Cleaning rear element on Pentax 110 70mm f2.8 lens

I've almost got a complete set of these beautiful lenses (still missing 18mm, the zoom lens and the teleconverter), but the 70mm arrived with some drops of what looks like oil on the inside of the rear element, and I couldn't, for the life of me, figure out how to disassemble it for cleaning. Not only the rear mount has no screws but also no notches to span the holding ring out of place.

Here is the lens in question:

In fact, the only screws that I could possibly see were the three extremely tiny ones in the middle of the lens, just under the rubber ring, but I dismissed them because it didn't seem like good idea to disassemble the whole thing and get to the rear element from the other end.

Well, those were actually the only screws in this lens and they held the whole thing together. The mechanical construction is very simple, especially that there is no aperture diaphragm mechanism or anything. Just two groups of beautiful glass screwed into each other for focusing.

To begin the disassembly, you need to first remove the three very tiny screws hidden under the rubber ring.

That's it. You're done. Unscrew the whole lens into its two main parts. Basically you have the cone-shaped front group, and the rear group is screwed into the rear mount from the inside. The ring with distance-markings functions as a limiter so you don't turn beyond infinity or closer than 1.5m (this lens's closes focusing distance) and also prevents you from disassembling it when the small three screws are in place. You should end up with this:

From left to right: rear cap, rear mount, rear lens group, distance marking ring and limiter, front group, front cap.

The glass looks very beautiful on the inside. Be very careful not to touch it, get dust into it, and be especially careful not to touch the focusing threads with the rear groups glass because it's greased.

Because I'm after the rear-most element, I'll need to attack this part to the right:

The rear element is held in place with a retaining ring that is screwed in place. I still could not tell whether it's glued or just a bitch to turn, but I used the minutest amount of WD-40 on the sides away from the glass making sure the amount is less than to run anywhere anyway. I waited until the next morning and.... nothing. Still wont turn.

Trying to turn it with my two bare fingers didn't help. I heard these retaining rings are usually so thin that when you press them with your finger you can deform them ever so slightly, enough for them to resist turning. The only solution is to span or turn from many different points on the periphery at the same time. I decided to use a whiteboard marker's cap because the size was right, and I simply cut some electrical tape to add thickness and grip to the ring.

With a couple layers of tape, however, my fingers were able to turn to thing out of place without the need for the cap, and so I could finally access the rear element.

You should be able to see the couple of layers of black electrical tape that helped me span this thing out of place.

Here's the rear element. As you can see it is made up of two glass elements cemented together. All the more reason for you to be extremely careful and not to get anything like WD-40 anywhere near this thing.

I cleaned the element, the retaining ring, and where it's supposed to go in the rear group, put it all back together and the lens was back as new (aside from a mark I caused when I first tried to turn the rear ring without disassembling the lens... needless to say, not a good idea).

And here is my Pentax 70mm f2.8 on my DiY-gripped EOS-M using my own DiY P110-to-EOSm adapter. Covers the whole frame and produces beautiful pictures.

Please share your thoughts or let me know if this was of any help to you.

DIY grip for EOS M

Before I move on to the science of using things not as their makers intended, I'll share a very simple but extremely useful DIY grip for the Canon EOS M mirrorless camera body.

If you have an EOS M and you've tried to use it for video recording, then you must be aware of a major design flaw in this handsome little gizmo. Since most video recording is done handheld, it is very difficult to stabilize the flat little thing. This, however, is not the major problem.

What often happens is that whenever the camera shakes, and this happens more often if you're using a bigger EF lens probably, your finger will turn the ring around the shutter release back into photo mode, thus cutting off your video recording.

By the time you realize what just happened, your moment is gone bye bye.

You cannot turn back the hands of time, but you can definitely do something to prevent this from happening again. All this camera needs is a little thickness to grip on so you can stabilize the camera without losing its balance and switching it to photography mode, so of course you will go to your trusty search engine and look up "EOS M grip" and find nothing.

That was the first step. Second, you will make one on your own.

I used thermal plastic to make my grip, which is basically a plate the size of the bottom of the camera that protrudes a little to the front at the right side, where it extrudes upwards to form the grip itself.

It works really well, does the job, and the best part is that it will never scratch the camera. You can actually mould it on the camera body while the plastic is still soft, or even press your fingers to create a grip that is perfect just for you.

Initially I only had the thermal plastic as my grip, but it didn't look particularly pretty. Not because it was white, but because, due to the difficulty of molding and shaping this thing, it will almost never end up looking "even". So I simply got the grip section out of an old Canon EOS 1000F SLR camera that I had turned into pieces a long time ago, and molded the plastic into it. Now it's black and even has texture.

Make sure you put the grip at a distance far enough from the lens for your fingers to slip in and give you a good hold. The 1000F grip will protrude a bit outside the camera body on the right side but that's alright because that makes it an even better grip. You can use the thermal plastic to fill in the cracks and crannies to smooth the contours and corners of your creation. I didn't do that because I didn't want to leave the gas on. I'm saving for my next energy bill. I'm on a budget remember?

Total cost is a few quid for the thermal plastic that you can use and reuse, probably a pound or something for the 1/4" screw unless you have one lying around, and maybe £3 if you wanna buy a broken EOS SLR camera to take the grip form. You can even take the female 1/4" tripod mount from the old EOS SLR, mold it into the bottom of your grip's plate to create an extra tripod hole. This works well if you thicken the plate enough to cover the thickness of the 1/4" screw you've used to mount your grip on the camera. This way you can have a replacement screw mount right next to it, and at the same level. Try it out!

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Disclaimer: apparently, Canon is now aware of this problem that I've just talked about and produces the EH23-CJ half case which is supposed to address this problem. My DIY grip was made well before this came out, and I've only learned about this case today as I was writing this blog entry. If you have £40 to spend on half a case that gives you the grip you want then go for it. If I had £40 to spend on this issue, I would have kept my cooker on a bit longer to refine the shape of my grip instead.

First Post

Hello. This is my first post in this blog dedicated to photography on a budget. So who am I and why photography on a budget?

My name is Noah. And I'm on a budget.

I'm actually a student in a country that is not home. I have expenses to worry about, rent and bills to pay, and a family to warm and feed. My resources are limited because I am not allowed by the law to have a full time job, and I can hardly find a part-time job anyway because of both my supposed commitment to my research as my current raison-d'être, and because the job market is simply hard as it is. So I'm not actually a photographer in the professional sense. I do not make money out of any photos that I take, yet; but neither do you, otherwise you wouldn't be here.

I caught the photography bug a couple years ago, and ever since I have developed a case of G.A.S. leading me to want to put my hands on almost everything, which in fact is a good source of distraction from the many depressing things happening in my life.

There is always something I want to touch. And it feels good when I do.

In this site, I will blog anything I think is worth mentioning about gear that I put my hands on. I will talk about what you can do with things you have available at your disposal. I will also blog any DIY stuff that I come up with. I did come up with a couple interesting things so far so this blog might be worth a bookmark.

Who am I?

I'm a photographer on a budget.