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Best 400mm for Moon shooting?
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PostPosted: Tue Jan 27, 2015 3:16 pm    Post subject: Reply with quote

cooltouch wrote:
Yes, it's Nikon, but I can tell only because of that little divot in the flange that indicates it's AIs. That mount looks like it's had part of the mount removed, though. Although I suspect it'll still mount up -- just no aperture control, etc.

Visualopsins -- whether before or after, I don't see how it would make much difference. Just a 180-degree change in the direction of the shadows or thereabouts. As a practical matter, I don't do a lot of planning ahead for moon photography. If it looks like it's full and I'm in the mood, I'll take some pics. And then I check a calendar to see if it is full or not. Just the way it worked out -- most of my best shots were taken when the moon was one day past full.


Well, before, the left side is not lit to the edge, after it's the right side...so depending on which side has most details...

I don't see how having more best pics after determines that after is best time. Wink


PostPosted: Wed Jan 28, 2015 5:42 am    Post subject: Reply with quote

This conversation reminded me of a bit of photoshopping I did, and I couldn't find it -- until just now. This is a combination of two photos, both taken with a 10.1mp Canon EOS XS (1000D). 1/125, f/8, ISO 100. These are both 100% crops with no PP done to either one. The top photograph was taken with my old but very good Century Precision Optics Tele Athenar II 500mm f/5.6 and the bottom photo was taken with a Tamron 52BB 500mm f/8 mirror. One of the criticisms often leveled at mirrors is that their photos just don't have the contrast of a good refractor (like the CPO here). Well, as you can see, yes the Tamron has a softer contrast -- but it's really a small amount, isn't it. And it would be an easy thing in post to bump it up a notch or two such that its contrast would be equal to the CPO 500mm. Now, as for sharpness, which to me is the most important element of a photo like this, there is no discernable difference at 10.1 mp. So, bottom line, yes, the Tamron 500mm mirror really is as good as people claim it is. At least when shooting at infinity, or close to it.



PostPosted: Wed Feb 04, 2015 11:50 pm    Post subject: Reply with quote

Alright, I've just received the Tamron!
At first glance everything seems to be working just fine, and that's a relief Smile
Can't wait to test it out.


PostPosted: Thu Feb 05, 2015 4:49 am    Post subject: Reply with quote

Didn't go well.
There's no way I can get the moon in focus. Basically, the lens doesn't focus to infinity, this is as far as I can go:



100% crop (@ f/32 and still some CA here!):



Is it because it's defective? Is there a way to fix this?
It's a shame, because at first glance I kind of like it (post in PS):







PostPosted: Thu Feb 05, 2015 6:21 am    Post subject: Reply with quote

cgustav wrote:
Didn't go well.
There's no way I can get the moon in focus. Basically, the lens doesn't focus to infinity, this is as far as I can go:


the most usual issue is that is focusing past infinity - focus back slightly and check. The other pictures seem really ok.
No need to close to f/32 (diffraction!); you can remove CA by switching to b&w.


PostPosted: Thu Feb 05, 2015 6:29 am    Post subject: Reply with quote

enzodm wrote:
cgustav wrote:
Didn't go well.
There's no way I can get the moon in focus. Basically, the lens doesn't focus to infinity, this is as far as I can go:


the most usual issue is that is focusing past infinity - focus back slightly and check. The other pictures seem really ok.
No need to close to f/32 (diffraction!); you can remove CA by switching to b&w.


Hm... I'm almost sure I tried to focus a tad back and it seemed was just getting worse.
I'll give it another try but I feel is not going to get better, I was checking with the focus magnifier on the A6000. Hopefully I just missed the focus.

Edit: just made another test, I can confirm that: focusing back doesn't help, simply makes the image even more out of focus.
At this point I'm wondering if it's possible to mod the lens in order to get to the infinity focus mark.


PostPosted: Thu Feb 05, 2015 11:29 am    Post subject: Reply with quote

Check your adapter. It could be too thick and you can't reach infinity. All it takes is a fraction of a millimeter.
Have this issue with a cheap Nikon F/Ai to Sony E mount adapter.

Most lenses from that era uses a screwed stop to calibrate infinity. But it will require you to disassemble part of your lens to get to it.

The other photos look great!


PostPosted: Thu Feb 05, 2015 2:43 pm    Post subject: Reply with quote

On many of these old 400's infinity focus can be adjusted by repositioning the front element. The front elements are in a mount that screws in the front end. A small grub screw locks the unit in - scrutinise the outside of the front end barrel. Loosen the grub screw and try screwing in the element in its unit - lens spanner best but if it's not tight a small screwdriver in one of the notches will work - 180deg and check infinity focus on a suitably distant object using magnified live view. Repeat as necessary when satisfactory re-tighten the grub screw.

