600mm Mirror lens, terrible results

Started Mar 30, 2011 | Discussions
imashination Regular Member • Posts: 415
600mm Mirror lens, terrible results

So I stuck a sigma 600mm lens on my gf1, are they all this terrible? The first image here is a 100% crop of the middle of my 45-200, the second image is the entire frame of the 600m scaled down. Im about to send it back as its got a bit of fungus anyway, but not enough to affect the image quality yet.

Paradoxical_Cat Forum Member • Posts: 60
Re: 600mm Mirror lens, terrible results

No. I have the same lens (OM mount) and they are all not that bad. However, I don't know how attentive you were to focusing. The catadioptric lens has a notoriously narrow depth of field and (in my experience with a G1) really are hard to use with anything other than an optical viewfinder.

On the other hand, the poor contrast is classic "cat". And don't get people started on the bokeh.

There is a reason cats are so inexpensive. They really are a stopgap, not a true solution. At least for those who are spoiled by refractor lenses.

I use mine for astrophotography and certain kinds of long range IR photography. Also, it is kind of cool to tell someone that you were using a 1200mm lens.

I might suggest trying the lens again, but if it has fungus....

By the way, what was the native mount? That may also affect the performance.

If I get a chance, I will post up some test photos I took with my Sigma f/8 600.

imashination wrote:

So I stuck a sigma 600mm lens on my gf1, are they all this terrible? The first image here is a 100% crop of the middle of my 45-200, the second image is the entire frame of the 600m scaled down. Im about to send it back as its got a bit of fungus anyway, but not enough to affect the image quality yet.

El Capitano Forum Member • Posts: 70
Re: 600mm Mirror lens, terrible results

imachine, Even your 45-200 photo looks hazy. Was that a cloudy day?

OP imashination Regular Member • Posts: 415
Re: 600mm Mirror lens, terrible results

Hi. These were both focussed on a solid tripod indoors using a remote release shutter after a few seconds to let any vibrations fade. Focussing just never gets crisp; you turn the grip.. its gets better, better, starting to get focussed... but no it starts getting worse before it was anywere near being usable.

Ive sat here with brickwalls, signs, fences, trees. At no point can I say the lens was focussed.

The contrast isnt a biggie, thats an easy post fix.

The mount is FD, but my adaptor here is fine and has been used for many other fd lenses without a hitch.

Gregm61 Forum Pro • Posts: 15,843
Re: 600mm Mirror lens, terrible results

There are some really good quality cat lenses, and a lot of mediocre to bad cat lenses. As a cheap solution for this system where no made-for-micro solution exists, I'd say there are probably better "cat" alternatives to the Sigma you tried, but they will probably all be expensive.

Vivitar made (actually, Perkin Elmer made them for Vivitar) some really good solid (one glass piece) cat designs (600mm f8 and 800mm f11) under the Series one name, and they also offered a 450mm f4.5 Series One mirror. Any of those three are hard to find and expensive when you do find them.

If you find a cat lens and it's really cheap, you should go into the process expecting image quality results comensurate with the price and not be disappointed when it is.

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OP imashination Regular Member • Posts: 415
Re: 600mm Mirror lens, terrible results

Yes its overcast, and remember the first image was just a tiny crop of this:

Gregm61 Forum Pro • Posts: 15,843
Re: 600mm Mirror lens, terrible results

Gregm61 wrote:

There are some really good quality cat lenses, and a lot of mediocre to bad cat lenses. As a cheap solution for this system where no made-for-micro solution exists, I'd say there are probably better "cat" alternatives to the Sigma you tried, but they will probably all be expensive.

Vivitar made (actually, Perkin Elmer made them for Vivitar) some really good solid (one glass piece) cat designs (600mm f8 and 800mm f11) under the Series one name, and they also offered a 450mm f4.5 Series One mirror. Any of those three are hard to find and expensive when you do find them.

Here's one of those beauties right now for sale. Note the price. The seller obviously knows what they have..

http://cgi.ebay.com/Vivitar-Series-1-600-8-Solid-Catadioptric-VMC-44762470-/370308382635?pt=Camera_Lenses&hash=item5638197fab

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OP imashination Regular Member • Posts: 415
Re: 600mm Mirror lens, terrible results

Well the quality of the one I have sat here is whats puzzling me. It seems VERY solidly designed and manufactured; extremely solid, every part sits flush where it should, even the accessories come in solid cases, padded leather holders etc. Thats why im so puzzled that the image quality is something akin to a fisherprice plastic lens.

Actually ive just done another test, focussed on the middle of a naked spiny tree and taken a shot. Even if im somehow ham-fisted enough to get the focus wrong, something in the tree must be in focus, but nothing is.

Len_Gee
Len_Gee Veteran Member • Posts: 9,880
Re: 600mm Mirror lens, terrible results

Agree.
Mirror lenses have pretty low contrast.
I have the Vivitar 800 solid cat, and don't find it all that useful on my GF-1.

Plus the round donut bokeh looks pretty bad and makes the background really distracting..
Using the lens as an ashtray paperweight these days.

Regards

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Gregm61 Forum Pro • Posts: 15,843
Re: 600mm Mirror lens, terrible results

Yeah, there's no telling what type of life a second-hand lens has led before finding its' way into your hands. There may be an optical problem you can't see externally, mount allignment problem, etc., etc...

You do know, Sigma is short for SIG(nificant) MA(lfunctions), right?! It's a reputation they've had to live down. They were probably earning it about the time that lens was made.

