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Mirror lens: Perkin-Elmer 680mm f/12 Compact Telephoto
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PostPosted: Sun Apr 04, 2010 9:35 pm    Post subject: Reply with quote
Much appreciated inputs, in more than one way. I'll be at it. Smile

PS. Camera used is a 1Ds markI, and the lens focuses down to appr 35 feet.


PostPosted: Mon Apr 05, 2010 12:01 am    Post subject: Reply with quote
One test you could do is to find a long textured wall (brick or something similar), and stand so that you are relatively close to it but looking down it the long way. Find a distinct point a moderate distance down the wall, then focus on that. The idea is that once the picture is taken, due to the angle of the wall it is guaranteed that at least SOME point of the wall will be in focus, even if you were a bit off on your focusing.

Essentially, it is a large scale version of the "ruler test" that people do to see if their AF is focusing correctly, or if their focusing screen is calibrated correctly.




This would be a quick way to determine if the sharpness is a focusing issue or a lens issue.


PostPosted: Mon Apr 05, 2010 11:22 am    Post subject: Reply with quote
What kind of adapter you are using (source, with or without chip etc.) ?

Wink


PostPosted: Thu Dec 02, 2010 2:46 am    Post subject: Reply with quote
Bump For Scheimp!


PostPosted: Thu Dec 02, 2010 7:39 am    Post subject: Reply with quote
Thanks mo. Cool

I was reminded of this thread by another one about solid cats... Thommes, were you ever able to get satisfactory results out of your lens?

I took another look at your sample photo... It actually responded pretty well to some post-processing:


There was about 6 pixels of diagonal motion blur, which was probably the biggest impact to the sharpness. I fixed that the best I could, then applied a bit of large radius USM to change the contrast, and the photo above was my result. It's certainly not perfect (several JPG passes through different programs, and fixing motion blur essentially can't be done without artifacts)... but I think it shows that your lens has some potential. Cool


Here is the original again, to make it easier to compare them:
ulfengen wrote:
Attached is a typical image.


(both photos can be clicked on to view their full size versions)


PostPosted: Thu Dec 02, 2010 11:26 am    Post subject: Reply with quote
Hi, sorry, I must admit that I almost gave up on this project, but you have given me some new hope. - can I ask how you measured that there was 6 pixels motionblur? - I am using a simple dumb (no chip) m42 adapter. - I will do some more tests and come back with them - thanks again for the encouragement Smile


PostPosted: Thu Dec 02, 2010 8:06 pm    Post subject: New test samples - taken w 40D - new tripod - remote trigger Reply with quote
I tried to pull them as far as possible, too far if you ask me .... Confused

You find them at:
http://s1213.photobucket.com/albums/cc471/ulfengen/

what has happened to this lens I dont know, are the mirrors decaying over time?

Maybe I am doing something horribly wrong.

I remember I also tried to take away the thin glass at the rear to see if that had decayed, but to no avail.

If I compare to this http://www.mflenses.com/gallery/v/russian_lens/3m-6a/3M-6A-500mm_f6_3-08.jpg.html? ... no comment needed


Comments and suggestions are very welcome.

yours
Thommes
Norway


PostPosted: Sat Dec 04, 2010 6:13 pm    Post subject: Reply with quote
I feel like a complete fool, which I am when it comes to this ...

I WAS making a mistake, I had no idea that the field would be that shallow, until I discovered the zoom function in live-view on my 40D ....

focus corrected, about 35 feet to object:
http://i1213.photobucket.com/albums/cc471/ulfengen/_MG_7622corrtopazinfocus.jpg

original:
http://i1213.photobucket.com/albums/cc471/ulfengen/_MG_7622.jpg

... will do a couple of new outdoor tests tomorrow, if the sun is out, .... and I do not freeze my fingers off ... Smile


yours sincerely
Thommes
Norway


PostPosted: Sun Dec 05, 2010 2:09 am    Post subject: Reply with quote
So you were missing the focus? Yes, you don't have much margin for error with these lenses. If focus is not spot on, the shot is lost. And because this lens is very slow, you'll need a lot of light or good stabilization.

Can you post some photos of this lens? The auction link doesn't work anymore.


PostPosted: Mon Dec 06, 2010 7:08 am    Post subject: Reply with quote
ulfengen wrote:
Hi, sorry, I must admit that I almost gave up on this project, but you have given me some new hope. - can I ask how you measured that there was 6 pixels motionblur? - I am using a simple dumb (no chip) m42 adapter. - I will do some more tests and come back with them - thanks again for the encouragement Smile


No problem! Cool

The motion blur was a bit hidden at first... I can't say that I noticed it the first time around due to the general lack of contrast or hard edges. When I tried some basic USM however, I noticed that on the closest roof line, the white edging on the right side was considerably sharper than the edging on the left... so that was the giveaway that there was motion blur, and that it was more-or-less aligned with the slope of that right roof section.

I then grabbed an old copy of "Focus Magic" to fix it... which does an OK job but leaves much to be desired... I think 5 or 6 pixels was the input I ended up giving Focus Magic to correct the motion, and as I had thought, an angle similar to that right roof line gave the best result.


ulfengen wrote:
I feel like a complete fool, which I am when it comes to this ...

