AF Nikkor 28-70mm f/3.5-4.5 flare

mmathu

Hi, I'm a new forum member.

I've tried some star photography over the past few months and am getting what I'd call a "flare" on some of the brighter star images at the periphery of my image. An example is here:
https://www.flickr.com/photos/mark_mathu/14703465134/sizes/o/
This exposure was ƒ/3.8, 38.9 mm, 30 seconds, ISO 250.
You can see the flare on some of the stars on the right side of the image – they look almost like a badminton birdie.

I'm using an AF Nikkor 28-70mm f/3.5-4.5 which I bought new about 20+ years ago with a Nikon D7000 body. I almost always keeps a Teffen Haze-1 filter over the lens which would be from the same vintage as the lens... so although I didn't keep specific notes I'm pretty sure it's been on the lens when I've taken the photos.

Any suggestions on how to reduce the problem? Is it just the old filter I'm using? Has the lens coating gone to hell? Is this just a shortcoming of that particular lens? I've never noticed this before, but then on the other hand I've not really tried much photography like this prior to getting my D7000.
____
Mark

PB_PM

Hi, welcome aboard.

First thing I'd do is take off the filter, as that can cause some flare. In addition, I think some of what you are seeing is motion blur, as all the stars are showing slight movement. That movement would be enhanced on the bigger brighter stars. It's also possible that some of the blur could be due the lens itself when used at F3.5, which could easily result in softness in the corners.

Golf007sd

Hi Mark, Welcome to NRF.

For astrophotography, you want to use a lens that has a large or constant aperture....ie. 2.8, 1.8, or 1.4. A wide angle prime lens would be perfect. In addition, I highly recommend removing any filter on the lens.

Please have a look at the following topics...they should provide addition answers to your question.

Request For Help With Night Sky Photography

Lens suggestion for night photography with a Nikon D7100

mmathu

Golf007sd: Thanks, I suspected the variable-focal length would be part of the problem. So this is to be expected/accepted for all variable-focal-length lenses?

I also have a prime Nikkor 50mm f/1.8 50mm lens (also about the same age) which didn't have such noticeable flares in recent night shots. I used the zoom lens for the shot because all my lenses are all vintage from 35mm era and so they are all a little narrower field of view than I'd prefer for DX format. The 28-70 is the widest-field lens I have.

I was from the 35mm film school of thought that you should keep a UV/haze filter on the lens at most times to protect the actual lens (I am an amateur, after all...) but have been considering dumping the filters for all my photography because:

1) UV filters don't improve rendering because digital cameras don't record blues and UV the way that film used to;

2) My lenses are getting old enough, I really don't have a lot of investment in the lens to protect, considering their age - I'd like to / wish I could get a VR lens or lenses for my digital body.

Agree, or disagree with those two assumptions?

mmathu

PB_PM: I'm aware that the 30-second shot would cause movement of the stars. But the "badminton-birdie-shaped" flares I'm referring to are around the periphery and biased towards the top and right side of the image.

mmathu

I should also have mentioned that I have a pretty simple circular rubber hood for the lens - not a flower-shaped hood. Not sure if the lens hood in conjunction with that particular lens would cause troubles under this specific lighting condition.

Golf007sd

So this is to be expected/accepted for all variable-focal-length lenses?

1) UV filters don't improve rendering because digital cameras don't record blues and UV the way that film used to;

2) My lenses are getting old enough, I really don't have a lot of investment in the lens to protect, considering their age - I'd like to / wish I could get a VR lens or lenses for my digital body.

Agree, or disagree with those two assumptions?

1) It is the aperture of the lens that is the key factor. So long at it is constant you are good. Two such lens come to mind: Nikon 14-24 2.8 & 24-70 2.8. The 14-24 is just amazing and you are welcome to look at the Nikon 14-23 Flikr user group for images of the sky. Keep in mind that these lens do come at a high price. For you D7000, should you consider getting a more modern lens, the Nikon DX 35 1.8 is the best bang for money. For wide angle, consider the Tokina 11-16 2.8.

2) Should you decide to get UV filters for your future lenses, get good ones...nothing cheep (i.e. Hoya, B&W etc.) They will help protect the front element of your lens; and the loss of light hitting the sensor is keep at a minimal.

3) VR is a nice feature to have; however I highly recommend using a tripod for shooting the sky. Should you have a lens that has VR, to turn it off. You do not want the elements inside the lens to move when shooting long exposure. Moreover, you want to shoot fully manual.

mmathu

Yes, I understand the limitations of VR when used with a tripod. I got my daughter a point & shoot Coolpix L830 a few month back and I've been impressed with the VR technology. I'd like to be able to get an extra stop or two out of either the shutter speed or aperture compared to what I can achieve with hand-held shots using my 20-year-old lenses.

IanG

1) It is the aperture of the lens that is the key factor. So long at it is constant you are good.

Why?

PB_PM

@IanG Lenses with consistent apertures tend to have better performance, because they are usually designed better than most variable aperture lenses. That is not always true, and in some cases it is just personal preference. In the case of @mmathu 's lens (AF 28-70mm f3.5-4.5) it is an old design, and not a great performer to start with.

IanG

OK - thanx

Symphotic

The birdie shaped things are not flare. That is a typical coma aberration with some astigmatic blurring.

The coma happens with even very good lenses. My Noct-Nikkor has it. If you want to get rid of it, I'm told the Zeiss OTUS has very little.

mmathu

@Symphotic:
"The birdie shaped things are not flare. That is a typical coma aberration with some astigmatic blurring."


Thanks!!! I tried a similar photo tonight with my prime 50 mm f/1.8 lens with no filter and got similar results. I looked at some info on coma aberration, and that certainly looks like the culprit. Short of getting a specialized lens, it sounds like stopping down the lens is my best approach to limit the aberration.

heartyfisher

The birdie shaped things are not flare. That is a typical coma aberration with some astigmatic blurring.

The coma happens with even very good lenses. My Noct-Nikkor has it. If you want to get rid of it, I'm told the Zeiss OTUS has very little.

You dont need the otus ! LOL .. for star and star trail photography(very specialised functionality) there are several well regarded lenses that are cheap and good. Check out the following lenses
Rokinon/Bower/Samyang 14mm f/2.8 (Full-Frame or APS-C)
Rokinon/Bower/Samyang 16mm f/2.0 (APS-C)
Rokinon/Bower/Samyang 24mm f/1.4 (Full-Frame or APS-C)
http://www.lonelyspeck.com/best-lenses-for-milky-way-photography-nikon/