nice photos (linked), good contrast and sharpness, I like it way more then Minolta glass, impressed with your speedbooster pics so far... still thinking about it due to the blue spot issueboardsy wrote:
your examples look good - my Canon FDn lenses are pretty good to the edges on the Zhongyi Lens Turbo e.g. 50/1.4:
But I will probably get a Speedbooster/LT for my Minolta lenses, as they have nicer bokeh and also will gain more from the Speedbooster sharpness boost.
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Regards,
Alan
my Flickr
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85€ Speedbooster NEX-Minolta MD
- Thread starter chkugler
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Between f5.6 and f8. And it happens at larger apertures against bright skies. But no "masochistic intent" that you spoke of, or anything to puzzle Chinese vendors - just regular shots against bright skies, and reflective water "helps".Tom Caldwell wrote:
Alanboardsy wrote:
I haven't tried to get blue dots out of some masochistic perversion; I take regular photos with FD lenses with the Zhongyi LT at regular apertures and it shows up regularly:
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Regards,
Alan
my Flickrl
Seems classic blue dot country - dark around the trees and an hyper-reflective white sky as background. Were you using the third blue dot troika - a small aperture?
It happens.
Well, every lens can have a different rear element distance?
Haha - everything in photography is a compromise of some sort!
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Regards,
Alan
my Flickr
Er, mine's bigger, softer and less naked than yours? :-|Larnus wrote:
I'm Jealous - my dot is a lot smaller and a lot clearer - plus distinctly hexagonal.boardsy wrote:
I haven't tried to get blue dots out of some masochistic perversion; I take regular photos with FD lenses with the Zhongyi LT at regular apertures and it shows up regularly:
--
Regards,
Alan
my Flickr
But mine's without a focal reducer and just bare naked lens.
--
Regards,
Alan
my Flickr
Thanks - and the sharp edges were the biggest surprise for me, these FDs are even more impressive now! I think Minolta lenses have nicer bokeh and are marginally less less sharp than FD, so I'd like to try them out on the LT for the combined sharpness boost and more OOF visible.proxy wrote:
nice photos (linked), good contrast and sharpness, I like it way more then Minolta glass, impressed with your speedbooster pics so far... still thinking about it due to the blue spot issueboardsy wrote:
your examples look good - my Canon FDn lenses are pretty good to the edges on the Zhongyi Lens Turbo e.g. 50/1.4:
But I will probably get a Speedbooster/LT for my Minolta lenses, as they have nicer bokeh and also will gain more from the Speedbooster sharpness boost.
--
Regards,
Alan
my Flickr
The blue spot is real, but you have to shoot against a bright sky, and water helps too. In my example above there's no trace of it.
--
Regards,
Alan
my Flickr
What I meant was that there is a fixed distance between the mount and the first element of the focal reducer block. But there could be 1001 areas where a problem could arise. The published lens diagram for the Smart Adapter and the lens diagram associated with Zhongyi publicity are quite distinctly different. There seems little if any similarity. No cloning going on here, seems original research which must need a bit more work yet,
Ah hah! Focal reducer enhanced and a stop faster too boot. I am jealous as well. Unfortunately my only experience was a contrived one and fairly ugly at that.Larnus wrote:
I'm Jealous - my dot is a lot smaller and a lot clearer - plus distinctly hexagonal.boardsy wrote:
I haven't tried to get blue dots out of some masochistic perversion; I take regular photos with FD lenses with the Zhongyi LT at regular apertures and it shows up regularly:
--
Regards,
Alan
my Flickr
But mine's without a focal reducer and just bare naked lens.
So are we looking at specific lenses that are causing a problem?
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Tom Caldwell
zygh
Senior Member
I suspect the blue spot issue on the Mitakon adapter is due to the coating. Seems like this new adapter does not have those issue. Might just get me one of these adapters.
Thanks for posting the example shots!
Any idea who makes this adapter?
Thanks for posting the example shots!
Any idea who makes this adapter?
The unbranded focal reducer adapters are a revised design and all made by RJ Shanghai (Jinfinance) and are resold by many resellers in Hong Kong.
To quote from "Camera Lenses, from Box Camera to Digital" by Gregory Hallock Smith page 42:
"But even multi-coated surfaces, introduced in the 1970's, reflect some light. Most bothersome are the resulting ghost images of bright light sources, such as light bulbs or the sun, located in or near the field of view. These ghosts look like concentrated spots or blobs. The more nearly focused these blobs are, the smaller and brighter they appear."
I am not a lens expert and cannot even comment on whether this applies to the blue spots on issue. But it does sound more like what is commonly known as lens flare.
It was also mentioned that it could be a lens exit pupil reflection.
However these might be possible causes without suggesting a solution. It seems that some users are bothered by having more blue spot problems than others, this might even possibly relate to different combinations of lens used + focal reducer adapter.
zygh
Senior Member
Thanks for clearing that out for me, Tom.
RussellInCincinnati
Senior Member
Roxsen wrote back promptly explaining that their Minolta MD speed reducer weighs around 150 grams.
