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Minolta 500mm F8 Reflex, can it be a bit sharper?

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David_Anim View Drop Down
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Post Options Post Options   Quote David_Anim Quote  Post ReplyReply Direct Link To This Post Topic: Minolta 500mm F8 Reflex, can it be a bit sharper?
    Posted: 13 April 2022 at 08:43
Hi everyone, been lurking for a few years, but this is my first post so I'll give a short introduction.

I've been an A-Mount user since 2011 when I purchased my first DSLR, the Sony A55. This camera was my main and I picked up a few other lenses along the way (Sigma wide 10-20mm, Tamron zoom 70-300mm and then I sold my kit lens and got the Sony prime 35mm 1.8). Loved my camera.. but then in 2019 the camera died. I figured, fair enough.. I'll upgrade to something new..
to my shock, A-mount had been discontinued.. and all of these new Sony cameras I had been seeing were all E-mount... heart breaking.
Because I was due to change mount anyway, and feeling a little betrayed by Sony.. I looked elsewhere.. with plenty of hunting and reviews, I ended up in Fujifilm land, using the rather vintage looking mirror-less XT-20.
turns out though, Fujifilm (at the time) lacks serious 3rd party lens support, leaving mostly very expensive Fuji lenses. they are amazing, but just damn expensive. Was happy to see that manual focus adapters exist, and getting A-Mount lenses on a Fuji-X body is cheap and easy.
so now all my A-mount lenses get used again with lovely modern fuji features. Since then I have actually purchased more A-mount lenses, mostly vintage from japan while bargain hunting.. My A55 eventually got sent in for repair so thats back in my roll out now too, so I can get AF on all those A-Mount vintage lenses.

TLDR: I use A-Mount on both A55 and Fuji XT-20


So recently, taking advantage of the currently crippled Japanese Yen...
I threw a bid on a Minolta 500 F8 reflex. Won it for an incredibly low price. According to the seller, the lens had spent most of its life in an electronic dry cabinet. Pretty good condition, lens hood and both filters included.

I took it out for a few test shots.. and was rather disappointed with image quality. Hard to get a sharp image.
I noticed there were some smears and other gunk on the primary mirror... so using a very helpful disassemble guide posted on these forums.. and a whole lot of nerve! I managed to open it up, and using a blower and microfiber cloth I wiped off most of the gunk from the mirror. I wasn't able to get it completely clean, as the cloth left some minor smears which I'd probably need some kind of special cleaning solution to completely remove.. being a vintage Mirror lens, I wasn't brave enough to try any solution so I let it be and reassembled.

It did make a huge difference... image quality greatly improved..

however it's still not perfect I have done test shots, in perfect lighting, tripod with shutter speed of 1000 or 2000 on stationary subjects like power poles down the street.

I have used both my Sony A55 with AF / MF and the Fujifilm adapted MF using MF assist features.
the Fuji actually gets a clearer image but that's probably because it's using de-noise/sharpening features.

the photos seem really good without any kind of cropping, but if taking photos of smaller birds, and I need to crop the image to half its original size.. the details just look out of focus when zoomed in.

I understand its a vintage lens, trying to survive in the digital world with a locked F8 aperture, so focusing must be done carefully with that shallow DOF.
but I just always imagined it would perform better than this. I'm pretty sure I've seen other users get better results on the forums, though I wouldn't know how far they are from their subject and cropping, etc.

So finally, for the questions.....

Can I get this thing sharper? Should I try my luck opening it again and can someone offer a cleaning solution to get the mirror completely smudge free.

Is there anyway to check if the mirrors have become misaligned.. or better, any way to realign them?

I've heard of other users adding their own extended lens hoods to mirror lenses to help with image contrast.. I'm willing to try this when I find something around the house to DIY a lens hood.

Or.. am I just pixel peeping too much? is the reality that my modern image sensors are just demanding too much from this old Lens.

I'll attach some images to show what I mean.







These were shot Using the Sony A55 and AF
to be honest, I think these are actually not so bad..

but then compared to these two..






worth mentioning, the power post was shot using my FujiFilm with adaptor, manual focus, and using electronic shutter.
The bird was again using the Sony with AF.

