Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
08-19-2013, 03:43 PM   #1
Forum Member
Mr_Radzins's Avatar

Join Date: Jul 2013
Location: Riga and Tukums
Posts: 67
Zoom lenses for shooting moon.

Hello guys!
It's a nice clear sky tonight in Guernsey and a full moon, so i tried to take some pics of it. Took out my Sigma 70-300mm and a manual Optomax 400mm f6.3 and went out. Sigma focused well on the moon and i could see it quite close, but of-course i understand 300mm isn't that much to see it really up-close. So i switched to the 400mm Optomax ( tried it really for first time now), and was pretty shocked ( if it's the right word? . All i saw was just a big white blurred spot in the viewfinder. Tried all range of aperture, no help. The lens itself is old, but looks like it was never used. So i am thinking now, can it be the problem of the lens focusing on infinity, or i might be doing something wrong? BTW it is a screw mount if it changes anything. Just wanted to hear any ideas from you guys. Thanks.

08-19-2013, 03:55 PM   #2
Site Supporter
boriscleto's Avatar

Join Date: Dec 2009
Location: Liverpool, NY
Photos: Gallery
Posts: 12,869
How are you attaching it to the camera? Are you using a T-ring?

T-mount - Wikipedia, the free encyclopedia
08-19-2013, 03:57 PM   #3
Pentaxian
Na Horuk's Avatar

Join Date: Feb 2012
Location: Slovenia, probably
Photos: Gallery | Albums
Posts: 10,863
Does the lens focus on something closer? What kind of adapter do you use? I assume its an m42 lens. Because some adapters prevent infinity focus. This holds for thick adapters and adapters with a flange. The genuine Pentax m42 adapter allows infinity focus, as do all other brand adapters of similar size.
If it has a flange or collar, then it probably won't allow infinity focus, but it should allow near focus. Though, with some lenses, that makes them virtually useless. Feel free to search the forum for threads about m42 adapters, as there have been many, some discussing bad adapters and others pointing out good cheap ones.

Another problem could be optical quality. For example, if the lens is flaring badly, if the optical elements are not aligned properly, if there is haze inside, etc.

The third type of problem is technique: if you are overexposing, using a shutter that is too long (because the moon moves surprisingly fast when you have a focal length like that), using a light tripod that doesnt steady the long lens, etc.

its probably the adapter
08-19-2013, 04:24 PM   #4
Pentaxian




Join Date: Jan 2011
Location: New York
Posts: 3,309
Try the 400mm lens in daylight. See if you can focus on something distant. If not, the adapter might not allow infinity focus or maybe the lens is broken. If you can reach focus, retry the moon.

08-19-2013, 04:25 PM   #5
Forum Member
Mr_Radzins's Avatar

Join Date: Jul 2013
Location: Riga and Tukums
Posts: 67
Original Poster
Well, the only thing written on the adapter is Pentax K/M, i am screwing it on and then attacing to the camera, there's definately no electric contacts on the adapter. Doesn't look like there would be any flange or anything.
And it's probably might not be a problem with the technique, cause i can't really see anything sharp in the viewfinder.
Yeah, and near focus with 400mm isn't realy useful, is it?
08-19-2013, 04:35 PM   #6
Pentaxian
Na Horuk's Avatar

Join Date: Feb 2012
Location: Slovenia, probably
Photos: Gallery | Albums
Posts: 10,863
Does your adapter look more like this one:
Pentax Mount Adapter K30120 B&H Photo Video

or like this one:

Dot Line Lens Mount Adapter for M42 to Pentax K BayonetDL-0620
08-19-2013, 04:45 PM   #7
Forum Member
Mr_Radzins's Avatar

Join Date: Jul 2013
Location: Riga and Tukums
Posts: 67
Original Poster
Here's the pic of it. I don't think it is really either of those, looks thicker to me. This adapter came with the lens.
Attached Images
 
08-19-2013, 04:58 PM   #8
Site Supporter
skunktail's Avatar

Join Date: Jan 2013
Location: Sydney, NSW
Photos: Gallery | Albums
Posts: 287
looks like a T mount adaptor

It may be a case of having to screw the lens in or out a bit to get the right registration distance
(I've had to do this with my telescope and T adaptor)

But then, I haven't seen the lens either.

08-19-2013, 05:10 PM   #9
Forum Member
Mr_Radzins's Avatar

Join Date: Jul 2013
Location: Riga and Tukums
Posts: 67
Original Poster
There it is...
Attached Images
 
08-19-2013, 05:37 PM   #10
Pentaxian
Bob from Aus's Avatar

Join Date: Jul 2011
Location: Australia
Photos: Gallery
Posts: 1,085
I have had trouble doing moon shots because my sigma 70-300 is crap at 300 and my sigma 50-500 is crap at infinity (so much for packing a tripod to get good moon shots in the desert.)

