Home

Please support mflenses.com if you need any graphic related work order it from us, click on above banner to order!

SearchSearch MemberlistMemberlist RegisterRegister ProfileProfile Log in to check your private messagesLog in to check your private messages Log inLog in

Safe to subject a 25mm Super Comat f1.9 to a hair dryer?
View previous topic :: View next topic  


PostPosted: Thu Feb 28, 2013 1:33 am    Post subject: Safe to subject a 25mm Super Comat f1.9 to a hair dryer? Reply with quote

I acquired a Taylor Hobson 1" f1.9 Super Comat (the England version) c-mount lens. The good news is that the aperture ring is stuck at a relatively fast f2 permitting decent pics to be taken. The bad news is that the aperture ring appears immovable. I am pondering whether to subject the lens to hot air from a hair dryer to see if the ring loosens. Is there any damage this can cause?

Alternatively, I see a couple screws - one near the focus ring which works fine, and another near the aperture ring. Might this screw be put to some advantageous use?

Sorry about the jejune topic but hoping a cine lens expert might offer a pointer or two. TIA.


PostPosted: Thu Feb 28, 2013 4:20 am    Post subject: Reply with quote

A few drops of Naptha (lighter fluid) should do the job and some mild (!!) warm air. At least in my cases it did...


PostPosted: Thu Feb 28, 2013 6:10 am    Post subject: Reply with quote

I have dismantled some old cine lenses in the past, like Wollesaks and Kern Switars, and what often happens is the helical grease coagulates to the point that it takes on the consistency of paraffin or crayon -- like wax, in other words. When it gets like this, it will take more than a drop or two of naphtha to loosen things up. I ended up cleaning the dried stuff out from these lenses using dental picks, but I did use naphtha to help speed things along. In retrospect, it would seem that applying hot air would actually be a good idea because it will help liquify the wax.

Most hair dryers don't have enough heat output to damage the lens, I would think, especially if you're waving the dryer back and forth. In other words, I wouldn't just park the lens in front of the hairdryer and let it run for a long time.


PostPosted: Thu Feb 28, 2013 5:32 pm    Post subject: Reply with quote

kds315* and cooltouch

Thanks for the responses. I will give the hair-dryer a try. If it doesn't do the trick, I will try the naptha route. A few more questions if I may--

1. kds315* mentioned that naptha is the same as lighter-fluid. I do have a bottle of lighter fluid used for backyard barbecue -- is this the same thing?

2. Do I simply put a drop or two on the OUTSIDE of the lens near the gap between aperture ring and body?

3. Are the hair-dryer and/or naptha approaches temporary or permanent solutions? What I mean is will the gunk that's made thinner by heat or fluid solidify again in an hour or two?


Update: Hair-dryer did not do the trick. Instead, the c-screw-mount has decided to begin turning...ugh. The 3 screws at the rear near the mount look pretty tempting...hopefully I will hold off doing something rash until you guys see this thread again.


PostPosted: Thu Feb 28, 2013 6:29 pm    Post subject: Reply with quote

I usually put some naptha on a toothpick and apply it to the slit where the focusing is and hold the lens so that gravity allows the naptha find its way towards the helicoid inside. Usually 1..2 little droplets do. That after having warmed up the lens. THEN I let that work some 20-30 minutes and try to move it gently. Sometimes I repeat the process...

If that DOES NOT work, I send it to my lens service tech...


PostPosted: Fri Mar 01, 2013 4:36 am    Post subject: Reply with quote

new_berlin wrote:
kds315* and cooltouch

Thanks for the responses. I will give the hair-dryer a try. If it doesn't do the trick, I will try the naptha route. A few more questions if I may--

1. kds315* mentioned that naptha is the same as lighter-fluid. I do have a bottle of lighter fluid used for backyard barbecue -- is this the same thing?

2. Do I simply put a drop or two on the OUTSIDE of the lens near the gap between aperture ring and body?

3. Are the hair-dryer and/or naptha approaches temporary or permanent solutions? What I mean is will the gunk that's made thinner by heat or fluid solidify again in an hour or two?


1. Yes, naphtha and lighter fluid are indeed the same, although it's a lot cheaper when you buy it as naphtha. Your bbq lighter fluid is probably very close to naphtha, if not the same thing, and I would think could be used in its place.

2. Klaus gave a good answer to this.

3. No they are not permanent solutions, and yes the grease will resolidify. What has happened to the lubricant is this: its "light ends" have cooked off. In other words, the more volatile components of the grease slowly evaporated over time, leaving the heavy, waxy solids behind. Warming it up will work only for as long as its warm, and naphtha will just evaporate, leaving you where you were to start with. You need to replace the lube.


PostPosted: Tue Mar 05, 2013 11:46 am    Post subject: Reply with quote

I had a old lens which had been in storage for 40+ year.

The grease had actually crystallised


PostPosted: Sun Mar 17, 2013 9:42 pm    Post subject: Reply with quote

OP here and here's what I've been up to Smile

Lighter fluid didn't help. So I unscrewed all the screws (3 at the back, and 1 at front near aperture ring). I managed to unscrew the big parts and the result was what you see in picture 1.

Interestingly, when I took a toothpick and pushed the black part (pointed at with an arrow), it rotates silky smooth -- and guess what -- the aperture blades move beautifully. So I don't think the aperture blades are stuck. So I think the outside-apertureadjustment-ring is the problem, i.e the issue is more at the surface.

[img]

Picture 2 shows the aperture ring from up close. This ring does not budge at all. I removed 1 long screw from the hole seen but to no avail. Any ideas on how to remove this ring? Does it unscrew? I can't for the life of me see how this aperture ring moves the black cylinder seen through the T-shaped hole.

[/img]

Ideas on removing the outer chrome aperture ring would be great. If I know it unscrews, I would have more confidence forcing it with a tool. TIA.