Perhaps the image quality drops as the subject gets further away, and also perhaps the mirror does not like when the lighting is too intense.. hence why they supply a dark filter?

Would appreciate any insight or thoughts from other Mirror lens users.
thanks for reading my long, bloated post.

Any thoughts?
 



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Jozioau View Drop Down
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Post Options Post Options   Quote Jozioau Quote  Post ReplyReply Direct Link To This Post Posted: 13 April 2022 at 09:07
David,
First of all welcome to active Dyxum involvement. Now you've dipped your toe in the water you'll find it's a warm place to be.

I've been a fan of the Minolta 500mm f8 AF Reflex from when I was using a Minolta 505si Super 35mm camera, and I've continued to use the lens through my various digital a-mount cameras through to this day. Most recently on a new a7iv body via an LA-EA5 adapter. In fact, I'd have to say the images I've captured with this lens on my a99ii and my a7iv (both pretty hi tech), are amongst the best I've got.

You can see sample images of mine (and others) in the Lens database here Minolta AF Reflex page5, and as you can see they are very much sharper, having better IQ than the samples you've posted.

I've never opened a Reflex lens, and wouldn't know what to advise, but I'd think your lens might do well with a service. That's the next challenge - in my experience Phototronics in New Zealand are excellent, but you do have to add the cost of trackable postage there and back. You could ask for a quote via <admin@phototronic.co.nz>.

Maybe others at Dyxum can tell you more about DIY?

Anyway, good luck with it all.




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Bob J View Drop Down
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Post Options Post Options   Quote Bob J Quote  Post ReplyReply Direct Link To This Post Posted: 13 April 2022 at 10:21
I've generally been impressed with the 500AF. Reflex lenses are rather good value for money when it come to reach.

I did an article over at 35mmc on it a few months ago: https://www.35mmc.com/26/10/2021/minolta-af-reflex-500-review/
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Post Options Post Options   Quote neilt3 Quote  Post ReplyReply Direct Link To This Post Posted: 13 April 2022 at 11:14
The images look to be more out of focus rather than soft/a lack of sharpness .
That's what you need to look at first .

Stand diagonally to a wall or fence and place a target on the wall/fence .
Focus on the target both manually and a/f , then review the images .
I've an idea that you might have a bit of back or front focus .
Don't forget a 500mm lens on a crop sensor camera ( so effectively a 750mm lens ) , even at f/8 still gives you very thin DOF .

EDIT ; just to add , the reason you stand diagonally to the wall is so you can see where the plane of focus AF has got in relation to the target .
The shot of a bird on a wire doesn't give any indication of the plane if focus .
Hence the test .

The image of the bird on the wire could also be down to atmospheric haze / pollution .
The further away a target is , the worse it gets , the hotter the day gives even more problems with a shimmering heat haze . Was the shot taken outside or through a window ?

A few things to rule out before you look for other issues .

Edited by neilt3 - 13 April 2022 at 13:40
see my photostream on flickr;
http://www.flickr.com/photos/neilt3/
C & C welcome.
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Post Options Post Options   Quote gigo Quote  Post ReplyReply Direct Link To This Post Posted: 13 April 2022 at 11:25
I just recently submitted two 500 Reflex photos to the "A-mount Retirement Party".
https://www.dyxum.com/dforum/amount-retirement-party-thumbnail-thread_topic140773_post1683388.html#1683388

New 1 and 3 were taken with 500 Reflex and not trimmed. As you can see, it's sharp enough. Since the A1 is a monster camera, any lens will bring out its full potential. In other words, 500 Reflex can be used practically enough.

I'm not sure why your equipment set isn't performing as it should, but I remember replacing the Minolta 500 Reflex with a SONY one to improve image quality. In the world of astronomical telescopes, it is known that the reflection type is more difficult to handle and painful than the refracting type.
Also, the reflection type generally requires four times the accuracy of the refraction type.

I made a long lens hood with a 3D Printer and it worked well but I haven't used it recently. Lightroom's PP is easier.

