No specialized equipment is needed, costs are low, and you dont need to actually control it within .1 degree C. You will never see the diffrence being .1 degree off, only a densitometer and color analyzer will be able to detect those differences. I say this based on personal experience devbeloping color slide film over the past year. Slide is the more difficult and sensitive of the two also (C41 is more tolerant). With slide, as long as you are within .5 degrees Celcius when you start processing, which is very easy to do using tap water from your kitchen sink and an inexpensive styrofoam cooler, you will get great results.
Here is what you need:
-a Paterson Hand Developing Tank. The 5 roll tank new is only $42 with free shipping. Or, get the 1 roll $25 tank.
Dead Link Removed
-a $10 digital cooking thermometer for measuring water temperature
-a $5 digital cooking timer/stop watch for accurately measuring time the film is in each developer
-a $3 styrofoam cooler, big enough to fit 3 bottles that will hold your color chemicals, and enough extra space to hold a good amount of hot/warm water. This is your hi-tech water bath system, although you could pay hundreds more for professional JOBO machine to do the same - and then worry about maintenance and repairs;-)
-3 empty 1.0L water bottles to hold your color chemicals. Dont use empty pop or fruit juice bottles, as the residual acidity can ruin the first developer solution. Cost - free to $3
-a glass measuring beaker from the cooking section of your local store, $5 maximum. you use this to mix up your color chemistry. what the heck, splurge and get 3 (1 for each chemical), so you dont have to worry about thoroughly rinsing between chemicals to avoid cross contamination.
-some rubber gloves and plastic eye protectant glasses, to protect your hands and eyse, should you accidentally splash or spill the chemistry. $5-10 total.
-the most expensive item, the film chemistry. recommend a $40-$100 Tetenal 1L - 5L kit. easy to use and mix up, gives fantastic results. German Engineering (chemistry made in Germany, these guys know what they are doing). Or the Kodak C41 chemistry (kodak is tops, but getting hard to buy in reasonably small quantities for the home user, otherwise I would recommend over Tetenal), or even teh Arista and Rollei kits. The 5 Liter Tetenal kit develops 60 rolls of slide film with great results, even on the 60th roll (I was sceptical, but it does indeed do 60 rolls without contrast or quality issues, and could probably do more if you want to exepriment.)
Freestyle Photo will begin selling the Tetenal kits in early July!
http://www.freestylephoto.biz/c1000-Color-Chemicals
That is it! You mix up your chemicals with water and pour into the empty water bottles. Fill the cooler with water at say 42-44C. put the chemistry bottles in the cooler water bath, this heats the color chemistry. let the water and bottles cool, checking temperature until the water bath (and bottles) reaches 38-38.5C, then you are ready to begin developing, and you have very precise temperature. Only the first step/first developer is really critical anyways.
You already loaded your film into the Peterson tank, like I do in my basement pantry at night with lights out (no windows). Or, you have a small film changing bag to do in a fully lit room.
Turn on your kitchen sink, adjust the water temperature to approximately 38-39C, then do a pre rinse. Fill the paterson tank with this warm tap water, then pour out. You just brought your tank and film up to temperature. Now, pour in the first developer (remember, its now at 38-38.5C floating in the cooler/hi-tech water bath), start the timer, and repeat for each of the 3 steps/developers using the time specified in the instructions.
Bam, then rinse with water a few times, and as the final step, you pour in the room temperature Stabilizer/preservative bath. Let sit 2 minutes in the Stabilizer, then pour back into the bottle.
You are now done. open that Paterson tank, and hang those beautiful slides/negatives to dry in your shower.
Low tech, easy, inexpensive, fantastic quality results (never again scratched negatives or ruined film at the lab), and did I mention - Fun! Put on some music in the background while developing, enjoy.