dust spots using Photoshop beforehand, which is quite easy to do. Both Shutterstock and IStockPhoto will reject due to dust spots, but IStockPhoto is extremely anal and will find ones that make you squint. Luckily, when they do find them they send you the portion of your image that contains the spots or dead pixels still requiring removal.
Next, I will discuss the types of shots that will be accepted.
Copyright - You cannot take pictures of anything that is copyrighted and then sell your photo. For instance, if you take a picture of a downtown street and there is a coca cola sign in your shot, you must Photoshop out the Coca Cola sign first, or obscure it beyond recognition. Both Shutterstock and IStockPhoto will reject due to copyrighted photos, but there is a big difference here. On some occasions, you can submit a shot to Shutterstock and mark it as editorial (or annoyingly their submitters sometimes do that for you - even if the subject is not copyrighted). It is then up to the downloader to honor the editorial rights. IStockPhoto takes no such chances here and they are much more astute in finding copyrighted items. For instance, I once had a kitchen photo rejected due to the tiny logo on the refrigerator (I removed the logo and the shot was accepted). The general rule is if there is anything, no matter how small, copyrighted in the shot, it will be rejected by IStockPhoto.
An exhaustive list of what is and what is not copyrighted is beyond the scope of this blog. IStockPhoto and elsewhere are good lists to start out with. Many of these are quite strange - for instance it is OK to sell a picture of the Eiffel Tower during the daytime, but not at night, unless it is part of a panorama of Paris (this is because the light show is copyrighted). It is not OK to sell pictures of the Space Needle by itself, day or night. However if the Space Needle is part of the Seattle skyline it is OK. This does not apply to hotel logos though. If you take a picture of a city skyline and one of the buildings' hotel logos is present, the picture cannot be sold.
Same old things - There are a number of subjects that microstock sites are simply sick of. They have enough shots of these and will not accept any new ones unless it is amazing. In general, don't even think of submitting shots of seagulls, sunflowers, eye closeups, or fire. The vast majority of sunset shots will also be rejected, though if you have an interesting sunset of an interesting place or landmark, and you use the location in the title and keywords it may be accepted. Flowers are also very tough and are usually always rejected. However an interesting picture of a non-ordinary flower or a flower used in a unique way will be considered.
Saleable content - Remember that the goal of the microstock site is to sell these pictures. Think who would want this picture. Many pictures are technically correct but just not saleable.
So what types of pictures sell? From what I have heard people shots sell the best, though I generally stay away from these shots so I can't verify this from personal experience. I suspect that very good people shots are among the best selling pictures, but given the huge number of these type of shots available, I suspect there are many which are poor sellers.
Of my pictures, vacation shots have sold the best. By far my best sellers are my Dubai shots, particularly of the Burj al Arab hotel. Since we stayed at the hotel we had photographic access that most others did not and therefore I was able to get unique viewpoints. Other shots from Italy, Peru, Singapore, and Thailand have also sold decently well.
Real estate shots (outside or inside) also sell very well as do isolation shots. However, if you do isolation shots make sure you make the isolation perfect. Both stock sites are very tough here, though IStockPhoto is the toughest.
My favorite shots are insect shots, which do sell but rarely. Based on the fact that most of my shots here have little competition because of my equipment, I would venture to say that few people purchase insect shots. Animal shots likely perform a bit better, depending on the animal.
In general your best bet for having photos that sell well is to take a picture of something for which there are few other shots available. If you happen to find something that is both in demand and has little competition you will find a much higher rate of sales.
Finally keep in mind that with the microstocks keywords are just as important (or more so) than the actual picture. If people can't find your shot then no one will buy them. I have perfected a keywording technique over the last year and I use a special program I wrote to do this, but for now I have to keep some secrets, don't I. :)