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3M-5A 500mm - Some questions
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PostPosted: Sat Jul 13, 2013 1:34 pm    Post subject: 3M-5A 500mm - Some questions Reply with quote
Hello everyone!

I recently have bought a mirror lens - a 3M-5A 500mm f8 - and I felt a bit disappointed with the IQ. Below are some samples I took with the lens, I was using a tripod and a 2sec retarder.

So I was wondering if I could have any better IQ or if the lens limits were already reached ?..

1.


2. This picture was taken at 1/1000 and I applied some PP on it.


3. Taken at 1/350


PostPosted: Sat Jul 13, 2013 2:22 pm    Post subject: Reply with quote
Hi!

What, exactly, don't you like about the IQ?

1. The fine detail looks quite good, though it's hard to tell where exactly you focused. What equipment did you use, what aperture? Perhaps the lack of perfect focus is your issue?

2. What issues do you see here? Total resolution?

3. 1/350s is quite slow for a 500mm lens, particularly on a crop camera, which you most likely have. Even on tripod, unless your camera has no shutter actuation or mirror vibration.


Cheers!


PostPosted: Sat Jul 13, 2013 2:39 pm    Post subject: Reply with quote
To my understanding, f/8 is the only aperture. When I look at mirror lens results, I rate based on lesser expectations. This looks pretty good based on those expectations, but when compared with normal glass optics, not at that level. I had just looked at performance from a Prakticar 500/5.6 and was quite impressed, but the downside is the size and weight difference.

Since the aperture is fixed and the camera was already on a tripod with delayed shutter release, I don't think anything more can be done except skillful post processing.


PostPosted: Sat Jul 13, 2013 3:19 pm    Post subject: Reply with quote
I have found that it takes some time getting used to shooting a mirror lens. Back in the 80s, when I first bought my Sigma 600mm f/8, I was convinced early on that the lens was no good. But I kept practicing with it and found that, as I grew more familiar with it and as my technique improved, so did the images. One of the things I found to be quite useful back then was an eyepiece magnifier. That allowed me to adjust critical focus, and it really improved my images. With my DSLR, which has Live View, I can emulate the eyepiece magnifier by selecting either a 5x or 10x magnification of the image.

Just recently I took some evaluation shots with my Tamron 55BB mirror. One of the things I like about the Tamron is the almost 360 degree focus throw. A tighter focus throw makes focusing very touchy. And I was surprised when viewing my subjects at 10x magnification that just the slightest touch of the focusing collar would push the image out of focus. And that was with the Tamron and its very long focus throw. I didn't even want to think about what it would have been like, trying to focus a mirror lens with a shorter focus throw than my Tamron.

Looking at your images, they look to be about what I would expect out of a decent quality 500mm f/8 mirror. With practice, you might even be able to eke out a bit more sharpness out of it. If your camera has a mirror up feature, try using it. If not, try setting your self-timer to 10 seconds. Two seconds, I've found, is usually not long enough to let things settle down so no vibrations are still present-- even when shooting with a very stout tripod.


PostPosted: Sat Jul 13, 2013 3:55 pm    Post subject: Reply with quote
cooltouch wrote:
Just recently I took some evaluation shots with my Tamron 55BB mirror. One of the things I like about the Tamron is the almost 360 degree focus throw. A tighter focus throw makes focusing very touchy. And I was surprised when viewing my subjects at 10x magnification that just the slightest touch of the focusing collar would push the image out of focus. And that was with the Tamron and its very long focus throw. I didn't even want to think about what it would have been like, trying to focus a mirror lens with a shorter focus throw than my Tamron.


After I started using my NEX with the magnified focus aids I too was struck by how little a movement of the focus would take an image from perfect to something less. This made me realize that many of my earlier pictures taken with an optical viewfinder and my eye's best judgment likely were not in absolute perfect focus. Today with the aid I am getting 90+ percent of my shots perfectly in focus. It becomes just a matter of at what point on the subject where I focused.


PostPosted: Sat Jul 13, 2013 4:26 pm    Post subject: Reply with quote
Well, thanks you for your answer!

In fact, I compare those results with the ones I got from my achromatic refractor and the latter is way better than the mirror lens, which I found incredible.. (I thought those russian mirror lens would be better than any "cheapish" - especially achromatic - refractor paid 200€...).

So I've already struggle with vibrations with my long gun. I set the tripod to the lowest height possible (ie, center column, etc) and I shoot "with care" ( Laughing I mean I push gently/softly the button to take the shot).

For the focusing, I use the x10 magnification (liveview) on my Pentax k-x..

glasslover wrote:

2. What issues do you see here? Total resolution?


This is that. I don't think there "is" sharpness in any my shots, surely a lack of resolution. I was wondering if the mirror lens would need a collimation ? But I don't know how I can do it..

