[Piotrek K]

I use rubber front "rings" for my 18 mm and 24 mm lenses, and was also not able to stop them down this way. But it also seems that they shade quite big part of unused front glass when used on the oiginal Q.




It looks, it looks like, well it works



This photo shows how tiny is 24 mm lens on the Q. And also why I think it is better to use kind of front ring then any kind of conventional hood - it would be to big compared to the lens.

The image below was made using 18 mm lens stopped down to 5.6 (aperture glued to the rear lens element) and fitted with front shade made from washer rubber and step down ring.

[hinman]

This raises my heart-beat when I visit this thread on Pentax auto 110 lenses, can anyone with a modification on the lens aperture please post pictures of the modification such as the front disk or the aperture disk. I tried before on Sony nex 5N but my f/5.6 blade is a black paper disk with black tape, it does stop down but not very feasible to use and exchange.


DSC02306
by Hin Man, on Flickr
shot with 70mm, don't remember if I stop down on this one

Thanks,
Hin

---------- Post added 05-10-15 at 04:24 PM ----------

110 50mm with Gubmod reinforcement stopdown

Do you have a picture of the Gubmod? I will share my attempts that don't work well before. Last I remember getting a bunch of tool and Lensbaby plastic disk for experiment but I go no where with the idea.


DSC02198
by Hin Man, on Flickr
shot with 24mm wide open, panned with Sony 5N


DSC02293
by Hin Man, on Flickr
failed variable disk as vignette happens quite bad on the aps-c sensor


DSC02291
by Hin Man, on Flickr


The variable disk don't work at all in aps-c attempt as the aperture hole is too far from the lens opening and hence blocking light to the sensor, may work better on 4/3 or the Q. Best disk that I have tried is have the disk placed as near as it can get to the back of my Kipon 110 to E adapter.


DSC00099
by Hin Man, on Flickr

The above is crude but the stop down seems to help a bit but I fall short in carrying this further. Any tips and help with Do you have a picture of the Gubmod? will re-kindle my interest with 110 lenses. I have 18 pan focus, 18 regular, 24mm, 50 and 70 and at one point I sold the 1.7x TC. I never have the close up filter or any of the original filters. Among the bunches, the 50mm is under-value, I think. The 24mm and the 18 pan-focus are the most fun one for me.

Cheers,
Hin

[GUB]

The image below was made using 18 mm lens stopped down to 5.6 (aperture glued to the rear lens element) and fitted with front shade made from washer rubber and step down ring

If I have thought this through correctly the 18mm @ f5.6 would only be using 3.2mm of the front glass. (18/5.6 => 3.2).
You should post an example of what you are doing on the adapted lens thread.
I am now thinking of using a disc on my M28 3.5 I do a lot of landscape with on my K30. DoF is not a factor in landscapes so I tend to use it at f5.6 or 8. So 28/5.6 => 5mm. So say a 7mm disc wouldn't affect anything but would cut out a lot of stray light.

[Piotrek K]

My DIY hood for 18 mm lens is little bit more "elegant" compared to 24 mm lens "shade" - I post some images below. It has 3 parts: 30 - 25 mm step down ring glued to deglassed 30.5 mm filter and small rubber washer.

[GUB]

My DIY hood for 18 mm lens is little bit more "elegant" compared to 24 mm lens "shade" - I post some images below. It has 3 parts: 30 - 25 mm step down ring glued to deglassed 30.5 mm filter and small rubber washer.

Nicely done.
The only thing that bothers me is the thickness of the rubber meaning the edge of the aperture is a cylinder with the potential to reflect random light. It is probably matt enough to not matter though.
My idea about the 28mm on my K30 above was really dumb. Due to the inherent DoF ability of the 28mm all I get is vignetting even though the disc is right on the glass.
And the concept of the iris aperture dimensions (mm) being focal length / intended f stop does not work at all in the 28mm. May be it is something to do with the retrofocus design of the 28mm intended for SLR work.