I have been reading a bit more - nothing like a dumb cluck trying to understand book full of "big words". I will try and get my head around it. However I now think that the above quote is just an explanation on the effect of "normal" lens flare. The blue spot issue must be something else and if it has a proper technical name then there is a chance that it can be properly sorted out.
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Tom Caldwell
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I have been trying to get to the bottom of the issue of the blue spot in my own amateurish way.
There are various types of chromatic aberrations but they all seem to improve when stopping down, The blue spot in question here seems to get worse when the lens is at minimum aperture.
This link on Flickr comments directly on Nikon lenses that have a problem with a blue spot without a focal reducer and it seems eerily similar to the blue spot that bedevils some when using focal reducer adapters. It also hints at a reasoning for the problem.
www.flickr.com
Not that this is "blame Nikon" but I wonder if some lens/focal-reducer combinations generate a similar situation more than others. This might explain why some are more plagued with the problem than others.
In the explanation of Axial (Longitudinal) Chromatic Aberration on the "cambrideincolour" site tutorial it is stated "worse with light sources at night, stars and direct reflection off water." But I am still not sure that what is seen is really "Longitudinal Chromatic Aberration" - especially when it is reliably and constantly stated as reducing when the lens is stopped down.
I also see frequent references to built in corrections for a broad range of camera/lens combinations built into popular raw conversion software. Also a specific reference to the problem "Axial Chromatic Aberration" on the Nikon (again - sorry) Europe customer help site. But of course the problem discussed here does not seem to be Axial (Longitudinal) Chromatic Aberration but something more like the problem discussed on the linked site where Nikon lenses are discussed in particuler.
There are various types of chromatic aberrations but they all seem to improve when stopping down, The blue spot in question here seems to get worse when the lens is at minimum aperture.
This link on Flickr comments directly on Nikon lenses that have a problem with a blue spot without a focal reducer and it seems eerily similar to the blue spot that bedevils some when using focal reducer adapters. It also hints at a reasoning for the problem.
No metering lenses on Nikon DSLRs
This is a group for people using old Nikkor, Nikon or other brand lenses on modern Nikon DSLR's. There is a difference between using the manual focus lenses and the non metering ones. No metering means that you have to set aperture on your lens and adjust shutter speed on your camera to create a...
www.flickr.com
Not that this is "blame Nikon" but I wonder if some lens/focal-reducer combinations generate a similar situation more than others. This might explain why some are more plagued with the problem than others.
In the explanation of Axial (Longitudinal) Chromatic Aberration on the "cambrideincolour" site tutorial it is stated "worse with light sources at night, stars and direct reflection off water." But I am still not sure that what is seen is really "Longitudinal Chromatic Aberration" - especially when it is reliably and constantly stated as reducing when the lens is stopped down.
I also see frequent references to built in corrections for a broad range of camera/lens combinations built into popular raw conversion software. Also a specific reference to the problem "Axial Chromatic Aberration" on the Nikon (again - sorry) Europe customer help site. But of course the problem discussed here does not seem to be Axial (Longitudinal) Chromatic Aberration but something more like the problem discussed on the linked site where Nikon lenses are discussed in particuler.
Tom,
The Tamron SP 90mm f/2.5 adaptall macro exhibits a central spot issue which becomes more distinct as the lens is stopped down. (link to one such report)
The explanation of the cause usually involves a reflection of the aperture somehow bounces off the reflective sensor surface onto the very flat rear element of the lens and then back to the sensor. I don't understand how this all works.
The Nikon AIs 50mm f/1.4 is also reported to have this "hot spot" in the flicker link you gave and that is also the lens that Brian Caldwell used in this post where he compared it with a Speed Booster and a Jinfinance focal reducer. You will remember there was a blue spot with the Jinfinance focal reducer and not with the Speed Booster.
It seems strange that the use of a focal reducer sometimes brings on the "blue spot" and other times it may minimize (or even eliminate) it from a lens known to have the issue.
I have the Tamron SP 90mm f/2.5 macro and never noticed the blue spot issue with film usage or in the very limited usage it has seen on digital.
The Tamron SP 90mm f/2.5 adaptall macro exhibits a central spot issue which becomes more distinct as the lens is stopped down. (link to one such report)
The explanation of the cause usually involves a reflection of the aperture somehow bounces off the reflective sensor surface onto the very flat rear element of the lens and then back to the sensor. I don't understand how this all works.
The Nikon AIs 50mm f/1.4 is also reported to have this "hot spot" in the flicker link you gave and that is also the lens that Brian Caldwell used in this post where he compared it with a Speed Booster and a Jinfinance focal reducer. You will remember there was a blue spot with the Jinfinance focal reducer and not with the Speed Booster.
It seems strange that the use of a focal reducer sometimes brings on the "blue spot" and other times it may minimize (or even eliminate) it from a lens known to have the issue.
I have the Tamron SP 90mm f/2.5 macro and never noticed the blue spot issue with film usage or in the very limited usage it has seen on digital.
- John
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