I WAS making a mistake, I had no idea that the field would be that shallow, until I discovered the zoom function in live-view on my 40D ....

focus corrected, about 35 feet to object:
http://i1213.photobucket.com/albums/cc471/ulfengen/_MG_7622corrtopazinfocus.jpg

original:
http://i1213.photobucket.com/albums/cc471/ulfengen/_MG_7622.jpg

... will do a couple of new outdoor tests tomorrow, if the sun is out, .... and I do not freeze my fingers off ... Smile


Wow, that is a considerable difference! Shocked

I imagine that being a f/12 lens, the lack of light probably makes it harder to focus as well...

I look forward to your next set of tests. Cool


PostPosted: Mon Dec 06, 2010 8:32 am    Post subject: Reply with quote
Thank you for responses and explanations Smile more images will follow shortly.

Thommes


PostPosted: Sun Feb 20, 2011 7:48 pm    Post subject: Reply with quote
A friend brought me a Perkin-Elmer 680mm f12 asking if the mount can be changed.


PostPosted: Sun Feb 20, 2011 9:15 pm    Post subject: Reply with quote
lbailey wrote:
A friend brought me a Perkin-Elmer 680mm f12 asking if the mount can be changed.


Welcome to the forums! Cool

What mount is on it, and what mount do you need?


PostPosted: Sun Feb 20, 2011 9:30 pm    Post subject: Reply with quote
It has been more than 30 years since I dealt with this keep of equipment and I cannot identifly the brand name of the mount. It has locking ring withn three grooves. I tried to post pics but got an error message. A nikon mount would be nice. I'm currently using a Nikon D200.


PostPosted: Mon Feb 21, 2011 1:33 am    Post subject: Reply with quote
Welcome to the forum, Larry. As an anti-spam measure, this place is set up so that a new member cannot post images in the first message. Now that you've posted two messages, you can post images.

Looking forward to seeing that old Perkin Elmer optic. Hopefully its mount is something a T-mount can be used with?


PostPosted: Mon Feb 21, 2011 1:50 am    Post subject: Reply with quote
Still not letting me upload pics


PostPosted: Thu Feb 24, 2011 4:50 pm    Post subject: Reply with quote
Michael.

I there another way for me to send pics of the lens and mount to you?


PostPosted: Thu Feb 24, 2011 6:14 pm    Post subject: Reply with quote
Well, yeah, you could send them to me as email attachments, but I'd rather you figure out how to post your images here for us all to see.

There are two ways you can do it. If you have a site on the internet where you can store your images -- like with a hosting service, for example -- you can then provide links to them using the {Img} button above: Click on {Img}, paste the link, then click on {Img} again. Or you can upload them to the mflenses server.

I've never uploaded images to the server here, so I don't know the procedure. Hopefully someone else can chime in with directions to do this.


PostPosted: Thu Feb 24, 2011 6:44 pm    Post subject: Reply with quote
http://www.pbase.com/bailliwick/680mm_lens

This is a link to pbase where I have posted the pics of the lens.

thanks for the help


PostPosted: Thu Feb 24, 2011 9:22 pm    Post subject: Reply with quote
Very interesting, Larry. That lens looks to be very compact for a 680mm.

Let's see if this works . . .





Yep!


PostPosted: Thu Feb 24, 2011 9:41 pm    Post subject: Reply with quote
Looks like a Canon FD mount.


PostPosted: Thu Feb 24, 2011 11:24 pm    Post subject: Reply with quote
Michael,

I can't read what ypu posted. There are only small boxes with x's in them.

Larry


PostPosted: Thu Feb 24, 2011 11:26 pm    Post subject: Reply with quote
My mount is easy to remove with only a retaining ring. The ring also has a glass element in it.

Larry


PostPosted: Fri Feb 25, 2011 3:52 am    Post subject: Reply with quote
lbailey wrote:
Michael,

I can't read what ypu posted. There are only small boxes with x's in them.

Larry

I upload the photos to the server. The mount should be T mount or something similar.





PostPosted: Tue Apr 18, 2017 10:03 pm    Post subject: Re: Trouble, asking for advice: Reply with quote
ulfengen wrote:
Hello friends, after some time I finally figured out that this was not a T2 lens (it came with a T2 adapter attached) but a std M42. Which is great.

But I also found out that the images are hopelessly washed out and milky/hazy. Not sharp at all, at any distance.

I have put a std rubber sun-shade on the lens, to fend off light hitting the front element, but to no avail.

What are the steps I should pursue to resolve this? 1 - 2 - 3 ...

Thommes

PS. The lens is quite easy to pick apart, so Id love to hear if there is something I could do myself. Attached is a typical image.



Have you tried the lens with a film camera?

I do not know what has given rise to your washed-out results. However, this series of lenses seriously predates the digital era, and was not designed with digital cameras in mind. In particular, the rear filters are not provided with adequate coating. They can interact with digital camera sensors, depending on the camera body.

If it is inconvenient to use a film camera, I suggest you test on a digital camera with the rear UV/haze filter removed entirely. After all, you have nothing to lose. Sure your washed-out result could be owing to something else. But taking a couple of shots without a filter is easy to do and it is worth a try. Good luck.
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