[Transit]

[B]Do you have a picture of the Gubmod?.....
Hin

sorry about the delay

It is a paper ringbinder reinforcement, blacked out both sides apart from a small ring that sticks on. This being the smc 110/50
...must blow some of that dust off
Pete

[GUB]

sorry about the delay

It is a paper ringbinder reinforcement, blacked out both sides apart from a small ring that sticks on. This being the smc 110/50
...must blow some of that dust off
Pete

Doesn't get more budget than that does it Pete?
The hardest thing is to stick the ring on central without getting your grubby little finger on the lens

[Transit]

I use an 'applicator' rather than the grubby finger
The economics of it improve with each lens converted

[hinman]

sorry about the delay

It is a paper ringbinder reinforcement, blacked out both sides apart from a small ring that sticks on. This being the smc 110/50
...must blow some of that dust off
Pete

That is so cool. You should think of running the modification service for a small fee. Is the ring-binder paper permanently attached or does it come back out at ease if you want it wide open for night time/indoor pictures?

Thanks,
Hin

---------- Post added 05-12-15 at 09:47 PM ----------

My DIY hood for 18 mm lens is little bit more "elegant" compared to 24 mm lens "shade" - I post some images below. It has 3 parts: 30 - 25 mm step down ring glued to deglassed 30.5 mm filter and small rubber washer.

Your solution is just as elegant but it is harder to reproduce your setup. Thanks for all the tips and inspiration.

Cheers,
Hin

[Transit]

That is so cool. You should think of running the modification service for a small fee. Is the ring-binder paper permanently attached or does it come back out at ease if you want it wide open for night time/indoor pictures?

Thanks,
Hin

I could start spitting them out but Gub would have to kill me
I just leave it on. I bump the iso and go mono if need be

[Piotrek K]

This lens is quite handy for close - up's. One can use it for butterflies/flowers standalone and for some smaller objects with its dedicated close-up. Quality-wise it is maybe not that good as my Nikkor enlarger lens, but it is versatile and in many cases enables to use really handy one-lens-setup for normal and 'macro' images.

The lens is stopped down to 5.0 - 5.6 as described earlier. First photo with the lens close to its MFD (25 cm), next two also with genuine Pentax close-up lens (W-21 diopter).

[CWRailman]

Anyone interesting in experimenting with the 110 lenses etc on the Q series cameras, I just listed some of these lenses as well as the adapter, lens baby disks, filters and other related items in the Pentax sale pages. If they do not sell here I will list them on Ebay but I thought I would give this group first chance.

[Piotrek K]

Before people here started to stop down the 110-lenses I saw also some reports stating that Pentax Auto-110 50 mm lens is sharp on the Q even with no modifications. So I want to ask if it is usable wide open?

There is a great thread here:
https://www.pentaxforums.com/forums/136-pentax-q/256849-comparing-adapted-lenses-q.html

...in which good results are shown with 50 mm lens stopped down, but if someone could share own opinion on its performance from normal use rather then testing I will appreciate this!

On the contrary I have nice genuine Pentax diopter for this lens, which I could use but rather when using improvised aperture. I found the diopter very useful with my DA 40XS lens on the DSLR, so I hope this should be great also in its natural environment.

[wombat2go]

I saw also some reports stating that Pentax Auto-110 50 mm lens is sharp on the Q even with no modifications. So I want to ask if it is usable wide open?

I just ran a "fence test" for you on the P110 50mm with no stop (f/2.8) and 4.5mm stop (f/11)
These are on M43, so you can crop to see the effect on your camera.
I focussed on the street sign.

No Stop
https://app.box.com/s/td5h83018kklml0wrd3t6e3d2sf1opjs
f/11 stop.
https://app.box.com/s/ceu3qwgetqi02r4lbiozh0r9srab99r7

The difference at image centre is not much.
However my earlier test( on PF way back) with Waterhouse on the P110 18mm indicated the stop is definitely needed on the 18mm.
The stop is positioned in my home brew adaptor according to this:
https://app.box.com/s/b9319930073aad14e911

Let us know how your lens turns out.

[Piotrek K]

I just ran a "fence test" for you on the P110 50mm with no stop (f/2.8) and 4.5mm stop (f/11)

Let us know how your lens turns out.

Thanks for this! I can confirm that for 18 mm the improvement is really big. But if 50 mm iż noticeably better wide open compared to 18 mm I hope with some PP work it could be acceptable without stopping down.