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Archive 2013 · Flare spot (hot spot) with Mamiya 120/4
  
 
JohnJ
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p.1 #1 · p.1 #1 · Flare spot (hot spot) with Mamiya 120/4


I've come across a few flare spots with various lenses. A pox on them. Found this flare spot with the Mamiya A 120/4, on a 5D2 with Mirex adapter. The flare spot, or hot spot, can bee seen fairly clearly in the gifs below. This might depend on magnification too. Note that this test was a high contrast scenario where the black subject is on a white background, a situation likely to provoke flare.

F4 and F32 only. The round spot in the centre of the F32 image is a flare spot.






This gif shows every aperture, F4 all the way to F32, and it can be seen that the flare spot is really only visible at F16 and smaller.






I use this lens all the time and have never noticed this although I tend not to stop it down very much.

Edited on Jan 12, 2013 at 12:31 PM · View previous versions



Jan 12, 2013 at 12:14 PM
mpmendenhall
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p.1 #2 · p.1 #2 · Flare spot (hot spot) with Mamiya 120/4


Can you avoid the hot spot by using the Mirex tilt to put the lens out of straight alignment with the sensor (e.g. set tilt so the smaller threads on the left and the knurling on the right are in focus at f4, before stopping down to get everything else reasonably focused)?


Jan 12, 2013 at 12:25 PM
JohnJ
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p.1 #3 · p.1 #3 · Flare spot (hot spot) with Mamiya 120/4


mpmendenhall wrote:
Can you avoid the hot spot by using the Mirex tilt to put the lens out of straight alignment with the sensor (e.g. set tilt so the smaller threads on the left and the knurling on the right are in focus at f4, before stopping down to get everything else reasonably focused)?


I don't know, but I'll try it.
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Edit.
This is with the lens tilted approx 5 degrees. I think it's essentially the same.








Jan 12, 2013 at 12:32 PM
dbehrens
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p.1 #4 · p.1 #4 · Flare spot (hot spot) with Mamiya 120/4


Bummer. All I can say is that my Mamiya A 120/4 on a Fotodiox Pro never experienced such flare. My only gripe is that I cannot get infinity focus with the Fotodiox Pro.
Dave



Jan 12, 2013 at 02:15 PM
jcolwell
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p.1 #5 · p.1 #5 · Flare spot (hot spot) with Mamiya 120/4


I haven't seen it either. Like Dave, I use my A 120/4 on a fixed Fotodiox Pro adapter. Also, I rarely use it with apertures smaller than f/11. I've taken many (very many) similar high contrast photos of lenses - I find it helps with sales. Most of those photos were taken with my Mamiya C 80/4N Macro and A 120/4 Macro.

I use 35/3.5N, 55/2.8N, 80/2.8N, and A 150/2.8 lenses on my Mirex. My 80/4N Macro, A 120/4 Macro, and A 200/2.8 APO lenses each have their own fixed Fotodiox Pro adapter, and rarely go on the Mirex. I use a Mamiya Auto Bellows N system for closeup/macro photos where I want movements.



Jan 12, 2013 at 03:04 PM
Toothwalker
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p.1 #6 · p.1 #6 · Flare spot (hot spot) with Mamiya 120/4


JohnJ wrote:
I use this lens all the time and have never noticed this although I tend not to stop it down very much.


Well, you noticed it now. Are these examples the entire image or a crop?
I presume you have no filter attached to the lens.



Jan 12, 2013 at 03:41 PM
jcolwell
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p.1 #7 · p.1 #7 · Flare spot (hot spot) with Mamiya 120/4


Dave, I just tested my A 120/4 Macro for infinity focus on a Fotodiox Pro adapter and a Jiaying adapter, and it was fine. It should be a simple task for somebody with the right skills to adjust the infinity focus stop for you. I have that sort of thing done at my local Camera Repair Centre. It probably cost about $30 last time I had one done.


Jan 12, 2013 at 04:13 PM
AhamB
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p.1 #8 · p.1 #8 · Flare spot (hot spot) with Mamiya 120/4


If you look carefully you'll see that it's reducing the contrast (and causing a green-cyan cast) at every aperture. It's just not conspicuous as a central spot unless you shoot something that's dark and plain in most of the center.

I know that the Tamron 90/2.5 macro version 52B has the same issue with a blue aperture spot at small apertures and that is was reportedly solved in the later 52BB version (the one with the plastic barrel).



