Sigma 600 mirror

CuriousOne · Joined: 31 Dec 2013 Posts: 669 Location: Home

Quite a lot of them available in that price range on eBay recently. I'm going to adapt it to Sony Alpha mount and equip with AF confirm chip, so OIS will work. Btw, does anyone heard about 500mm exit chips for Sony alpha? Ones I own, and listed on eBay, all have only 50 mm F 1.7 exif embedded.

WNG555 · Joined: 18 Dec 2014 Posts: 784 Location: Arrid-Zone-A, USA

Thanks Michael! Yes, last night's shot was quite satisfactory. After tweaking a test shot from earlier this month, I realized this Sigma had good resolution, and I just have to get familiar with using it, just like I had to with the Tamron.
If it's not sharp, then it's user error not nailing the focus.

CuriousOne,

My white version is the same as your winning bid. Hope it's a good sample!

WNG555 · Joined: 18 Dec 2014 Posts: 784 Location: Arrid-Zone-A, USA

Here are tonight's Moon results..I think the best one was with the Sigma, I nailed the focus.

DSC06175a_Sigma 600mm f8 by wNG 555, on Flickr

And for comparison, the Tamron 55BB, didn't get the focus perfect...

DSC06194a_Tamron SP 500mm f8 55BB by wNG 555, on Flickr

cooltouch · Joined: 15 Jan 2009 Posts: 9096 Location: Houston, Texas

WNG555 · Joined: 18 Dec 2014 Posts: 784 Location: Arrid-Zone-A, USA

I recall that CPO image from another thread. And it spurred me on to pursue more focal length.
The contrast and resolution from that CPO is fantastic. There is a member on another forum shooting with a Canon FDn 400mm L that is achieving similar results. Nothing like a well dialed in refractive lens for contrast.

I'm quite satisfied with the Tamron too. I was curious what an extra 100mm will buy me from the Sigma. I note there is some CA introduced by the Sigma's rear elements that is absent from the Tamron. Although shorter, the Tamron is also sharper and brighter.
My long focal length LBA has reached its end....for now. Very Happy

I think a big Celestron telescope will be necessary in order to get closer and do better. The 2x teleconverter results aren't good enough.

Here's where that impact crater is located in your photo....

CuriousOne · Joined: 31 Dec 2013 Posts: 669 Location: Home

Five Star 500/8 (non-mirror)

1/40, ISO 100, F11, Sony A77mkII

No PP, only crop, jpeg straight from the camera.

WNG555 · Joined: 18 Dec 2014 Posts: 784 Location: Arrid-Zone-A, USA

^^ Excellent results!! That's a great lens.

CuriousOne · Joined: 31 Dec 2013 Posts: 669 Location: Home

But this is the 4th copy I have.
I had them in Spiratone, Soligor, Rokinon brand. This "Five star" one turned out to be the best performer.

BeardsAreBest · Joined: 09 May 2014 Posts: 286 Location: Australia

Getting the focus is tricky with this thing.
All these great moon shots inspired me to have another go tonight.
Had a couple of goes to get the focus.
I've adjusted exposure and contrast a bit but thats all.

cooltouch · Joined: 15 Jan 2009 Posts: 9096 Location: Houston, Texas

BeardsareBest, is that shot of yours from a Sigma 600? It looks to me like you managed to get it into sharp focus.

BeardsAreBest · Joined: 09 May 2014 Posts: 286 Location: Australia

Yes this is with the Sigma. Smile

That Five star unit looks like a pretty good performer as well Curious One.

WNG555 · Joined: 18 Dec 2014 Posts: 784 Location: Arrid-Zone-A, USA

[BeardsAreBest]
A brilliant result from your Sigma! Your's is definitely getting a bit better resolution than mine. Been comparing the Sigma and Tamron these past two evenings.
My Sigma can't match the Tamron, but yours can. I noticed a bit of CA from my Sigma (red and blue edges at Moon's perimeter.) and suspect it's a slight decentering of the rear lens element(s).

I definitely like capturing partial phases instead of the Full Moon. So much more detail!

My best Sigma result to date, two days ago.

DSC06211b_Sigma 600mm f8 by wNG 555, on Flickr

Compared to the Tamron about 2 hours later.

DSC06248a_Tamron SP 500mm f8 55BB by wNG 555, on Flickr

Last night's result with the Tamron, before clouds ended the fun and didn't give the Sigma a try...

DSC06297a_Tamron SP 500mm f/8 55BB by wNG 555, on Flickr

CuriousOne · Joined: 31 Dec 2013 Posts: 669 Location: Home

My Sigma will be here in next week, so I'll join the "competition". It comes in FD mount, so I'll have to mod it. Anyone have close-up photos of how it's rear part is constructed, so I can prepare?

btw, wish we all have lens with such magnification:

cooltouch · Joined: 15 Jan 2009 Posts: 9096 Location: Houston, Texas

CuriousOne, when you get your Sigma, you'll see how Sigma sort of duplicated the look and some of the feel of the New FD mount, while having it continue to operate as a breechlock mount. It's easier just to give you a heads-up about it than it is to try and describe it. Quite clever, I've always thought.

