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06-09-2014, 01:04 AM   #751
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QuoteOriginally posted by jacobsr Quote
Hey rendition, where do you get all these lenses?
cool stuff. Lots of lenses lots of fun.

JR
Hi jacobsr. always ebay. I'm always looking for cheap/good deal. I got all three Arco-cine lens for less than $30. Though I think I'm about to be done with looking for D-mount len as I collected a few and I should take picture instead of hoarding lens

Anyway, here's a picture of the Arco-cines.


The 6.5mm f/1.4 does not vignette BUT it has this weird corner blurring at wide-open aperture that I have not seen anywhere else with my other lens...Other than that, very good cine 8mm lens.


Also, we have a tiny group of Pentax Q on facebook https://www.facebook.com/groups/1384395448506058/

I also did a detail post on one of the D-mount len Votar 38.1mm f/1.4 that I converted to C-mount that can dual mount on both Pentax Q and m43 (Olympus EPL5) and can reach infinity focus.

https://www.facebook.com/media/set/?set=a.1385551445067014.1073741831.100008...1

06-09-2014, 10:01 AM   #752
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Index updated, thanks for the submissions.
06-09-2014, 02:33 PM   #753
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What lens?

Pardon my ignorance, but can somebody please tell me what lens or what mount this is? Would it work on the Q? I can't seem to figure out the focus point either.
I got this lens from a thrift store for about $5 and I think I wasted the money. What do you think? Please help, and thanks in advance.


Jacob
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Last edited by jacobsr; 06-09-2014 at 02:39 PM. Reason: add text
06-09-2014, 02:50 PM   #754
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QuoteOriginally posted by jacobsr Quote
Pardon my ignorance, but can somebody please tell me what lens or what mount this is? Would it work on the Q? I can't seem to figure out the focus point either.
I got this lens from a thrift store for about $5 and I think I wasted the money. What do you think? Please help, and thanks in advance.


Jacob
hi Jacob:

From your picture it is look like one of those non-focusing C-mount TV Zoom Canon/Minolta zoom len. Unfortunately, some TV Zoom len are NOT mean to be removed from the camera body as it still has its REAR element inside the camera body. In your case, someone removed the len and FORGOT to remove the rear element that still remained inside the original camera body, and therefore rendering your zoom len nonfunctional since it is missing the rear element that focuses the light rays. You will need to find another rear element to adapt otherwise put it on a display case

One thing I learned from looking online/browsing through thrift store is to HOLD UP your len and see if an image circle is forming from a small distance. If there is no image circle forming, in all likelihood it is missing a rear element.


There are more knowledgeable people on this facebook group (C-mount) that can answer your question https://www.facebook.com/groups/cmountm43/

I attached a proper C-mount Navitar TV Zoom 16-160mm f/2 which makes it a telephoto len 89.6mm to 896mm. I got this online for $40 (a bargain!) and there is NO label on the LEN. It can do close up and infinity focus.






Last edited by rendition; 06-09-2014 at 03:27 PM.
06-09-2014, 03:48 PM   #755
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I think you are right about the rear element, rendition. I did not think about that.
It explains why I can't find the focal length or focus point on this lens. I tried to mount it on the Q with varied distances from the sensor and I can't get anything but a complete blur.
I was puzzled looking through this lens, normally I thought the image should look upside down, but not this lens, the image is right side up. And you can see clearly like looking through glass. So I was suspecting something wrong, but what do I know. I'm still learning.
Thanks for your quick response rendition, I learned something, and I appreciate it.