Jan 12, 2013 at 05:46 PM
mcbroomf
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p.1 #9 · p.1 #9 · Flare spot (hot spot) with Mamiya 120/4


I believe this is internal flare caused because sensors are more reflective than film surfaces. Modern lenses have better coatings on the back lens surface to take care of this. The excellent Tamron Adaptall 2 SP 90/2.5 is well known for this, but also only at small apertures. I use it on Nex bodies and keep to F11 and wider and never see it.

Mike



Jan 12, 2013 at 05:50 PM
jcolwell
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p.1 #10 · p.1 #10 · Flare spot (hot spot) with Mamiya 120/4


AhamB wrote:
If you look carefully you'll see that it's reducing the contrast (and causing a green-cyan cast) at every aperture. It's just not conspicuous as a central spot unless you shoot something that's dark and plain in most of the center.

I know that the Tamron 90/2.5 macro version 52B has the same issue with a blue aperture spot at small apertures and that is was reportedly solved in the later 52BB version (the one with the plastic barrel).


Very interesting. By coincidence, a few hours ago I was reading the SP 90/2.5 description at Adaptall-2 (link below). This includes the comment " The model 52BB is merely a cosmetically redesigned version of the original 52B.".

I was just about to forward this info to the site, only to discover that Adaptall-2.org is a "rescued site", now hosted by MFLenses.com. The last update to teh Adaptall-2 site (aside from its copyright notoce) seems to be from 2007. Oh well.

OTOH, thanks Benjamin. I was considering putting a bid on a 52B version. Now I'll wait for a 52BB.

http://www.adaptall-2.org/lenses/52B.html



Jan 12, 2013 at 06:34 PM
 

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AhamB
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p.1 #11 · p.1 #11 · Flare spot (hot spot) with Mamiya 120/4


mcbroomf wrote:
I believe this is internal flare caused because sensors are more reflective than film surfaces. Modern lenses have better coatings on the back lens surface to take care of this. The excellent Tamron Adaptall 2 SP 90/2.5 is well known for this, but also only at small apertures. I use it on Nex bodies and keep to F11 and wider and never see it.

Mike


I remember reading that the rear element of the Tamron is nearly flat, which would the reason why the reflection off the sensor is reflected back onto itself again by the lens. I don't know if the 52BB version simply has improved coatings on the rear element or an actually differently shaped rear element. It would be interesting to find out.



Jan 12, 2013 at 07:02 PM
dbehrens
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p.1 #12 · p.1 #12 · Flare spot (hot spot) with Mamiya 120/4


jcolwell wrote:
Dave, I just tested my A 120/4 Macro for infinity focus on a Fotodiox Pro adapter and a Jiaying adapter, and it was fine. It should be a simple task for somebody with the right skills to adjust the infinity focus stop for you. I have that sort of thing done at my local Camera Repair Centre. It probably cost about $30 last time I had one done.


Hmmm - I think I'll do that! Thanks!



Jan 12, 2013 at 07:15 PM
RustyBug
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p.1 #13 · p.1 #13 · Flare spot (hot spot) with Mamiya 120/4


Before you "throw your baby out with the bathwater" ... I would look at the Mirex as a possible culprit as well.

I had an adapter that caused such an issue ... and sadly I sold a pristine 35/3.5 N because I didn't realize till later that my adapter was problematic source. Are you experiencing the same when using a different adapter than your Mirex?



Jan 12, 2013 at 07:36 PM
jcolwell
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p.1 #14 · p.1 #14 · Flare spot (hot spot) with Mamiya 120/4


Here's a few photos that I took to try and replicate the problem on (1) a Mirex adapter, and (2) a Fotodiox Pro adapter, with images at f/4 and f/32 for both cases. I used the A 120/4 Macro on my 5DII, with three indirect flash units (600EX, 2x580EX). The f/4 photos are at ISO 100 (Mirex), ISO 800 (Fotodiox, doh), and both f/32 are at ISO 3200. You can see an overall slight increase in reflected light for both f/32 examples, but there is no evidence of the central bright spot. Of course, there are so many variables that this is certainly not conclusive. I also tried some direct reflection images off the shiny inside surface of an EF lens cap, but saw no difference between apertures.

I'm pretty sure the increase in light for the example images at f/32 relatove to f/4 is because the flash units were firing at relatively high output for the f/32 photos. I could probably get more consistent illumination and use constant ISO with my strobes & softboxes, but most of that stuff is packed up right now.

For me, the largest apparent difference between f/4 and f/32 is the softening effect of diffraction at f/32.





A 120/4 Macro at f/4 on Mirex







A 120/4 Macro at f/32 on Mirex







A 120/4 Macro at f/4 on Fotodiox Pro







A 120/4 Macro at f/32 on Fotodiox Pro




Jan 12, 2013 at 09:19 PM
jcolwell
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p.1 #15 · p.1 #15 · Flare spot (hot spot) with Mamiya 120/4


JJ, what's the inside of your Mirex look like?