I've heard that Micro Focus Adjustment works, but I don't think the A55 had this feature. Since the distance measurement sensor and the image sensor are the same for mirrorless cameras, the optical path lengths of both sensors are exactly the same, so this function itself is unnecessary.
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Post Options Post Options   Quote SnowFella Quote  Post ReplyReply Direct Link To This Post Posted: 13 April 2022 at 11:30
Have to admit I haven't used my 500AF much as of late, it was always intended as a backup long lens for situations when I didn't want to haul along my dedicated birding lens. Though as I'm mainly a birder and hauling that big/heavy kit along is what I do 99% of the time has sat sadly gathering dust.

When I've taken it out though I have no issues with sharpness, may need a tad of manual focus at times to fine tune things but generally it seems rather spot on.

Few ancient examples.

DSC00164 by Johan Olsson, on Flickr

DSC00034 by Johan Olsson, on Flickr

Silly crop out of the above shot.

DSC00034-2 by Johan Olsson, on Flickr
 



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Post Options Post Options   Quote David_Anim Quote  Post ReplyReply Direct Link To This Post Posted: 13 April 2022 at 18:16
Thanks everyone! I'm really impressed to see so many instant responses, I was a little worried this might be
one of those times where I'm left waiting months just to get a single response on a forum.

Some more information on the situation, my profile says I'm in Australia, because I'm there most of the time,
but I also half live in Taiwan, where I reside currently. There are many old camera repair stores in Taipei,
I may contact them and see if any are familiar with the lens or mirror lenses in general.

Also worth noting, my lens in particular has 1988 printed on the mount... Which I suppose makes it from the initial line up.


@Jozioau
Oh this forum is great, I've visited Japan a couple of times and I love visiting the second hand camera stores.
any time I find a new Minolta lens, I can just jump on Dyxum and find everything about the lens from user reviews and the specs page. very useful.
You've got some good photos there, hopefully I can eventually pull the same quality with mine.
Whenever I return to Australia, I only get to bring about half a few of my lenses. Unfortunately, I don't think the 500 Reflex will be one of them,
so I can't see myself shipping it to NZ, thanks for the suggestion though, hopefully I can find someone in Taiwan capable of giving it a service, at least I suppose Japan is just a stone throw away.

@Bob J
Thanks Bob, I was also very impressed with the 500 going by the sample images I had been seeing. Really hope a good service can bring her up to speed.
I think I may have stumbled across your article earlier as I was making my final decision to purchase the lens, It's a good read.

@neilt3
I think that's a good suggestion, thanks. I'm not sure when I'll get the time to do more experiments like that but hopefully soon. All of the shots were taken outside, not behind glass...
I think you're right, focusing is definitely an issue. I've probably taken at least 100 shots with it by now, mostly by hand with the high shutter speed.
but all the ones I've uploaded were on tripod, I think the shot of the mango with the insect is perhaps the sharpest I've managed to get it now.
I use manual focus assist modes on both camera bodies, sometimes taking quite a long time rolling the focus wheel. but I think it just never reaches a point where the subject is truly in focus.

Actually, here is a shot I took last week down at the wetlands. No tripod though, but I was seated and had the lens resting on my knees.
ISO 200, SS 1/1000

Now zooming in, It's clear the focus is actually somewhere behind the bird, not the bird itself.
But If you look at the water around the bird, you can see the point where the water gains focus and where it loses it, and as you can see, it never really achieves an acceptable level of sharpness.
I didn't include this image as it wasn't on a tripod, and the water wasn't especially choppy that day, but perhaps 1/1000 was still too low.
Thanks for your help.

@Gigo
That's some good insight, thanks. As I've mentioned earlier in this post, my Minolta lens has 1988 stamped on it, hopefully It can perform just as well as the newer revisions. I had heard that the optics stayed the same for the most part.
In case it comes to it, do you know of any places in Japan that would be able to service and calibrate the mirror?
I'm hoping I don't need to sent it back to Japan though, it only came from there 2 weeks ago haha.


Love your photos too. great job!

@SnowFella
Amazing shots there, if I could get anything like that with this lens, I would be very happy.
What model do you have? is it the Minolta, or Sony? what year?