I also have a Pentacon 300mm f4 which is a wonderful lens, but maybe I expect too much from this mirror lens? I would have loved to buy the 500mm f5.6 but it is a bit too expensive to me.



cooltouch wrote:
Looking at your images, they look to be about what I would expect out of a decent quality 500mm f/8 mirror. With practice, you might even be able to eke out a bit more sharpness out of it. If your camera has a mirror up feature, try using it. If not, try setting your self-timer to 10 seconds. Two seconds, I've found, is usually not long enough to let things settle down so no vibrations are still present-- even when shooting with a very stout tripod.


This is interesting. I always had the impression that 2sec was not enough for my refractor and I think it is. My Pentax permits me to use 10sec timer but the mirror is only moving a few msec before the shot (as a normal shot), so it's useless... I will buy a camera remote, I think this can help me!

EDIT: I was also wondering why when I look view the liveview the "picture" seems razor sharp and when I shot the picture becomes blurry ? I mean, even at high speed on tripod..

EDIT 2: Here is another picture. Speed is 1/1500, ISO 1600. One can see the narrow DOF. I focused in the center of the image (or at least, I tried but it looked razor sharp in the liveview..). Tripod and 2sec retarder



PostPosted: Mon Jul 15, 2013 9:49 pm    Post subject: Reply with quote
DiY171 wrote:

In fact, I compare those results with the ones I got from my achromatic refractor and the latter is way better than the mirror lens, which I found incredible.. (I thought those russian mirror lens would be better than any "cheapish" - especially achromatic - refractor paid 200€...).


You should post some 100% crops. For comparison, this Tokina 500/8 review that I wrote includes some sample shots with 100% crops.

Most reflex lenses are not as sharp as decent refractor ones. They lack microcontrast and sometimes resolution as well, but you'll get very nice results with a bit of sharpening. The advantage over a refractor lens is portability and the fact that you may not need to use a tripod - unfortunately, these advantages are kind of lost in the Russian models that are large and heavy. But take a lens like the Tokina 300mm for MFT, and you've got a very compact and light telephoto.

DiY171 wrote:
So I've already struggle with vibrations with my long gun. I set the tripod to the lowest height possible (ie, center column, etc) and I shoot "with care" ( Laughing I mean I push gently/softly the button to take the shot).


I recommend using the 2 sec delay which does the mirror up on Pentax cameras as well as using the remote shutter control instead of pressing the shutter manually.

DiY171 wrote:
For the focusing, I use the x10 magnification (liveview) on my Pentax k-x..


This could be a problem because the LiveView implementation of the K-x is not very good. I used the K-x with mirror lenses for moon shots and I was never quite sure of whether focus was achieved. Better than using the OVF, but not optimal.

DiY171 wrote:

glasslover wrote:

2. What issues do you see here? Total resolution?


This is that. I don't think there "is" sharpness in any my shots, surely a lack of resolution. I was wondering if the mirror lens would need a collimation ? But I don't know how I can do it..


Mirror lenses can get out of alignment. This is what the solid cat designs were trying to prevent. But I would look into this only if the lens really performs worse than expected, which remains to be determined.

DiY171 wrote:
This is interesting. I always had the impression that 2sec was not enough for my refractor and I think it is. My Pentax permits me to use 10sec timer but the mirror is only moving a few msec before the shot (as a normal shot), so it's useless... I will buy a camera remote, I think this can help me!


Actually, with the 2 sec delay, the mirror should be lifted first. The remote will definitely help, because pressing the shutter will induce vibrations on a tripod.

DiY171 wrote:
EDIT: I was also wondering why when I look view the liveview the "picture" seems razor sharp and when I shot the picture becomes blurry ? I mean, even at high speed on tripod..


Because after you shoot, you zoom into the picture and you start seeing details that you couldn't notice in LiveView. LiveView may also apply a different kind of processing to the image.

DiY171 wrote:
EDIT 2: Here is another picture. Speed is 1/1500, ISO 1600. One can see the narrow DOF. I focused in the center of the image (or at least, I tried but it looked razor sharp in the liveview..). Tripod and 2sec retarder


Looks ok at this size.


PostPosted: Tue Jul 16, 2013 6:55 am    Post subject: Reply with quote
For lens tests I would reccomend to test without extender or reducer/Shapley lens. As far as I know these shapley lenses often correct some common image defects of a special optical setup. Without this setup the add optical abberations.

But from the full images quality does not look bad. 100% crops would be helpful.


PostPosted: Tue Jul 16, 2013 6:56 pm    Post subject: Reply with quote
Laurentiu Cristofor wrote:

You should post some 100% crops.