My Tamron Nestar is also a bit iffy with infinity focus. And I suspect that the tests this chinese blogger did on a number of 400's showed up a similar issue on the tamron he was testing (poor results long range out of sync with the rest of the test).


PostPosted: Thu Feb 05, 2015 6:34 pm    Post subject: Reply with quote

WNG555 wrote:
Check your adapter. It could be too thick and you can't reach infinity. All it takes is a fraction of a millimeter.
Have this issue with a cheap Nikon F/Ai to Sony E mount adapter.

Most lenses from that era uses a screwed stop to calibrate infinity. But it will require you to disassemble part of your lens to get to it.

The other photos look great!


Thanks.

Do you know where can I find information about how to disassemble the lens?

marcusBMG wrote:
On many of these old 400's infinity focus can be adjusted by repositioning the front element. The front elements are in a mount that screws in the front end. A small grub screw locks the unit in - scrutinise the outside of the front end barrel. Loosen the grub screw and try screwing in the element in its unit - lens spanner best but if it's not tight a small screwdriver in one of the notches will work - 180deg and check infinity focus on a suitably distant object using magnified live view. Repeat as necessary when satisfactory re-tighten the grub screw.

My Tamron Nestar is also a bit iffy with infinity focus. And I suspect that the tests this chinese blogger did on a number of 400's showed up a similar issue on the tamron he was testing (poor results long range out of sync with the rest of the test).


I'll look closer to the front elements and see if I can spot anything that might be tweaked... I've zero experience in disassembling lenses. I just don't understand if this particular lens is defective or they just were all like this.

But also doesn't make much sense why I can't turn the ring past 300 (infinity mark is there though):



PostPosted: Thu Feb 05, 2015 7:06 pm    Post subject: Reply with quote

From the photo, it looks like you are lined up at infinity....note dot at 6.9, and red line at infinity.


PostPosted: Thu Feb 05, 2015 7:22 pm    Post subject: Reply with quote

WNG555 wrote:
From the photo, it looks like you are lined up at infinity....note dot at 6.9, and red line at infinity.


Does that mean I can reach infinity only at 6.9?
By the way, when I'm turning the focus ring, as I reach 300 it doesn't go further than that.


PostPosted: Thu Feb 05, 2015 8:19 pm    Post subject: Reply with quote

check out (for example):

https://www.youtube.com/watch?v=CiUbC-4dtvc

http://www.alanrossphotography.com/2012/03/understanding-lenses-depth-of-field/


PostPosted: Thu Feb 05, 2015 9:16 pm    Post subject: Reply with quote

marcusBMG wrote:
check out (for example):

https://www.youtube.com/watch?v=CiUbC-4dtvc

http://www.alanrossphotography.com/2012/03/understanding-lenses-depth-of-field/


Thanks marcusBMG,

I know how depth of field works in relation to f stop, what I'm trying to figure out with this Tamron is if it's defective or what.

With all my other lenses I can go infinity focus and also, using adapters with old lenses, I'm aware in some cases I need to dial the focus ring a little back (for instance with my Nikon 24mm f/2.Cool.

What I'm finding confusing with this Tamron is that I can't dial the focus ring up to the infinity focus mark.


PostPosted: Thu Feb 05, 2015 10:09 pm    Post subject: Reply with quote

cgustav wrote:
WNG555 wrote:
From the photo, it looks like you are lined up at infinity....note dot at 6.9, and red line at infinity.


Does that mean I can reach infinity only at 6.9?
By the way, when I'm turning the focus ring, as I reach 300 it doesn't go further than that.


What WNG55 is telling you is that the lens in the picture is indeed focused at infinity. The mark on 300m refers to calculated depth of field ( it is one side of a bracket), the focus distance is on red line.


PostPosted: Fri Feb 06, 2015 5:07 am    Post subject: Reply with quote

I've just realized that this lens has three rings!
First one is the focus ring, then the f-stop. Yesterday I didn't notice that the other ring, right next to the f-stop, it's independent.
Not completely actually, as it rotates when I change f-stop, in fact @ 6.9 I can't dial the ring at all.

So, when I stop to f/32 I get the maximum rotation for this third ring and it actually tune up the focus even further, perhaps that may be the reason why I couldn't focus.

Tonight is hazy (of course), hopefully tomorrow I'll get a better luck to test it out again.


PostPosted: Fri Feb 06, 2015 6:32 am    Post subject: Reply with quote

cgustav wrote:
I've just realized that this lens has three rings!
First one is the focus ring, then the f-stop. Yesterday I didn't notice that the other ring, right next to the f-stop, it's independent.
Not completely actually, as it rotates when I change f-stop, in fact @ 6.9 I can't dial the ring at all.