Mine's shown below, on the right, with the FotodioxPro on the left. You can see some reflection from the internal grooves on the Mirex, but it's not too bad considering the 600EX-RT is pointing straight at the Mirex.

Gotta go watch some football. Probably missed the kickoff, as usual.





Fotodiox Pro (left) and Mirex (right)




Jan 12, 2013 at 09:24 PM
JohnJ
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p.1 #16 · p.1 #16 · Flare spot (hot spot) with Mamiya 120/4


Toothwalker wrote:
Well, you noticed it now. Are these examples the entire image or a crop?
I presume you have no filter attached to the lens.


The images are not cropped, ie they are full frame. There are no filters in use. There is no hood in use either but the front lens is deeply recessed into the lens body so a hood might not make any difference. A good hood can help to reduce the effect of a flare spot. I know this because I use a Meopta Meogon which has a strong flare spot so I have to use a hood to minimise the effect.

AhamB wrote:
If you look carefully you'll see that it's reducing the contrast (and causing a green-cyan cast) at every aperture. It's just not conspicuous as a central spot unless you shoot something that's dark and plain in most of the center...


Yes, flare spots are just flare that is concentrated into a visible spot. At larger apertures they act as veiling glare so you tend not to notice them. All lenses have some flare.

RustyBug wrote:
Before you "throw your baby out with the bathwater" ... I would look at the Mirex as a possible culprit as well.

I had an adapter that caused such an issue ... and sadly I sold a pristine 35/3.5 N because I didn't realize till later that my adapter was problematic source. Are you experiencing the same when using a different adapter than your Mirex?


I don't have any other Mamiya/Canon adapters so I can't test this. If anyone in Melbourne (Aust) wants to lend me one then please PM me.

I wouldn't discount the possibility without actually testing it so I don't know if it is an adapter related issue. Previously when I've had flare from adapters (various adapters) it's acted as veiling glare rather than a flare spot. All I can do is guess and I would guess that it has more to do with the lens, high contrast and the reproduction ratio (it might not even happen at a different focus setting, I haven't tried it).



Jan 12, 2013 at 09:56 PM
JohnJ
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p.1 #17 · p.1 #17 · Flare spot (hot spot) with Mamiya 120/4


jcolwell wrote:
Here's a few photos that I took to try and replicate the problem on (1) a Mirex adapter, and (2) a Fotodiox Pro adapter, with images at f/4 and f/32 for both cases. I used the A 120/4 Macro on my 5DII, with three indirect flash units (600EX, 2x580EX). The f/4 photos are at ISO 100 (Mirex), ISO 800 (Fotodiox, doh), and both f/32 are at ISO 3200. You can see an overall slight increase in reflected light for both f/32 examples, but there is no evidence of the central bright spot. Of course, there are so many variables that
...Show more

Interesting. I agree that if there is a flare spot in your examples it's much less obvious. There is a highlight right in the centre of the images which might mask it some what, but still there's very little sense of a flare spot there.

jcolwell wrote:
JJ, what's the inside of your Mirex look like?

Mine's shown below, on the right, with the FotodioxPro on the left. You can see some reflection from the internal grooves on the Mirex, but it's not too bad considering the 600EX-RT is pointing straight at the Mirex.

Gotta go watch some football. Probably missed the kickoff, as usual.


My Mirex is the same.



Jan 12, 2013 at 10:07 PM
LightShow
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p.1 #18 · p.1 #18 · Flare spot (hot spot) with Mamiya 120/4


I would try some different settings(focus distance and light placement) to see if they have an effect on size or intensity.


Jan 12, 2013 at 11:08 PM
RustyBug
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p.1 #19 · p.1 #19 · Flare spot (hot spot) with Mamiya 120/4


Mine was definitely spot flare from internal reflection.

I was able to reduce it somewhat with some flocking material, but due to certain design issues, I couldn't get the flocking to contend with it fully. BTW ... mine was a shift capable adapter. I replaced it with my Fotodiox Pro ... no more issues (but no movements either).

Obviously the Mirex has its value in its movements ... wondering if there's any flare that might be kicking up off a "wear spot" that needs some touch up.



Jan 13, 2013 at 02:53 AM
LightShow
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p.1 #20 · p.1 #20 · Flare spot (hot spot) with Mamiya 120/4


I wonder if using a very flat black paint would help, it's like carbon from a candle's flame.
http://www.rangefinderforum.com/forums/showthread.php?t=73188



Jan 13, 2013 at 03:15 AM
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