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deathrox
04-10-2017, 7:55pm
I have a new 500mm mirror lens. Not really enjoying it. Hard to focus. I don't mind the fixed apature of F8 and it has a really nice tactile feel to it.
I just can't get a sharp picture from it.

Does anyone use a mirror lens, are there "tricks" to it?

http://www.henrywho.xyz/temp/DSC_3737-Pp.jpg

arthurking83
05-10-2017, 8:37am
I have a new 500mm mirror lens. Not really enjoying it. ...

It takes time to understand how to enjoy this(type of) lens.
Is it a Nikon or other brand?
If Nikon, which model.

I have the older C model which isn't the best version, but they can produce a sharp enough image.



.... Hard to focus ....
Yep!
D5500 with it's smaller darker less accurate pentamirror viewfinder makes this even harder than it should/could be too.
One of the major reasons I HAD to get a better focus screen for my D300.
I ended up with a Katzeye focus matte, which made a world of difference. Unfortunately tho Katzeye went out of business(only due to the owner getting ill) and no one makes a matte screen that is anywhere near as good now.
Focusingscreen dot com make them, but they're only good quality .. not anywhere near as good as the Katzeye.
** reason I mention that Katzeye went out of business some years back due to illness is that the last I saw, they still had some old stock products to offload but it was hard to contact them to acquire some(I tried via email but got no response).


.... I just can't get a sharp picture from it. ...
It's hard due to manual focus and the f/8 shutter speed.
So:
1/. you're fighting getting good focus combined with
2/. your shutter speed needs to be high(1/500s as a minimum).

So for testing purposes you would find a static subject that simply does not move(eg. a fence post) in very bright(as in midday) light. You'd then use the fastest frame rate possible on your camera and focus bracket.
Focus bracketing is where you adjust focus position in very small increments as the camera is exposing at a fast frame rate.
Testing this gives you a feel for if the issue is simply misfocus camera blur or both!

Live view on a very very very stable tripod is the only way to achieve perfect focus positioning with this lens.
**Note the use of 'very very very'!! .. most average tripods and heads are simply not up to the task unless you maintain this 1/500s shutter speed. Mirror and or shutter slap is very likely to be an issue on a tripod too.

The other issue with sharp images is that this lens is just not as sharp as modern lenses.. This lens was made to a price and that was many years ago and technology has moved on since then .. and you camera allows you to view at a much more 'magnified' view if you assess images at 100% pixel view on your device too.

Lastly on the topic of focus is that: Nikon cameras have a green dot system for manually focusing. Look in your viewfinder at the lower LH corner for it. It comes and goes very quickly if you're not specifically trying to get it to light(ie, lens in focus)
Find a subject, have camera and lens very stably mounted and look for this green dot as you focus on the subject. That green dot is called the 'range finder' and that name is a more accurate description of what it does. It determines a range rather than an exact distance.
ie. this method is not entirely accurate, but can be sometimes.



.... Does anyone use a mirror lens, are there "tricks" to it? ...
I do.
Tips: don't stress too much about ultimate sharpness from this lens. You just won't get the same sharpness as you will from a modern lens. So get an image that you don't have to crop to achieve a result. Cropping is zooming into it's not so sharp rendering of that subject.

tricks: Not much but I hoped that a product called the Dandelion chip would help to make this lens more usable more of the time. It did, but it didn't last. Reason is that the Dandelion chip is just not a durable product. I reckon mine lasted about 20 or so mount/dismount procedures before it committed suicide. That is, the body of this addon chip disintegrated.
I have a thread on here about what this thing is and does.

Another tip/trick thing is that you need to have the rear LC37c 39mm filter attached to the back of the lens. This not only stops stuff getting into the lens, but is also part of the optical formula too. So the lens doesn't focus if this filter is not present.
When you got your mirror lens, if it is a Nikon did it come in the case, with the filter set? This kit has some coloured filters(red and yellow) and a ND3(I think) and the clear LC37c. If you remove one, you need to use another.


Last couple of tips is that;
* this lens for me is more of a fun lens, not a serious way to shoot on a modern camera. if you want critically sharp subjects this is the wrong lens. hard to work with and hence frustrating (as you've found out). S the tip is to use it as a fun lens and 'sharpen up your photography skills at the same time!
* Do not try to get an alternate focus screen with either a focus aid like a split prism of prismatic collar. At f8 only they just don't work. In my testing, only the Katzeye does in this regard(why I rave about it). More accurate focus mattes are also a bad idea for this lens too again due to the f8 aperture. These more accurate focus mattes only work well with faster lenses, and slower than f/5.6 lenses make them much darker than standard.

deathrox
05-10-2017, 9:29am
It takes time to understand how to enjoy this(type of) lens.
Is it a Nikon or other brand?

No it's a cheap job. But from what you have said here I suspect it's working fine, I've just bought a lens that is of little use to me.

I wanted a larger telephoto to get sharper images of the moon.

D5500 with it's smaller darker less accurate pentamirror viewfinder makes this even harder than it should/could be too.


