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Can't focus on infinity

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stuartmayo56 View Drop Down
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Post Options Post Options   Quote stuartmayo56 Quote  Post ReplyReply Direct Link To This Post Topic: Can't focus on infinity
    Posted: 05 June 2020 at 01:08
Just spent 3 hours searching for answers and hope that someone on here can help.
Recently bought a sigma 400mm f5.6 APO macro (Nikon mount) plus simple adapter for use on my a7ii.
Works well enough on manual as that's what I bought it for (an outdoor music concert) but came to use it today to photograph my car as a project called 'Mundane Motors' when I found that it wouldn't focus at infinity.
I had it on a tripod and it would focus perfectly on things nearby but not on the car.
I wanted to blur the background so used f5.6 but this was useless. It improved very slightly using f22 but when I got back home none of the images were useable.
Is it the lens or am I doing something wrong?
Cheers

Edited by stuartmayo56 - 05 June 2020 at 01:34
 



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sybersitizen View Drop Down
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Post Options Post Options   Quote sybersitizen Quote  Post ReplyReply Direct Link To This Post Posted: 05 June 2020 at 01:15
Originally posted by stuartmayo56 stuartmayo56 wrote:

Recently bought a sigma 400mm f5.6 APO macro (Nikon mount) plus manual mount for use on my a7ii.

By 'manual mount' I assume you mean a simple lens adapter.

If the lens can't focus to infinity, one possible explanation is the adapter is too thick. But you can't rule out a problem with the lens unless you test it with another adapter, or on a real Nikon camera.
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stuartmayo56 View Drop Down
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Post Options Post Options   Quote stuartmayo56 Quote  Post ReplyReply Direct Link To This Post Posted: 05 June 2020 at 01:33
Yes sorry simple adapter, my mistake.
Okay I hadn't thought of that, unfortunately I have no way of testing it further.
Will probably sell on and ask person to bring their camera to try it on.
Thank you
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addy landzaat View Drop Down
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Post Options Post Options   Quote addy landzaat Quote  Post ReplyReply Direct Link To This Post Posted: 05 June 2020 at 08:07
Do you have another Nikon lens? Then you know if it is the adaptor or the lens. Or get an adaptor, you can get them cheap, especially used. Just a thought.
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nandbytes View Drop Down
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Post Options Post Options   Quote nandbytes Quote  Post ReplyReply Direct Link To This Post Posted: 05 June 2020 at 08:43
my flickr
A7RIV
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stuartmayo56 View Drop Down
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Post Options Post Options   Quote stuartmayo56 Quote  Post ReplyReply Direct Link To This Post Posted: 05 June 2020 at 09:39
Unfortunately no, just Sony and Minolta lenses.
Sony fe
Minolta MC and MD and they all work fine.
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stuartmayo56 View Drop Down
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Post Options Post Options   Quote stuartmayo56 Quote  Post ReplyReply Direct Link To This Post Posted: 05 June 2020 at 09:58
Just looked at this adapter and it seems identical in everyway apart from the name.
Mine is K&F, the Gobe ones look slightly different and I do have a lot of faith in their products.
I could order one then return it if it has the same outcome.
Cheers
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pegelli View Drop Down
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Post Options Post Options   Quote pegelli Quote  Post ReplyReply Direct Link To This Post Posted: 05 June 2020 at 10:06
Is there a way to remove one of the mounts on the adapter and maybe remove some shims below to make it shorter and thereby make the lens reach infinity?

My experience with K&F adapters (I have several) is that they're excellent quality and usually focus just a tiny bit beyond infinity, or in other words, they are a tiny bit too short.
Mind the bandwidth of others, don't link pictures larger then 1024 wide or 960 pix high, see here
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neilt3 View Drop Down
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Post Options Post Options   Quote neilt3 Quote  Post ReplyReply Direct Link To This Post Posted: 05 June 2020 at 10:34
For a 400 mm lens to be unable to focus at infinity , the adaptor must be a heck of a lot too long !
With a short lens , 28mm for example , a few shims too much and they behave like an extension tube , losing infinity focus .
The same amount on 400mm is barely noticeable , if at all .
Between some long lenses focusing beyond infinity and the adaptors usually being a fraction short ( to prevent these issues ), you shouldn't be having this problem .

It sounds to me like the lens has been apart for cleaning and one of the rear elements have been put back in the wrong way around .

Do you know anyone with a Nikon camera to test the lens on ?
I'm guessing taking the lens to a camera shop to try us out if the question ? ( Most of the world being closed !)
see my photostream on flickr;
http://www.flickr.com/photos/neilt3/
C & C welcome.
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stuartmayo56 View Drop Down
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Post Options Post Options   Quote stuartmayo56 Quote  Post ReplyReply Direct Link To This Post Posted: 05 June 2020 at 11:03
Ah good idea, I'll have a good luck and in the meantime I've decided to buy the Gobe adapter and see if that makes any difference.
Cheers
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stuartmayo56 View Drop Down
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Post Options Post Options   Quote stuartmayo56 Quote  Post ReplyReply Direct Link To This Post Posted: 05 June 2020 at 11:14
Thanks
Really! Disappointed as I can't find where I purchased the lens from (other than Facebook advert but the seller has disappeared).
I shone a light into the lens yesterday and there was a very slight patch of hazing on the lower elements towards the middle. I don't know anyone with a Nikon camera to try it on unfortunately.
I don't want to sell it to anyone blindly but after I paid £250 for it I don't want to be too much out of pocket especially as I bought it for an outdoor concert that was cancelled so only got to use it properly yesterday after buying it March of this year. I suppose I can wait until the camera shops are open again.
Cheers
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neilt3 View Drop Down
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Post Options Post Options   Quote neilt3 Quote  Post ReplyReply Direct Link To This Post Posted: 05 June 2020 at 11:50
Sounds like the seller knew what he had .
Especially as he's now dissapeared with your money .

I only buy from reputable shops , it off eBay with its buyer protection .

What's it's maximum focus distance ?
How far out is it ?


see my photostream on flickr;
http://www.flickr.com/photos/neilt3/
C & C welcome.
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addy landzaat View Drop Down
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Post Options Post Options   Quote addy landzaat Quote  Post ReplyReply Direct Link To This Post Posted: 05 June 2020 at 12:03
Wow, that is, well, hazy.

That was not cheap, but it depends on the version. Ffordes has a first generation A-mount Sigma 400/5.6 for 99 GBP. But a Telemacro version will be more expensive. (I know not everybody is a fan of Ffordes)

Rereading your post, it seems to be quite far off...
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nandbytes View Drop Down
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Post Options Post Options   Quote nandbytes Quote  Post ReplyReply Direct Link To This Post Posted: 05 June 2020 at 12:10
Originally posted by neilt3 neilt3 wrote:

For a 400 mm lens to be unable to focus at infinity , the adaptor must be a heck of a lot too long !
With a short lens , 28mm for example , a few shims too much and they behave like an extension tube , losing infinity focus .
The same amount on 400mm is barely noticeable , if at all .
Between some long lenses focusing beyond infinity and the adaptors usually being a fraction short ( to prevent these issues ), you shouldn't be having this problem .

It sounds to me like the lens has been apart for cleaning and one of the rear elements have been put back in the wrong way around .

Do you know anyone with a Nikon camera to test the lens on ?
I'm guessing taking the lens to a camera shop to try us out if the question ? ( Most of the world being closed !)


This is a very good point actually! scrap the trying another adapter idea.
my flickr
A7RIV
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