Jacob

Last edited by jacobsr; 06-09-2014 at 03:59 PM. Reason: missing text
06-09-2014, 04:48 PM   #756
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The Q maybe too thick to focus with this lens.Try holding the lens up (without camera) and use a bit of white paper at the back. Move paper to gain focus. Good luck.
Have fun.
barondla
06-09-2014, 08:48 PM   #757
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Desert Noon - Pentax Q + D-mount Yashinon 38.1mm f/1.4

06-09-2014, 11:51 PM   #758
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Above - Pentax Q + C-mount Computar TV Lens 8mm f/1.4



06-10-2014, 03:10 PM   #759
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"High Noon #1" - Pentax Q + Yashinon 6.5mm f/1.4 at f/8 composite shot




"High Noon #2" - Pentax Q+ Arco-Cine 38.1mm f/1.4

06-10-2014, 04:14 PM   #760
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QuoteOriginally posted by rendition Quote
"High Noon #1" - Pentax Q + Yashinon 6.5mm f/1.4 at f/8 composite shot




"High Noon #2" - Pentax Q+ Arco-Cine 38.1mm f/1.4
You might want to split the post, the needs for the index is one lens type one post
06-11-2014, 11:41 AM   #761
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Hi GUB,
Your posting about using the ring binder reinforcing rings on 110 lenses (post 661) was great and is an excellent idea. That inspired me to think of another way that might be easier to stop the 110 lenses. And that is by using a black rubber washer with centered hole, inserted in the 110 adapter.

If you or who ever is interested in this method of stopping down the 110 lenses. Get yourself a thin black rubber washer with smooth surface, approximately the same diameter size of the adapter. You can purchase these washers from any hardware store for about .50 to .70 cents. They are already black and with the hole centered. The hole in the washer is even smaller than the ring binder reinforcing rings, I'm guessing the f stop equivalent around f5.6 or so.
Before use I would wash it with soap and water to get rid of factory chemicals and other residue.

I don't know what kind 110 adapter you have, mine is by generic, there is a ridge inside my adapter where you can insert the washer and let sit against it. If yours don't have it I think it will still work.

My washer is a bit oversized. I like it that way, so I kind squeeze it into the adapter. I push the center of the washer with my index finger from the rear of adapter until it hits the ridge then push a little more to get the curve shape I want, so the hole in the washer almost touches the rear element of the lens. The washer can stay there permanently if you want, and It's easy to remove with a reverse push of your finger. I leave mine inside most all the time, that way when I change lenses, they're already stopped down.
I hope this works for you as it worked for me.
Jacob
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PENTAX Q10  Photo 
View Picture EXIF
PENTAX Q10  Photo 
View Picture EXIF
PENTAX Q10  Photo 

Last edited by jacobsr; 06-11-2014 at 12:11 PM. Reason: Add text
06-11-2014, 11:33 PM   #762
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18mm f2.8 110 lens

To see any improvement when using the rubber washer on the 110 lenses, I took some test shots and most of my four lenses were tested showed considerable improvement in image quality. It seems to me that the wider the lens the greater the improvement.
Here is a sample of a test shot using the 18mm lens, the upper photo is using the bare 18mm lens at f2.8.
the lower is with the rubber washer I'm guessing is at f5.6. Both photos are a crop from a shot taken at a great distance with the same focus point.

Jacob
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06-12-2014, 02:20 AM   #763
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Massive improvement jacobsr !
The face of the washer looks quite reflective, maybe a shot of matt paint would knock it back a bit.
06-12-2014, 09:20 AM   #764
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QuoteOriginally posted by Transit Quote
Massive improvement jacobsr !
The face of the washer looks quite reflective, maybe a shot of matt paint would knock it back a bit.
Yes I agree, very good that you've noticed and I'm glad you've mention it.
Just to show it will work the way it is, but you are right, with darker black matt paint to the washer I believe the image quality will improve even more.

Thanks for your comment
Jacob

Last edited by jacobsr; 06-12-2014 at 10:18 PM.
06-14-2014, 03:17 PM   #765
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Pentax 110 70mm f2.8 lens

I shot these through the window, Pentax 110 f2.8 70mm lens at f5.6 using rubber washer (post 761) inside the 110 to Q adapter.
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Last edited by jacobsr; 06-16-2014 at 12:15 PM. Reason: add text
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