One of the major reasons I HAD to get a better focus screen for my D300.
I ended up with a Katzeye focus matte, which made a world of difference. Unfortunately tho Katzeye went out of business(only due to the owner getting ill) and no one makes a matte screen that is anywhere near as good now.


What in blazes is a focus screen, I have an idea from the name but how is that a replacable item?



It's hard due to manual focus and the f/8 shutter speed.
So:
1/. you're fighting getting good focus combined with
2/. your shutter speed needs to be high(1/500s as a minimum).

So for testing purposes you would find a static subject that simply does not move(eg. a fence post) in very bright(as in midday) light. You'd then use the fastest frame rate possible on your camera and focus bracket.
Focus bracketing is where you adjust focus position in very small increments as the camera is exposing at a fast frame rate.
Testing this gives you a feel for if the issue is simply misfocus camera blur or both!

Live view on a very very very stable tripod is the only way to achieve perfect focus positioning with this lens.
**Note the use of 'very very very'!! .. most average tripods and heads are simply not up to the task unless you maintain this 1/500s shutter speed. Mirror and or shutter slap is very likely to be an issue on a tripod too.



A stable tripod is my other problem, I have a tripod but it's crap. I was using "quiet shutter" mode and a remote.

Overcast today, I will give your suggestions ago once the sun is in full bloom again.
Alas I think I've wasted my money. I will see if I can return it or exchange it for a non-mirror telephoto.

ameerat42
05-10-2017, 10:04am
DR. It ZOUNDS! bad to me. You could have seriously compromised optics.
The 1st one I ever had (brand forgotten) was HORRIble! All images looked
like yours here. But when converted into a small telescope (by the attachment
of an eyepiece lens) it was tack sharp:confused013:confused013

So that's what I used it for until... one fateful day my house got flooded, and
the silver coating on the mirror got wrecked. Oddly, I felt :) about its demise.

After that, I thought I'd try a Clestron C90. (You know, good brand and all:nod:)
I tried it for a week - it took that long before I could return it - and it was just
as hopeless as the other one I'd had.

Yet more years passed, and I took a punt on a Tamron BBAR 500/8 mirror lens,
2nd had, for a "good Price". (I actually jumped at this one because I had tried
a new one in a camera store and was imPRESSed!!)

And now to the present: I ONLY don't use it because of its lack of image stabilisation
of any sort, but I had decades of use from it.

So, what an eyepiece onto it and try it as a spotting scope, or...

- - - Updated - - -

PS: I had also a BBAR 2X converter (Tamron) for it, but MOST sadly it's lenses got milky
with fungus:(

- - - Updated - - -

PPS: Looking at your image, I suspect that its low quality is the result of dispersion
caused by the interference of the secondary mirror holder. That's got to be "just right".

arthurking83
05-10-2017, 7:16pm
Cheapie mirrors are made to a price.
Can't help in terms of quality of optics and stuff like that .. sorry.

I had the Tamron that Am refers too, and I found it worked well enough. As always tho, the issue is mainly getting focus, whilst trying to estimate exposure and managing hand holding technique ... I may have one or two successful images out of the hundreds I'd tried with it!

Don't go with a cheapie long telephoto either tho .. you may of them no name 600mm for something like $100 or so .. avoid!

A good cheapie 500 mirror is Nikkor 500/8. Older C models are cheaper(as I said before some come with the case/kit) usually in good condition. Avoid if not.
You can pick up a Nikkor 500 C for under $200 easily(I got mine under that).

For slightly better quality the newer(still old tho) N model Nikkor can be had for under $300 if you're patient.

Note that Sigma used to make a half decent quality 600/8 mirror too. No idea on average prices.

That image of the butterfly just looks front focused to me. That is, you either didn't focus far enough or if you did initially focus deep enough then the subject may have moved backwards a little more.

A good test of these lenses to see if they actually do have any image quality in them is to take a photo of a picket or paling fence.
Actually any fence will do as long as there are discernible subject matter at various points along the depth of field.
Then take a shot with the lens, hand held focused through the viewfinder. Just be sure that it's in very bright light, and that shutter speed is at 1/500s as a minimum. faster will be better.
Remember the point that you focused on and view the image at 100% view to determine if any of those subjects along the depth of the fence has rendered sharp(ly).

Try to keep the distance to the subject at about 5-10m or more if you can too.

Lance B
06-10-2017, 8:54am
You'll need more than 1/250sec shutter speed which is what the EXIF states on your posted photo. On your D5500 you will probably need more like 1/500sec as an absolute minimum and more like 1/1000sec and this is if the subject matter is completely still. Don't forget your subject matter may be moving and if it is you could need up to 1/3200sec for flying birds.

ameerat42
06-10-2017, 9:21am
Interesting to see the results of more controlled focusing tests:nod:

arthurking83
06-10-2017, 9:49am
Interesting to see the results of more controlled focusing tests:nod:

I would advise against holding of your breath tho! I dare say(don't know this for sure, just an edumacated guess coming up) that it will simply reveal the obvious observation we all expect from a cheap optic.