Well, if you click on my previous pictures, I think you have access to full size picture, so 100%..

Last weekend I took several pictures handheld and I must admit I was :

* Completely in love with the weight and size Cool
* Ok with the quality

I read somewhere that Attila said the 3M-5A was nearly as good as the Tamron mirror lens (please excuse me if I'm wrong Embarassed) but my results don't seem as good as the ones that come from the Tamron..

Laurentiu Cristofor wrote:

This could be a problem because the LiveView implementation of the K-x is not very good.


Could you please explain me this ? I often shoot with liveview (because I use long lens and the only AF lens I have is the da35 and the kit lenses).


Laurentiu Cristofor wrote:

But I would look into this only if the lens really performs worse than expected, which remains to be determined.


That's what I'm trying to find/determine Smile In fact, after some "real" shots (understand : no boring/test shots) I became a little more happy with this lens.

Now, it's more : "Could my shots get any better ?" or "Does the lens need alignment?" or any tips that could help me.

I think I'm too much into pixel peeping, I see a lot of "enthousiast photographers" that came to me and show their pictures, which are tack sharp..

All handheld :

1. 400 ISO 1/500




2. 800ISO 1/1500




3. 800ISO 1/350




There were no PP at all.

Last edited by DiY171 on Tue Jul 16, 2013 7:09 pm; edited 1 time in total


PostPosted: Tue Jul 16, 2013 6:58 pm    Post subject: Reply with quote
ZoneV wrote:
For lens tests I would reccomend to test without extender or reducer/Shapley lens. As far as I know these shapley lenses often correct some common image defects of a special optical setup. Without this setup the add optical abberations.

But from the full images quality does not look bad. 100% crops would be helpful.


I'm sorry I don't really understand. What is a Shapley lens?


PostPosted: Thu Jul 18, 2013 4:48 am    Post subject: Reply with quote
DiY171 wrote:

Well, if you click on my previous pictures, I think you have access to full size picture, so 100%..


Hmm, not sure how I missed that. I thought I clicked on the images already. Smile

Anyway, the lens looks ok to me. The roof and wall shots have good detail. The other two less so - could be stabilization or the strong light (direct or reflected) might have caused a loss of contrast due to some internal reflections. Mirror lenses can be vulnerable to strong frontal light, so you should try the lens in different conditions and see when it works best.

DiY171 wrote:

* Completely in love with the weight and size Cool
* Ok with the quality


That sounds about right. You can get better quality from a regular lens, but it will be larger, bulkier, as well as costlier.

DiY171 wrote:

I read somewhere that Attila said the 3M-5A was nearly as good as the Tamron mirror lens (please excuse me if I'm wrong Embarassed) but my results don't seem as good as the ones that come from the Tamron..


Never used the Tamron, but I heard similar statements from other sources. I think that once you figure out the limitations of the lens and when it produces the best results, you'll start liking it more.

DiY171 wrote:

Could you please explain me this ? I often shoot with liveview (because I use long lens and the only AF lens I have is the da35 and the kit lenses).


The easiest way is to try the implementation on a mirrorless camera - then you will see how much smoother the liveview image is. On the K-x (as well as on the K-7), the image is always "trembling" when you're zoomed in at high magnification, even on a tripod. That makes it harder to check focus than it is on the MILCs I used. I sure hope Pentax has fixed this aspect in their latest models.

DiY171 wrote:

That's what I'm trying to find/determine Smile In fact, after some "real" shots (understand : no boring/test shots) I became a little more happy with this lens.


Looks good to me.

DiY171 wrote:

Now, it's more : "Could my shots get any better ?" or "Does the lens need alignment?" or any tips that could help me.


I don't think the lens needs alignment and I also think that your shots will get better as you get used to what this lens can do.

DiY171 wrote:

I think I'm too much into pixel peeping, I see a lot of "enthousiast photographers" that came to me and show their pictures, which are tack sharp..


I'd venture a guess that they don't handheld a 500mm lens for those shots. It is one thing to get a sharp shot with a 200mm, another thing entirely to do the same with 500mm. Even if the lens is perfect optically, you'll be challenged to get the best out of it.

DiY171 wrote:

All handheld :


In #1 I think you have a bit of motion blur and you seem to have front focused with respect to the elements in the 100% crop
#2 again suffers from stabilization - focus seems to be on the neck. Strange that this looks the worst despite using the fastest shutter speed.
#3 is the best but again this seems to suffer from image stabilization - shutter speed is pretty low there though. Still, this is a very usable image that would look very good with very little PP.

BTW, you did set the focal length for the Pentax IS to 500mm, right?