So, when I stop to f/32 I get the maximum rotation for this third ring and it actually tune up the focus even further, perhaps that may be the reason why I couldn't focus.

Tonight is hazy (of course), hopefully tomorrow I'll get a better luck to test it out again.


It's a classical preset lens: with one ring you set the aperture you want to shoot with, let the other fully open to aid in focus (better made fully open) and then you close down to the preset level without the need for looks how much. These rings do not tune focus, except for the different depth of field you have with different apertures. But your lens should be able to focus at infinity even at 6.9, if not there is something to fix (adapter etc, as told by others).
Do not shoot f/32 on digital if not needed: diffraction reduces resolution. And no need for f/32 to shoot the moon.


PostPosted: Fri Feb 06, 2015 6:55 am    Post subject: Reply with quote

Ha! I'm learning something new, never used a preset lens before Smile
I guess I'll have to play with it and just get used to it.

Thanks for the info enzodm.


PostPosted: Thu Feb 12, 2015 7:14 am    Post subject: Reply with quote

Best of luck to you now that you've discovered how a preset lens works, but if your earlier photo at f/32 is any indication, you might still not be achieving infinity focus.

Actually, marcusBMG had a good suggestion about repositioning the front element. Alll of these old preset telephotos have basically the same optical formula, which is an achromatic doublet up front and a bunch of air space behind it. Some of the better ones may also have an optical flat located toward the rear of the lens, but this flat doesn't affect the focal properties in terms of focusing. So if you can move the front element(s) you are changing the point of focus. If you can move the elements farther out, you will be setting the point of "infinity" focus closer in, which you don't want for a moon shot, and if you're able to move them farther in, thereby shortening the overall length of the lens, you'll be extending the point of infinity focus. Which is what you want for a moon shot, but this is probably also the more difficult setting to achieve.

I'd also try as was suggested and try more than one t-mount adapter. This might make a difference.


PostPosted: Thu Feb 12, 2015 2:05 pm    Post subject: Reply with quote

WNG555 wrote:
Check your adapter. It could be too thick and you can't reach infinity. All it takes is a fraction of a millimeter. ...


Hmmm, T2 adapters are thicker than M42 adapters -- could this be a M42 mount lens, not T2 mount?

BTW, a wide angle lens may not reach infinity if adapter thickness is "a fraction of a millimeter" too much, but for a telephoto lens, "a fraction of a millimeter" matters very little.


PostPosted: Thu Feb 12, 2015 8:17 pm    Post subject: Reply with quote

visualopsins wrote:
WNG555 wrote:
Check your adapter. It could be too thick and you can't reach infinity. All it takes is a fraction of a millimeter. ...


Hmmm, T2 adapters are thicker than M42 adapters -- could this be a M42 mount lens, not T2 mount?

BTW, a wide angle lens may not reach infinity if adapter thickness is "a fraction of a millimeter" too much, but for a telephoto lens, "a fraction of a millimeter" matters very little.


Yes, I tried over and over and I also tried another Nikon adapter, still no changes.
It must be the lens.

So, at this point I either keep it as is, since I can use it for other type of shooting and look for something else for the moon, or I'll try to disassemble it, just I don't feel much comfortable doing it as I never did it before.
Unless I find someone in the LA area who may do this type of job, but I guess it'll cost some money and at that point not sure it'll worth the bucks.


PostPosted: Thu Feb 12, 2015 10:10 pm    Post subject: Reply with quote

Could be someone has re-assembled the helical incorrect. That was the problem with my S-M-C Takumar 1:4.5/500...I tried nearly every starting position of the helical threads before getting it just right...now I think about it, the infinity focus was off about the same as with your lens...


PostPosted: Thu Feb 12, 2015 11:00 pm    Post subject: Reply with quote

I was apprehensive the first time I took apart a lens. A Tokina AT-X 80-200 f/2.8 covered in black goo externally, and fungus internally that was nearly opaque. Since I had nothing to loose, I looked at a few videos and jumped right in.

It turned out to be easier than imagined. Just be systematic about it. If you wish, take macro photos of each step before disassembling.
Mark alignments with a Sharpie before loosening anything that may require re-alignment.

Being that this is a mirror lens, I will assume it's going to be simpler mechanically and much easier to access the target area.


PostPosted: Thu Feb 12, 2015 11:05 pm    Post subject: Reply with quote

WNG555 wrote:
... take macro photos of each step before disassembling.
Mark alignments with a Sharpie before loosening anything that may require re-alignment.


Yes! Except I kept forgetting to photograph some steps. So now I use a camcorder -- works great!


PostPosted: Thu Feb 12, 2015 11:53 pm    Post subject: Reply with quote

Have a read of this, it may help
http://forum.mflenses.com/tamron-400-6-9-preset-t-mount-an-early-collectible-t10679.html