which lenses dont have the hot spot with R72

[ifurlong]

somewhere I saw a list of which lenses do and dont have the 'hoy spot' when using a R72 infrared filter

[msvadi]

I've heard a theory that blooming - hot spot is caused by the light leaking through the viewfinder during long exposures and covering the viewfinder solves the problem. I have no idea if it's true. may be somebody who has the filter can check it.

[Guillermo Freige]

I've heard a theory that blooming - hot spot is caused by the light leaking through the viewfinder during long exposures and covering the viewfinder solves the problem. I have no idea if it's true. may be somebody who has the filter can check it.

It´s not. My S50 has the hot spot (and it doesn´t have a viewfinder connected to the sensor in any way) and the 18-55 kit lens has also the hot spot even when the viewfinder is covered. If fact if you don´t cover the viewfinder even during AE, the exposure is way wrong.

[msvadi]

thanks, good to know ;)

[where1]

I just tried this in my basement, (it is nighttime and raining, so outside is out of the question for now), under flourecent lighting at a 30 second exposure using a Hoya R72 filter. I had it mounted on my 85mm 1.8 lense. I had no hot spot with or without viewfinder covered. I had a light on behind the camera so there would be light shinning into the viewfinder.

I'm excited now, I just got a new DRebel tonight as a replacement for my broken one. The broken one had a real hotspot problem with the 85mm and the kit lenses, but I never tried it indoors. Tomorrow I will try some outdoor shots using a couple different lenses.

Note: I never tried the 50mm on the old camera.

[where1]

I tried several shots outside to day with the R72 filter at f5 at 2, 4, and 8 second shutter. I shot in manual mode, braketing 1 stop. I used a custom WB that I set before I started shooting.

The covering of the viewfinder made no difference to the hotspot, however it made a slight difference on exposure. I think if you aren't using the viewfinder, cover it.

The kit lense had a hotspot at 18mm but it lessened as it got longer. At 35 it seemed to disappear.

The 50mm showed no hotspot for me.

The 85mm showed a hotspot. It was so slight that it was almost gone at the 2 second exposure.

The hotspots I did encounter were very slight compared to the DRebel I was shooting with prior to yesterday. In fact, the prior camera was so bad, I had given up on IR. This will change for me now. :)

Note: Yesterday my DRebel broke again, but this time I couldn't get it working. I took it back to Best Buy and they exchanged the body and kit lense for me. :)

[Longwatcher]

I have eliminated the viewfinder as the problem of the hotspot (at least for me).

I have noted that the smaller the aperture (larger nuber) the less the hotspot shows up. Also using higher ISO (which results in faster shutter) cuts down on the hotspot. and angle to Sun seems to make a slight difference as in aiming away from the Sun good and right angles BAD. Right at sun during Sunset no hotspot (probably due to short shutter speeds).

Lastly I tend to notice the hotspot more on my better lenses (good thing I still have that 75-300 IS.)

Just my experience.