Home

Please support mflenses.com if you need any graphic related work order it from us, click on above banner to order!
SearchSearch MemberlistMemberlist RegisterRegister ProfileProfile Log in to check your private messagesLog in to check your private messages Log inLog in

Hot spot with Meogon 80/2.8
Post new topic   Reply to topic
Home   Manual Focus Lenses
View previous topic :: View next topic  


PostPosted: Wed Apr 11, 2012 2:43 pm    Post subject: Hot spot with Meogon 80/2.8 Reply with quote
The IR guys are used to this kind of thing but it's probably not very common with visible spectrum lenses. This is a Meogon 80/2.8 enlarging lens on a helicoid.

For comparison, the same adapter/helicoid was used with a very similar (but different) lens and there was no hot spot.

JJ

Last edited by jjphoto on Sat Mar 30, 2013 10:38 am; edited 1 time in total


PostPosted: Wed Apr 11, 2012 2:57 pm    Post subject: Reply with quote
Is that the difference in lens coating - or lack of coating ?


PostPosted: Wed Apr 11, 2012 4:11 pm    Post subject: Reply with quote
Tamron SP 90mm f/2.5 both models 52B 52BB can also produce hot spot on some dSLR. Theoretically, the relatively flat rear lens element reflects the shiny sensor. In my experience, a bright central hot spot can show on crop Canon XT, but is not as visible on full frame Canon 5D. On full frame the hot spot is much bigger; is more diffuse; it visibly reduces contrast. Using a hood helps sometimes. Worst with bright light source in frame.

The rear element is very flat! (from Tamron sales paper 905EC309B):




PostPosted: Wed Apr 11, 2012 9:47 pm    Post subject: Reply with quote
Lloydy wrote:
Is that the difference in lens coating - or lack of coating ?


No. Both lenses are coated, although they are also both enlarging lenses so are designed for a different applicaction, light path.

JJ


PostPosted: Wed Apr 11, 2012 9:51 pm    Post subject: Reply with quote
visualopsins wrote:
Tamron SP 90mm f/2.5 both models 52B 52BB can also produce hot spot on some dSLR. Theoretically, the relatively flat rear lens element reflects the shiny sensor. In my experience, a bright central hot spot can show on crop Canon XT, but is not as visible on full frame Canon 5D. On full frame the hot spot is much bigger; is more diffuse; it visibly reduces contrast. Using a hood helps sometimes. Worst with bright light source in frame.

The rear element is very flat! (from Tamron sales paper 905EC309B):
...


Thanks. I think I need to experiment a bit more to see what other factors contribute to the hot spot.

JJ
Post new topic   Reply to topic
Home   Manual Focus Lenses
Page 1 of 1