I recommend more practice. A 500mm lens will be very demanding on your handholding technique. It is pretty much my limit for handholding on APS-C. Beyond that I tend to use a monopod or a tripod for reliable results. Brace yourself against something if you can; keep your elbows close to the body; breathe in, expire half the air, then hold your breath before pressing the shutter. And hold the lens from the front, to stabilize it better.


PostPosted: Fri Jul 19, 2013 8:17 pm    Post subject: Reply with quote
Laurentiu Cristofor wrote:

The easiest way is to try the implementation on a mirrorless camera - then you will see how much smoother the liveview image is. On the K-x (as well as on the K-7), the image is always "trembling" when you're zoomed in at high magnification, even on a tripod. That makes it harder to check focus than it is on the MILCs I used. I sure hope Pentax has fixed this aspect in their latest models.


Now I see what you mean, I'm 100% agree with you!


Laurentiu Cristofor wrote:

I don't think the lens needs alignment and I also think that your shots will get better as you get used to what this lens can do.


I will try this WE to do some more pictures with it Smile

Laurentiu Cristofor wrote:

I'd venture a guess that they don't handheld a 500mm lens for those shots. It is one thing to get a sharp shot with a 200mm, another thing entirely to do the same with 500mm. Even if the lens is perfect optically, you'll be challenged to get the best out of it.


In fact they never used such a long lens, only (quality) modern zoom such as a Canon IS @ 600€... I paid 50€ for this mirror lens, there is a big gap of price, isn'it ?

Laurentiu Cristofor wrote:

In #1 I think you have a bit of motion blur and you seem to have front focused with respect to the elements in the 100% crop
#2 again suffers from stabilization - focus seems to be on the neck. Strange that this looks the worst despite using the fastest shutter speed.
#3 is the best but again this seems to suffer from image stabilization - shutter speed is pretty low there though. Still, this is a very usable image that would look very good with very little PP.


In fact, I'm trembling sooo much, I need to control it. Sometimes even with a 200mm I can experience some troubles..

Laurentiu Cristofor wrote:

BTW, you did set the focal length for the Pentax IS to 500mm, right?


Of course ! One day I forgot I had set it to 50mm when I was used a 300mm lens, such a mess Laughing

Laurentiu Cristofor wrote:

I recommend more practice. A 500mm lens will be very demanding on your handholding technique. It is pretty much my limit for handholding on APS-C. Beyond that I tend to use a monopod or a tripod for reliable results. Brace yourself against something if you can; keep your elbows close to the body; breathe in, expire half the air, then hold your breath before pressing the shutter. And hold the lens from the front, to stabilize it better.


Thank you very much for your advice and comments, sure this helped me and will help others people !

Cheers!


PostPosted: Fri Jul 19, 2013 8:33 pm    Post subject: Reply with quote
DiY171 wrote:
ZoneV wrote:
For lens tests I would reccomend to test without extender or reducer/Shapley lens. As far as I know these shapley lenses often correct some common image defects of a special optical setup. Without this setup the add optical abberations.

But from the full images quality does not look bad. 100% crops would be helpful.


I'm sorry I don't really understand. What is a Shapley lens?


Oh, sorry, overred the "sec" in your "2sec retarder " and thought you used a kind of focal length reducer. These are sometimes called Shapley lens in astronomy.


PostPosted: Fri Jul 19, 2013 8:48 pm    Post subject: Reply with quote
ZoneV wrote:

Oh, sorry, overred the "sec" in your "2sec retarder " and thought you used a kind of focal length reducer. These are sometimes called Shapley lens in astronomy.


Nevermind, I learned something new Smile


PostPosted: Sat Jul 20, 2013 5:14 pm    Post subject: Reply with quote
Here are some shots I took today. I post them in the resolution I usually set on photos on the web. I must say I'm really impressed : used with the monopod and with good light, the 3M-5A can give beautiful results. I had to set ISO up to 800 and due to the PP (to add contrast) some noise can be visible in the background..


1.


2.


3.


4.


5.


6.


7.


8.


PostPosted: Sat Jul 20, 2013 6:32 pm    Post subject: Reply with quote
Nice shots! You have discovered a thing that is almost certain in 99,99% of the situations, good photographie needs good light!

Cheers,

Renato


PostPosted: Mon Jul 22, 2013 3:32 am    Post subject: Reply with quote
DiY171 wrote:
Here are some shots I took today. I post them in the resolution I usually set on photos on the web. I must say I'm really impressed : used with the monopod and with good light, the 3M-5A can give beautiful results. I had to set ISO up to 800 and due to the PP (to add contrast) some noise can be visible in the background..


Good job. I also think of these as "summer lenses" Smile I don't use them much during the rest of the year. You seem to have figured out how to exploit this lens. Keep them coming!
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