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Paradoxical_Cat Forum Member • Posts: 60
Re: 600mm Mirror lens, terrible results

Assuming that you are focusing properly, then it is either the lens or the mount adapter. If the lens seems solid and the optics clean, then I might look at the adapter. (No guarantees, though.) However, focusing with the GF1 may be too much to ask. The cats have a very narrow depth of field. Can you post the image of the tree?

One minor possibility (long shot), is the rear filter adapter installed? (I cannot remember if a filter blank is needed in the light path when a filter is not being used.) It may cause a problem, but you would probably have noticed if something was amiss.

OP imashination Regular Member • Posts: 415
Re: 600mm Mirror lens, terrible results

Ive tried it with and without the filter and adaptor, no difference. Heres the tree, focus was on the large X the branches form, not a breath of wind and everything was perfectly still.

Paradoxical_Cat Forum Member • Posts: 60
Re: 600mm Mirror lens, terrible results

Yeah, if there was motion, you'd be taking an abstract...

I think that you are actually focusing behind (I think..the tree doesn't provide much depth cueing) your target. The bottom right of the image is more in-focus than the rest. If you care to, I'd suggest taking a picture with more depth to it, that way you can actually gauge the focal plane.

imashination wrote:

Ive tried it with and without the filter and adaptor, no difference. Heres the tree, focus was on the large X the branches form, not a breath of wind and everything was perfectly still.

kenw
kenw Veteran Member • Posts: 6,843
Re: 600mm Mirror lens, terrible results

Cats are notorious for low contrast. The also are rarely super sharp, but some are passable. I have a Tamron Adaptall 500/8 reflex which is regarded as a very good reflex design. It is a bit soft at 100% of course, but not awful.

Your photo does look pretty horrible. There are a lot of horrible cats out there. And my understanding was that they can be very intolerant of any sort of misalignment.

I did find this test of a Sigma 600 and the user found cropping 200mm to be a better solution as well:

http://www.nobell.org/%7Egjm/photography/fdadapter/mirror.html

Perhaps your's is a combination of not a very good lens to start with and this one is also misaligned somehow. Certainly looks disappointing! My 500/8 is much, much better than that and I still question whether it is worth it...
--
Ken W

Rebel XT, XTi, Pany G1, LX3, FZ28, Fuji F30, and a lot of 35mm and 4x5 sitting in the closet...

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CWilt Senior Member • Posts: 2,436
Re: 600mm Mirror lens, terrible results

They have low contrast but also very little CA. I use my cheap 500mm for atmospheric shots where I am not looking for great detail.

This was the 500mm mirror plus a 1.4x teleconvertor, E-P1 and mounted on a heavy tripod. The smoke was 38 miles from the camera.

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Charles
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Be sure of your subject.
Never, force the shot.

Paradoxical_Cat Forum Member • Posts: 60
Re: 600mm Mirror lens, terrible results

Here are two cat test images and a comparator. The first is a shot of a reflected sign taken with a Sigma 600mm f/8 on a G1. The second is the same subject taken with a Lumix 45-200. The third shot is what a cat does best, but you can clearly see the shallow depth of field. (This was shot handheld, by the way, so any short-comings are mine...)

Regardless, the cat does produce pretty sharp, if low contrast, images. I am guessing your lens (or adapter) is defective.

(Oh, the sign was 300 meters away. The moon, 400,000km, I think. )

Paradoxical_Cat Forum Member • Posts: 60
Re: 600mm Mirror lens, terrible results

Sorry, I just saw this after I posted my last....

imashination wrote:

Hi. These were both focussed on a solid tripod indoors using a remote release shutter after a few seconds to let any vibrations fade. Focussing just never gets crisp; you turn the grip.. its gets better, better, starting to get focussed... but no it starts getting worse before it was anywere near being usable.

Do you zoom to focus? I am thinking that with the narrow depth of field, that it may not help. But, I am beginning to agree that the lens is misaligned (see the off-center focal point on your tree photo.) It could be the optics or the mount, but it probably doesn't matter at this point.

The mount is FD, but my adaptor here is fine and has been used for many other fd lenses without a hitch.

Understood. But this is not any "other" FD lens. It's a cat, and it's as finicky as the feline sort.

Oh well. Send this stray cat home.....

tedolf
tedolf Forum Pro • Posts: 28,610
I am wondering if....

what you are seeing in the tree is gross chromatic aberations coupled with low contrast that is making it look OOF?

Just a thought. Cheap mirror lenses were known for bad CA.

The better mirror lenses (e.g. Minolta 250mm) are selling on e-bay for far more than what they sold for when new. That is why new reasonably priced 250mm mirror lens for a 4/3 image circle would be a big success.

Tedolph

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Paradoxical_Cat Forum Member • Posts: 60
Re: I am wondering if....

tedolf wrote:

what you are seeing in the tree is gross chromatic aberations coupled with low contrast that is making it look OOF?

Possibly. I don't see the characteristic color fringing, but with a Cat's circular bokeh, they'd look pretty similar.

Just a thought. Cheap mirror lenses were known for bad CA.

The better mirror lenses (e.g. Minolta 250mm) are selling on e-bay for far more than what they sold for when new. That is why new reasonably priced 250mm mirror lens for a 4/3 image circle would be a big success.

The key is "reasonably priced", but with the 100-300mm f/4 (35mm 200-600) a 250mm Cat (35mm 500) with all of its limitations would be a non-starter, IMHO. Even a 600mm Cat would be a limited interest lens. I think that, until someone refines the catadioptric optics to eliminate its limitations, the long range refractors will rule.

Tedolph

DonTom Contributing Member • Posts: 535
Re: I am wondering if....

Here's a picture I found, taken with a Vivitar 800mm Mirror lens on a Nikon D100

I'd be happy with that!

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