I have hand held my new sigma 500 at the moon in an urban area and got better photos.

I have found two things when trying to get moon photos
- the moon is really bright and the exposure required was a lot faster than I really thought it would be.
-I get much better photos of a half moon as there are shadows on the moon.

hope you get some good results.
08-19-2013, 06:20 PM   #11
Emperor and Senpai
VoiceOfReason's Avatar

Join Date: Jun 2010
Location: Nashville, IN
Posts: 5,416
I've found my Sigma 150-500 takes decent moon shots, but using a t mount adapter on my telescope it seems that the registration distance is off, and I can not get good focus unless I put a barlow on it, then it still looks soft and has CA like mad, but you can see what it is at least. perhaps that is your issue.
08-19-2013, 06:26 PM   #12
Site Supporter
Sandy Hancock's Avatar

Join Date: Feb 2012
Location: Adelaide Hills, South Australia
Photos: Gallery | Albums
Posts: 5,719
Get a Q. It's the bomb for moon shots. This was taken with a 300mm lens, so your Sigma should get you there.


Q Moon
08-20-2013, 01:30 AM   #13
Forum Member
Mr_Radzins's Avatar

Join Date: Jul 2013
Location: Riga and Tukums
Posts: 67
Original Poster
QuoteOriginally posted by VoiceOfReason Quote
I've found my Sigma 150-500 takes decent moon shots, but using a t mount adapter on my telescope it seems that the registration distance is off, and I can not get good focus unless I put a barlow on it, then it still looks soft and has CA like mad, but you can see what it is at least. perhaps that is your issue.
Yeah... English is not my native language, so i don't always understand slang or specific tech words.... VoiceOfReason, could you explain please what did you mean with "putting a barlow on it"? As funny it might sound, but the only translation i found on the web is "big foldable pocket knife". I guess it is not what you meant, right?
08-20-2013, 05:10 AM   #14
Emperor and Senpai
VoiceOfReason's Avatar

Join Date: Jun 2010
Location: Nashville, IN
Posts: 5,416
QuoteOriginally posted by Mr_Radzins Quote
Yeah... English is not my native language, so i don't always understand slang or specific tech words.... VoiceOfReason, could you explain please what did you mean with "putting a barlow on it"? As funny it might sound, but the only translation i found on the web is "big foldable pocket knife". I guess it is not what you meant, right?
Ahh, here's an article on wikipedia explaining what a barlow is http://en.wikipedia.org/wiki/Barlow_lens.

Of course a big knife mounted to a lens would allow you to use your camera to hack through the underbrush, then have it at the ready for that wildlife, and for street photography in a bad area/ Well, let's just say the camera wouldn't get stolen!

Last edited by VoiceOfReason; 08-20-2013 at 05:42 AM.
08-20-2013, 05:20 AM   #15
Senior Member




Join Date: Aug 2012
Location: Doylestown, PA
Posts: 200
I've experienced this exact same problem myself, with a Vivitar branded 400mm lens.

The problem is you're using a T-mount adapter, but it's actually an M42 lens. M42 and T use the same thread (so you can physically screw them in to either one), but the T-mount is much thicker. An m42 adapter should be very thin.

The T-mount adapter basically acts as a tiny extension tube for an m42 lens, which shortens the minimum focus distance, but you lose infinity.

BH has m42 adapters for about $30. eBay has cheap chinese ones for around $5.
Reply

Bookmarks
  • Submit Thread to Facebook Facebook
  • Submit Thread to Twitter Twitter
  • Submit Thread to Digg Digg
Tags - Make this thread easier to find by adding keywords to it!
400mm, guys, k-mount, lens, moon, optomax, pentax lens, sigma, slr lens
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
Shooting the moon Tako Kichi Photographic Technique 35 04-14-2014 06:24 AM
Help me decide: which QUIET zoom lens for everyday shooting? yellowbrick Pentax SLR Lens Discussion 25 06-03-2013 09:39 PM
Night Shooting for the Moon eaglem Post Your Photos! 2 09-21-2010 11:50 PM
Wide angle zoom for night shooting. hahifuheho Pentax SLR Lens Discussion 10 04-20-2009 12:54 PM
Shooting for the moon knumbnutz Post Your Photos! 12 04-22-2008 05:05 AM



All times are GMT -7. The time now is 10:23 AM. | See also: NikonForums.com, CanonForums.com part of our network of photo forums!
  • Red (Default)
  • Green
  • Gray
  • Dark
  • Dark Yellow
  • Dark Blue
  • Old Red
  • Old Green
  • Old Gray
  • Dial-Up Style
Hello! It's great to see you back on the forum! Have you considered joining the community?
register
Creating a FREE ACCOUNT takes under a minute, removes ads, and lets you post! [Dismiss]
Top