But ultimately it's stilll just a breechlock mount. However, unlike other breechlock mounts, I believe where you start the dismantling process is with the back plate. there will be four or five screws holding it in place. From that point forward, conversion to EOS will be pretty much the same as any other FD mount lens, I'm guessing. That is, if you''re planning to convert to EOS. Any other adaptations, I haven't a clue as to how to proceed.

WNG555 · Joined: 18 Dec 2014 Posts: 784 Location: Arrid-Zone-A, USA

CuriousOne · Joined: 31 Dec 2013 Posts: 669 Location: Home

I've googled a bit more and found that there was anoter monster mirror lens from Sigma - 500mm F4. But no sample photos to be found, anyone used that behemoth?

calvin83 · Joined: 12 Apr 2009 Posts: 7555 Location: Hong Kong

CuriousOne · Joined: 31 Dec 2013 Posts: 669 Location: Home

Thanks!

too bad that most lens samples here are macros, flowers, close-ups, etc. Very rarely portraits, cityscapes or any other shots that will demonstrate real world usage of the lens. Maybe this forum should be renamed to "macroflowers only" forum? Smile

WNG555 · Joined: 18 Dec 2014 Posts: 784 Location: Arrid-Zone-A, USA

That's quite a jump in size! But it's still only a 500mm focal length.

This Sigma is too, but it's a biggie! Smile

http://petapixel.com/2011/09/20/hilarious-customer-reviews-for-the-sigma-200-500mm-lens-on-amazon/

But this is one is a BIG mirror... Very Happy

http://petapixel.com/2015/04/27/massive-2540mm-f8-nasa-lens-shows-up-on-ebay/

CuriousOne · Joined: 31 Dec 2013 Posts: 669 Location: Home

I can't forgive myself. I had 600mm telescope mirror, and I GAVE IT AWAY FOR FREE.

I already manufactured FD<>M42 adapter and even equipped it with 2x APO teleconverter (removed from junked Minolta AF 2x teleconverter ) can't wait for my Sigma to arrive Smile

cooltouch · Joined: 15 Jan 2009 Posts: 9096 Location: Houston, Texas

Over at the Tamron 55BB thread I began recently I posted an image of the moon I shot a few days ago with my Sigma 600, showing the sort of results I was getting with it. Not good. Well, today, I remembered a routine I don't often use in my processing software, and I was amazed by the amount it cleaned up the image. So even though the original image was very soft, the detail was still there. It just had to be brought out. So here's an example of before and after. The "Before" shot was with no image processing, except reduction to be shown here, and the "After" image is one that I've put through a series of PP steps. I think the difference between the two is remarkable. But I still wish my Sigma was naturally as good as the ones that some of you guys have.

Before:

After:

By the way, over in the Tamron 55BB thread, WNG555 posted a link to a site that shows how to check the collimation of a mirror scope or lens. This is the site:

http://www.mira.org/ascc/pages/lectures/collim.htm

I used it with my Sigma 600, and it isn't as easy as they make it out to be. But at first it looked as if the lens was indeed out of collimation, so I dismantled it to see if there were any obvious adjustments at all. There weren't any. I didn't remove the rings holding the elements in place because it's been my experience that an element sits in its receptacle in one position only and there is no adjustment possible. So for this reason, I didn't loosen or remove any glass. So anyway, I put it back together and checked the collimation a little more closely, under a little better light, and this time, everything lined up the way it's supposed to. So if my Sigma is out of collimation, it is by a very, very small amount. So whatever the problem is with it, it isn't collimation. The glass is spotless. No haze, fungus, dust or anything else. So maybe it's something like the original uncorrected optics on the Hubble Space Telescope. Remember that? It was nearsighted, or something similar because of a mistake in the way the mirror was ground, and NASA ended up having to send up a crew to install a set of corrective lenses so that it could "see" normally. I wonder if something similar may be going on with this lens. Perhaps the mirror was ground just a bit off. Possible, I suppose. A good mirror is ground to within angstroms of being the correct shape.

WNG555 · Joined: 18 Dec 2014 Posts: 784 Location: Arrid-Zone-A, USA

Dramatic before and after...nice job pulling out so much detail.

Too bad that link wasn't more helpful.

CuriousOne · Joined: 31 Dec 2013 Posts: 669 Location: Home

I've talked to a senior lens maker about such problems with mirror lenses. He said, most likely this is mirror defect - wear of device spares used to make mirror, so it's shape not properly parabolic. He said, by introducing a large compensating optical element in front of mirror will correct the problem, but it will be heavy and cost will diminish all usability of mirror lens. So, speaking shortly - you can't do anything. Let's see how my sigma lottery will work out Smile

cooltouch · Joined: 15 Jan 2009 Posts: 9096 Location: Houston, Texas

CuriousOne, your mirror lens expert pretty much confirmed what I already thought. Wear on the machines used to make the optics. If they no longer hold tight tolerances, then they will produce inferior products unless watched very closely. Thus some lenses are great and some are not -- from the same time period of manufacture.

cooltouch · Joined: 15 Jan 2009 Posts: 9096 Location: Houston, Texas