Thanks everyone for your example images and suggestions.
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Post Options Post Options   Quote XKAES Quote  Post ReplyReply Direct Link To This Post Posted: 13 April 2022 at 18:42
There were different versions of the Minolta 500mm f8 -- and I'm not talking just about MF vs AF. But on the MF 500mm, there was an screw-in, integral UV filter on the rear. I don't know if the AF version required this filter too. Perhaps other users of the AF will know. That might make a difference.
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Post Options Post Options   Quote neilt3 Quote  Post ReplyReply Direct Link To This Post Posted: 14 April 2022 at 00:10
Originally posted by XKAES XKAES wrote:

There were different versions of the Minolta 500mm f8 -- and I'm not talking just about MF vs AF. But on the MF 500mm, there was an screw-in, integral UV filter on the rear. I don't know if the AF version required this filter too. Perhaps other users of the AF will know. That might make a difference.


The A/F version uses drop in filters like the 300mm and 400mm lenses .
It doesn't affect image quality regardless of if a filter is inserted.
If you were to focus with the clear filter in and change to the ND or coloured filters , it will still be in focus correctly.
If you were to focus without a filter in and then inset one , focus would be off , as each piece of glass effects the focal length of the lens , therefor effecting focusing .

see my photostream on flickr;
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Post Options Post Options   Quote gigo Quote  Post ReplyReply Direct Link To This Post Posted: 14 April 2022 at 03:27
Even if the basic design is the same, the processing accuracy of parts, the assembly accuracy of products, and the design intent can be quite different.
As another example, Sony itself says that the 50 / 2.8 macro "has the same basic design as Minolta, but intentionally increases its sharpness to meet modern demands."

Reflective lenses have strict requirements for accuracy and are structurally liable to be out of order, and deterioration due to fogging is also large, so it is difficult to maintain performance and aging deterioration cannot be ignored. This is also one of the reasons why the evaluation of reflective lenses is unequally low.

There are many old lens repair workshops in Japan, but I haven't actually asked for one and I can't recommend it. Since service manuals are available, I think it is not difficult to adjust the optical axis if the store has equipment.

Regarding mirrors, in the case of a reflective astronomical telescope, since the mirror is not sealed, it is usually damaged quickly and re-plated in a certain period of time, so if you are a country with astronomical enthusiasts, there will be a workshop that will take care of it. Don't forget not only the primary mirror but also the secondary mirror.
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Post Options Post Options   Quote 4paul Quote  Post ReplyReply Direct Link To This Post Posted: 14 April 2022 at 04:44
Agree with gigo a mirror cleaning might help, I have a MD 500/8 that is better after I took the back off and gave it a gentle rub with a lens cloth, including the small mirror in the front element. Just taking it apart and putting it back together might mitigate a small alignment problem. Good luck!
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Post Options Post Options   Quote angora Quote  Post ReplyReply Direct Link To This Post Posted: 14 April 2022 at 09:16
Originally posted by Jozioau Jozioau wrote:

David,
First of all welcome to active Dyxum involvement. Now you've dipped your toe in the water you'll find it's a warm place to be.

how beautifully said

hi David!
noticed that you are aiming at the far and distant. subjects covering just a fraction of the frame. hence a Q?
did you try to shoot anything within reach as well? something this FL was designed for? (+ an extra 150%, when using an A55?).

(as it seems you are trying to capture the 'impossible', stuff that would require a 5000 mm rather than a 500? ;)
-for what it's worth? coming from someone who is by no means an 'expert', on the contrary?!!-   
I've also tried to capture things that were too far away. (period!). desperate attempts, because I simply didn't have more mm's to add.
like a Ross' gull, for instance, that decided to land here. needless to say, it was a bad recipe.
unfortunately our tele's often turn out to be 'shorter' than we'd hoped. too often? IMHnincompoopO.   

and there are more challenges when shooting long distance. not just concerning the AF, but weather conditions as well.
like atmospheric haze, either foggy or heat haze?).

long story 'short'- pretty sure actually that the birds in the gorgeous pics that Johan aka SnowFella has shown us, were already covering a substantial part of the frame. (?? ).
so love those donuts!

hope you'll figure it out.
very best of luck!