Seen this too many times not to expect history repeating itself.

deathrox
06-10-2017, 5:39pm
Interesting to see the results of more controlled focusing tests:nod:

http://www.henrywho.xyz/temp/Tape%20-%20Mirror%20Lens%20-01.jpg

I've already requested to return it.

ameerat42
06-10-2017, 5:43pm
Hmm! What a faux pas!

Now I'm NOT interested in seeing any more:eek::eek::eek:

Like I said, see if it's any good as a spotting scope.:confused013
(If not, and you're not expecting any floods, is there a running creek you can toss it into?)

deathrox
06-10-2017, 6:24pm
Hmm! What a faux pas!

Now I'm NOT interested in seeing any more:eek::eek::eek:

Like I said, see if it's any good as a spotting scope.:confused013
(If not, and you're not expecting any floods, is there a running creek you can toss it into?)

Live and learn, no more mirror lens' from now on. I see NO point in making a lens that can't produce a sharp image.

- - - Updated - - -


I would advise against holding of your breath tho! I dare say(don't know this for sure, just an edumacated guess coming up) that it will simply reveal the obvious observation we all expect from a cheap optic.

Seen this too many times not to expect history repeating itself.

The good news is...... 30 day return policy. Woo Hoo. I'll loose just under $10 (retun postage guess) for this failure, I've payed much more for other failures.

ameerat42
06-10-2017, 7:02pm
At least!

I will differ a bit from your opinion, though. For a long while my Tamron lens was the go-to
for telephotery.

If you are into BODY BUILDING (and little else) try a Russian MTO mirror lens (1100mm/8 from memory).
Now that was SHARP! But the trouble is getting them. It was also a treat with the Σ2x converter.

(I borrowed one once for a few weeks.)

deathrox
06-10-2017, 8:04pm
At least!

I will differ a bit from your opinion, though. For a long while my Tamron lens was the go-to
for telephotery.

If you are into BODY BUILDING (and little else) try a Russian MTO mirror lens (1100mm/8 from memory).
Now that was SHARP! But the trouble is getting them. It was also a treat with the Σ2x converter.

(I borrowed one once for a few weeks.)

I have a feeling that paying for it might be more of a challenge than lifting it!

arthurking83
06-10-2017, 9:15pm
Live and learn, no more mirror lens' from now on. I see NO point in making a lens that can't produce a sharp image.

....

I think the term sharp image has different meanings to different people ... but more importantly! an understanding of what the lens is doing helps to assess the lens's ability(or otherwise).

if you don't mind me interloping and posting an image from my Nikkor 500/8 C.
it's an old lens, been beaten about a bit, inferior optic design to most modern lenses, cheap cheery fun lens that produces a unique outcome that not many other lens types can do.

132714
This image is a 50% crop and then resized to 1000pixels for the forum software to accept. Even at a straight out 1000 pixel crop the detail rendered looks OK(enough).

If exif is not in tact, then the specs are D800E, 500/8 model C mirror lens, 1/250s(sorry Lance :p), obviously f/8(that's the only option) .. but what isn't obvious in the exif is that this is just after I installed this Dandelion CPU chip onto the lens. So the lens specs in the exif come up as 500mm f/8 G. If you know about Nikon lenses you'll know that the G nomenclature is their second most recent in terms of modernity(and this becomes important .. if you care to read the info below)

As I said earlier the durability of this little Dandelion CPU device is pretty hopeless, but the important feature that it offers is that it almost makes the lens an AF lens.

obviously it doesn't transform a manual focus lens into an AF one(you need a special adapter for that, which you need to hack and .. too long a story to tell here!) .. but back onto what this cpu chip offers.

On some cameras you can set the camera to only make an exposure when focus is achieved. That's the default method that most Niko's come out of the box.
I don't know if this works on a D5500 .. and probably never find out .. but with the chip installed, the camera thinks it's an af lens, and that it's it's autofocusing it. Of course it's not, but as long as the camera thinks it is, this trick works.
Because the camera thinks it's autofocusing the lens, I manually focus the lens. I hold my finger all the way down on the shutter and nothing happens .. but as soon as the camera thinks it's now in focus, as I'm already holding the shutter release down, it automagically makes the exposure the moment focus is achieved.

So the action needed to do all this is a split moment and what woudl be normal operation. Press and hold shutter .. Nothing happens as the there is no focus... I focus the lens as per normal manual focus lens... Nikon's have a rangefinder focus system that works for manual focus lenses .. the instant I fluke focus in my tuning the focus ring the camera snaps the image.

This is only due to the way the Dandelion chip can be programmed to use what's known as focus trap.
There are camera settings that need to be made too, but it's all quite simples.

The only way to get a decently half usable image out of this lens prior to this Dandelion CPU was to focus bracket.
That lil birdy shot was a single exposure. 1 in 3 shots made was in focus, actually I think the other's are just blurry due to slow shutter speed(see! Lance was right :D)

Like I said before, there are tricks to owning a mirror lens and getting 'satisfaction' from it. Sharpness and intricate detail rendering is not one of the qualities you get this lens for, but with a bit of patience, there should be enough to warrant having one at hand.