Cambria hybrid with purple spots on three of its leaves
 

I just bought a Cambria hybrid, I'm still not sure of it's exact id. I noticed it has these purple spots on three of it's leaves; the worst one is pictured here. What can I do to get rid of this? And is it contagious, or can I safely put it on a windowsill with another healthy orchid?

In my oppinion it's the best one. Your cambria must have, probably, red or purple (or between) flowers.
The key word here is: Anthocyanin.
Wikipedia provides a good explanation about it.

In case of a cambria it means your giving it too much light, I think, because anthocyanin high concentration prevents red wavelengths to be absorbed. Thus, they are reflected, that's why we see the red colour in leaves and flowers. Basically, anthocyanins are a natural sunscreen in the botanical world. Their production in the cells is stimulated by high light intensity.

Oh, I see. It may not be so bad then. I will read the wikipedia article as soon as I have time, either tonight or tomorrow. It may be that it had a bit too much light then, in the store I bought it from today, or from being outside in the sun for a few hours afterwards when I removed it from the plastic pot from the store into a glass one with drainage. I didn't look too closely at all the leaves when I bought it. It now rests on my windowsill where there is less light, but still some sunlight every day. So if it's as you think, should the spots dissapear in a few days if it now gets less direct sunlight? I also watered it a little, with fertilizer. Only a little water, and with fertilizer for orchids. It was very dry when I bought it. I understand they don't need much water, so I watered very sparingly.

Edit: The flowers are yellow and a rusty red or purple. I added a picture.

Probably they will but it might take a while or they will never disappear. But that's not an issue, unless you don't like them.:)
The important thing here is to know that is a sign of high light intensity, which is ok if that's what your plant needs.
In case of cattleyas, for ex, that's something you want to see in the leaves 'cause catts need high light to bloom.

I was searching in orchid related sites for flowers just like yours but couldn't find any. They look like brassias but there's a whole range of different culture needs for this genera. Maybe someone knows better than I.
Anyway, for now I would avoid direct sunlight.
It all depends on the plant needs.

They don't need to be completely red or purple. When we see those spots we can say there's a high probability for the flowers to have red colours in them (as well as other, of course).

Sorry for a late reply, I've been busy renovating the past couple of days and couldn't keep up on both threads. I see, nothing to worry about then so far. It's on my windowsill now, but it's a cloudy day. I'll try to keep it out of direct sunlight for a while to see what happens. I don't mind the spots, now that I know what causes them. Thanks again!

Also, I noticed today my orchid has secreted a few small drops of clear, sticky, what I assume to be sap, from the stalks. Does this mean I've given it too much water?

Very pretty orchid. The sap is called happy sap. It's sweet tasting, your plant is happy.

Thank you. Yeah, I googled it and I believe you are right. It's also called honeydew, from what I've read? And I see no signs of insects or anything else amiss.

---------- Post added at 10:36 AM ---------- Previous post was at 09:36 AM ----------

Oh no, there is something else amiss here. Bloody orchid snails! I saw one when I took it out of the plastic pot from the shop just after I bought it, which I removed. Didn't see anything else since then, but after showering my orchid today I did a thorough inspection of the potting material surface and removed three more of the bastards. I read a thread about them here now and I put a leaf of spinach on there that will hopefully attract some of them until I can go to the shop and look for some pesticide.

Always learning. Altough it makes sense I didn't knew that trick...but I also never had a snail problem in my orchids.

I read it in this thread http://www.orchidboard.com/community...id-snails.html

Although it said salad leaves, spinach is the closest I have in my home at the moment. I guess I'll find out if it works tonight, as the snails apparently are active at night. I think the snails came with mine from the store, as I found the first one right as I removed it from the plastic pot from the store. Glad to hear you haven't had them; from what I've read they can be difficult to get rid off, so going to do what I can for mine.

Actually, that has nothing to do with light level nor anthocyanin.

Notice how they start out with yellow and then turn brown in the center, and then the whole thing turns black. These are called necrotic spots.

Many of these Oncidium Intergeneric hybrids tend to exhibit this symptoms.
I have read some perplexing stuff about them, from harmless "Oncidium thing" to pathogenic in origin like fungal and viral. I think it is more like case by case and it just is nearly impossible to tell by just visual inspection.

I stopped growing certain Oncidium hybrids that gets spotty easily. It just grossed me out and took the fun of the hobby out of it, so I said bye. much happier since! :)

Last, for the practical note, I don't think these spots generally jump on other plants easily. At least I haven't seen it going around in my collection in the past. but then I only had the spotted ones for just a little while and got rid of them all, though. didn't want to take a chance.