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Post Options Post Options   Quote Miranda F Quote  Post ReplyReply Direct Link To This Post Posted: 14 April 2022 at 11:54
Some more thoughts. I think both your cameras are APS-C which means they are already cropped before you do any PP. I've used a lot of mirror lenses over the years and the best ones (including the AF Reflex) can be very sharp compared to other FF lenses, but in APS-C you can often match or beat them with a good modern APS-C lens of ~300mm or so.

Be aware also that the hole in the lens reduces micro-contrast significantly, even when the actual resolution is there, and you need to compensate for this. Pictures taken in dull light or against bright backgrounds are difficult to get right in PP anyway - think before you shoot!

IMHO the 'right' way to use the mirror lens is to adjust EV, contrast and sharpening on the camera up before you use it (and down afterward) and use the FL and physical size of the lens to get the object large in the VF (ie get in close) so cropping is minimal. Under those conditions you can get excellent images. But sticking the mirror on without some thought and just snapping away will often be disappointing.

For me the big benefit of the Reflex is that you can hand-hold it in a way that's almost impossible with other FF 500mm lenses unless you have biceps like the incredible hulk, but if you're taking APS-C pictures a decent small xx-300mm zoom can work too.

On a more general note, I'm reminded of the guy who said (of astronomy) that trying to get good photos killed the interest in it. I've been inclined to think that about birds, too. Just buy a decent pair of binoculars and leave the long lenses for racing cars ...

Edited by Miranda F - 14 April 2022 at 11:59
Miranda F & Sensorex, Sony A7Rii, A58, Nex-6, Dynax 4, 5, 60, 500si/600si/700si/800si, various Sony & Minolta lenses, several Tamrons, lots of MF primes and *far* too many old film cameras ...
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Post Options Post Options   Quote fritzenm Quote  Post ReplyReply Direct Link To This Post Posted: 14 April 2022 at 13:47
Hi,
well I can't comment on the optical issues that may be related to dust/smear on the mirror and the cleaning attempt, especially if this could be done by DIY w/o special adjustment tools for checking optical axis and calibration.

So concentrating exclusively on aspects of practical usage and result. I've owned the Minolta f/8-500mm reflex for some years and used it on cams from the KM 7D through the Sony A100, later A700 and finally A850 before I sold it (had purchased it 2nd hand already). At the beginning the result were a mixed bag of some pretty impressive results to plain disappointing. Over the time and especially later deeper analyse and increasing experience shooting long(er) focal length told me that the main responsible for pretty much all of the poor results was right behind the cam: photographer's fault :-)

For starters due to the slow aperture of f/8 it's a lens that "likes" good light which is easier to get the needed short exposure times and also rises the image contrast which makes focussing easier but also combats the certain lower contrast of the produced images of this type of lenses.

An important lesson to learn though is that long FL means usually best performance over "shorter distances", this is, smaller subjects over some meters of distance or bigger subjects over some meters more. It helps to get "optically closer" as to fill the frame with a subject which would move off if getting too close - like birds or wild animals. However the long focal length also "compresses the space", including the "package of air" with all of its content like insects, dust, vapor and this together with heat oscilation of the air, increasing over the distance, takes its toll concerning resulting image quality.

The naked human eye (or brain) mostly ignores those effects when looking at the subject but with a little more attention though one actually can see the air oscilating when looking across surfaces (or close to them). So the desired "good light" has also its downside as it increases the air oscilation and hence reducing achievable image sharpness / detail rendition - the worse, the longer the shooting distance.

One of my "eyeopeners" for this issue was shooting a working harvester in the filed on a summer's afternoon. This was with a zoom lens, fully extended, plenty short enough exposure time, aperture at a good balance between DOF and max optical sharpness - and the result an almost unusable blurry mess, definitely not caused by shake :-) Just heat waves.

Now a step back to the lenses optics: I don't remember right now if it was mentioned already but the presence of one of the provided insert filters in the slot is, AFAIK, part of the optical formula so at least the clear glass filter should be placed.

Hope you get things sorted and make the lens sing.

Edit: Shooting across water bodies, especially on a sunny day and from pretty low vantage point is a special chapter. It's the waves tricking AF, it's water evaporation, heat waves, many adverse factors. Again, the longer the distance, the worse and the hotter the worse.

Edited by fritzenm - 14 April 2022 at 13:53
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